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Main forestry products are timber and pulpwood, but residues from forestry, such as tops, branches and stumps can be harvested for energy purposes. Currently, the major part of the harvested residues is used in heat plants and combined heat and power plants. However, forest residues also have a large potential as a feedstock to produce biofuels. By gasification and further treatment residues can be used to produce e.g. methanol, ethanol, DME, hydrogen, Fischer-Tropsch  diesel and substitute natural gas (SNG). By pre-treatment and fermentation,  forest residues can be utilised for ethanol production. Another potential lies in the different high-value products that can be co-produced when forest residues are utilized in so called biorefineries.

Forest management

IIn Sweden, the productive forest area is around 22 million hectares. The dominating forest type is conifer (spruce and pine), but also broadleaved and mixed forest types are common. A rotation period can vary from 50 years in southern Sweden to over 100 years in the north. Common practice is to plant seedlings, however natural sowing from seed trees can also be used. Thinning is done to concentrate the growth to fewer trees in order to achieve better timber quality. There is a large energy potential in collecting forest residues from thinning, even though this is not currently done in any considerable scale in Sweden, mainly due to practical problems of transporting the trees out of the forest without damaging the remaining trees. Final felling is in Sweden often done as clear-cutting.

Tops and branches

Tops and branches is the part of the biomass left in the forest after final felling. The tops of the trees are cut, since this part is too small to be used as timber or pulpwood. Tops and branches make up about 15-20% of the mass of the whole tree. During the felling, tops and branches are put in stacks, along with the timber and pulpwood. The stacks of tops and branches are left in the clearing to dry for a period of time and for the needles to fall off, since needles make a good forest nutrient. The semi-dried tops and branches are then taken out of the forest to be stored in windrows alongside the nearest road, before transport to user.

There are many different operational and logistic management options for handling of tops and branches. The residues are bulky; therefore they can be chipped in the forest with mobile chipping equipment before transportation, so that trucks can be effectively loaded. The bulky residues can also be transported to a central chipping facility, before the residues are distributed to heat plants. Storing of chipped wood can be problematic as it leads to dry matter losses. It also leads to heat development and risk for selfignition. Storing wet wood chip can lead to molding, with risks of spreading spores that are unhealthy to inhale. Therefore longtime storage of wood chips is rarely recommended. This requires a balance between supply and demand, which is a logistical challenge.

Stumps

At present almost all stumps are left in the forest after final felling in Sweden. With about 15-20% of the whole tree’s energy contained in the stump, there is a large potential in using stumps for bioenergy. The Swedish research on stump harvesting and its consequences looks to e.g. Finland for experiences, where stump harvesting has already been in commercial operation for some time.

Stump harvesting can be done using an excavator with a harvesting head. There are two main type of harvesting heads, shearing or refractive heads. The shear head has a forked part, which is pressed against a wedge in order to split the stump before lifting. Each piece of the stump then has to be lifted individually.

A refractive head has prongs that are pressed under the stump and pulling it up until it comes loose. The stumps are generally  contaminated with stones, sand etc, of which as much as possible needs to be shaken off before the stumps are hauled to a windrow at roadside. From roadside, stumps can either be crushed at site with mobile crushing equipment or transported to a terminal for  crushing. Crushing on site dramatically increases the pay load on each truck. After crushing, whether on site or at terminal, the stump fuel can be run through a drum sieve, to remove as much contaminants as possible, lowering the ash content to below 5%.

Current production and potential

In 2010, residues from forestry in Sweden contributed with about 14 TWh of energy, with only a small part of this deriving from stumps. The residues are mainly used for heat and electricity production; there is currently no commercial production of biofuels from forest residues in Sweden. It is difficult to obtain statistics on how many hectares the residues are collected from, which can be explained by the reporting routines. The forest owners are only obliged to report the intention to take out residues after final felling, but this intention is not always followed through. During 2010, 155 000 hectares of forest was reported as intended for harvesting of tops and branches, and about 7 600 hectares for harvesting of stumps.

The energy potential in residues from forestry is large, and the total theoretical potential, no restrictions applied, is calculated to 141 TWh annually. But for different reasons not all residues can be collected. For example harvesting should not at all be done on wetlands or steep grounds, stumps cannot be harvested during thinning, and a certain amount of the residues needs to left in the forest for ecological reasons, especially in broadleaved forests. Including these restrictions, there is an estimated total potential of 16 TWh per year in tops and branches, and 21 TWh in stumps for residues after final felling. Including residues from thinning will increase the potential, but removing residues from thinning is connected with practical and economic difficulties.

Energy crops are crops produced with the objective to be used in the energy system. The energy crops presented here are not suitable as food. They include the species willow, reed canary-grass, poplar and aspen. These crops can be used to produce a variety of biofuels using different processes. By gasification and further treatment they can be used to produce e.g. methanol, DME, hydrogengas, Fischer-Tropsch diesel and substitute natural gas (SNG). By fermentation they can be used to produce ethanol, and by anaerobic digestion to produce biogas, although some pre-treatment is be required.

Willow

The genus Salix includes a large amount of species and is found wild in all  continents except Australia. In Sweden a few species have been selected for breeding programs to form new varieties suitable for growing in different climates. Energy willow can be grown up to the southern parts of northern Sweden. It needs nutrient rich soil with a pH above 6 and a good supply of water and light to grow well. Clay soils to fine sand soils are appropriate.

After preparation of soil, planting is done from cuttings, and is performed from end of April to middle of June. About 13 000 cuttings per hectare are planted in rows, with more space between every second row to facilitate harvesting. Weed control is very important during the establishment since the weeds compete with the willow plants for light, water and nutrients. Both mechanical and chemical weed killing is needed during the planting year. In Sweden, about 11 580 hectares willow was cultivated in 2010.

Use of fertilizers, mainly nitrogen, increase growth significantly. Ideally fertilizing should be done every year, but due to practical problem it is mainly done the first and second year in each rotation, when the plants are small enough to give access for the spreader. In soils with low pH lime or ash can be applied.

Harvesting is done during winter every 3-5 years. It is time for harvest when the biggest stems are 7-10 cm in diameter at the base. The output is 20-25 dry tonnes/hectare during first harvest and 30-35 dry tonnes/hectare onwards. Common harvesting systems include direct chipping at harvest and harvesting of whole stems. The economic lifetime of a plantation is 20-25 years.

Reed canary-grass

Reed canary-grass is a perennial grass that grows wild in wetlands in most of the northern hemisphere and can be grown in all parts of Sweden, even in the north. It can be grown in most kinds of soils, but grows best in wet soils with high organic matter content. When grown in bog soils, spreading of lime or ash may be needed to increase the pH value. Different kinds of soils give the grass different properties. For example the ash content in the grass is higher when grown in clay soils. In 2010, about 800 hectares of reed canary-grass were cultivated in Sweden.

Preparation of the land includes ploughing and weed killing before sowing. Weed killing during the first year of growth may also be necessary. Sowing is done in early spring for the grass to establish properly before autumn.

Harvesting is done either in spring or autumn. The first harvest is done in the second year, and then every year onwards. The outputis 4-6 dry tonnes/hectare. Harvesting in the spring gives a brittle grass with low moisture content, and no further drying is needed. The amount of potassium, chlorine, phosphorus and nitrogen is also lower in the spring, resulting in lower ash content and higher ash melting point. Harvesting in the autumn gives a higher yield, but the moisture content is also higher, this would e.g. be more appropriate for biogas production.

The need for fertilizing is largest the first two years. Autumn harvesting removes a lot of nutrients together with the grass while if the harvesting is done in the spring, most of the nutrients are in the roots and are left on the field. Therefore less fertilizing is needed if a system with spring harvesting is used.

Hybrid aspen and poplar

The genus Populus includes about 30 species and grows wild in most of the northern hemisphere. They are commercially interesting since they grow fast and can reproduce from cuttings. As energy crops, different kinds of hybrid varieties are used. They grow best on farmland or fertile forest land, in soils with a pH between 5.5 and 7.5. Nutrient rich light clay soils are suitable. Locations that are frost exposed during the establishment period should be avoided and there need to be a good supply of water.

Preparation of the soil includes loosening to allow the roots to grow deeper, and weed killing. Weeds can compete with the plants and reduce growth but also constitute a favourable environment for voles, which can cause significant damage to the plants. Especially aspen is also very popular to deer, and fencing is often necessary.

Planting is made from rooted cuttings in May or June. The amount of plants and the management during the growing  period is determined by the intended use of the biomass (energy, pulp and/or timber). Suggested rotation time for energy use is 15-25 years and felling is done with traditional forestry techniques. Growth is 7-9 dry tonnes/hectare and year.

After felling, shoots develop in large amounts, which can be used to establish a second generation plantation, either by keeping all the shoots and after a few years harvest, similar to a willow plantation, or by continuous thinning to establish a new plantation with sparser stems. The latter however is very labour intensive. Another alternative is to pull the stumps and make a new planting with rooted cuttings. However, experience of poplar and aspen growing in Sweden is limited and more research is needed. About 490 hectares poplar and 240 hectares aspen were cultivated in Sweden during 2010.

Residues from agriculture include a variety of products, such as straw from cereal and  oilseed cultivation, tops from potato and sugar beet cultivation, and manure from livestock keeping. All of these can be used for biofuel production in different ways. Using residues is a way of increasing energy production from agriculture without competing with food production.

Straw

Straw is the stalks from cereal or oil plants. Straw can be harvested or left in the field for different reasons: because there is no demand for it, to maintain soil quality, or because the weather or time does not allow for collection. The straw harvested in Sweden is mainly used as bedding material and feedstuff for animals, but the excess straw could be used for energy purposes. Fuel qualityfor different types of straw vary and wheat straw is commonly considered as suitable due to e.g. high yields and low content ofash. The content of alkali metals and chlorine can be reduced if the straw is left in the field and exposed to rain before harvesting.

Harvesting of cereal is done with a harvesting combine that cuts the plants and feed them into a thresher where grains are separated from the straw. The straw is then placed in rows on the field for collection. The straw yield varies with respect to species and stubble height, but is generally in the range of 1-5 tonnes dry matter/hectare.

There are many systems to collect and store straw. Capacity is always important when collecting straw, due to economic and time constrain reasons. The straw can be pressed into square or round bales, with square bales usually having a higher density and also being easier to transport and store because of their shape. Another method for collection is to load chopped straw directly onto a collecting trailer. The expenses for baling can then be avoided, but chopped straw has low density, making transportation and storage expensive.

When straw that is not dry enough is stored, it can lead to molding and spores can spread that could cause health problems such as lung disease. It also leads to dry matter losses, heat development and risk of self-ignition. The straw can hold sufficiently low moisture content at point of collection, but the moisture content is very weather dependent.

Potato and sugar beet tops

Tops that remain from cultivation of potato and sugar beet is currently a non-utilized feedstock with potential for harvesting asfeedstock for anaerobic digestion.

In potato cultivation the tops are terminated about three weeks prior to harvest, to prevent mold contaminated green tops to cause damage to the potatoes, and to make the harvesting easier. In conventional farming this is done by spraying the tops with herbicides, and in organic farming it is done mechanically by breaking or burning of the tops. In most cases, the tops are left on the field. There is no standard collecting method yet developed. However, there is ongoing research, including development of a front mounted stem shredder, a side mounted elevator and a collecting trailer. Harvest is estimated to vary between 1-4 tonnes dry matter/hectare.

In sugar beet cultivation the tops are generally left on the field, but can be collected during the harvest. Many beet harvesting machines can separate the tops from the beet, and by using an elevator they can be collected in a trailer. The harvest of beet tops varies between 3-8 tonnes dry matter/hectare. However, removing tops from the field also removes nutrients. This could be compensated for by returning sludge from the anaerobic digestion to the field.

Manure

Manure is the feces and urine from livestock. There is a distinction between liquid manure with a low content of dry matter, and solid manure with a higher content of dry matter that is mixed with bedding materials like straw and feeding residues. In principal all manure in Sweden is used as a fertilizer on farmland.

Storing of manure leads to emissions of methane as the organic matter decomposes. Therefore, manure is a good substrate for anaerobic digestion as this method avoids emissions of methane to the atmosphere, and at the same time allows for energy production. However, manure often needs to be co-digested with other substrates as the methane yield is rather low.

Current production and potential

The estimated total amount of straw available on Swedish fields corresponds to an energy potential of about 27 TWh per year. Dueto weather conditions and time constraints during harvest season it is not possible to harvest all of it. Some straw also has to be leftin the field in order to maintain soil quality, and some is needed as bedding material for livestock. This taken into account, the potentialfor use of straw for energy purposes in Sweden is estimated to around 4 TWh per year. Another 5 TWh is harvested as beddingmaterial in livestock keeping, from which a large share will end up as manure that can also be used for energy purposes.

The annual potential for tops is estimated to about 0.4 TWh from potatoes and 1 TWh from sugar beets.

The current Swedish livestock population produces manure with an energy potential of approximately 14 TWh per year. This also includes the manure that ends up on pasture land during grazing season. Studies of biogas potential from collected manure range between 4-6 TWh per year, depending on assumed biogas yield, number of animals, amount of manure and grazing period. The total production of biogas from manure was about 210 GWh in 2012, of which 145 GWh was upgraded to vehicle gas.

Bioethanol is the most commonly used biofuel for transportation. It can be produced from many different raw materials and through different production processes. Today, mainly technologically conventional methods are used, such as fermentation from sugar- and starch-based feedstock. Production of so called second generation, or advanced, bioethanol utilizes methods developed to make use of lignocellulosic types of  biomass, e.g. residues from the forestry and agriculture sector and waste material.

Primary area of use

Bioethanol and synthetic ethanol are chemically the same molecule, and therefore identical from a usage perspective. Low blending of ethanol into vehicle fuel was introduced as an oxygen agent to reduce CO2 emissions. The usage is spread and extensive around the world, mainly as low blending in gasoline. Ethanol can be mixed with gasoline in different properties. Today, blends up to E25 are marketed and used in conventional cars, meaning that 25% of the volume is ethanol. In Europe as well as in many countries around the world, E5 to E10 are the most commonly used blends. In the U.S. most of the gasoline is E10, with E15 lately being introduced to increase the ethanol use. In Brazil E20 to E25 is used in all gasoline.

Ethanol is also used in flexi fuel cars that can run on any mixture from pure gasoline up to E95, i.e. ethanol with 5% water. This market is so far most developed in Brazil, U.S., and Sweden. In Brazil, 90% of new car sales are flexi fuel. A similar trend can be seen in the U.S., however not on the same level. In Europe, the development has been slower. The extra cost for the flexi fuel technology in a car is less than € 100 compared to a normal gasoline car. If the car manufacturer chooses to charge the extra cost depends on the  current situation for competition.

For heavy vehicles, a slightly modified diesel engine with compression ignition can use ED95, an ethanol fuel with 5% water and addition of 3-5% ignition improver.

The suitability and flexibility of ethanol for transportation is good compared to gasoline and diesel of today. The thermal efficiency of ethanol when used in gasoline engines (Otto-engines) is higher than for pure gasoline, especially if the high octane number is utilized in the design of the engine. However, the energy content per liter is 34% lower in ethanol than in gasoline. When ethanol is used as E5 these effects equals out and the ethanol substitutes the same volume of gasoline. For higher ethanol blends, the fuel volume increases, leading to shorter driving range with the same tank size. In the diesel engine, ED95 has the same thermal efficiency as diesel, which means 20–30% higher than an Ottoengine.

Feedstock and production

Ethanol can be produced from almost all types of biomass. Today’s commercial plants use sugar and starch rich biomass like sugarcane, sugar beet, corn, wheat, and other grains. The process used for production of ethanol is fermentation of sugars. For grains, an enzyme hydrolysis of the starch is needed. Cellulose biomass needs a pre-treatment step to open up the structure before enzymatic hydrolysis and fermentation of the formed sugars can be performed.

Another route to produce ethanol is by gasification of biomass to carbon oxide and hydrogen. The gas is catalytically reformed or biochemically transformed to ethanol. In the US there are some ongoing demonstration projects with this technology.

Current production volumes

Ethanol is the most commonly used biofuel today, and in terms of volume it counts for about 90% of global consumption. The global ethanol production in 2013 was approximately 23 429 Millions of US Gallons, with the US as the largest producer.

Production and use of ethanol has during the last decade increased drastically, but due to the world finance crises and a massive media blackening, it has leveled.

Distribution system

The distribution of E5 to E25 and E85 is generally handled by the normal gasoline and diesel companies in each country, since ethanol is blended in the oil depot. The risk handling and classification are almost the same as for gasoline. The distribution of ED95 is adapted to the customer as they mainly consist of fleet owners. Transporting of ethanol over long distances is done in tankers and implies no problem. Dewatered ethanol for blending in gasoline is hydroscopic (meaning it takes up water) and during storage and transportation nitrogen is used to replace air and minimize breathing in the tanks, caused by temperature differences.

Recent cellulose-to-ethanol projects

Technology to produce ethanol from cellulosic biomass has been developed and verified by several companies, e.g. SEKAB, DONG/Inbicon, Chemtex, Abengoa, Poet-DSM, and Iogen, in pilot scale and small demo scale up to 5 million liters/year.

In Crescentino, Italy, Beta Renewables (earlier M&G/Chemtex) opened the first commercial scale plant in Europe in October 2013. It produces bioethanol from agricultural residues and energy crops, using enzymatic conversion.

In Emmetsburg, Iowa, US, Poet-DSM’s first commercial cellulosic bioethanol plant, Project Liberty, opened in September 2014. The Liberty Project plant produces biofuels from crop residues provided to the plant from local farmers.

Iogen Corp. announced in December 2014 the production start of cellulosic ethanol at Raízen’s newly expanded Costa Pinto sugar cane mill in Piracicaba, São Paulo, Brazil. The facility will convert biomass such as sugar cane bagasse and straw into 40 million litres per year of advanced, second generation cellulosic biofuel.

Biomethane is a gaseous fuel which consists of mainly methane. Biomethane is normally produced by upgrading (purifying) biogas. Biogas is the raw gas formed by anaerobic digestion of sewage sludge, food waste, manure etc. Before use in vehicles, biogas is always upgraded to biomethane. Biomethane can also be produced synthetically, e.g. by gasification of biomass followed by methanation; it is then called  SNG (Synthetic Natural Gas or Substitute Natural Gas).

Primary area of use

Biomethane can be used as a transport fuel, often as a mixture of biomethane and natural gas with fossil origin. Other areas of use are heat and power production, and as raw material for chemical products. The dominating use of biogas in many countries is for electricity production without prior upgrading to biomethane.

Methane is an ideal fuel for the Otto engine, but it can achieve an even higher energy efficiency if used in an engine that uses the Diesel cycle combustion process. However, the high ignition temperature of methane is a challenge in the Diesel combustion cycle and requires additional ignition assistance, usually in the form of a small pilot injection of diesel fuel. This type of engine is called a dual fuel engine. Although it has the potential of achieving higher efficiencies than the Otto engine, it comes with higher  complexity and cost.

There are two ways in which biomethane (or natural gas of fossil origin) can be stored in the vehicle fuel tanks: as compressed natural gas (CNG) at approx. 200 bar and ambient temperature, or as liquefied natural gas (LNG) at approx. 10 bar and -125°C.  Today CNG is much more common than LNG. LNG is suitable for heavy trucks that need to carry large amounts of fuel due to their long driving distances. Sometimes, fuel made of 100% biomethane is called compressed biogas (CBG) and liquefied biogas (LBG), but the terms CNG and LNG are generally usedirrespective of the biomethane content.

Feedstock and production

Biogas typically contains 60% methane and 40% carbon dioxide. It is produced through anaerobic digestion of easily degraded biomass (e.g. sugars, fatty acids, proteins). It is a naturally occurring process where microbial communities degrade biomass into hydrogen, carbon dioxide and acetic acid, synthesizing methane from these intermediates. Also, slow anaerobic digestion naturally takes place in landfills containing organic waste and the collected biogas of this type is denoted landfill gas. Several types of biomass can be used to produce biogas: the organic fraction of municipal solid waste and industrial waste, wastewater treatment sludge, agricultural residues,  manure and energy crops. Before injection into a natural gas grid and/or use in vehicles, biogas needs to be upgraded to  approximately 97% methane and purified from contaminants such as siloxanes and sulfur.

SNG can be produced by thermochemical gasification, achieved by heating biomass to high temperatures (>700°C) without combustion. The intermediate product is a synthesis gas consisting of methane, hydrogen, carbon monoxide and carbon dioxide. Depending on the type of gasification process, the composition of the synthesis gas differs and thus its suitability for methanation (the final process step where methane is formed from hydrogen and carbon monoxide). Alternatively, other fuels than methane can be produced from the synthesis gas, e.g. diesel, methanol or petrol. The raw material for thermochemical gasification is lignocellulosic biomass including energy crops and residues from forestry and agriculture; coal can also be used as raw material, though in that case the result is of course not a biofuel.

SNG can also be produced from carbon dioxide and hydrogen. For a low carbon footprint, the hydrogen is produced by electrolysis using renewable electricity. Carbon dioxide can e.g. be supplied from a conventional biogas upgrading plant. Other hydrocarbon fuels such as diesel, methanol and petrol can be synthesized in a similar way; all such fuels are usually denoted electrofuels.

Current production volumes

The use of biomethane as a vehicle fuel, which is small compared to bioethanol and biodiesel, is concentrated to Europe, more specifically to Sweden, Germany, Switzerland, the Netherlands, and Austria. European statistics for biomethane used as vehicle fuel are difficult to find, probably because the volumes are still very small and the final use is difficult to trace when biomethane is co-distributed with natural gas in a gas grid. According to the Swedish Energy Agency, production volumes for upgraded biogas in Sweden amounted to 1 TWh during 2014, of which almost all was used in the transport sector. This is equivalent to 9% of the biofuel use, and 1.1% of total use of fuels for domestic transport in Sweden. Even though the production of biomethane for use in vehicles is limited in Europe today, there is a large  production of raw biogas that potentially could be upgraded to biomethane. The biogas production in Europe amounted to 156 TWh (primary  energy) during 2013 (EurObserv’ER 2014).

System of distribution

Biomethane may be distributed from production site to fuel station by road transport either under high pressure (CNG) or in a liquefied state (LNG). Compressed biomethane may also be injected in the natural gas grid which in turn supplies many fuel stations (although that is not common in Sweden).

SNG projects in Europe

GoBiGas (Göteborg Energi) in Gothenburg, Sweden. A demonstration plant producing biomethane by gasification of forest residues with 20 MW SNG output is in operation since 2014.

Audi/ETOGAS plant in Werlte, Germany. The plant uses hydrogen from intermittent wind power and carbon dioxide from biogas upgrading to produce biomethane which is injected into the natural gas grid. The corresponding amount of methane is sold to Audi car owners.

HEFA (Hydroprocessed Esters and Fatty Acids), also called HVO (Hydrotreated Vegetable Oil), is a renewable diesel fuel that can be produced from a wide array of vegetable oils and fats. The term HEFA or HVO is used collectively for these biogenic hydrocarbon-based renewable biofuels. HVO is free of aromatics and sulfur and has a high cetane number. It is a so-called drop-in fuel, meaning that it is chemically equivalent to fossil diesel fuel and can be used in existing diesel engines without technical blend walls. One challenge that the production of HVO is facing is to find enough suitable and sustainable feedstock.

Primary area of use

HVO is an attractive alternative fuel due to the fact that it is  chemically equivalent to petroleum diesel and can be used in diesel engines without the blend walls or modifications required for e.g. biodiesel. However, European diesel standards limit the HVO blend due to density limits and the use of 100% HVO must be approved by the vehicle manufacturer. HEFA can also be used for biojet fuel in a blend with petroleum fuels of up to 50%. Several airlines have done trials with biojet fuels in commercial flights.

The fact that cold properties of HVO can result in clogged fuel filters and injectors may be a limiting factor. However, through isomerization of the HVO, the cloud point of the fuel can be adjusted, lowering the temperature at which wax in the fuel becomes solid.

Distribution system

HVO is a liquid fuel and distributed as low blends in fossil diesel that are sold at the fuel companies’ filling stations. Since HVO can be blended with fossil diesel, investments in new transport or distribution system are not necessary.

Preem sells HVO in a blend with biodiesel and fossil diesel, which is marketed as Evolution Diesel. Besides Preem, fuel companies such as OKQ8 (DieselBio+), St1 (CityDiesel) and Statoil (Miles Diesel) provide HVO blends of diesel based on imported HVO mainly from Europe. The OKQ8 diesel, BioMax, with 100% HVO, is currently undergoing tests.

Feedstock and production

HVO can be produced from many kinds of vegetable oils and fats. This includes triglycerides and fatty acids from vegetable oils, (e.g. rapeseed, soybean and corn oil), tall oil, (a co-product from the pulp and paper industry) in addition to the use of animal fats.

The simplified production process of HVO from vegetable oil.

HVO is produced through the hydrotreating of oils, in which the oils (triglycerides) are reacted with hydrogen under high pressure in order to remove oxygen. The hydrocarbon chains produced are chemically equivalent to petroleum diesel fuel. Propane is typically produced as a by-product. Investment costs are much higher for HVO than biodiesel production, which requires large scale production plants to allow the production to be economic. Production may be carried out in stand-alone plants producing only HVO or in integrated plants together with fossil fuels.

Raw materials for HVO production in Sweden are primarily of Swedish and European origin, but are also imported from countries outside of Europe. All HVO must fulfill the sustainability criteria set out in the Renewable Energy Directive (RED). RED sets sustainability criteria for biofuels and bioliquids identical to the Fuel Quality Directive. Availability of sustainable feedstock can be a limiting factor for HVO production, as many raw materials occur in limited amounts and may be subject to competing application areas. Of the HVO sold on the Swedish market, the raw material consists of 35% slaughterhouse wastes, 23% vegetable or animal waste oils, 22% crude tall oil, 15% palm oil and 5% animal fat. Globally, vegetable oil and palm oil are used to a larger extent.

The HVO produced in Sweden is currently (2016) based mainly on crude tall oil. The esterified tall oil used in production comes from SunPine in Piteå, which is thereafter hydrogenated to HVO at the Preem refinery in Gothenburg together with fossil raw material.

Current production and use as fuel

The sold amounts of HVO in Sweden have increased rapidly from 45 million litres in 2011 to approximately 439 million litres in 2014.

In 2015, roughly 160 million litres of HVO were produced in Sweden by Preem. The company is currently the only Swedish producer and reports that their Evolution diesel, containing up to 50% HVO, reduces fossil CO2 emissions by up to 46%. Preem recently extended their production capacity to 220 million litres, and is currently investigating new raw materials in addition to crude tall oil.

Globally, the installed capacity was about 3.8 billion litres per year in 2014. Neste Oil is the largest producer and is using waste fats and vegetable oils such as palm oil, rapeseed oil and soybean oil as feedstock. Production of HVO occurs in Singapore, Europe and the USA.

Future developments

Several actors have announced their plans to start up or expand HVO production, among them Diamond Green Diesel in the USA, who are expanding their production capacity to over 1 billion litres per year in 2018. The feedstock will be animal fats and used cooking oil.

Since feedstock availability is one of the main challenges for HVO production, there is ongoing research on new resources, for example algae oil, camelina oil and jatropha oil. In Sweden, the potential of lignin for biofuel production have raised interest. Lignin is an abundant resource which could be suitable for biogasoline production, which is however not in a strict since a HVO fuel.

Methanol is the simplest form of alcohol and it is produced via synthesis gas (H2 and CO) mainly derived from fossil feedstocks, such as natural gas and coal. Approximately 60% of the global methanol demand is currently used in the chemical industry, but the fuel and energy markets are increasing steadily and represent around 40% of the global use. Bio-methanol is a so called second generation or advanced biofuel and can be used blended with petrol, as marine fuel, or in fuel cells. Compared to conventional fossil based production of methanol, bio-methanol is currently produced at small scale.

Primary area of use

Today methanol is mainly used for production of chemicals like formaldehyde, acetic acid and MTO (methanol-to-olefins). Furthermore, through intermediate chemicals, many common products are produced from methanol, such as paints, antifreeze, plastics, and propellants.

Methanol can be used as a transportation fuel in several ways: blended with petrol, as a precursor to methyl tertiarybutyl ether (MTBE) which is used as an octane enhancer in petrol, in the  transesterification process when making FAME (fatty acid methyl ester) biodiesel, and as a diesel replacement after conversion to dimethyl ether (DME) or oxymethyl ether (OME). Methanol demand for energy purposes has been increasing steadily over the last decade, driven mainly by growing demand as a transportation fuel in China, where methanol currently represents 7% of the total transportation fuel use.

Methanol has a high octane number making it a good alternative to fossil petrol, which has been demonstrated for e.g. M15, M85 and M100. The EU allows low blending up to 3% in petrol, but this is currently not commonly used. When the blend-in level exceeds 15%, modifications are required, e.g. higher fuel injection to compensate for the lower energy density, modification to the ECU (Engine Control Unit), as well as material modifications to endure the corrosiveness of methanol. Emissions in the form of carbon monoxide, nitrogen oxides and hydrocarbons are lower from methanol compared to petrol, and methanol contains very low levels of impurities of sulphur or metals. The energy content (Lower heating value, LHV) is 15.8 MJ/litre (or 19.8 MJ/kg), slightly less than half of that of petrol.

Due to the high hydrogen content, methanol is an excellent hydrogen carrier than can be converted to hydrogen for usage in fuel cells without prior fuel pre-treatment. Direct Methanol Fuel Cell (DMFC) as well as High Temperature Polymer Eloctrolyte Membrane (HTPEM) fuel cell technologies have the potential of fuel efficiencies of around 40%.

There is also significant interest for methanol as a marine bunker fuel, due to international regulatory changes and cost advantages relative to other fuels. Methanol is sulphur free with low emissions and can be produced to lower cost than marine distillate fuel (when produced from fossil sources).

Feedstock and production

Methanol can be synthesised from a wide range of raw materials via two production steps. First, the feedstock (currently mainly fossil fuels like natural gas and coal) is converted into a synthesis gas consisting of CO, CO2, H2O and H2 through catalytic reforming or partial oxidation. In the second step methanol is synthesised catalytically. Each of these steps can be carried out in a number of ways using different technologies. The methanol process has a high selectivity leading to high production efficiency.

Recent developments in gasification technology provide opportunities to shift the use from fossil based feedstock to biomass, agricultural waste, municipal solid waste, and other lignocellulosic resources.

Distribution and storage systems

The technology for distributing and storing methanol is very similar to the current systems used for petrol and diesel, including pipelines, barges, chemical tankers, rail tankers and trucks. Material components must however be replaced to endure the corrosiveness of methanol. In Sweden, some distribution systems are adapted to alcohols, and systems adapted for E85 can also store M85 or GEM fuels (gasoline-ethanol-methanol).

Small risks are associated with the transportation and distribution of methanol. Methanol is highly toxic to humans and can cause blindness or even death on ingestion. Methanol is classified like petrol or diesel regarding toxicity, but is nonmutagenic and methanol vapour does not involve any health risks under practical conditions. Methanol biodegrades very rapidly in aerobic as well as anaerobic conditions and it will not persist in the environment. The half-life in groundwater is several hundred days shorter for methanol in comparison to petrol components.

Biomethanol projects

In Edmonton, Canada, Enerkem operates a commercial scale plant producing 38 million liters per year of methanol from municipal waste. A similar facility is planned in Rotterdam, the Netherlands, involving a number of European partners.

In Iceland, Carbon Recycling International is producing renewable methanol via CO2 captured from geothermal power generation and hydrogen produced via electrolysis. The production capacity is 5 million liters per year.

BioMCN in the Netherlands produces and sells industrial quantities of bio-methanol, by converting biogas from waste digestion into methanol. The annual production capacity of bio-methanol is around 250 million litres, with plans to further expand the renewable share in the future.

Methanol production via gasification of black liquor has also been successfully demonstrated at pilot scale at the LTU Green Fuels plant in Piteå, Sweden, but operation was terminated in 2016.

Dimethyl ether (DME) can be produced from coal, natural gas or biomass and it is used for a variety of purposes including as an aerosol propellant and chemical precursor. DME is an attractive alternative for diesel substitution due to its high cetane number and low tail-pipe emissions. Since it is in gaseous form under normal conditions, it cannot be blended with diesel. BioDME is a so called second generation, or advanced, biofuel. BioDME production via gasification of black liquor has been successfully demonstrated on pilot scale, including long-time fleet tests in heavy duty vehicles.

Primary area of use

DME is currently used primarily blended with liquefied petroleum gas (LPG) for home heating and cooking (mostly in China), as an aerosol propellant in hairspray and other personal care products, as a refrigerant, and as a feedstock for the production of several chemicals, most commonly dimethyl sulphate. As an aerosol propellant and refrigerant DME does not deplete the ozone layer like the chlorofluorocarbons and freons it replaces. Similar physical properties means that LPG infrastructure can easily be modified to handle DME, enabling wider spread.

DME is also an attractive diesel fuel substitute, due to good combustion characteristics, a high cetane number and a low octane number (see “Properties” info box). DME combusts without creating soot, the main material responsible for PM 2.5 particulate emissions. Further, combustion of DME produces no sulphur oxides at all, and any nitrogen oxides generated are simple to remove in the absence of the particulates.

DME used in conventional compression ignition engines requires a new fuel storage and injection system compared to when using liquid diesel fuels. Typically, DME is pressurized to about 5 bar being in liquid phase at normal temperature. When used as a fuel, DME is in a liquid phase all the way from the tank to the combustion chamber. The injection pump in a DME truck goes up to about 500 bar compared to about 1400 bar for regular diesel engines.

This is possible as the DME is easier to atomize resulting in an improved combustion process. DME is not corrosive, although some elastomers may swell in contact with DME. Another benefit is that the noise level of a DME engine is lower than in a conventional diesel engine.

The energy content of DME (LHV, Lower heating value) is 19.3 MJ/litre (28.8 MJ/kg), roughly 70% of the energy content of fossil-derived diesel. Thus, the fuel tank size must be bigger to enable the same driving range as for diesel vehicles. Furthermore, DME has poor lubricity, demanding special additives to avoid excessive wear in engines.

Feedstock and production

DME is currently mainly produced by means of methanol dehydration according to the following reaction:

2 CH3OH (Methanol) → CH3OCH3 (DME) + H2O

It is also generated directly from synthesis gas from thermochemical gasification of coal or through natural gas reforming.

Recent developments in gasification technologies provide the opportunity to also use biomass based fuels such as by-products from the paper and pulp industry, forest and agricultural residues, solid municipal waste and other renewable feedstocks. Using thermochemical biomass gasification the feedstock is first converted into a synthesis gas (syngas) stream consisting mainly of CO, CO2, H2O and H2. After cleaning and conditioning of the syngas in order to obtain a gas suitable for the synthesis reactions, DME is synthesised catalytically via methanol. Each of these steps can be carried out in a number of ways and various technologies offer a spectrum of possibilities which may be most suitable for any desired application.

Distribution and storage systems

DME is liquefied at moderate pressures and it can be handled like LPG due to its similar properties. Existing on- and off-shore infrastructure for LPG could therefore be used for transportation, storage, and distribution of DME with minor modifications.

Current production

The current global production of (fossil) DME is approximately 5 million tons per year, with the majority of production in China from coal-derived methanol. Commercial production facilities are also located in Japan, Germany, the Netherlands, Russia, South Korea, Turkey and the United States, with the first large-scale plant in the Americas (in Trinidad and Tobago) scheduled for  completion in 2018. China’s National Development and Reform Commission forecasts an annual DME production capacity of 20 million tons by the year 2020.

BioDME projects

BioDME production from black liquor, a lignocellulosic by-product from the pulping process, was successfully demonstrated at the LTU Green Fuels (formerly Chemrec) pilot plant in Piteå, Sweden (2011-2016). During the time in operation, about 1,000 tons of DME and methanol was produced in the facility, which has been operating for over 10,000 hours with biofuel production. The produced DME was used for field-testing with ten heavy duty trucks (Volvo Trucks) that were run in commercial traffic using biofuels produced in the pilot plant. Operation in the plant was terminated in 2016.

Currently no other DME projects based on fully renewable feedstocks are ongoing globally.

Fatty acid methyl ester, FAME, is a nontoxic, biodegradable biodiesel that can be produced from a wide array of vegetable oils and fats. It is used both as a blending component in fossil diesel and as a pure fuel. It is then called B100 (see separate fact sheet). FAME, together with Bioethanol, is the leading renewable liquid fuels on a global basis. In Sweden, FAME is the second largest renewable liquid fuel on the market. All FAME on the Swedish market is based on rapeseed methyl ester (RME) to comply with climate related requirements.

Primary area of use

Fatty acid methyl ester, FAME, generally goes under the name biodiesel and is used as fuel in diesel engine vehicles. It is normally used as a blend-in component in fossil diesel to increase the renewable content of the fuel. The current European diesel standard allows up to 7% v/v of FAME in diesel fuel without any modifications in vehicles or the distribution system. FAME is fully miscible with fossil diesel and apart from increasing the renewable content, it improves the lubricating properties. However, FAME is sensitive to cold climate and different grades are therefore sold depending on the climate zone of the distribution area. In Sweden, most grades allow operation down to -20°C.

FAME can also be used as a pure fuel, called B100 (see separate fact sheet). Pure FAME is nontoxic and biodegradable if spilled into nature. However, the biodegradable properties have a negative impact on the storage time, and pure FAME should therefore be consumed within six months to avoid problems with oxidation and polymerization. Vehicles that run on pure FAME must be approved for this by the vehicle manufacturer to ensure compatibility of materials and engine settings. Today, several trucks, busses and light transportation vehicles have been approved for the use of pure FAME. In Sweden the market for B100 has grown rapidly during the last years, but knowledge about the fuel has now quite spread to the rest of Europe.

Distribution system

FAME is a liquid fuel and does not require any modification to the distribution systems when blended into fossil diesel. Nearly all diesel distributed today at filling stations in Sweden contains roughly 5-7 % v/v FAME, depending to some extent on seasonal and geographical conditions.

Feedstock and production

most common feedstock in Europe is rapeseed and sunflower oil. In the US soybean, corn or rapeseed oil are most common, while palm oil is used in Asia. Generally, FAME can be produced from any fatty acid source, meaning that algae, jatropha, animal fats and other waste oils can be used. However, the fatty acid composition of the feedstock determines the properties of the final product. Generally, unsaturated and polyunsaturated fatty acids have low melting points. On the other hand, too much polyunsaturated fatty acids increase the oxidation tendency and hence shortens the storage time of the fuel. Therefore, climate zone, required filterability, etc. must be considered in the choice of feedstock or feedstock mix.

FAME is produced through transesterification of fatty acids and methanol. Oil and fat consist of triglycerides that separate to form FAME and glycerin in a transesterification process by replacing the glycerol-backbone in the triglyceride with an alcohol, typically methanol, under the action of a catalyst (i.e. sodium hydroxide). The triglycerides and methanol then form straight-chain methyl esters that are separated and purified in several steps to meet the fuel specification. The methanol used in the production is typically of fossil origin, but it can also be produced from renewable raw materials. Glycerol is a byproduct from the biodiesel process and depending on its purity, it is sold in different market segments.

The transesterification reaction for producing FAME from a vegetable oil.

In 2013, 293 000 m³ of FAME were consumed in Sweden. Of this 240 000 m³ was sold in low blends and 42 000 m³ was sold as pure FAME, B100. To fulfil the demand of the Swedish market, FAME is also imported. The amount of FAME imported has increased during the last three years. FAME is mainly imported from Lithuania, Germany, the Netherlands, Denmark, Norway and Italy. Svenska Petroleum och Biodrivmedels Institutet, SPBI, has reported that low blend diesel with FAME represented 2,7 % of the the total use of fuel in the Swedish transport sector in 2012 (on energy basis). The corresponding figure for pure FAME, B100, is 0,4 %.

The largest producer of FAME/biodiesel globally is USA with a production of roughly 5 billion liters in 2013, followed by Germany, Brazil and Argentina.

Current production and use as fuel

The consumed FAME in Sweden during 2015 was 425 000 m3, representing to 31% of the liquid renewable fuels on the market (HVO, FAME and bioethanol). Out of this, 247 000 m3 was sold as low blends and 178 000 m3 was sold as pure FAME, B100. To fulfil the demand of the Swedish market, about 70% of the FAME was imported, mainly from Europe.

The European Union, EU (28), is the largest producer of FAME globally with a production of roughly 12 700 000 m3 in 2014. Germany, France, The Netherlands and Spain are the main producers. EU is followed by US, which had a production of 8 000 000 m3 in 2015. South America produced about 6 900 000 m3 and Asia Pacific (APAC) roughly 5 400 000 m3 in 2014.

In Sweden there are two main production sites of RME, the basis for FAME; Perstorp in Stenungsund, producing roughly 150 000 m3 RME per year and Ecobränsle in Karlshamn with a production capacity of almost 40 000 m3 RME per year. There are also many small Swedish production sites, for example Tolefors Gård in Östergötland that produces roughly 400 m3 RME per year from used cooking oil.

FAME/biodiesel projects

Unclear political steering systems, land usage discussions and removal of tax incentives in Sweden have raised many concerns for the FAME industry the past years. Nonetheless, the global development of biodiesel continues, and new production plants are being built. Despite the uncertain political situation in EU, several European countries want to increase biodiesel use even more and in August 2015 a new European Standard, EN 16709, was approved, allowing B20 and B30 blends in fossil diesel (14-20 % v/v or 24-30 % v/v FAME in diesel fuel) for designated vehicles. However, this is not applicable in Sweden today; as the Swedish law for transportation fuels (Drivmedelslag 2011:319) does not allow marketing of diesel fuels containing more than 7 % v/v of FAME.

B100 is a diesel fuel consisting of 100% fatty acid methyl esters (FAME). It is a nontoxic, biodegradable fuel that can be produced from a wide array of vegetable oils and fats. The choice of feedstock has impacts on the fuel quality. Since B100 is used as a pure fuel, it replaces use of fossil diesel with a more sustainable option. In Sweden, FAME – including B100 – is the second largest renewable fuel on the market. All B100 on the Swedish market is based on rapeseed methyl ester (RME) to apply with climate related requirements.

Primary area of use

B100 is used as fuel in diesel engine vehicles in the transportation sector. Vehicles that run on B100 must be approved for this by the vehicle manufacturer to ensure compatibility of materials and engine settings. Today, several trucks, buses and light transportation vehicles have been approved for this service. In Sweden, the market for B100 has grown rapidly during the last years, but it is still a quite unknown fuel in the rest of Europe. The European standard for biodiesel, EN 14 214, contains a climate table, regulating the fuels’ cold properties. Different grades are therefore sold depending on the climate zone of the distribution area. In Sweden, most grades allow operation down to -20°C.

B100 is a nontoxic fuel that is biodegradable if spilled into nature. However, the biodegradable properties have a negative impact on the storage time. B100 should therefore be consumed within six months from the production date to avoid problems with oxidation and polymerization that could plug engine filters.

Distribution system

B100 is a liquid fuel and has similar properties to fossil diesel, except that it is nonflammable. This results in fewer demands on the distribution system. Today, the distribution of B100 is primarily limited to direct deliveries to large customers with private filling stations. The number of public filling stations that add pumps for B100 fuel is however continuously increasing.

Feedstock and production

As pure FAME, B100 can be produced from a wide array of oils and fats. Due to the Nordic climate, rapeseed oil is used in Sweden. The balance between mono and polyunsaturated fats affects the fuel properties. Generally, unsaturated fatty acids have low melting points. In turn, a larger share of polyunsaturated fatty acids increases the oxidation tendency and hence shortens the storage time of the fuel. Therefore, climate zone and required filterability, etc., need to be considered when the feedstock or mix of feedstocks is chosen.

B100 is produced through transesterification of fatty acids and methanol. Oil and fat consist of triglycerides that are separated to form FAME and glycerin in a transesterification process by replacing the glycerol-backbone in the triglyceride with an alcohol, typically methanol, under the action of a catalyst (i.e. sodium hydroxide). The triglycerides and methanol then form straightchain methyl esters, which are separated and purified in several steps to meet the fuel specification. The methanol used in the production is typically of fossil origin, but it can also be produced from renewable raw materials. Glycerol is a byproduct from the biodiesel process, and depending on its purity, it is sold into different market segments.

The transesterification reaction for producing B100 (FAME/Biodiesel) from a vegetable oil.

Current production and use as fuel

The consumed FAME in Sweden during 2015 was 425 000 m³, which represented 31% of the liquid renewable fuels on the market (HVO, FAME and bioethanol). Out of this, 247 000 m³ was sold as low blends and 178 000 m³ was sold as B100. To fulfil the demand of the Swedish market, about 70% of the FAME was imported, mainly from Europe.

In Sweden there are two main production sites; Perstorp in Stenungsund, producing roughly 150 000 m³ RME per year and Ecobränsle in Karlshamn with a production capacity of almost 40 000 m³ RME per year. There are also many small Swedish production sites, for example Tolefors Gård in Östergötland, which produces roughly 400 m³ RME per year from used cooking oil.

FAME/biodiesel projects

Unclear political steering systems, land usage discussions and removal of tax incentives in Sweden have raised many concerns for the FAME industry the past years. Nonetheless, the global development of biodiesel continues, and new production plants are being built. Despite the uncertain political situation in EU, several European countries want to increase biodiesel use even more and in August 2015 a new European Standard, EN 16709, was approved, allowing B20 and B30 blends in fossil diesel (14-20% v/v or 24-30% v/v FAME in diesel fuel) for designated vehicles. However, this is not applicable in Sweden today; as the Swedish law for transportation fuels (Drivmedelslag 2011:319) does not allow marketing of diesel fuels containing more than 7% v/v of FAME.

The fact sheet is at this point only available in Swedish.

Förhållanden mellan markanvändning och biodrivmedel diskuteras i många sammanhang. Att uppta mark för biodrivmedelsproduktion kan potentiellt leda till att matproduktion flyttar till andra platser, och att ny odlingsmark behöver tas i anspråk. Detta kan påverka både livsmedelspriser och utsläpp av växthusgaser. Men vad säger den senaste forskningen?

Vad är ILUC?

I debatten används ofta uttrycken direkt och indirekt förändrad markanvändning. De brukar förkortas DLUC (eng. Direct Land Use Change) och ILUC (eng. Indirect Land Use Change).

DLUC innebär att mark byter användning, från exempelvis skog till åkermark, för att möjliggöra odling av grödor till biodrivmedel. Det är viktigt att ta med i beräkning av klimatprestanda för biodrivmedel från länder där det sker avskogning. DLUC kan beräknas via mätningar av mängden kol i mark och biomassa innan och efter den ändrade markanvändningen, eller via modeller. Även om det finns stora osäkerheter i bedömningen finns en direkt koppling mellan grödan och den ändrade markanvändningen.

Samband mellan efterfrågan på grödor och direkta och indirekta effekter på markanvändning.

ILUC är ett mer komplicerat begrepp, grundat i ekonomiska resonemang. Om vi inom EU upptar stora arealer för odling av grödor till biodrivmedel, kan det bli en påverkan på livsmedelspriserna. Vår matproduktion kan då flyttas till andra områden inom EU, eller till andra delar av världen där maten är billigare att producera. Det kan leda till att ny odlingsmark tas i anspråk, mark som tidigare kanske varit i träda, skog eller extensiv betesmark. Det behöver inte vara negativt; om mark i träda som inte används kommer i bruk, kan vi producera mat och biodrivmedel och samtidigt binda in mer kol i marken.

Högre livsmedelspriser kan innebära att bönderna ser möjlighet till investeringar i jordbruket och kan intensifiera sin odling, vilket ofta är klimatsmart. Högre livsmedelspriser kan även påverka konsumtionsmönster. ILUC-teorin uttrycks alltså i flera steg och är svår att härleda till biodrivmedel då det finns många andra faktorer som påverkar bönders och konsumenters val. ILUC brukar därför uppskattas med hjälp av ekonomiska jämviktsmodeller.

Hur stor klimatpåverkan ger ILUC?

Det finns en stor mängd litteratur som försöker uppskatta ILUC. Resultaten varierar mycket och beror på val av modelleringsverktyg, systemgränser, indata och så vidare. Spannet varierar mellan -75 och 55 g koldioxidekvivalenter (CO₂-ekv) per megajoule (MJ) biodrivmedel enligt senaste IPCC-rapporten om markanvändning. Det kan jämföras med utsläpp från ett fossilt bränsle på ca 94 g CO₂-ekv per MJ. Ofta får grödbaserade drivmedel högre ILUC än lignocellulosabaserade drivmedel. Notera att ILUC i vissa fall kan bli negativt, det vill säga en besparing av utsläpp. Det kan hända i de fall där biprodukter ersätter andra mer resurskrävande produkter, till exempel när drank ersätter soja.

Bör vi ta hänsyn till ILUC?

På grund av de stora osäkerheterna gällande metoder för att uppskatta ILUC, rekommenderar de flesta handböcker i livscykelanalys att inte inkludera ILUC i klimatberäkningar av enskilda produkter.

I ett globalt perspektiv går det att ifrågasätta relevansen av ILUC. När en ändring i markanvändning sker, räknas den som DLUC för den gröda som odlas på platsen. Att samma markanvändning sedan även ska bokföras som ILUC för en annan gröda blir en dubbelräkning. ILUC är alltså ett högst teoretiskt sätt att beräkna markanvändning, i verkligheten finns bara DLUC.

Men att beräkna ILUC kan vara relevant i vissa sammanhang, till exempel inom explorativ forskning, där effekterna på markanvändning vid införande av en policy undersöks. Vissa forskare, som Timothy D Searchinger, anser även att all markanvändning som inte producerar enligt sin maxkapacitet, leder till ILUC-effekter och bör tas med i utvärdering av markanvändning.

Oavsett diskussionen, är det extremt viktigt att värna om mark som en resurs både i Sverige och internationellt. Vi måste upprätthålla god markhälsa och minska skövling av värdefull skog. I störst möjliga mån bör bioenergi integreras i existerande system, utan att äventyra produktion av livsmedel. Det bör emellertid nämnas att biodrivmedelsgrödor utgör ett fåtal procent av den globala jordbruksmarken; vi behöver också fokusera på övriga drivkrafter till ändrad markanvändning, till exempel den globalt ökande köttkonsumtionen.

Hur hanteras ILUC i lagstiftningen?

Det är mycket svårt att lagstifta bort indirekta effekter som kan ske på andra sidan jordklotet. Men att ignorera att all markanvändning idag sammanlänkas genom ett globalt nät av förflyttningar av grödor, livsmedel och biodrivmedel är inte heller en framkomlig väg.

I EU har frågan om ILUC diskuterats länge. I det senaste direktivet om förnybar energi (2018:2001) har ILUC-risk för jordbruksråvaror delats upp i två nivåer, låg och hög. Lågrisk-ILUC tillskrivs grödor där man undviker omflyttningseffekter av foder- och livsmedelsgrödor, grödor producerade genom förbättrade jordbruksmetoder samt grödor från områden som tidigare inte användes för odling av grödor. Grödor som inte återfinns i dessa kategorier anses vara högrisk-ILUC; dessa får inte räknas in i EU:s ramverk efter 2030.

The fact sheet is currently only available in Swedish.

Jet A1, också benämnt som flygfotogen eller jetbränsle, är det drivmedel som används i flygplan och helikoptrar drivna med jetmotorer. När biobaserade bränslen blandas i flygbränsle brukar det kallas biojet. Det är i dagsläget bränsle från fyra olika biobaserade produktionsvägar som är certifierat som tillsats (upp till 50%) i konventionell Jet A1 enligt standarden för flygbränsle: hydrerade estrar och fettsyror (HEFA), Alcohol-to-Jet (AtJ), Fischer-Tropsch (FT) och direktfermentering av socker (DSHC).

För att ge biojet bra klimatprestanda är det viktigt att vätgasproduktionen som processteg görs hållbar. I svenska bioflygbränsleprojekt är det främst tre av de biobaserade produktionsvägarna som är intressanta att utveckla, HEFA, AtJ och FT, vilka presenteras närmare i detta faktablad. Längs värdekedjan för respektive teknik finns olika faktorer som påverkar status för bioflygbränslena, och därmed också hur de kan bidra till luftfartssektorns klimatmål.

De fyra produktionsvägarna för biobaserade drop in-bränslen certifierade för inblandning i flygbränsle enligt standard ASTM 7566-18. Med inblandning av dessa kallas flygbränslet för Biojet.

HEFA – hydrerade estrar och fettsyror

Hydrerade (vätebehandlade) estrar och fettsyror, HEFA, produceras ur vegetabiliska och animaliska oljor och fetter, också avfallsoljor som använd matolja. Råvaran vätebehandlats för att reducera syreinnehåll och konvertera fetter och oljor till kolväten. En förbehandling krävs för att använda förorenade råvaror.

HEFA är ASTM-certifierad för en inblandning i flygbränsle på upp till 50%.

HEFA-processen är den enda produktionsprocess som idag har kommersiell produktion av bioflygbränsle. Eftersom tillverkningsprocessen till stor del är densamma som för HVO (hydrerad vegetabilisk olja) som finns på marknaden för vägtransporter, kan anläggningar ha en flexibel produktmix, dvs fördelning mellan olika produkter (t ex mellan flygbränsle, andra fordonsbränslen och kemikalier). Men det betyder också att en konkurrenssituation om vissa råvaror kan uppstå mellan drivmedelsproduktion för flyget respektive vägtransporter. En ökad efterfrågan på vegetabiliska oljor kan orsaka tryck på ändrad markanvändning i vissa fall. Lignocellulosaråvaror har mycket högre tillgänglighet och lägre indirekta miljöeffekter men kan med dagens teknik inte användas för HEFA-produktion.

Investeringskostnader har i exempel beräknats ligga kring 8 000 SEK/årston för storskaliga anläggningar vilket ger ett uppskattat lägsta försäljningspris för HEFA på i storleksordningen 8-12 SEK/l beroende på råvara. [1, 2] De relativt låga produktionskostnaderna är delvis beroende av synergier med annan kolväteproduktion. Andra uppskattningar av produktionskostnader är högre, t ex 15-17 SEK/l för använd matolja som råvara. [3]

Omvandlingsprocessen från biomassa till bioflygbränsle har vätgas som viktigaste insatsvara i tillägg till olja/fett-råvaran. Tillverkat av förnybara och hållbara råvaror kan bioflygbränsle med HEFA minska utsläppen av växthusgaser med 70-80% jämfört med konventionellt jetbränsle. [2, 3]

AtJ – Alcohol to Jet

Alcohol to Jet (AtJ) innebär att biojetbränsle framställs katalytiskt ur någon av alkoholerna butanol eller etanol. Dessa alkoholer kan ha framställts ur många olika biogena råvaror och en mängd olika biologiska processer. Det innebär att det finns många varianter av AtJ som produktionsväg.

För s k första generationens etanol används främst socker från sockerrör och stärkelse från sädesslag som råvara. Men användningen av grödor för drivmedelsproduktion är omdebatterad och EU har satt ett tak för den. För att bredda råvarubasen har teknik för att producera såväl etanol som butanol från lignocellulosa, t ex trä och halm, tagits fram. Restströmmar från befintlig industri kan också vara ett viktigt komplement till råvarubasen.

Att omvandla biomassa till AtJ-baserat bioflygbränsle kan ske med låg miljöpåverkan. Den övergripande miljöprestandan är en kombination av val och metod för insamling av råvara och den specifika produktionsvägen. I allmänhet betraktas rest- och biprodukter från skogsbruk och jordbruk samt biogena avfall som de viktigaste framtida råvarorna. De är enligt reglerna för växthusgasberäkning som tillämpas i förnybarhetsdirektivet [4, 5] associerade med låga utsläpp av klimatpåverkande gaser. Jämfört med fossila bränslen ger bioflygbränsle producerat från någon av dessa råvaror enligt AtJ en signifikant växthusgasreduktion. I typfallet är minskningen större än 80%. [2]

Som process är AtJ relativt mogen och ett flertal aktörer bedriver aktivt utvecklingsarbete. Tekniken är dock ännu inte demonstrerad i kommersiell storskalig produktion. Detta innebär att den ekonomiska prestandan för AtJ-processen är osäker. [6] Det är dock tydligt att produktionsekonomin skiljer sig beroende på vilken råvara som används. Priser på 25-35 SEK/l har t ex angivits för de första anläggningarna som producerar AtJ-bränsle från lignocellulosa. Med mogen teknik förväntas de sjunka till 15-25 SEK/l. [2, 7, 8]

ASTM-certifiering som tillåter upp till 50% inblandning i fossilt jetbränsle finns för produktion både via butanol och etanol.

FT – Fischer Tropsch

Fischer Tropsch (FT) är en serie kemiska reaktioner som kan användas för att uppgradera syntesgas (H2 och CO) till vätskeformiga bränslen. Råvaran för framställning av syntesgasen kan vara av både fossilt ursprung eller biomassa och avgör alltså om slutprodukten är bioflygbränsle. Det finns i dagsläget ingen storskalig produktion av flygbränsle från biomassa baserat på FT-teknik, men snarlik teknik, baserad på fossila råvaror, har sedan länge använts för kommersiell produktion av flygbränsle. Två kommersiella produktionsanläggningar är 2019 under uppförande i USA med planerad start 2020.

Det är inte möjligt att producera enbart bioflygbränsle i en FT-process, men 50-70% av produkten kan bli bioflygbränsle med förnybar diesel som den viktigaste andra produkten. Effektiviteten beror mycket på processkonfiguration och råvara men typiskt kan 35-50% av energin i råvaran bli till drivmedel. Dessutom bildas en stor mängd värme som kan vara värdefull om produktionen integreras med andra processer eller i ett fjärrvärmenät.

Det är svårt att generalisera produktionskostnader för FT-baserade bioflygbränslen. Skälet är att de i hög grad beror på lokalisering, råvaruval, anläggningens storlek och vald produktmix. Generellt präglas kostnadsprofilen av höga investeringskostnader men låga råvarukostnader jämfört med de flesta andra produktionstekniker. För FT-baserade bioflygbränslen anges ofta produktionskostnader i ett intervall om 10-20 SEK/l. [2, 3, 8, 9] Kostnader i den lägre delen av intervallet kan sannolikt nås för kommande anläggningar som byggs integrerade med befintlig industri, exempelvis svensk skogsindustri.

Att omvandla biomassa till FT-baserat bioflygbränsle har potential att göras med mycket liten miljöpåverkan från själva omvandlingsprocessen eftersom få ytterligare insatsvaror används och endast lite avfall bildas. Det innebär att så länge hållbart producerade och insamlade råvaror används, kan totalt sett god miljöprestanda nås med denna produktionsväg. Med de regler för växthusgasberäkning som tillämpas i förnybarhetsdirektivet [4, 5] är dessa associerade med låga klimatgasutsläpp och ger växthusgasreduktion för producerat bioflygbränsle med >90% jämfört med fossila bränslen. [7]

Lignocellulosic biomass can be converted into fuels and chemicals using thermochemical or biochemical process pathways. Biochemical processes involve biocatalysts. They can be enzymes that degrade biomass to a mixture of sugars, which can be fermented by microorganisms to produce a wide range of valuable compounds such as fuels, organic acids, alcohols, etc. When the aim is to produce liquid and gaseous biofuels, mainly two biochemical conversion processes are used: fermentation for ethanol production and anaerobic digestion for biogas production.

Fermentation process for ethanol

A typical process to convert biomass to ethanol consists of four main steps: pretreatment, enzymatic hydrolysis, fermentation, and product recovery (Figure 1).

Pretreatment

Lignocellulose is a very resistant material. It consists of an intertwined network of cellulose (30-50%), hemicellulose (20-30%) and lignin (20-30%) that provides strength and resistance to the plant structure. Converting lignocellulose to sugar molecules requires pretreatment to open its structure and make it easier to break down the cellulose fibers consisting of glucose linked together in long chains. The pretreatment step can separate the cellulose from hemicellulose and lignin.

Several pretreatment methods, including biological, physical, and chemical pretreatments, have been studied. In a biomass-to-ethanol process at commercial scale, steam pretreatment has so far been the main choice. During steam pretreatment high-pressure steam is used to increase the temperature of the biomass to 160-240°C for a certain time, after which the pressure is released causing most of the hemicellulose and part of the lignin to solubilize. The cellulose remains undissolved but becomes more available for the enzymes.

Enzymatic hydrolysis

During enzymatic hydrolysis, the cellulose fibers and hemicellulose which were not degraded in the pretreatment are decomposed into simple sugar molecules. Cellulases, a mixture of several types of enzymes acting in synergy, are used to attack the bonds between glucose molecules in different regions of the cellulose. As hemicellulose mainly consists of other types of sugars than glucose, and has a different structure compared to cellulose, its hydrolysis requires different enzymes (hemicellulases). In the end of the enzymatic hydrolysis a solution that is rich in various kinds of sugars is obtained and can be fermented.

Fermentation

The sugars produced can be fermented to ethanol by yeast or bacteria. Due to it generally being recognized as safe, robust, and presenting high ethanol tolerance, ordinary baker’s yeast (Saccharomyces cerevisiae) is the most preferred microorganism. But ordinary baker’s yeast can only ferment sugars that contain six carbon atoms, such as glucose. To convert sugars from hemicellulose containing five carbons (e.g. xylose and arabinose), the yeast needs to be genetically modified or replaced with other microorganisms, e.g. bacteria. Enzymatic hydrolysis and fermentation can be carried out in two main configurations: consecutively, known as separate hydrolysis and fermentation, or at the same time in one vessel, known as simultaneous saccharification and fermentation (see Figure 1).

Product recovery

To obtain a high-purity product that can be used for fuel production, ethanol needs to be recovered from the fermentation by distillation and dehydration. Residues from distillation are separated into solids and liquids. The solid residue, which is rich in lignin, can either be burnt to produce steam, heat, and electricity, or converted to various coproducts. The liquid residue is sent to an anaerobic digestion plant to produce biogas. Ethanol obtained by this process is blended with gasoline at different ratios (E5-E85) or can even be used as a pure ethanol fuel (E100).

Anaerobic digestion for biogas production

Anaerobic digestion (AD) is the microbial decomposition of biomass into biogas without the presence of oxygen. Biogas is mainly composed of 55-65% methane and 35-45% carbon dioxide, but it can also contain small amounts of e.g. nitrogen, hydrogen, oxygen, hydrogen sulfide, and ammonia. The composition of the resulting biogas depends on the type of biomass used.

It is possible to break down biomass by means of AD without pretreatment. However, higher biogas yields can be achieved in shorter time if pretreatment is applied. The four main steps of AD are hydrolysis, acidogenesis, acetogenesis, and methanogenesis (Figure 2). In each step, different groups of microorganisms are used.

In the hydrolysis step, large macromolecules such as carbohydrates, lipids and proteins are broken down by enzymes to smaller compounds, such as simple sugars, amino acids, fatty acids. These are further degraded in the acidogenesis to organic acids and alcohols, which are in turn converted to acetate, as well as to carbon dioxide and hydrogen in the acetogenesis. In the final step, methanogenesis, biogas, i.e. a mixture of methane and carbon dioxide, is produced by two different types of bacteria. One converts acetate and the other type utilizes carbon dioxide and hydrogen to produce biogas.

Biogas obtained from AD can be burnt and the energy released can be used for heating purposes. Alternatively, after removal of carbon dioxide, biogas can be compressed the same way as natural gas and used as a vehicle fuel.

Lignocellulosic biomass can be converted into fuels and chemicals using thermochemical or biochemical process pathways. Thermochemical technologies apply heat and chemical processes in order to produce bioenergy from biomass. There are four main thermochemical conversion processes: direct combustion, gasification, pyrolysis and liquefaction. Direct combustion produces heat while the three latter can produce various types of energy carriers that can be converted into fuels.

Direct combustion

Direct combustion is the burning of biomass in open air, or, in the presence of excess air, converting the chemical energy stored in biomass into heat, mechanical power or electricity. Direct combustion is carried out using stoves, furnaces, steam turbines, or boilers at a temperature range starting at 800°C. All types of biomass can be burned, but in practice, direct combustion is only performed for biomass that has low moisture content (less than 50%). Biomass containing higher levels of moisture needs to be dried prior to combustion, or it may be better suited to biochemical conversion.

Gasification

Gasification is the partial oxidation of biomass at high temperatures (over 700°C) in the presence of a gasification agent, which can be steam, oxygen, air or a combination of these. The resulting gas mixture is called syngas or producer gas, and can be used in various processes to produce liquid fuels such as methanol, ethanol and Fischer-Tropsch diesel, and gaseous fuels, such as hydrogen and methane.

Syngas is comprised mainly of hydrogen and carbon monoxide, but could also contain methane, carbon dioxide, light hydrocarbons (e.g. ethane and propane) and heavy hydrocarbons (e.g. tars). Undesirable gases, such as hydrogen sulfide may also be present. The composition of the syngas depends on the type of biomass, the gasifier, the gasification agent, and on the temperature used in the process. Generally, when the biomass has high content of carbon and oxygen, the syngas produced via gasification is rich in carbon monoxide and carbon dioxide.

The most common biomass feedstocks used in the gasification process to produce biofuels are different kinds of wood, forestry wastes and agricultural residues. The heat for the high temperature gasification process can be supplied either directly by oxidation of part of the biomass in the gasifier, or indirectly by transferring energy to the gasifier externally.

Pyrolysis

Pyrolysis is the thermal decomposition of biomass to liquid, solid and gaseous fractions at high temperatures in the absence of oxygen in order to avoid significant levels of combustion. The liquid fraction is called bio-oil or bio-crude; a dark brown, viscous liquid with a high density, composed by a mixture of oxygen-containing organic compounds. Due to its high oxygen content, bio-oil is not suitable for direct use as a drop-in transportation fuel. However, it can be easily transported and stored, and after upgrading it has the potential to substitute crude oil, which makes it the most interesting product of pyrolysis. The solid fraction obtained from pyrolysis is called biochar, i.e. charcoal made from biomass, and the gasous fraction is syngas. The relative proportions of these fractions depend on the type of reactor employed and the feedstock used. It is controlled by varying the temperature, the heating rate and the residence time of the material in the reactor.

Depending on the heating rate employed, there are three main types of pyrolysis processes: slow, fast and flash pyrolysis. Slow pyrolysis has been used for thousands of years for the production of solid fuel. It is a decomposition process at relatively low temperatures (up to 500°C) and low heating rates (below 10°C/min), which takes several hours to complete, and results in solid biochar as the main product.

Fast pyrolysis is currently the most widely used process. It occurs at controlled temperature of around 500°C employing relatively high heating rates and only takes a few seconds to complete. The key product from fast pyrolysis is bio-oil (60-75%). In addition, biochar (15-25%) and syngas (10-20%) are also produced.

When heating rates and reaction temperatures are even higher, and the reaction time is shorter than that of fast pyrolysis, the process can be described as flash pyrolysis. Flash pyrolysis can result in a high yield of bio-oil and high conversion efficiencies (up to 70-75%).

Liquefaction

Hydrothermal liquefaction is the conversion of biomass to bio-oil in the presence of water, with or without a catalyst. During hydrothermal liquefaction, large compounds in the biomass are broken down into unstable shorter molecules that in turn reattach to each other and form bio-oil. In contrast to pyrolysis and gasification, the liquefaction process does not require the use of dry biomass, which reduces the cost of drying. The resulting bio-oil has lower oxygen content than the bio-oil obtained from pyrolysis, and therefore, it requires less upgrading prior to utilization as a transportation fuel.

Recent articles and statements in the media [1, 2] raise concerns over the climate effects of using forest biomass for bioenergy. As some statements seem to reflect misconceptions about forest bioenergy, IEA Bioenergy here provides a brief overview of key facts about the use of forest biomass for climate change mitigation. [3]

This fact sheet reproduces a text developed by Göran Berndes, Annette Cowie, Luc Pelkmans and members of IEA Bioenergy Task 45, the IEA Bioenergy Technology Collaboration Programme (TCP). f3 publishes the text as a whole with permission from IEA Bioenergy.

The IEA Bioenergy TCP is organised under the auspices of the International Energy Agency (IEA) but is functionally and legally autonomous. Views, findings and publications of the IEA Bioenergy TCP do not necessarily represent the views or policies of the IEA Secretariat or its individual member countries.

In summary

Energy from woody biomass can contribute to climate change mitigation, as a renewable fuel. It should be used efficiently, and when harvested from forests, it must come from sustainably managed forests, where carbon stocks are maintained or enhanced on a regional or national basis. Forest bioenergy can support rapid transformation of the energy sector. Furthermore, bioenergy linked with carbon capture and storage (BECCS) is one of the options that can deliver negative emissions, likely to be required to meet the temperature targets of the Paris Agreement. Forest management that maintains or increases carbon stocks, while also producing timber, fibre and energy, contributes to climate change mitigation by storing carbon on land and replacing carbon-intensive materials and fossil fuels.

1. Forest bioenergy is not by definition carbon neutral; emissions in the supply chain and impacts on forest carbon stock must be included.

Bioenergy is sometimes said to be “carbon neutral” in the sense that the carbon that is released during combustion (biogenic carbon emissions) has previously been sequestered from the atmosphere and will be sequestered again as the plants regrow.

But “carbon neutrality” is an unhelpful term because it is ambiguous and used differently in different contexts. As is further elaborated below, biogenic carbon needs to be considered in assessments in order to fully reflect how bioenergy will affect atmospheric GHG concentrations. If extraction of biomass for energy leads to a decline in the forest carbon stock or carbon sink strength, this needs to be accounted for. Furthermore, assessments need to consider all emissions associated with the production, processing, transport and use of bioenergy. Finally, the bioenergy scenario should be compared with a counterfactual scenario, in which energy is provided by another source, to quantify the net effect on GHG emissions.

2. Forest biomass is not treated as carbon neutral in national greenhouse gas inventories.

The treatment of bioenergy in greenhouse gas inventories has been criticized for containing a loophole because bioenergy is “counted as carbon neutral”. This is incorrect. Under the agreed approach for preparation of national greenhouse gas inventories, countries report harvest of forests for any purpose, including bioenergy, as a CO2 emission in the land use sector. [4] CO2 emissions from combustion of biomass for energy are not counted in the energy sector to avoid double counting with the land use sector. Thus, there is no accounting error that requires correction, or emission that is overlooked in reporting, and bioenergy is not assumed to be carbon neutral: if bioenergy leads to a reduction (or slower growth) in forest carbon stock this is reflected in national inventories. [5] Fuel use in the supply chain is counted in the energy sector of the country where the fuel is consumed, as for all other traded materials including energy carriers.

Where biomass for bioenergy is traded, the importing country reports no emissions, while the exporting country reports the emissions in the land sector. This convention could be criticised as supporting “outsourcing” of emissions by the importing country. This issue applies also to off-shore manufacturing. For instance, a large share of emissions associated with production of goods consumed in Europe is reported by China, where manufacturing occurs. [6] The case of biomass imports for bioenergy is an example where policymakers have recognized and taken action to address this challenge. [7] The EU RED II requires that forest biomass is sourced only from locations where legislation at national/subnational level, or management systems at the forest sourcing area, ensure that forests are regenerated and that carbon stocks and sink levels in the forest are maintained or strengthened over the long term. [8] Specifically concerning EU pellet importation from the United States, data show that forest carbon stocks in the south-eastern United States (SE US) where biomass is sourced, are steadily increasing, [9 ] and biomass harvests for wood pellets represent only a small fraction of harvest removals from forests in the SE US. [10]

3. Climate effects of using woody biomass cannot be determined at stand level; assessments need to be made at the landscape (estate) level.

A forest estate is generally managed as a series of stands of different ages, harvested at different times, to produce a constant supply of wood products. When considered at stand level, much of the carbon that has been sequestered into the stand as the trees grow is abruptly lost from the stand at the time of harvest, and is not fully sequestered again until the stand has reached harvest age. Stand-level assessments that start the accounting when the stand is harvested will, therefore, show upfront emissions and a delay before forest bioenergy contributes to net reductions in atmospheric CO2, particularly in long-rotation forests.

However, across the whole forest estate (landscape), i.e., at the scale that forests are managed, carbon losses in harvested stands are balanced by carbon gains (growth) in other stands, so the carbon stock of production forests is roughly stable. The magnitude of the carbon stocks in forest landscapes depends on biophysical factors such as soil and climate conditions, historic and current management regimes, and events such as storms, fires and insect outbreaks. To quantify the climate effects of harvesting woody biomass for energy and other products, the effect of this harvesting on the development of carbon stocks at the landscape level needs to be determined.

Landscape-scale assessment can provide a more complete representation of the dynamics of forest systems, as it integrates the effects of all changes in forest management and harvesting that take place in response to – experienced or anticipated – bioenergy demand. The landscape approach therefore helps to identify how total forest carbon stocks are affected by specific changes in forest management. For instance, if a new management regime with more residues and/or trees extracted, or a shorter rotation length, leads to a long-term decline in the carbon stock and carbon sink capacity of the forest estate, this would reduce the climate benefit. On the other hand, an increase in demand for bioenergy and other forest products could also incentivise changes in forest management (e.g., improved site preparation, use of nurse trees, advanced genetics, measures to reduce risks for forest fires or pests/diseases) that enhance forest sink strength and carbon stocks.

4. Forest biomass is a renewable energy source if forest productivity is maintained.

Forest biomass is renewable if it is harvested from forests that are managed such that there is no loss of productive capacity – i.e., so that growth rate and therefore capacity to sequester carbon are maintained over successive rotations. Sustainable forest management is key to maintaining healthy and productive forests. Biomass derived from deforestation should not be recognized as renewable.

5. The climate change effect of using biomass for energy cannot be determined by comparing GHG emissions at the point of combustion.

It is sometimes stated that CO2 stack emissions per MWh inevitably increase when biomass replaces coal. However, at the point of combustion, wood and coal have similar CO2 emission factors, as the ratio of heating values between the two fuels is similar to the ratio of carbon content. Furthermore, biomass fuel characteristics (moisture content, grindability, heating value) affect the energy efficiency of co-firing systems. In large coal power plants, there can be a derating of a few percent, as there is more flue gas generated per GJ of fuel, which leaves the stack at a temperature above the ambient temperature resulting in so-called stack losses. However, when the co-firing ratio is low (<10%) there is usually no significant efficiency penalty. Fuel type (both coal and biomass) also matters. For low rank coal, biomass co-firing (especially torrefied biomass) can increase the boiler efficiency and net power plant efficiency. The outcome also depends on modifications made when power plants are adapted to using biomass (e.g., investments in steam turbine upgrades and internal waste heat utilization to dry biomass fuel).

More importantly, comparing emissions at the point of combustion does not show the effect on atmospheric GHG concentrations of switching from fossil fuels to biomass. There is a fundamental difference between fossil fuels and biomass: burning fossil fuels releases carbon that has been locked up in the ground for millions of years, while burning biomass emits carbon that is part of the biogenic carbon cycle. In other words, fossil fuel use increases the total amount of carbon in the biosphere-atmosphere system, while bioenergy systems operate within this system; if the forest carbon stock is constant there is no net transfer of carbon to the atmosphere.

Instead of comparing GHG emissions at the point of combustion, the biogenic carbon flows and fossil GHG emissions associated with the complete life cycle of the bioenergy system need to be compared with the GHG emissions in a realistic reference situation (counterfactual scenario) where energy sources other than bioenergy are used. Also, indirect impacts (positive or negative) on land use, wood products and fossil fuel use need to be considered.

6. Long-distance transport does not negate the climate benefits of woody biomass as a renewable energy source.

Fossil energy used in the biomass supply chain is generally small compared to the energy content of the bioenergy product, even when transported internationally. For example, the fossil fuel use related to cultivation and processing of wood pellets corresponds to between 2.5 and 15 g CO2/MJ. [11] Transporting pellets between North America and Europe increases supply chain emissions by up to 5 g CO2/MJ [12] (for comparison: the life cycle GHG emissions of hard coal (supply & combustion) is around 112 g CO2/MJ). Thus, long-distance transport does not negate the climate benefits of forest-based bioenergy; these supply chains still offer substantial climate benefit when sourced from sustainable biomass.

7. Switching from coal to woody biomass reduces atmospheric CO2 over time scales relevant to climate stabilisation.

Some articles point to the fact that forest-based bioenergy systems can cause a short-term increase in emissions, although delivering mitigation in the longer term, and claim that bioenergy is not compatible with climate change goals if it has a payback period of more than a decade, due to the urgent need to address climate change.

First, there remains disagreement about the appropriate methodological approach for calculating payback time. Stand-level assessments are in our view not appropriate since they represent the assessed system as a strict sequence of events (e.g., site preparation, planting or natural regeneration, thinning and other silvicultural operations, final felling) that in reality occur simultaneously0 across the forest landscape (see point 3). The outcome for stand-level assessments will vary dramatically for the same system, depending on which starting point is chosen (time of replanting or time of harvest). Moreover, defining a realistic counterfactual for the calculation of payback times is critical, but challenging, considering the dynamics of forestry systems. Some studies use unrealistic assumptions for counterfactuals, e.g. assuming that forests planted for commercial use are left unharvested when there is no demand for bioenergy, and ignoring that most forest biomass used for bioenergy is a by-product of high value timber.

Second, the relationship between net emissions, global warming and climate stabilisation is complex. The IPCC 1.5 report [13] shows many alternative trajectories towards stabilization temperatures of 1.5 and 2°C. The IPCC emphasizes the need for transformation of all the major sectors of society to achieve net zero CO2 emissions, and finds a requirement for carbon dioxide removal in many scenarios. The IPCC’s assessment of current scientific understanding does not conclude that individual measures towards achieving transformation need to meet specific “payback periods”.

The most important climate change mitigation measure is to transform energy and transport systems so that we can leave fossil carbon in the ground. Using bioenergy now, in conjunction with other renewables, is an important measure to achieve this. Biomass is a storable, dispatchable energy source that can support the rapid expansion of intermittent renewables, providing grid stability and balancing. In the longer term, biomass is likely to be primarily used in applications where the substitution of carbon-based fuels is particularly difficult, such as in aviation and long-distance marine transportation. Biomass may also be increasingly used in applications that deliver net negative GHG emissions. For the mid – to longer term, the IPCC 1.5 report found most scenarios that deliver climate stabilisation at 1.5 or 2°C require substantial deployment of negative emissions technologies. Bioenergy linked with carbon capture and storage (BECCS) is one of the major available options for achieving negative emissions. The further transformation of existing power systems will depend on how biobased and other technologies develop to meet future demands, including the development of technologies for providing negative emissions that are not based on biomass.

Concern about near-term emissions is not a strong argument for stopping investments that contribute to net emissions reduction beyond 2030, be it the scaling-up of battery manufacturing to support electrification of car fleets, the development of rail infrastructure, or the development of biomass supply systems and innovation to provide biobased products displacing fossil fuels, cement and other GHG-intensive products. We assert that it is critical to focus on the global emissions trajectory required to achieve climate stabilization, acknowledging possible trade-offs between short- and long-term emissions reduction objectives. A strong focus on short-term carbon balances may result in decisions that make long-term climate objectives more difficult to meet.

8. Sustainability governance is required to ensure that woody biomass used for energy makes a positive contribution to addressing climate change and other societal goals.

Scientific studies have shown that forest-based bioenergy can make a substantial contribution to climate stabilisation. Sustainability governance is needed to support achievement of this potential and minimise the risk of negative outcomes. Many countries have rigorous forest management regulations requiring implementation of sustainable forest management practices. [14] Sustainable forest management, such as defined by FSC- or PEFC-endorsed schemes, is used to manage hundreds of millions of hectares of forest worldwide, and these practices should be deployed more broadly. Sustainability requirements have been developed to govern the eligibility of forest biomass for renewable energy in several countries as well as under the updated European Renewable Energy Directive. Regulations governing eligibility for bioenergy subsidies in the Netherlands, for example, stipulate that natural forests cannot be converted, that biodiversity and forest vitality are at least maintained, that forests must be regrown, and that forest carbon stock must be maintained or increased in the long term. To secure sustainability compliance and oversight throughout the chain, all economic operators are supervised by public authorities and the certification schemes involved.

9. Managed forests can provide greater climate benefits than conservation forests.

The cessation of harvesting from forests, to allow them to sequester carbon, has been proposed as a climate change mitigation option that also can provide other benefits such as biodiversity protection. There are indeed many good reasons for protecting natural forests. With respect to climate, the IPCC has pointed out that forests managed for producing sawn timber, bioenergy and other wood products can make a greater contribution to climate change mitigation than forests managed for conservation alone. This is for three reasons. First, the sink strength diminishes as conservation forests approach maturity; production forests maintained in an actively growing state have high sink strength. Second, wood products displace GHG-intensive materials and fossil fuels. Third, carbon in forests is vulnerable to loss through natural events such as insect infestations or wildfires, as recently seen in many parts of the world including Australia and north America. Managing forests can help to increase the total amount of carbon sequestered in the forest and wood products carbon pools, reduce the risk of loss of sequestered forest carbon, and reduce fossil fuel use.

10. Managed forests produce wood for multiple products, not just bioenergy.

The picture, which is often presented, that whole forest stands are cut for bioenergy alone, is misleading. Forest biomass for bioenergy is typically obtained from forests managed for multiple purposes, including production of pulp and saw logs, and provision of other ecosystem services (e.g., air quality improvement, water purification, soil stabilization, biodiversity conservation). Bioenergy systems are components in value chains or processes that aim to produce forest products such as sawnwood, paper and chemicals. Stems that meet quality requirements are used to produce high value products such as sawnwood and wood panels, displacing carbon-intensive building materials such as concrete, steel and aluminium, while residues from forestry operations (tops, branches, thinnings, wood that is unsuitable for lumber) and wood processing residues are used for bioenergy. (e.g. [15]). When bioenergy from forest biomass displaces fossil fuels, this adds to the climate benefits of managed forestry.

Footnotes

1. For example: BBC News 23.02.2017 “Most energy schemes are a ‘disaster’ for climate change”; EASAC press release 10.09.2019 “EASAC’s Environmental Experts call for international action to restrict climate-damaging forest bioenergy schemes”; The Guardian 16.12.2019 “Converting coal plants to biomass could fuel climate crisis, scientists warn”; EASAC press release 26.08.2020 “Emissions Trading System: Stop Perverse Climate Impact of Biomass by Radically Reforming CO2 Accounting Rules”
2. For example: Brack, D., 2017. Woody biomass for power and heat: Impacts on the global climate. Environment, Energy and Resources Department, Chatham House.; Searchinger, T.D., Beringer, T., Holtsmark, B., Kammen, D.M., Lambin, E.F., Lucht, W., Raven, P. and van Ypersele, J.P., 2018. Europe’s renewable energy directive poised to harm global forests. Nature communications, 9(1), pp.1-4.; Sterman, J.D., et al., 2018. Does replacing coal with wood lower CO2 emissions? Dynamic lifecycle analysis of wood bioenergy. Environmental Research Letters, 13(1), p.015007.; Norton, M.et al., 2019. Serious mismatches continue between science and policy in forest bioenergy. GCB Bioenergy, 11(11), pp.1256-1263.
3. IEA Bioenergy, 2020. The use of forest biomass for climate change mitigation: dispelling some misconceptions. https://www.ieabioenergy.com/wp-content/uploads/2020/08/The-use-of-biomass-for-climate-change-mitigation-dispelling-some-misconceptions-August-2020-Rev1.pdf
4. UNFCCC reporting sectors Agriculture, Forestry and Other Land Use (AFOLU), formerly Land use, Land-use change and Forestry (LULUCF) sector.
5. However, there is incomplete coverage under the Kyoto Protocol because only some countries account for their GHG emissions in the second (2013- 2020) commitment period. Under the Paris Agreement, commencing 2020, all parties will include the land sector in their national accounting.
6. E.g. Chen, Q., Löschel, A., Pei, J., Peters, G.P., Xue, J. and Zhao, Z., 2019. Processing trade, foreign outsourcing and carbon emissions in China. Structural Change and Economic Dynamics, 49, pp.1-12.
7. see EU Renewable Energy Directive II, L 328/97 (point 102), ‘… harvesting in forests is carried out in a sustainable manner in forests where regeneration is ensured …’
8. EU Renewable Energy Directive II, L 328/131-132, Article 29, par. 6-9
9. Woodall, C. et al. (2015). The U.S. Forest Carbon Accounting Framework: Stocks and Stock Change, 1990-2016. USDA Forest Service, Newtown Square, PA. https://www.fs.fed.us/nrs/pubs/gtr/gtr_nrs154.pdf [November 28, 2019].
10. Dale, V. et al. (2017). Status and prospects for renewable energy using wood pellets from the southeastern United States. GCB Bioenergy (2017)
11. or up to 25 g CO2/MJ when fossil fuel is used for drying, which is uncommon in modern pellet plants.
12. J. Giuntoli, A. Agostini, R. Edwards, L. Marelli, 2015. Solid and gaseous bioenergy pathways: input values and GHG emissions. JRC Report EUR 27215 EN.; Jonker, J.G.G., Junginger, M. and Faaij, A., 2014. Carbon payback period and carbon offset parity point of wood pellet production in the South-eastern United States. Global Change Biology Bioenergy, 6(4), pp.371-389.
13. IPCC, 2018: Summary for Policymakers. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. World Meteorological Organization, Geneva, Switzerland, 32 pp. https://www.ipcc.ch/sr15/chapter/spm/
14. For example, the Montréal Process (https://www.montrealprocess.org/) countries contain 90% of the world’s temperate and boreal forests and produce 49% of the world’s roundwood.
15. Enviva’s website identifies that 17% of feedstock is mill residues, with the remainder being forest biomass. This forest biomass is not high-value timber, but rather a mix of thinnings, limbs and low-quality stems, consistent with the biomass sources identified by Matthews et al. (2018) as having low risk, and leading to low GHG emissions.

Electrofuels is a way to produce renewable energy carriers from renewable electricity that can be used in segments of the transport sector where direct electrification is more challenging to implement. Some electrofuels can be used directly in vehicles, ships and airplanes today, without further demands on distribution and tank infrastructure. The biggest challenges connected to electrofuels are associated with low energy efficiency and high costs for production.

This fact sheet is currently only available in Swedish.

Electric Road Systems (ERS) allow vehicles to charge whilst driving, with electricity provided from the road infrastructure either in the roadside area or within the road construction. There are three major concepts of ERS: conductive overhead lines/catenary technology, conductive rails, and wireless induction technologies. Currently, several ERS technologies are in different stages of demonstration, in Sweden as well as abroad.