This article is about technology aspects to produce a type of renewable energy. For production of biomass for bioenergy generation, seebiomass (energy).
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Bioenergy is a type ofrenewable energy that is derived from plants and animal waste.[1] Thebiomass that is used as input materials consists of recently living (but now dead) organisms, mainly plants.[2] Thus,fossil fuels are not regarded as biomass under this definition. Types of biomass commonly used for bioenergy include wood, food crops such as corn,energy crops and waste from forests, yards, or farms.[3]
Bioenergy can help withclimate change mitigation but in some cases the required biomass production can increasegreenhouse gas emissions or lead to localbiodiversity loss. The environmental impacts of biomass production can be problematic, depending on how the biomass is produced and harvested. But it still produces CO2; so long as the energy is derived from breaking chemical bonds.[4]
TheIEA's Net Zero by 2050 scenario calls for traditional bioenergy to be phased out by 2030, with modern bioenergy's share increasing from 6.6% in 2020 to 13.1% in 2030 and 18.7% in 2050.[5] Bioenergy has a significant climate change mitigation potential if implemented correctly.[6]: 637 Most of the recommendedpathways to limit global warming include substantial contributions from bioenergy in 2050 (average at 200 EJ).[7]: B 7.4
TheIPCC Sixth Assessment Report definesbioenergy as "energy derived from any form ofbiomass or its metabolic by-products".[8]: 1795 It goes on to definebiomass in this context as "organic material excluding the material that is fossilised or embedded in geological formations".[8]: 1795 This means thatcoal or otherfossil fuels is not a form of biomass in this context.
The termtraditional biomass for bioenergy means "the combustion of wood, charcoal, agricultural residues and/or animal dung for cooking or heating in open fires or ininefficient stoves as is common inlow-income countries".[8]: 1796
Since biomass can also be used as a fuel directly (e.g. wood logs), the termsbiomass andbiofuel have sometimes been used interchangeably. However, the termbiomass usually denotes the biological raw material the fuel is made of. The termsbiofuel orbiogas are generally reserved for liquid or gaseous fuels respectively.[9]
Wood and wood residues is the largest biomass energy source today. Wood can be used as a fuel directly or processed intopellet fuel or other forms of fuels. Other plants can also be used as fuel, for instancemaize,switchgrass,miscanthus andbamboo.[10] The mainwaste feedstocks are wood waste,agricultural waste,municipal solid waste, andmanufacturing waste. Upgrading raw biomass to higher grade fuels can be achieved by different methods, broadly classified as thermal, chemical, or biochemical:
Thermal conversion processes use heat as the dominant mechanism to upgrade biomass into a better and more practical fuel. The basic alternatives aretorrefaction,pyrolysis, andgasification, these are separated mainly by the extent to which the chemical reactions involved are allowed to proceed (mainly controlled by the availability of oxygen and conversion temperature).[11]
Manychemical conversions are based on established coal-based processes, such as theFischer-Tropsch synthesis.[12] Like coal, biomass can be converted into multiple commodity chemicals.[13]
Biochemical processes have developed in nature to break down the molecules of which biomass is composed, and many of these can be harnessed. In most cases, microorganisms are used to perform the conversion. The processes are calledanaerobic digestion,fermentation, andcomposting.[14]
Based on the source of biomass,biofuels are classified broadly into two major categories, depending if food crops are used or not:[16]
First-generation (or "conventional") biofuels are made fromfood sources grown on arable lands, such assugarcane andmaize. Sugars present in this biomass are fermented to producebioethanol, an alcohol fuel which serves as an additive to gasoline, or in afuel cell to produce electricity.Bioethanol is made byfermentation, mostly fromcarbohydrates produced insugar orstarch crops such ascorn,sugarcane, orsweet sorghum. Bioethanol is widely used in theUnited States and inBrazil.Biodiesel is produced from the oils in for instance rapeseed or sugar beets and is the most common biofuel in Europe.[citation needed]
Second-generation biofuels (also called "advanced biofuels") utilizenon-food-based biomass sources such asperennial energy crops and agricultural residues/waste. The feedstock used to make the fuels either grow onarable land but are byproducts of the main crop, or they are grown on marginal land. Waste from industry, agriculture, forestry and households can also be used for second-generation biofuels, using e.g.anaerobic digestion to producebiogas,gasification to producesyngas or by direct combustion.Cellulosic biomass, derived from non-food sources, such as trees and grasses, is being developed as afeedstock for ethanol production, and biodiesel can be produced from left-over food products like vegetable oils and animal fats.[citation needed]
The surface power production densities of a crop will determine how much land is required for production. The average lifecyclesurface power densities for biomass, wind, hydro and solar power production are 0.30 W/m2, 1 W/m2, 3 W/m2 and 5 W/m2, respectively (power in the form of heat for biomass, and electricity for wind, hydro and solar).[17] Lifecycle surface power density includes land used by all supporting infrastructure, manufacturing, mining/harvesting and decommissioning.
Another estimate puts the values at 0.08 W/m2 for biomass, 0.14 W/m2 for hydro, 1.84 W/m2 for wind, and 6.63 W/m2 for solar (median values, with none of the renewable sources exceeding 10 W/m2).[18]
Carbon capture and storage technology can be used to capture emissions from bioenergy power plants. This process is known asbioenergy with carbon capture and storage (BECCS) and can result in netcarbon dioxide removal from the atmosphere. However, BECCS can also result in net positive emissions depending on how the biomass material is grown, harvested, and transported. Deployment of BECCS at scales described in some climate change mitigation pathways would require converting large amounts of cropland.[19]
Greenhouse gas emissions from bioenergy can be low because when vegetation is harvested for bioenergy, new vegetation can grow that will absorb CO2 from the air throughphotosynthesis.[21] After the biomass is harvested, energy ("bioenergy") is extracted in useful forms (electricity, heat,biofuels, etc.) as the biomass is utilized through combustion, fermentation, pyrolysis or other conversion methods.[22] Using bioenergy releases CO2. In BECCS, some of the CO2 is captured before it enters the atmosphere, and stored underground usingcarbon capture and storage technology.[23] Under some conditions, BECCS canremove carbon dioxide from the atmosphere.[23]
The potential range of negative emissions from BECCS was estimated to be zero to 22gigatonnes per year.[24] As of 2024, there are large-scale 3 BECCS projects operating in the world.[25] Wide deployment of BECCS is constrained by cost and availability of biomass.[26][27] Since biomass production is land-intensive, deployment of BECCS can pose major risks to food production, human rights, and biodiversity.[28]
Alternative system boundaries for assessing climate effects of forest-based bioenergy. Option 1 (black) considers only the stack emissions; Option 2 (green) considers only the forest carbon stock; Option 3 (blue) considers the bioenergy supply chain; Option 4 (red) covers the whole bioeconomy, including wood products in addition to biomass.[29]
The climate impact of bioenergy varies considerably depending on where biomass feedstocks come from and how they are grown.[30] For example, burning wood for energy releases carbon dioxide; those emissions can be significantly offset if the trees that were harvested are replaced by new trees in a well-managed forest, as the new trees will absorb carbon dioxide from the air as they grow.[31] However, the establishment and cultivation of bioenergy crops candisplace natural ecosystems,degrade soils, and consume water resources and synthetic fertilisers.[32][33]
Approximately one-third of all wood used for traditional heating and cooking in tropical areas is harvested unsustainably.[34] Bioenergy feedstocks typically require significant amounts of energy to harvest, dry, and transport; the energy usage for these processes may emit greenhouse gases. In some cases, the impacts ofland-use change, cultivation, and processing can result in higher overall carbon emissions for bioenergy compared to using fossil fuels.[33][35]
Use of farmland for growing biomass can result inless land being available for growing food. In the United States, around 10% of motor gasoline has been replaced bycorn-based ethanol, which requires a significant proportion of the harvest.[36][37] In Malaysia and Indonesia, clearing forests to producepalm oil for biodiesel has led toserious social and environmental effects, as these forests are criticalcarbon sinks andhabitats for diverse species.[38][39] Sincephotosynthesis captures only a small fraction of the energy in sunlight, producing a given amount of bioenergy requires a large amount of land compared to other renewable energy sources.[40]
Bioenergy can eithermitigate (i.e. reduce) or increasegreenhouse gas emissions. Local environmental impacts can be problematic. For example, forests are sometimes cleared for the production of sugarcane-derivedbioethanol, like in the case of a large-scale project in Indonesia in 2025.[41]
Biomass production can create significant social and environmental pressure in the locations where the biomass is produced.[42] The impact is primarily related to the lowsurface power density of biomass. The low surface power density has the effect that much larger land areas are needed in order to produce the same amount of energy, compared to for instancefossil fuels.[43]
Long-distance transport of biomass have been criticised as wasteful and unsustainable,[44] and there have been protests against forest biomass export in Sweden[45] and Canada.[46]
In 2020 bioenergy produced 58 EJ (exajoules) of energy, compared to 172 EJ fromcrude oil, 157 EJ from coal, 138 EJ fromnatural gas, 29 EJ from nuclear, 16 EJ fromhydro and 15 EJ fromwind,solar andgeothermal combined.[47] Most of the global bioenergy is produced from forest resources.[48]: 3 [49]: 1
Generally, bioenergy expansion fell by 50% in 2020. China and Europe are the only two regions that reported significant expansion in 2020, adding 2 GW and 1.2 GW of bioenergy capacity, respectively.[50]
Almost all available sawmill residue is already being utilized for pellet production, so there is no room for expansion. For the bioenergy sector to significantly expand in the future, more of the harvested pulpwood must go to pellet mills. However, the harvest of pulpwood (tree thinnings) removes the possibility for these trees to grow old and therefore maximize their carbon holding capacity.[51]: 19 Compared to pulpwood, sawmill residues have lower net emissions: "Some types of biomass feedstock can be carbon-neutral, at least over a period of a few years, including in particular sawmill residues. These are wastes from other forest operations that imply no additional harvesting, and if otherwise burnt as waste or left to rot would release carbon to the atmosphere in any case."[51]: 68
^Biomass for heat and power: Technology brief E05(PDF) (Report). International Energy Agency – Energy Technology Systems Analysis Programme and International Renewable Energy Agency. 2015. Retrieved9 September 2025.
^Fajardy, Mathilde; Köberle, Alexandre; Mac Dowell, Niall; Fantuzzi, Andrea (2019)."BECCS deployment: a reality check"(PDF). Grantham Institute Imperial College London.
^Correa, Diego F.; Beyer, Hawthorne L.; Fargione, Joseph E.; Hill, Jason D.; Possingham, Hugh P.; Thomas-Hall, Skye R.; Schenk, Peer M. (June 2019). "Towards the implementation of sustainable biofuel production systems".Renewable and Sustainable Energy Reviews.107:250–263.Bibcode:2019RSERv.107..250C.doi:10.1016/j.rser.2019.03.005.
Liu, Guangjian; Larson, Eric D.; Williams, Robert H.; Kreutz, Thomas G.; Guo, Xiangbo (2011-01-20). "Making Fischer−Tropsch Fuels and Electricity from Coal and Biomass: Performance and Cost Analysis".Energy & Fuels.25 (1). American Chemical Society (ACS):415–437.Bibcode:2011EnFue..25..415L.doi:10.1021/ef101184e.ISSN0887-0624.
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