Biomass 1

Biomass

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Biomass is biological material derived from living, or recently living organisms. It most often refers to plants orplant-derived materials which are specifically called lignocellulosic biomass.[1] As a renewable energy source,biomass can either be used directly via combustion to produce heat, or indirectly after converting it to various formsof biofuel. Conversion of biomass to biofuel can be achieved by different methods which are broadly classified into:thermal, chemical, and biochemical methods.Historically, humans have harnessed biomass-derived energy since the time when people began burning wood tomake fire.[2] Even in today's modern era, biomass is the only source of fuel for domestic use in many developingcountries.

IUPAC definition

Living systems and collection of organic substancesproduced by living systems that are exploitable as materials,including recent postmortem residues.

Note 1: Modified from ref. to be more general.

Note 2: In energy, fossil substances like oil and coal that areissued from the long-term transformation of substances of thebiomass are sometime considered as parts of the biomass.

Note 3: Living systems also produce minerals that are notintegrated in biomass.

Biomass sources

Wood is a typical source of biomass

Biomass is all biologically-produced matter based in carbon, hydrogenand oxygen. The estimated biomass production in the world is 146billion tons a year, consisting of mostly wild plant growth.Based on the source of biomass, biofuels are classified broadly intotwo major categories. First generation biofuels are derived fromsources such as sugarcane and corn starch etc. Sugars present in thesebiomass are fermented to produce bioethanol, an alcohol fuel. Whichcan be used directly in a fuel cell to produce electricity or serve as anadditive to gasoline. However, utilizing food based resource for fuelproduction aggravates food shortage problem. Second generationbiofuels on the other hand utilize non food based biomass sources such

as agriculture and municipal waste. It mostly consists of lignocellulosic biomass which is not edible and is a lowvalue waste for many industries. Despite being the favored alternative economical production of second generationbiofuel is not yet achieved due to technological issues. These issues arise mainly due to chemical inertness andstructural rigidity of lignocellulosic biomass.[3][4]

Wood remains the largest biomass energy source today; examples include forest residues (such as dead trees,branches and tree stumps), yard clippings, wood chips and even municipal solid waste. In the second sense, biomassincludes plant or animal matter that can be converted into fibers or other industrial chemicals, including biofuels.Industrial biomass can be grown from numerous types of plants, including miscanthus, switchgrass, hemp, corn,poplar, willow, sorghum, sugarcane, bamboo, and a variety of tree species, ranging from eucalyptus to oil palm(palm oil).Wood energy is derived by using lignocellulosic biomass (second generation biofuels) as fuel. This is either using harvested wood directly as a fuel, or collecting from wood waste streams. The largest source of energy from wood is pulping liquor or “black liquor,” a waste product from processes of the pulp, paper and paperboard industry.[citation

Biomass 3

needed]

Waste energy is the second-largest source of biomass energy.[citation needed] The main contributors of waste energyare municipal solid waste (MSW), manufacturing waste, and landfill gas. Energy derived from biomass is projectedto be the largest non-hydroelectric renewable resource of electricity in the U.S between 2000 and 2020.Plant energy is produced by crops specifically grown for use as fuel that offer high biomass output per hectare withlow input energy. Some examples of these plants are wheat, which typically yield 7.5–8 tons of grain per hectare,and straw, which typically yield 3.5–5 tons per hectare in the UK. The grain can be used for liquid transportationfuels while the straw can be burned to produce heat or electricity. Plant biomass can also be degraded from celluloseto glucose through a series of chemical treatments, and the resulting sugar can then be used as a first generationbiofuel. The use of plants as a biofuel source not only provides sustainability but also a way to reduce a majorgreenhouse gas, carbon dioxide.Biomass can be converted to other usable forms of energy like methane gas or transportation fuels like ethanol andbiodiesel. Rotting garbage, and agricultural and human waste, all release methane gas—also called "landfill gas" or"biogas." Crops, such as corn and sugar cane, can be fermented to produce the transportation fuel, ethanol. Biodiesel,another transportation fuel, can be produced from left-over food products like vegetable oils and animal fats.[5] Also,biomass to liquids (BTLs) and cellulosic ethanol are still under research.There is a great deal of research involving algal, or algae-derived, biomass due to the fact that it’s a non-foodresource and can be produced at rates 5 to 10 times those of other types of land-based agriculture, mainly corn andsoy. Once harvested, it can be fermented to produce biofuels such as ethanol, butanol, and methane, as well asbiodiesel and hydrogen. [citation needed] Algal biomass may be produced commercially for this specific purpose or as abyproduct of nutrient removal systems like the Algal Turf Scrubber used to re-oxygenate aquatic dead zones andwaste water treatment.[6] Efforts are being made to identify which species of algae are most suitable for energyproduction. Genetic engineering approaches could also be utilized to improve microalgae as a source of biofuel.The biomass used for electricity generation varies by region. Forest by-products, such as wood residues, are commonin the United States. Agricultural waste is common in Mauritius (sugar cane residue) and Southeast Asia (ricehusks). Animal husbandry residues, such as poultry litter, are common in the UK.[7]

Comparison of total biomass yields (dry basis)

Common commodity food cropsAlfafa: 4–6 tons/acre[8]

•• Algae:• Barley: grains – 1.6–2.8 tons/acre, straw – 0.9–2.5 tons/acre, total – 2.5–5.3 tons/acre[9]

• Canola: seeds –, stalks –, total –• Corn: grains – 3.2–4.9 tons/acre, stalks and stovers – 2.3–3.4 tons/acre, total – 5.5–8.3 tons/acre• Jerusalem artichokes: tubers –, stalks –, total –• Oats: grains – 1.4–5.4 tons/acre, straw – 1.9–3.2 tons/acre, total – 3.3–8.6 tons/acre• Potatoes: tubers –, tops –, total –• Rye: grains – 2.1–2.4 tons/acre, straw – 2.4–3.4 tons/acre, total – 4.5–5.8 tons/acre•• Sorghum:•• Soyabeans:•• Sugar beets:•• Sugar cane:

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•• Sun flowers:•• Sweet potatoes:•• Triticale:• Wheat: grains – 1.2–4.1 tons/acre, straw – 1.6–3.8 tons/acre, total – 2.8–7.9 tons/acre

Woody crops•• Coconuts:•• Gliricidia:•• Oil palm:•• Pine:•• Poplar:

Not yet in commercial planting•• Energy beets•• Energy cane• Giant miscanthus: 5–15 tons/acre [10]

• Switchgrass: 4–6 tons/acre

Genetically modified varieties•• Energy Sorghum

Biomass conversion process to useful energy

Thermal conversion

Biomass briquettes are an example fuel forproduction of dendrothermal energy

Thermal conversion processes use heat as the dominant mechanism toconvert biomass into another chemical form. The basic alternatives ofcombustion, torrefaction, pyrolysis, and gasification are separatedprincipally by the extent to which the chemical reactions involved areallowed to proceed (mainly controlled by the availability of oxygenand conversion temperature).

Energy created by burning biomass (fuel wood), also known asdendrothermal energy, is particularly suited for countries where thefuel wood grow more rapidly, e.g. tropical countries. There are anumber of other less common, more experimental or proprietarythermal processes that may offer benefits such as hydrothermalupgrading (HTU) and hydroprocessing. Some have been developed foruse on high moisture content biomass, including aqueous slurries, and allow them to be converted into moreconvenient forms. Some of the applications of thermal conversion are combined heat and power (CHP) andco-firing. In a typical dedicated biomass power plant, efficiencies range from 7–27% (HHV basis).[11] Biomasscofiring with coal, by contrast, typically occurs at efficiencies near those of the coal combustor (30–40%, HHVbasis).[12]

This type of energy is technically called dendrothermal energy, when used in power plants as a fuel for productionof energy.

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Chemical conversionA range of chemical processes may be used to convert biomass into other forms, such as to produce a fuel that ismore conveniently used, transported or stored, or to exploit some property of the process itself. Many of theseprocesses are based in large part on similar coal-based processes, such as Fischer-Tropsch synthesis, methanolproduction, olefins (ethylene and propylene), and similar chemical or fuel feedstocks. In most cases, the first stepinvolves gasification, which step generally is the most expensive and involves the greatest technical risk.[13] Biomassis more difficult to feed into a pressure vessel than coal or any liquid. Therefore, biomass gasification is frequentlydone at atmospheric pressure and causes incomplete combustion of biomass to produce a combustible gas consistingof carbon monoxide, hydrogen, and traces of methane. This gas mixture, called a producer gas, can provide fuel forvarious vital processes, such as internal combustion engines, as well as substitute for furnace oil in direct heatapplications.[14] Because any biomass material can undergo gasification, this process is far more attractive thanethanol or biomass production, where only particular biomass materials can be used to produce a fuel. In addition,biomass gasification is a desirable process due to the ease at which it can convert solid waste (such as wastesavailable on a farm) into producer gas, which is a very usable fuel.Conversion of biomass to biofuel can also be achieved via selective conversion of individual components ofbiomass. For example cellulose can be converted to intermediate platform chemical such a sorbitol, glucose,hydroxymethylfurfural etc. These chemical are then further reacted to produce hydrogen or hydrocarbon fuels.Biomass also has the potential to be converted to multiple commodity chemicals. Halomethanes have successfullybeen by produced using a combination of A. fermentans and engineered S. cerevisiae.[15] This method converts NaXsalts and unprocessed biomass such as switchgrass, sugar cane, corn stover, or poplar into halomethanes.S-adenosylmethionine which is naturally occurring in S. cerevisiae allows a methyl group to be transferred.Production levels of 150 mg L-1H-1 iodomethane were achieved. At these levels roughly 173000L of capacitywould need to be operated just to replace the United States’ need for iodomethane. However, an advantage of thismethod is that it uses NaI rather than I2; NaI is significantly less hazardous than I2. This method may be applied toproduce ethylene in the future.Other chemical processes such as converting straight and waste vegetable oils into biodiesel is transesterification.[16]

Biochemical conversion

A microbial electrolysis cell can be used to directly make hydrogen gas from plant matter.

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As biomass is a natural material, many highly efficient biochemical processes have developed in nature to breakdown the molecules of which biomass is composed, and many of these biochemical conversion processes can beharnessed.Biochemical conversion makes use of the enzymes of bacteria and other microorganisms to break down biomass. Inmost cases, microorganisms are used to perform the conversion process: anaerobic digestion, fermentation, andcomposting.

Environmental impact

A cogeneration station in Metz, France. The45MW boiler uses waste wood biomass as energy

source.

The biomass power generating industry in the United States, whichconsists of approximately 11,000 MW of summer operating capacityactively supplying power to the grid, produces about 1.4 percent of theU.S. electricity supply.

Currently, the New Hope Power Partnership is the largest biomasspower plant in North America. The 140 MW facility uses sugar canefiber (bagasse) and recycled urban wood as fuel to generate enoughpower for its large milling and refining operations as well as to supplyrenewable electricity for nearly 60,000 homes. The facility reducesdependence on oil by more than one million barrels per year, and byrecycling sugar cane and wood waste, preserves landfill space in urbancommunities in Florida.[17][18]

Using biomass as a fuel produces air pollution in the form of carbonmonoxide, carbon dioxide, NOx (nitrogen oxides), VOCs (volatileorganic compounds), particulates and other pollutants, in some cases at levels above those from traditional fuelsources such as coal or natural gas. Black carbon – a pollutant created by incomplete combustion of fossil fuels,biofuels, and biomass – is possibly the second largest contributor to global warming.[19] In 2009 a Swedish study ofthe giant brown haze that periodically covers large areas in South Asia determined that it had been principallyproduced by biomass burning, and to a lesser extent by fossil-fuel burning. Researchers measured a significantconcentration of 14C, which is associated with recent plant life rather than with fossil fuels.[20]

It is also proposed that use of biomass as an alternative source of energy will reduce further increase of carbondioxide in Earth's atmosphere. Carbon dioxide acts as a greenhouse gas by trapping heat leading to a rise in globalwarming. Biomass is sometimes considered a carbon neutral source of energy because the carbon dioxide releasedinto atmosphere by using biomass is recovered again by growth of new biomass. In contrast, use of fossil fuels,releases "new carbon" which has been locked away in the form of hydrocarbon fuels in the earths crust sincemillions of years.Biomass power plant size is often driven by biomass availability in close proximity as transport costs of the (bulky)fuel play a key factor in the plant's economics. It has to be noted, however, that rail and especially shipping onwaterways can reduce transport costs significantly, which has led to a global biomass market. To make small plantsof 1 MWel economically profitable those power plants have need to be equipped with technology that is able toconvert biomass to useful electricity with high efficiency such as ORC technology, a cycle similar to the water steampower process just with an organic working medium. Such small power plants can be found in Europe.[21][22][23][24]

On combustion, the carbon from biomass is released into the atmosphere as carbon dioxide (CO2). The amount ofcarbon stored in dry wood is approximately 50% by weight.[25] However, according to the Food and AgricultureOrganization of the United Nations, plant matter used as a fuel can be replaced by planting for new growth. Whenthe biomass is from forests, the time to recapture the carbon stored is generally longer, and the carbon storagecapacity of the forest may be reduced overall if destructive forestry techniques are employed.

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Industry professionals claim that a range of issues can affect a plant’s ability to comply with emissions standards.Some of these challenges, unique to biomass plants, include inconsistent fuel supplies and age. The type and amountof the fuel supply is completely reliant factors; the fuel can be in the form of building debris or agricultural waste(such as deforestation of invasive species or orchard trimmings). Furthermore, many of the biomass plants are old,use outdated technology and were not built to comply with today’s stringent standards. In fact, many are based ontechnologies developed during the term of U.S. President Jimmy Carter, who created the United States Departmentof Energy in 1977.The U.S. Energy Information Administration projected that by 2017, biomass is expected to be about twice asexpensive as natural gas, slightly more expensive than nuclear power, and much less expensive than solar panels. Inanother EIA study released, concerning the government’s plan to implement a 25% renewable energy standard by2025, the agency assumed that 598 million tons of biomass would be available, accounting for 12% of the renewableenergy in the plan.The adoption of biomass-based energy plants has been a slow but steady process. Over the pastdecadeWikipedia:Manual of Style/Dates and numbers#Chronological items, the production of these plants hasincreased 14%. In the United States, alternative electricity-production sources on the whole generate about 13% ofpower; of this fraction, biomass contributes approximately 11% of the alternative production. According to a studyconducted in early 2012, of the 107 operating biomass plants in the United States, 85 have been cited by federal orstate regulators for the violation of clean air or water standards laws over the past 5 years. This data also includesminor infractions.Despite harvesting, biomass crops may sequester carbon. For example, soil organic carbon has been observed to begreater in switchgrass stands than in cultivated cropland soil, especially at depths below 12 inches.[26] The grasssequesters the carbon in its increased root biomass. Typically, perennial crops sequester much more carbon thanannual crops due to much greater non-harvested living biomass, both living and dead, built up over years, and muchless soil disruption in cultivation.The proposal that biomass is carbon-neutral put forward in the early 1990s has been superseded by more recentscience that recognizes that mature, intact forests sequester carbon more effectively than cut-over areas. When atree’s carbon is released into the atmosphere in a single pulse, it contributes to climate change much more thanwoodland timber rotting slowly over decades. Current studies indicate that "even after 50 years the forest has notrecovered to its initial carbon storage" and "the optimal strategy is likely to be protection of the standingforest".[27]Wikipedia:Verifiability[28]

The pros and cons of biomass usage regarding carbon emissions are summed up in the ILUC factor. The biomassindustry has been trying to avoid or delay the usage of the ILUC factor.[29]

Forest-based biomass has recently come under fire from a number of environmental organizations, includingGreenpeace and the Natural Resources Defense Council, for the harmful impacts it can have on forests and theclimate. Greenpeace recently released a report entitled "Fuelling a BioMess" which outlines their concerns aroundforest-based biomass. Because any part of the tree can be burned, the harvesting of trees for energy productionencourages Whole-Tree Harvesting, which removes more nutrients and soil cover than regular harvesting, and can beharmful to the long-term health of the forest. In some jurisdictions, forest biomass is increasingly consisting ofelements essential to functioning forest ecosystems, including standing trees, naturally disturbed forests and remainsof traditional logging operations that were previously left in the forest. Environmental groups also cite recentscientific research which has found that it can take many decades for the carbon released by burning biomass to berecaptured by regrowing trees, and even longer in low productivity areas; furthermore, logging operations maydisturb forest soils and cause them to release stored carbon. In light of the pressing need to reduce greenhouse gasemissions in the short term in order to mitigate the effects of climate change, a number of environmental groups areopposing the large-scale use of forest biomass in energy production.[30][31]

Biomass 8

References[1] Biomass Energy Center (http:/ / www. biomassenergycentre. org. uk/ portal/ page?_pageid=76,15049& _dad=portal& _schema=PORTAL).

Biomassenergycentre.org.uk. Retrieved on 2012-02-28.[2] (http:/ / online. wsj. com/ article/ SB10001424052702303740704577524822063133842. html) Retrieved on 2012-04-12.[3] Renewable Energy World (http:/ / www. renewableenergyworld. com/ rea/ news/ article/ 2009/ 03/

ieas-report-on-1st-to-2nd-generation-biofuel-technologies) Retrieved on 2012-03-31.[4] biofuelstp.eu European Biofuels (http:/ / www. biofuelstp. eu/ fuelproduction. html) Retrieved on 2012-03-31.[5] Energy Kids (http:/ / www. eia. doe. gov/ kids/ energyfacts/ sources/ renewable/ biomass. html). Eia.doe.gov. Retrieved on 2012-02-28.[6] Mulbry, W., Kangas, P., & Kondrad, S. (2010, April). Toward scrubbing the bay: Nutrient removal using small algal turf scrubbers on

Chesapeake Bay tributaries. Ecological Engineering, 36(4), 536–541. doi:10.1016/j.ecoleng.2009.11.02[7] Frauke Urban and Tom Mitchell 2011. Climate change, disasters and electricity generation (http:/ / www. odi. org. uk/ resources/ details.

asp?id=5792& title=climate-change-disasters-electricity-generation). London: Overseas Development Institute and Institute of DevelopmentStudies

[8] Adding an alfalfa rotation with corn grown for ethanol improves energy efficiency, reduces environmental impact (http:/ / www. ars. usda.gov/ sp2UserFiles/ Place/ 36553000/ px-based_v3. 2/ educ-matrls/ pdfs/ FS_biomass-comparison. pdf), USDA Agriculture Research Services,Madison, Wisconsin

[9] Barley, Chemistry and Technology, MacGregor & Bhatty editors[10] Iowa State University, Department of Agronomy Factsheet, Biomass: Miscanthus (http:/ / www. extension. iastate. edu/ publications/ ag201.

pdf)[11] Owning and Operating Costs of Waste and Biomass Power Plants (http:/ / www. claverton-energy. com/

owning-and-operating-costs-of-waste-and-biomass-power-plants. html). Claverton-energy.com (2010-09-17). Retrieved on 2012-02-28.[12] Baxter, L. (2005). "Biomass-coal co-combustion: Opportunity for affordable renewable energy." Fuel 84(10): 1295–1302.[13] Liu, G., E. D. Larson, R. H. Williams, T. G. Kreutz and X. Guo (2011). "Making fischer-tropsch fuels and electricity from coal and biomass:

Performance and cost analysis." Energy & Fuels 25: 415–437.[14] Rajvanshi, A. K. “Biomass Gasification.” Alternative Energy in Agriculture, Vol. II, Ed. D. Yogi Goswami, CRC Press, 1986, pp. 83–102.[15] Alaimo, Peter & Amanda-Lynn Marshall (2010) “Useful Products from Complex Starting Materials: Common Chemicals from Biomass

Feedstocks” Chemistry – A European Journal 15 4970–4980.[16] Conversion technologies (http:/ / www. biomassenergycentre. org. uk/ portal/ page?_pageid=75,15179& _dad=portal& _schema=PORTAL).

Biomassenergycentre.org.uk. Retrieved on 2012-02-28.[17] Agreement for Generating Balancing Service (http:/ / www. ferc. gov/ EventCalendar/ Files/ 20070820160118-ER07-1070-000. pdf). (PDF)

. Retrieved on 2012-02-28.[18] Biomass: Can Renewable Power Grow on Trees? (http:/ / www. scientificamerican. com/ article. cfm?id=biomass-renewable-power-wood).

Scientificamerican.com. Retrieved on 2012-02-28.[19] 2009 State Of The World, Into a Warming World, Worldwatch Institute, 56–57, ISBN 978-0-393-33418-0[20] Biomass burning leads to Asian brown cloud (http:/ / pubs. acs. org/ isubscribe/ journals/ cen/ 87/ i04/ html/ 8704scic6. html), Chemical &

Engineering News, 87, 4, 31[21] Use of biomass by help of the ORC process (http:/ / www. gmk. info/ ORC_biomass. 548. html). Gmk.info. Retrieved on 2012-02-28.[22] How False Solutions to Climate Change Will Worsen Global Warming (http:/ / web. archive. org/ web/ 20081205110929/ http:/ / www.

globaljusticeecology. org/ globalwarming. php). globaljusticeecology.org[23] Biofuel crops may worsen global warming: study (http:/ / www. ctv. ca/ servlet/ ArticleNews/ story/ CTVNews/ 20080209/

biofuel_crops_080209/ 20080209). Ctv.ca (2008-02-09). Retrieved on 2012-02-28.[24] Biodiesel Will Not Drive Down Global Warming (http:/ / www. energy-daily. com/ reports/

Biodiesel_Will_Not_Drive_Down_Global_Warming_999. html). Energy-daily.com (2007-04-24). Retrieved on 2012-02-28.[25] Forest volume-to-biomass models and estimates of mass for live and standing dead trees of U.S. forests (http:/ / www. uvm. edu/ ~jcjenkin/

smith et al. 2003. pdf). (PDF) . Retrieved on 2012-02-28.[26] Soil Carbon under Switchgrass Stands and Cultivated Cropland (Interpretive Summary and Technical Abstract) (http:/ / www. ars. usda.

gov/ research/ publications/ Publications. htm?seq_no_115=164741,). USDA Agricultural Research Service, April 1, 2005[27] Jobs and Energy (http:/ / www. jobsandenergy. com). Jobs and Energy. Retrieved on 2012-02-28.[28] Edmunds, Joe; Richard Richets; Marshall Wise, "Future Fossil Fuel Carbon Emissions without Policy Intervention: A Review". In T. M. L.

Wigley, David Steven Schimel, The carbon cycle. Cambridge University Press, 2000, pp.171–189[29][29] "Biofuel Companies Question ARB's Inclusion of Indirect Effects in Low Carbon Fuel Standard". Green Car Congress. 2008-10-24.

Retrieved 2009-04-28.[30] Burning trees for energy puts Canadian forests and climate at risk: Greenpeace | Greenpeace Canada (http:/ / www. greenpeace. org/ canada/

Global/ canada/ report/ 2011/ 10/ ForestBiomess_Eng. pdf). November 2, 2011[31] NRDC fact sheet lays out biomass basics, campaign calls for action to tell EPA our forests aren't fuel | Sasha Lyutse's Blog | Switchboard,

from NRDC (http:/ / switchboard. nrdc. org/ blogs/ slyutse/ today_nrdc_and_our_partners. html). Switchboard.nrdc.org (2011-05-02).Retrieved on 2012-02-28.

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External links• Solid biomass EurObserv'ER barometer – 2012 PDF (http:/ / www. eurobserv-er. org/ pdf/ baro212biomassEu.

asp)• Biomass as an Energy Source – Växjö University (http:/ / www. vxu. se/ td/ english/ bioenergy/ blog/

biomass_as_an_energy_sour/ index. xml/ )

Article Sources and Contributors 10

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