Biomass

Biomass in the sense discussed here is plant or animal material not used for food or feed; it can be purposely grown energy crops (e.g. miscanthus, switchgrass), wood or forest residues, waste from food crops (wheat straw, bagasse), horticulture (yard waste), food processing (corn cobs), animal farming (manure, rich in nitrogen and phosphorus), or human waste from sewage plants.[1] Biomass is used for energy production, heat production, or in various industrial processes as raw material for a range of products.[2]

Burning plant-derived biomass releases CO2, but it has still been classified as a renewable energy source in the EU and UN legal frameworks because photosynthesis cycles the CO2 back into new crops. In some cases, this recycling of CO2 from plants to atmosphere and back into plants can even be CO2 negative, as a relatively large portion of the CO2 is moved to the soil during each cycle.

Cofiring with biomass has increased in coal power plants, because it makes it possible to release less CO2 without the cost assosicated with building new infrastructure. Co-firing is not without issues however, often an upgrade of the biomass is beneficiary. Upgrading to higher grade fuels can be achieved by different methods, broadly classified as thermal, chemical, or biochemical (see below).

Biomass feedstocks

Steven's Croft Biomass Plant - geograph.org.uk - 800207
Biomass plant in Scotland.
Waste wood 1
Wood waste outside biomass power plant.
Iznaga-Bagasse
Bagasse is the remaining waste after sugar canes have been crushed to extract their juice.
Miscanthus Bestand
Miscanthus x giganteus energy crop, Germany.

Historically, humans have harnessed biomass-derived energy since the time when people began burning wood to make fire.[4] Even in 2019, biomass is the only source of fuel for domestic use in many developing countries. All biomass is biologically-produced matter based in carbon, hydrogen and oxygen. The estimated biomass production in the world is approximately 100 billion metric tons of carbon per year, about half in the ocean and half on land.[5]

Wood and residues from wood, for instance spruce, birch, eacalyptus, willow, oil palm, remains the largest biomass energy source today.[4] It is used directly as a fuel or processed into pellet fuel or other forms of fuels. Biomass also includes plant or animal matter that can be converted into fuel, fibers or industrial chemicals. There are numerous types of plants, including corn, switchgrass, miscanthus, hemp, sorghum, sugarcane, and bamboo.[6] The main waste energy feedstocks are wood waste, agricultural waste, municipal solid waste, manufacturing waste, and landfill gas. Sewage sludge is another source of biomass. There is ongoing research involving algae or algae-derived biomass.[7] Other biomass feedstocks are enzymes or bacteria from various sources, grown in cell cultures or hydroponics.[8][9]

Based on the source of biomass, biofuels are classified broadly into two major categories:

First-generation biofuels are derived from food sources, such as sugarcane and corn starch. Sugars present in this biomass are fermented to produce bioethanol, an alcohol fuel which serve as an additive to gasoline, or in a fuel cell to produce electricity.[10]

Second-generation biofuels utilize non-food-based biomass sources such as perennial energy crops (low input crops), and agricultural/municipal waste. There is huge potential for second generation biofuels but the resources are currently under-utilized.[11]

Biomass conversion

Thermal conversions

Stacks and stacks of bales - geograph.org.uk - 566481
Straw bales

Thermal conversion processes use heat as the dominant mechanism to upgrade biomass into a better and more practical fuel. The basic alternatives are torrefaction, pyrolysis, and gasification, these are separated principally by the extent to which the chemical reactions involved are allowed to proceed (mainly controlled by the availability of oxygen and conversion temperature).[12]

There are other less common, more experimental or proprietary thermal processes that may offer benefits, such as hydrothermal upgrading. Some have been developed for use on high moisture content biomass, including aqueous slurries, and allow them to be converted into more convenient forms.

Chemical conversion

A range of chemical processes may be used to convert biomass into other forms, such as to produce a fuel that is more practical to store, transport and use, or to exploit some property of the process itself. Many of these processes are based in large part on similar coal-based processes, such as the Fischer-Tropsch synthesis.[13] Biomass can be converted into multiple commodity chemicals.[14]

Biochemical conversion

As biomass is a natural material, many highly efficient biochemical processes have developed in nature to break down the molecules of which biomass is composed, and many of these biochemical conversion processes can be harnessed. In most cases, microorganisms are used to perform the conversion process: anaerobic digestion, fermentation, and composting.[15]

Glycoside hydrolases are the enzymes involved in the degradation of the major fraction of biomass, such as polysaccharides present in starch and lignocellulose. Thermostable variants are gaining increasing roles as catalysts in biorefining applications, since recalcitrant biomass often needs thermal treatment for more efficient degradation.[16]

Electrochemical conversion

Biomass can be directly converted to electrical energy via electrochemical (electrocatalytic) oxidation of the material. This can be performed directly in a direct carbon fuel cell,[17] direct liquid fuel cells such as direct ethanol fuel cell, a direct methanol fuel cell, a direct formic acid fuel cell, a L-ascorbic Acid Fuel Cell (vitamin C fuel cell),[18] and a microbial fuel cell.[19] The fuel can also be consumed indirectly via a fuel cell system containing a reformer which converts the biomass into a mixture of CO and H2 before it is consumed in the fuel cell.[20]

Environmental impact

On combustion, the carbon from biomass is released into the atmosphere as carbon dioxide (CO2). After a few months, or years, or decades, the CO2 has been absorbed back by growing plants or trees. However, the carbon storage capacity of forests may be reduced overall if destructive forestry techniques are employed.[21][22][23][24]

All biomass crops sequester carbon. For example, soil organic carbon has been observed to be greater below switchgrass crops than under cultivated cropland, especially at depths below 30 cm (12 in).[25] For Miscanthus x giganteus, McCalmont et al. found accumulation rates ranging from 0.42 to 3.8 tonnes per hectare per year, [26] with a mean accumulation rate of 1.84 tonne (0.74 tonnes per acre per year), [27] or 20% of total harvested carbon per year. [28] The grass sequesters carbon in its continually increasing root biomass, toghether with carbon input from fallen leaves. Typically, perennial crops sequester significantly more carbon than annual crops due to greater non-harvested living biomass (roots and residues), both living and dead, built up over years, and less soil disruption in cultivation.

GHG (CO2 and N2O) life cycle emissions for Miscanthus x giganteus and SRC Poplar
GHG / CO2 / carbon negativity for Miscanthus x giganteus production pathways.
Relationship between existing amount of soil organic carbon and soil's potential for carbon sequestration (for Miscanthus x giganteus)
Relationship between above-ground yield (diagonal lines), soil organic carbon (X axis), and soil's potential for successful/unsuccessful carbon sequestration (Y axis). Basically, the higher the yield, the more land is usable as a GHG mitigation tool (including relatively carbon rich land.)

The simple proposal that biomass is carbon-neutral put forward in the early 1990s has been superseded by the more nuanced proposal that for a particular bioenergy project to be carbon neutral, the total carbon sequestered by a bioenergy crop's root system must compensate for all the emissions from the related, aboveground bioenergy project. This includes any emissions caused by direct or indirect land use change. Many first generation bioenergy projects are not carbon neutral given these demands. Some have even higher total GHG emissions than some fossil based alternatives.[29][30] [31] Transport fuels might be worse than solid fuels in this regard. [32]

Some are carbon neutral or even negative, though, especially perennial crops. The amount of carbon sequestrated and the amount of GHG (greenhouse gases) emitted will determine if the total GHG life cycle cost of a bio-energy project is positive, neutral or negative. Whitaker et al. estimates that for Miscanthus x giganteus, GHG neutrality and even negativity is within reach. A carbon negative life cycle is possible if the total below-ground carbon accumulation more than compensates for the above-ground total life-cycle GHG emissions.

The graphic on the right displays two CO2 negative Miscanthus x giganteus production pathways, represented in gram CO2-equivalents per megajoule. The yellow diamonds represent mean values. [33] Successful sequestration is dependent on planting sites, as the best soils for sequestration are those that are currently low in carbon. The varied results displayed in the graph highlights this fact. [34] For the UK, successful sequestration is expected for arable land over most of England and Wales, with unsucessful sequestration expected in parts of Scotland, due to already carbon rich soils (existing woodland) plus lower yields. Soils already rich in carbon includes peatland and mature forest. Grassland can also be carbon rich, however Milner et al. argues that the most successful carbon sequestration in the UK takes place below improved grasslands. [35] The bottom graphic displays the estimated yield necessary to compensate for the disturbance caused by planting plus lifecycle GHG-emissions for the related above-ground operation.

Forest-based biomass projects has received criticism for ineffective GHG mitigation from a number of environmental organizations, including Greenpeace and the Natural Resources Defense Council. Environmental groups also argue that it might take decades for the carbon released by burning biomass to be recaptured by new trees. Biomass burning produces air pollution in the form of carbon monoxide, volatile organic compounds, particulates and other pollutants.[36][37][38] In 2009 a Swedish study of the giant brown haze that periodically covers large areas in South Asia determined that two thirds of it had been principally produced by residential cooking and agricultural burning, and one third by fossil-fuel burning.[39] Use of wood biomass as an industrial fuel produce fewer particulates and other pollutants than the burning seen in wildfires or open field fires.[40]

See also

References

  1. ^ "Biomass - Energy Explained, Your Guide To Understanding Energy". U.S. Energy Information Administration. June 21, 2018.
  2. ^ Ur-Rehman, S; Mushtaq, Z; Zahoor, T; Jamil, A; Murtaza, MA (2015). "Xylitol: a review on bioproduction, application, health benefits, and related safety issues". Critical Reviews in Food Science and Nutrition. 55 (11): 1514–28. doi:10.1080/10408398.2012.702288. PMID 24915309.
  3. ^ Nagel, B.; Dellweg, H.; Gierasch, L. M. (1 January 1992). "Glossary for chemists of terms used in biotechnology (IUPAC Recommendations 1992)". Pure and Applied Chemistry. 64 (1): 143–168. doi:10.1351/pac199264010143.
  4. ^ a b [1] Retrieved on 2012-04-12.
  5. ^ Field, C. B.; Behrenfeld, M. J.; Randerson, J. T.; Falkowski, P. (1998). "Primary Production of the Biosphere: Integrating Terrestrial and Oceanic Components" (PDF). Science (Submitted manuscript). 281 (5374): 237–240. Bibcode:1998Sci...281..237F. doi:10.1126/science.281.5374.237. PMID 9657713.
  6. ^ Darby, Thomas. "What Is Biomass Renewable Energy". Real World Energy. Archived from the original on 2014-06-08. Retrieved 12 June 2014.
  7. ^ Randor Radakovits; Robert E. Jinkerson; Al Darzins; Matthew C. Posewitz1 (2010). "Genetic Engineering of Algae for Enhanced Biofuel Production". Eukaryotic Cell. 9 (4): 486–501. doi:10.1128/EC.00364-09. PMC 2863401. PMID 20139239.
  8. ^ Biomass-to-Fuel Conversion (Princeton University USA)
  9. ^ The Nocera lab
  10. ^ Martin, Marshall A. (1 November 2010). "First generation biofuels compete". New Biotechnology. 27 (5): 596–608. doi:10.1016/j.nbt.2010.06.010. PMID 20601265.
  11. ^ Kosinkova, Jana; Doshi, Amar; Maire, Juliette; Ristovski, Zoran; Brown, Richard; Rainey, Thomas (September 2015). "Measuring the regional availability of biomass for biofuels and the potential for microalgae". Renewable and Sustainable Energy Reviews. 49: 1271–1285. doi:10.1016/j.rser.2015.04.084.
  12. ^ Akhtar, A., Krepl, V., & Ivanova, T. (2018). A Combined Overview of Combustion, Pyrolysis, and Gasification of Biomass. Energy & Fuels, 32(7), 7294–7318.
  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. ^ Conversion technologies. Biomassenergycentre.org.uk. Retrieved on 2012-02-28.
  15. ^ "Biochemical Conversion of Biomass". BioEnergy Consult. 2014-05-29. Retrieved 2016-10-18.
  16. ^ Linares-Pastén, J. A.; Andersson, M; Nordberg karlsson, E (2014). "Thermostable glycoside hydrolases in biorefinery technologies" (PDF). Current Biotechnology. 3 (1): 26–44. doi:10.2174/22115501113026660041.
  17. ^ Munnings, C.; Kulkarni, A.; Giddey, S.; Badwal, S.P.S. (August 2014). "Biomass to power conversion in a direct carbon fuel cell". International Journal of Hydrogen Energy. 39 (23): 12377–12385. doi:10.1016/j.ijhydene.2014.03.255.
  18. ^ Kim, Ye Eun (17 May 2011). "Surface Modifications of a Carbon Anode Catalyst by Control of Functional Groups for Vitamin C Fuel Cells". Electrocatalysis. 2 (3): 200–206. doi:10.1007/s12678-011-0055-0.
  19. ^ Knight, Chris (2013). "Chapter 6 – Application of Microbial Fuel Cells to Power Sensor Networks for Ecological Monitoring". Wireless Sensor Networks and Ecological Monitoring. Smart Sensors, Measurement and Instrumentation. 3. pp. 151–178. doi:10.1007/978-3-642-36365-8_6. ISBN 978-3-642-36364-1.
  20. ^ Badwal, Sukhvinder P. S.; Giddey, Sarbjit S.; Munnings, Christopher; Bhatt, Anand I.; Hollenkamp, Anthony F. (24 September 2014). "Emerging electrochemical energy conversion and storage technologies (open access)". Frontiers in Chemistry. 2: 79. Bibcode:2014FrCh....2...79B. doi:10.3389/fchem.2014.00079. PMC 4174133. PMID 25309898.
  21. ^ Prasad, Ram. "SUSTAINABLE FOREST MANAGEMENT FOR DRY FORESTS OF SOUTH ASIA". Food and Agriculture Organization of the United Nations. Retrieved 11 August 2010.
  22. ^ "Treetrouble: Testimonies on the Negative Impact of Large-scale Tree Plantations prepared for the sixth Conference of the Parties of the Framework Convention on Climate Change". Friends of the Earth International. Archived from the original on 26 July 2011. Retrieved 11 August 2010.
  23. ^ Laiho, Raija; Sanchez, Felipe; Tiarks, Allan; Dougherty, Phillip M.; Trettin, Carl C. "Impacts of intensive forestry on early rotation trends in site carbon pools in the southeastern US". United States Department of Agriculture. Retrieved 11 August 2010.
  24. ^ "THE FINANCIAL AND INSTITUTIONAL FEASIBILITY OF SUSTAINABLE FOREST MANAGEMENT". Food and Agriculture Organization of the United Nations. Retrieved 11 August 2010.
  25. ^ Soil Carbon under Switchgrass Stands and Cultivated Cropland (Interpretive Summary and Technical Abstract). USDA Agricultural Research Service, April 1, 2005
  26. ^ «[…] it seems likely that arable land converted to Miscanthus will sequester soil carbon; of the 14 comparisons, 11 showed overall increases in SOC over their total sample depths with suggested accumulation rates ranging from 0.42 to 3.8 Mg C ha-1 yr-1. Only three arable comparisons showed lower SOC stocks under Miscanthus, and these suggested insignificant losses between 0.1 and 0.26 Mg ha-1 yr-1.» McCalmont, J. P., Hastings, A. , McNamara, N. P., Richter, G. M., Robson, P. , Donnison, I. S. and Clifton‐Brown, J. (2017), Environmental costs and benefits of growing Miscanthus for bioenergy in the UK. GCB Bioenergy, 9, page 493. https://doi.org/10.1111/gcbb.12294  This article incorporates text available under the CC BY 4.0 license. (The CC BY 4.0 licence means that everyone have the right to reuse the text that is quoted here, or other parts of the original article itself, if they credit the authors. More info: https://en.wikipedia.org/wiki/Creative_Commons_license)
  27. ^ «The correlation between plantation age and SOC can be seen in Fig. 6, […] the trendline suggests a net accumulation rate of 1.84 Mg C ha-1 yr-1 with similar levels to grassland at equilibrium.» McCalmont, J. P., Hastings, A. , McNamara, N. P., Richter, G. M., Robson, P. , Donnison, I. S. and Clifton‐Brown, J. (2017), Environmental costs and benefits of growing Miscanthus for bioenergy in the UK. GCB Bioenergy, 9, page 496. https://doi.org/10.1111/gcbb.12294  This article incorporates text available under the CC BY 4.0 license. (The CC BY 4.0 licence means that everyone have the right to reuse the text that is quoted here, or other parts of the original article itself, if they credit the authors. More info: https://en.wikipedia.org/wiki/Creative_Commons_license)
  28. ^ Given the EU average yield of 18.8 tonnes dry matter per hectare per year (see Clifton-Brown, above), and 48% carbon content (see Kahle et al,, above).
  29. ^ «The environmental costs and benefits of bioenergy have been the subject of significant debate, particularly for first‐generation biofuels produced from food (e.g. grain and oil seed). Studies have reported life‐cycle GHG savings ranging from an 86% reduction to a 93% increase in GHG emissions compared with fossil fuels (Searchinger et al., 2008; Davis et al., 2009; Liska et al., 2009; Whitaker et al., 2010). In addition, concerns have been raised that N2O emissions from biofuel feedstock cultivation could have been underestimated (Crutzen et al., 2008; Smith & Searchinger, 2012) and that expansion of feedstock cultivation on agricultural land might displace food production onto land with high carbon stocks or high conservation value (i.e. iLUC) creating a carbon debt which could take decades to repay (Fargione et al., 2008). Other studies have shown that direct nitrogen‐related emissions from annual crop feedstocks can be mitigated through optimized management practices (Davis et al., 2013) or that payback times are less significant than proposed (Mello et al., 2014). However, there are still significant concerns over the impacts of iLUC, despite policy developments aimed at reducing the risk of iLUC occurring (Ahlgren & Di Lucia, 2014; Del Grosso et al., 2014).» Whitaker, J. , Field, J. L., Bernacchi, C. J., Cerri, C. E., Ceulemans, R. , Davies, C. A., DeLucia, E. H., Donnison, I. S., McCalmont, J. P., Paustian, K. , Rowe, R. L., Smith, P. , Thornley, P. and McNamara, N. P. (2018), Consensus, uncertainties and challenges for perennial bioenergy crops and land use. GCB Bioenergy, 10: 150-164. https://doi.org/10.1111/gcbb.12488  This article incorporates text available under the CC BY 4.0 license. (The CC BY 4.0 licence means that everyone have the right to reuse the text that is quoted here, or other parts of the original article itself, if they credit the authors. More info: https://en.wikipedia.org/wiki/Creative_Commons_license)
  30. ^ «The impact of growing bioenergy and biofuel feedstock crops has been of particular concern, with some suggesting the greenhouse gas (GHG) balance of food crops used for ethanol and biodiesel may be no better or worse than fossil fuels (Fargione et al., 2008; Searchinger et al., 2008). This is controversial, as the allocation of GHG emissions to the management and the use of coproducts can have a large effect on the total carbon footprint of resulting bioenergy products (Whitaker et al., 2010; Davis et al., 2013). The potential consequences of land use change (LUC) to bioenergy on GHG balance through food crop displacement or ‘indirect’ land use change (iLUC) are also an important consideration (Searchinger et al., 2008).» Milner, S. , Holland, R. A., Lovett, A. , Sunnenberg, G. , Hastings, A. , Smith, P. , Wang, S. and Taylor, G. (2016), Potential impacts on ecosystem services of land use transitions to second‐generation bioenergy crops in GB. GCB Bioenergy, 8: 317-333. https://doi.org/10.1111/gcbb.12263  This article incorporates text available under the CC BY 4.0 license. (The CC BY 4.0 licence means that everyone have the right to reuse the text that is quoted here, or other parts of the original article itself, if they credit the authors. More info: https://en.wikipedia.org/wiki/Creative_Commons_license)
  31. ^ «While the initial premise regarding bioenergy was that carbon recently captured from the atmosphere into plants would deliver an immediate reduction in GHG emission from fossil fuel use, the reality proved less straightforward. Studies suggested that GHG emission from energy crop production and land-use change might outweigh any CO2 mitigation (Searchinger et al., 2008; Lange, 2011). Nitrous oxide (N2O) production, with its powerful global warming potential (GWP), could be a significant factor in offsetting CO2 gains (Crutzen et al., 2008) as well as possible acidification and eutrophication of the surrounding environment (Kim & Dale, 2005). However, not all biomass feedstocks are equal, and most studies critical of bioenergy production are concerned with biofuels produced from annual food crops at high fertilizer cost, sometimes using land cleared from natural ecosystems or in direct competition with food production (Naik et al., 2010). Dedicated perennial energy crops, produced on existing, lower grade, agricultural land, offer a sustainable alternative with significant savings in greenhouse gas emissions and soil carbon sequestration when produced with appropriate management (Crutzen et al., 2008; Hastings et al., 2008, 2012; Cherubini et al., 2009; Don- dini et al., 2009a; Don et al., 2012; Zatta et al., 2014; Rich- ter et al., 2015).» McCalmont, J. P., Hastings, A. , McNamara, N. P., Richter, G. M., Robson, P. , Donnison, I. S. and Clifton‐Brown, J. (2017), Environmental costs and benefits of growing Miscanthus for bioenergy in the UK. GCB Bioenergy, 9, page 490. https://doi.org/10.1111/gcbb.12294  This article incorporates text available under the CC BY 4.0 license. (The CC BY 4.0 licence means that everyone have the right to reuse the text that is quoted here, or other parts of the original article itself, if they credit the authors. More info: https://en.wikipedia.org/wiki/Creative_Commons_license)
  32. ^ «Significant reductions in GHG emissions have been demonstrated in many LCA studies across a range of bioenergy technologies and scales (Thornley et al., 2009, 2015). The most significant reductions have been noted for heat and power cases. However, some other studies (particularly on transport fuels) have indicated the opposite, that is that bioenergy systems can increase GHG emissions (Smith & Searchinger, 2012) or fail to achieve increasingly stringent GHG savings thresholds. A number of factors drive this variability in calculated savings, but we know that where significant reductions are not achieved or wide variability is reported there is often associated data uncertainty or variations in the LCA methodology applied (Rowe et al., 2011). For example, data uncertainty in soil carbon stock change following LUC has been shown to significantly influence the GHG intensity of biofuel production pathways (Fig. 3), whilst the shorter term radiative forcing impact of black carbon particles from the combustion of biomass and biofuels also represents significant data uncertainty (Bond et al., 2013).» Whitaker, J. , Field, J. L., Bernacchi, C. J., Cerri, C. E., Ceulemans, R. , Davies, C. A., DeLucia, E. H., Donnison, I. S., McCalmont, J. P., Paustian, K. , Rowe, R. L., Smith, P. , Thornley, P. and McNamara, N. P. (2018), Consensus, uncertainties and challenges for perennial bioenergy crops and land use. GCB Bioenergy, 10: 150-164. https://doi.org/10.1111/gcbb.12488  This article incorporates text available under the CC BY 4.0 license. (The CC BY 4.0 licence means that everyone have the right to reuse the text that is quoted here, or other parts of the original article itself, if they credit the authors. More info: https://en.wikipedia.org/wiki/Creative_Commons_license)
  33. ^ «A life‐cycle perspective of the relative contributions and variability of soil carbon stock change and nitrogen‐related emissions to the net GHG intensity (g CO2‐eq MJ−1) [gram CO2-equivalents per megajoule] of biofuel production via select production pathways (feedstock/prior land‐use/fertilizer/conversion type). Positive and negative contributions to life‐cycle GHG emissions are plotted sequentially and summed as the net GHG intensity for each biofuel scenario, relative to the GHG intensity of conventional gasoline (brown line) and the 50% and 60% GHG savings thresholds (US Renewable Fuel Standard and Council Directive 2015/1513); orange and red lines, respectively. Default life‐cycle GHG source estimates are taken from Wang et al. (2012) and Dunn et al. (2013); direct N2O emissions from Fig. 1; and soil carbon stock change (0–100 cm depth) from Qin et al. (2016). See Appendix S1 for detailed methods.» Whitaker, J. , Field, J. L., Bernacchi, C. J., Cerri, C. E., Ceulemans, R. , Davies, C. A., DeLucia, E. H., Donnison, I. S., McCalmont, J. P., Paustian, K. , Rowe, R. L., Smith, P. , Thornley, P. and McNamara, N. P. (2018), Consensus, uncertainties and challenges for perennial bioenergy crops and land use. GCB Bioenergy, 10: 150-164. https://doi.org/10.1111/gcbb.12488  This article incorporates text available under the CC BY 4.0 license. (The CC BY 4.0 licence means that everyone have the right to reuse the text that is quoted here, or other parts of the original article itself, if they credit the authors. More info: https://en.wikipedia.org/wiki/Creative_Commons_license)
  34. ^ «Whilst these values represent the extremes, they demonstrate that site selection for bioenergy crop cultivation can make the difference between large GHG savings or losses, shifting life‐cycle GHG [green house gas] emissions above or below mandated thresholds. Reducing uncertainties in ∆C [carbon increase or decrease] following LUC [land use change] is therefore more important than refining N2O [nitrous oxide] emission estimates (Berhongaray et al., 2017). Knowledge on initial soil carbon stocks could improve GHG savings achieved through targeted deployment of perennial bioenergy crops on low carbon soils (see section 2). […] The assumption that annual cropland provides greater potential for soil carbon sequestration than grassland appears to be over‐simplistic, but there is an opportunity to improve predictions of soil carbon sequestration potential using information on the initial soil carbon stock as a stronger predictor of ∆C [change in carbon amount] than prior land use.» Whitaker, J. , Field, J. L., Bernacchi, C. J., Cerri, C. E., Ceulemans, R. , Davies, C. A., DeLucia, E. H., Donnison, I. S., McCalmont, J. P., Paustian, K. , Rowe, R. L., Smith, P. , Thornley, P. and McNamara, N. P. (2018), Consensus, uncertainties and challenges for perennial bioenergy crops and land use. GCB Bioenergy, 10: 150-164. https://doi.org/10.1111/gcbb.12488  This article incorporates text available under the CC BY 4.0 license. (The CC BY 4.0 licence means that everyone have the right to reuse the text that is quoted here, or other parts of the original article itself, if they credit the authors. More info: https://en.wikipedia.org/wiki/Creative_Commons_license)
  35. ^ «Fig. 3 confirmed either no change or a gain of SOC [soil organic carbon] (positive) through planting Miscanthus on arable land across England and Wales and only a loss of SOC (negative) in parts of Scotland. The total annual SOC change across GB in the transition from arable to Miscanthus if all nonconstrained land was planted with would be 3.3 Tg C yr−1 [3.3 million tonnes carbon per year]. The mean changes for SOC for the different land uses were all positive when histosols were excluded, with improved grasslands yielding the highest Mg C ha−1 yr−1 [tonnes carbon per hectare per year] at 1.49, followed by arable lands at 1.28 and forest at 1. Separating this SOC change by original land use (Fig. 4) reveals that there are large regions of improved grasslands which, if planted with bioenergy crops, are predicted to result in an increase in SOC. A similar result was found when considering the transition from arable land; however for central eastern England, there was a predicted neutral effect on SOC. Scotland, however, is predicted to have a decrease for all land uses, particularly for woodland due mainly to higher SOC and lower Miscanthus yields and hence less input.» Milner, S. , Holland, R. A., Lovett, A. , Sunnenberg, G. , Hastings, A. , Smith, P. , Wang, S. and Taylor, G. (2016), Potential impacts on ecosystem services of land use transitions to second‐generation bioenergy crops in GB. GCB Bioenergy, 8: 317-333. https://doi.org/10.1111/gcbb.12263  This article incorporates text available under the CC BY 4.0 license. (The CC BY 4.0 licence means that everyone have the right to reuse the text that is quoted here, or other parts of the original article itself, if they credit the authors. More info: https://en.wikipedia.org/wiki/Creative_Commons_license)
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External links

Biochar

Biochar is charcoal used as a soil amendment. Biochar is a stable solid, rich in carbon, and can endure in soil for thousands of years. Like most charcoal, biochar is made from biomass via pyrolysis. Biochar is under investigation as an approach to carbon sequestration, as it has the potential to help mitigate climate change. It results in processes related to pyrogenic carbon capture and storage (PyCCS).

Independently, biochar can increase soil fertility of acidic soils (low pH soils), increase agricultural productivity, and provide protection against some foliar and soil-borne diseases. Regarding the definition from the production part, biochar is defined by the International Biochar Initiative as "The solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment".

Bioenergy

Bioenergy is renewable energy made available from materials derived from biological sources. Biomass is any organic material which has stored sunlight in the form of chemical energy. As a fuel it may include wood, wood waste, straw, and other crop residues, manure, sugarcane, and many other by-products from a variety of agricultural processes. By 2010, there was 35 GW (47,000,000 hp) of globally installed bioenergy capacity for electricity generation, of which 7 GW (9,400,000 hp) was in the United States.In its most narrow sense it is a synonym to biofuel, which is fuel derived from biological sources. In its broader sense it includes biomass, the biological material used as a biofuel, as well as the social, economic, scientific and technical fields associated with using biological sources for energy. This is a common misconception, as bioenergy is the energy extracted from the biomass, as the biomass is the fuel and the bioenergy is the energy contained in the fuelThere is a slight tendency for the word bioenergy to be favoured in Europe compared with biofuel in America.

Biofuel

A biofuel is a fuel that is produced through contemporary biological processes, such as agriculture and anaerobic digestion, rather than a fuel produced by geological processes such as those involved in the formation of fossil fuels, such as coal and petroleum, from prehistoric biological matter. If the source biomatter can regrow quickly, the resulting fuel is said to be a form of renewable energy.

Biofuels can be derived directly from plants (i.e. energy crops), or indirectly from agricultural, commercial, domestic, and/or industrial wastes. Renewable biofuels generally involve contemporary carbon fixation, such as those that occur in plants or microalgae through the process of photosynthesis. Other renewable biofuels are made through the use or conversion of biomass (referring to recently living organisms, most often referring to plants or plant-derived materials). This biomass can be converted to convenient energy-containing substances in three different ways: thermal conversion, chemical conversion, and biochemical conversion. This biomass conversion can result in fuel in solid, liquid, or gas form. This new biomass can also be used directly for biofuels.

Biofuels are in theory carbon-neutral because the carbon dioxide that is absorbed by the plants is equal to the carbon dioxide that is released when the fuel is burned. However, in practice, whether or not a biofuel is carbon-neutral also depends greatly on whether the land which is used to grow the biofuel (with 1st and 2nd generation biofuel) needed to be cleared of carbon-holding vegetation or not.

Bioethanol is an alcohol made by fermentation, mostly from carbohydrates produced in sugar or starch crops such as corn, sugarcane, or sweet sorghum. Cellulosic biomass, derived from non-food sources, such as trees and grasses, is also being developed as a feedstock for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form (E100), but it is usually used as a gasoline additive to increase octane and improve vehicle emissions. Bioethanol is widely used in the United States and in Brazil. Current plant design does not provide for converting the lignin portion of plant raw materials to fuel components by fermentation.

Biodiesel can be used as a fuel for vehicles in its pure form (B100), but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe.

In 2010, worldwide biofuel production reached 105 billion liters (28 billion gallons US), up 17% from 2009, and biofuels provided 2.7% of the world's fuels for road transport. Global ethanol fuel production reached 86 billion liters (23 billion gallons US) in 2010, with the United States and Brazil as the world's top producers, accounting together for about 90% of global production. The world's largest biodiesel producer is the European Union, accounting for 53% of all biodiesel production in 2010. As of 2011, mandates for blending biofuels exist in 31 countries at the national level and in 29 states or provinces. The International Energy Agency has a goal for biofuels to meet more than a quarter of world demand for transportation fuels by 2050 to reduce dependence on petroleum and coal. The production of biofuels also led into a flourishing automotive industry, where by 2010, 79% of all cars produced in Brazil were made with a hybrid fuel system of bioethanol and gasoline.There are various social, economic, environmental and technical issues relating to biofuels production and use, which have been debated in the popular media and scientific journals.

Biogas

Biogas refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen. Biogas can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste. Biogas is a renewable energy source.

Biogas is produced by anaerobic digestion with methanogen or anaerobic organisms, which digest material inside a closed system, or fermentation of biodegradable materials. This closed system is called an anaerobic digester, biodigester or a bioreactor.Biogas is primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes. The gases methane, hydrogen, and carbon monoxide (CO) can be combusted or oxidized with oxygen. This energy release allows biogas to be used as a fuel; it can be used for any heating purpose, such as cooking. It can also be used in a gas engine to convert the energy in the gas into electricity and heat.Biogas can be compressed, the same way as natural gas is compressed to CNG, and used to power motor vehicles. In the United Kingdom, for example, biogas is estimated to have the potential to replace around 17% of vehicle fuel. It qualifies for renewable energy subsidies in some parts of the world. Biogas can be cleaned and upgraded to natural gas standards, when it becomes bio-methane. Biogas is considered to be a renewable resource because its production-and-use cycle is continuous, and it generates no net carbon dioxide. As the organic material grows, it is converted and used. It then regrows in a continually repeating cycle. From a carbon perspective, as much carbon dioxide is absorbed from the atmosphere in the growth of the primary bio-resource as is released, when the material is ultimately converted to energy.

Biomass (ecology)

The biomass is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass, which is the mass of all species in the community. It can include microorganisms, plants or animals. The mass can be expressed as the average mass per unit area, or as the total mass in the community.

How biomass is measured depends on why it is being measured. Sometimes, the biomass is regarded as the natural mass of organisms in situ, just as they are. For example, in a salmon fishery, the salmon biomass might be regarded as the total wet weight the salmon would have if they were taken out of the water. In other contexts, biomass can be measured in terms of the dried organic mass, so perhaps only 30% of the actual weight might count, the rest being water. For other purposes, only biological tissues count, and teeth, bones and shells are excluded. In some applications, biomass is measured as the mass of organically bound carbon (C) that is present.

The total live biomass on Earth is about 550–560 billion tonnes C, and the total annual primary production of biomass is just over 100 billion tonnes C/yr. The total live biomass of bacteria may be as much as that of plants and animals or may be much less. The total number of DNA base pairs on Earth, as a possible approximation of global biodiversity, is estimated at (5.3±3.6)×1037, and weighs 50 billion tonnes. In comparison, the total mass of the biosphere has been estimated to be as much as 4×1012 tonnes of carbon.

Drax Group

Drax Group plc is a British electrical power generation company. The Group is made up of upstream and downstream enterprises. The principal downstream enterprises are based in the UK and include Drax Power Limited, which runs Europe’s biggest biomass-fuelled power station, Drax power station, near Selby in North Yorkshire – the UK’s largest decarbonisation project, as well as supplying between 7-8 per cent of the country’s electricity needs. Related businesses include Haven Power, a supplier of electricity (including sustainable biomass energy) to business. The group’s largest upstream enterprises are Drax Biomass, which sources sustainable biomass for Drax power station and Baton Rouge Transit, which handles storage and transport of finished biomass pellets from the Port of Baton Rouge, Louisiana.

The company is listed on the London Stock Exchange and is a constituent of the FTSE 250 Index.

Ecological pyramid

An ecological pyramid (also trophic pyramid, eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or bio productivity at each trophic level in a given ecosystem.

Biomass pyramids show how much biomass (the amount of living or organic matter present in an organism) is present in the organisms at each trophic level, while productivity pyramids show the procreation or turnover in biomass. There is also pyramid of numbers which represent the number of organisms in each trophic level. They may be upright (e.g. Grassland ecosystem), inverted (parasitic ecosystem) or dumbbell shaped (forest ecosystem).

Energy pyramids begin with producers on the bottom (such as plants) and proceed through the various trophic levels (such as herbivores that eat plants, then carnivores that eat flesh, then omnivores that eat both plants and flesh, and so on). The highest level is the top of the food chain

IN OTHER WORDS,

pyramid of biomass:-The total amount of organic matter present in an organism is called as pyramid of biomass.Biomass can be measured by Bomb calorimeter.

Electricity sector in India

The utility electricity sector in India has one National Grid with an installed capacity of 350.162 GW as on 28 February 2019. Renewable power plants constituted 33.60% of total installed capacity. During the fiscal year 2017-18, the gross electricity generated by utilities in India was 1,303.49 TWh and the total electricity generation (utilities and non utilities) in the country was 1,486.5 TWh. The gross electricity consumption was 1,149 kWh per capita in the year 2017-18. India is the world's third largest producer and third largest consumer of electricity. Electric energy consumption in agriculture was recorded highest (17.89%) in 2015-16 among all countries. The per capita electricity consumption is low compared to many countries despite cheaper electricity tariff in India.India has surplus power generation capacity but lacks adequate infrastructure for supplying electricity to all needy people. In order to address the lack of adequate electricity supply to all the people in the country by March 2019, the GoI launched a scheme called "Power for All". This scheme will ensure continuous and uninterrupted electricity supply to all households, industries and commercial establishments by creating and improving necessary infrastructure. It is a joint collaboration of the GoI with states to share funding and create overall economic growth.India's electricity sector is dominated by fossil fuels, and in particular coal, which in 2017-18 produced about three fourths of all electricity. However, the government is pushing for an increased investment in renewable energy. The National Electricity Plan of 2018 prepared by the Government of India states that the country does not need additional non-renewable power plants in the utility sector until 2027, with the commissioning of 50,025 MW coal-based power plants under construction and achieving 275,000 MW total installed renewable power capacity after retirement of nearly 48,000 MW old coal fired plants.

Energy in India

Energy in India describes energy and electricity production, consumption and import in India. Energy policy of India describes the policies and strategies of India for achieving sustainable energy security to its people. Electricity sector in India is the main article of electricity in India. The Ministry of New and Renewable Energy provides data regarding progress in the non-conventional energy sector.

Since 2013, total primary energy consumption in India has been the third highest in the world (see world energy consumption) after China (see energy in China) and the United States (see energy in the United States). India is the second top coal consumer in the year 2017 after China. India ranks third in oil consumption with 221 million tons in 2017 after the United States and China. India is net energy importer to meet nearly 45% of its total primary energy.

Fish stock

Fish stocks are subpopulations of a particular species of fish, for which intrinsic parameters (growth, recruitment, mortality and fishing mortality) are traditionally regarded as the significant factors determining the stock's population dynamics, while extrinsic factors (immigration and emigration) are traditionally ignored.

Gasification

Gasification is a process that converts organic- or fossil fuel-based carbonaceous materials into carbon monoxide, hydrogen and carbon dioxide. This is achieved by reacting the material at high temperatures (>700 °C), without combustion, with a controlled amount of oxygen and/or steam. The resulting gas mixture is called syngas (from synthesis gas) or producer gas and is itself a fuel. The power derived from gasification and combustion of the resultant gas is considered to be a source of renewable energy if the gasified compounds were obtained from biomass.The advantage of gasification is that using the syngas (synthesis gas H2/CO) is potentially more efficient than direct combustion of the original fuel because it can be combusted at higher temperatures or even in fuel cells, so that the thermodynamic upper limit to the efficiency defined by Carnot's rule is higher or (in case of fuel cells) not applicable. Syngas may be burned directly in gas engines, used to produce methanol and hydrogen, or converted via the Fischer–Tropsch process into synthetic fuel. Gasification can also begin with material which would otherwise have been disposed of such as biodegradable waste. In addition, the high-temperature process refines out corrosive ash elements such as chloride and potassium, allowing clean gas production from otherwise problematic fuels. Gasification of fossil fuels is currently widely used on industrial scales to generate electricity.

Pellet fuel

Pellet fuels (or pellets) are biofuels made from compressed organic matter or biomass. Pellets can be made from any one of five general categories of biomass: industrial waste and co-products, food waste, agricultural residues, energy crops, and virgin lumber. Wood pellets are the most common type of pellet fuel and are generally made from compacted sawdust and related industrial wastes from the milling of lumber, manufacture of wood products and furniture, and construction. Other industrial waste sources include empty fruit bunches, palm kernel shells, coconut shells, and tree tops and branches discarded during logging operations. So-called "black pellets" are made of biomass, refined to resemble hard coal and were developed to be used in existing coal-fired power plants. Pellets are categorized by their heating value, moisture and ash content, and dimensions. They can be used as fuels for power generation, commercial or residential heating, and cooking. Pellets are extremely dense and can be produced with a low moisture content (below 10%) that allows them to be burned with a very high combustion efficiency.Further, their regular geometry and small size allow automatic feeding with very fine calibration. They can be fed to a burner by auger feeding or by pneumatic conveying. Their high density also permits compact storage and transport over long distance. They can be conveniently blown from a tanker to a storage bunker or silo on a customer's premises.A broad range of pellet stoves, central heating furnaces, and other heating appliances have been developed and marketed since the mid-1980s. In 1997 fully automatic wood pellet boilers with similar comfort level as oil and gas boilers became available in Austria. With the surge in the price of fossil fuels since 2005, the demand for pellet heating has increased in Europe and North America, and a sizable industry is emerging. According to the International Energy Agency Task 40, wood pellet production has more than doubled between 2006 and 2010 to over 14 million tons. In a 2012 report, the Biomass Energy Resource Center says that it expects wood pellet production in North America to double again in the next five years.

Productivity (ecology)

In ecology, productivity refers to the rate of generation of biomass in an ecosystem. It is usually expressed in units of mass per unit surface (or volume) per unit time, for instance grams per square metre per day (g m−2 d−1). The mass unit may relate to dry matter or to the mass of carbon generated. Productivity of autotrophs such as plants is called primary productivity, while that of heterotrophs such as animals is called secondary productivity.

Renewable energy

Renewable energy is energy that is collected from renewable resources, which are naturally replenished on a human timescale, such as sunlight, wind, rain, tides, waves, and geothermal heat. Renewable energy often provides energy in four important areas: electricity generation, air and water heating/cooling, transportation, and rural (off-grid) energy services.Based on REN21's 2017 report, renewables contributed 19.3% to humans' global energy consumption and 24.5% to their generation of electricity in 2015 and 2016, respectively. This energy consumption is divided as 8.9% coming from traditional biomass, 4.2% as heat energy (modern biomass, geothermal and solar heat), 3.9% hydro electricity and 2.2% is electricity from wind, solar, geothermal, and biomass. Worldwide investments in renewable technologies amounted to more than US$286 billion in 2015, with countries such as China and the United States heavily investing in wind, hydro, solar and biofuels. Globally, there are an estimated 7.7 million jobs associated with the renewable energy industries, with solar photovoltaics being the largest renewable employer. As of 2015 worldwide, more than half of all new electricity capacity installed was renewable.At the national level, at least 30 nations around the world already have renewable energy contributing more than 20 percent of energy supply. National renewable energy markets are projected to continue to grow strongly in the coming decade and beyond.

Some places and at least two countries, Iceland and Norway generate all their electricity using renewable energy already, and many other countries have the set a goal to reach 100% renewable energy in the future.

At least 47 nations around the world already have over 50 percent of electricity from renewable resources.Renewable energy resources exist over wide geographical areas, in contrast to fossil fuels, which are concentrated in a limited number of countries. Rapid deployment of renewable energy and energy efficiency technologies is resulting in significant energy security, climate change mitigation, and economic benefits.

The results of a recent review of the literature concluded that as greenhouse gas (GHG) emitters begin to be held liable for damages resulting from GHG emissions resulting in climate change, a high value for liability mitigation would provide powerful incentives for deployment of renewable energy technologies.

In international public opinion surveys there is strong support for promoting renewable sources such as solar power and wind power.While many renewable energy projects are large-scale, renewable technologies are also suited to rural and remote areas and developing countries, where energy is often crucial in human development.

Former United Nations Secretary-General Ban Ki-moon has said that renewable energy has the ability to lift the poorest nations to new levels of prosperity.

As most of renewable energy technologies provide electricity, renewable energy deployment is often applied in conjunction with further electrification, which has several benefits: electricity can be converted to heat (where necessary generating higher temperatures than fossil fuels), can be converted into mechanical energy with high efficiency, and is clean at the point of consumption.

In addition, electrification with renewable energy is more efficient and therefore leads to significant reductions in primary energy requirements, because most renewable energy technologies do not need a thermodynamic cycle with high losses.Renewable energy systems are rapidly becoming more efficient and cheaper and their share of total energy consumption is increasing. Global installed electricity generating capacity in 2017 was 2.2 TW. Growth in consumption of coal and oil could end by 2020 due to increased uptake of renewables and natural gas.

Renewable energy in Lithuania

In 2016 Renewable energy in Lithuania constituted 27.9% of the country's overall electricity generation. Previously, the Lithuanian government aimed to generate 23% of total power from renewable resources by 2020, a goal was achieved in 2014 (23.9).

Renewable resource

A renewable resource is a natural resource which will replenish to replace the portion depleted by usage and consumption, either through natural reproduction or other recurring processes in a finite amount of time in a human time scale. Renewable resources are a part of Earth's natural environment and the largest components of its ecosphere. A positive life cycle assessment is a key indicator of a resource's sustainability.Definitions of renewable resources may also include agricultural production, as in sustainable agriculture and to an extent water resources. In 1962, Paul Alfred Weiss defined Renewable Resources as: "The total range of living organisms providing man with life, fibres, etc...". Another type of renewable resources is renewable energy resources. Common sources of renewable energy include solar, geothermal and wind power, which are all categorised as renewable resources.

Sustainable energy

Sustainable energy is a principle in which human use of energy "meets the needs of the present without compromising the ability of future generations to meet their own needs." Another definition of sustainable energy is that it is consumed at insignificant rates compared to its supply and with manageable collateral effects, especially environmental effects. Sustainable energy strategies generally have two pillars: cleaner methods of producing energy and energy conservation.

Sustainable energy technologies are deployed to generate electricity, to heat and cool buildings, and to power transportation systems and machines. When referring to methods of producing energy, the term "sustainable energy" is often used interchangeably with the term "renewable energy". In general, renewable energy sources such as solar energy, wind energy, geothermal energy, and tidal energy, are widely considered to be sustainable energy sources. However, implementation of particular renewable energy projects, such as the damming of rivers to generate hydroelectricity or the clearing of forests for production of biofuels, sometimes raises significant sustainability concerns. There is considerable controversy over whether nuclear energy can be considered sustainable.

Costs of sustainable energy sources have decreased immensely throughout the years, and continue to fall. Increasingly, effective government policies support investor confidence and these markets are expanding. Considerable progress is being made in the energy transition from fossil fuels to ecologically sustainable systems, to the point where many studies support 100% renewable energy.

The organizing principle for sustainability is sustainable development, which includes the four interconnected domains: ecology, economics, politics and culture. Sustainability science is the study of sustainable development and environmental science.

Trophic level

The trophic level of an organism is the position it occupies in a food chain. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it is from the start of the chain. A food chain starts at trophic level 1 with primary producers such as plants, can move to herbivores at level 2, carnivores at level 3 or higher, and typically finish with apex predators at level 4 or 5. The path along the chain can form either a one-way flow or a food "web". Ecological communities with higher biodiversity form more complex trophic paths.

The word trophic derives from the Greek τροφή (trophē) referring to food or nourishment.

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