An Introduction to Bioenergy: Feedstocks, Processes and Products


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An Introduction to Bioenergy: Feedstocks, Processes and Products

  1. 1. A project of the National Center for Appropriate Technology 1-800-346-9140 • www.attra.ncat.orgAn Introduction to Bioenergy:Feedstocks, Processes and ProductsBy Leif Kindberg, Bioenergy offers farmers an alternative to petroleum-based energy sources, and new market opportuni-NCAT Farm Energy ties for farm products. When biomass feedstocks are burned, fermented or reacted through an energySpecialist conversion process, they return some carbon dioxide and water and release the sun’s energy. Because© 2010 NCAT plants have the capability to store and then release energy in this way, they act as a natural battery. This introduction to bioenergy offers a brief and non-technical overview of bioenergy feedstock production with discussion on how bioenergy is made.ContentsIntroduction ......................1 IntroductionFeedstock Basics..............1 Bioenergy uses renewable biomass feedstocks Sugar and Oil from many sources. Renewable biomass feed- Feedstocks ....................1 stocks use the process of photosynthesis in plants Sugar Feedstocks .......2 to capture the sun’s energy by converting carbon Oilseed Feedstocks....2 dioxide (CO2) from the air and water (H2O) into carbohydrates and complex oil and fiber Cellulosic Feedstocks ....................2 compounds made up of carbon, hydrogen and Agricultural oxygen. These energy-rich carbohydrates, oils Residues .........................3 and fibers can be harvested and used for many Animal Manure ............3 types of bioenergy. There are hundreds of waysThe Production to turn biological materials into energy, althoughof Bioenergy .....................3 currently only a few of them represent legitimate Thermochemical short-term opportunities for the average farm or Conversion ....................3 rural landowner. Carbon cycling is the foundation of sustainable bio- Biochemical energy. Source: BC Bioenergy Strategy. Conversion ....................6 Bioenergy was used in industrial processes well before petroleum and coal-fired electricity wereConclusion .........................8 commonly available. Although a great deal of animal parts and many other biological materials.Further Resources ...........9 attention goes to solar and wind energy, bioen- The benefits of one feedstock versus another areAdditional Online ergy BTUs (British thermal units of energy) gen- regionally specific. This makes feedstock selectionResources ...........................9 erated from biomass make up 53 percent of all a key consideration in bioenergy production.References .........................9 renewable energy in the United States, according Feedstocks may be dedicated to energy produc- to the Energy Information Administration. That tion or non-dedicated. Feedstocks that are dedi- is more than all other renewable sources com- cated are often called energy crops. Each feed- bined (EIA, 2009). However, bioenergy presents stock has advantages and disadvantages that may a complex set of energy topics. This publication include how much usable biomass they produce,The National Sustainable will discuss many of these complex topics but soil types required, water and energy inputs,Agriculture Information Service,ATTRA (, will only mention others. Topics that will not be energy density, air quality benefits, productionwas developed and is managed discussed in any detail in this introductory pub- cost and other the National Center forAppropriate Technology (NCAT). lication include most feedstock pre-processingThe project is funded through considerations such as transporting, sizing, dry-a cooperative agreement withthe United States Department ing and storage. Sugar and Oil Feedstocksof Agriculture’s Rural Business- Sugar and oil feedstocks often include seeds,Cooperative Service. Visit the grains and plants that are made up of sugar,NCAT website ( formore information on Feedstock Basics starch or oil, and animal fats or tallow. Today,our other sustainable Bioenergy can be produced from feedstocks these feedstocks are often used to produce theagriculture andenergy projects. such as trees, agricultural crops, plant residues, biodiesel and ethanol fuels we are familiar with.
  2. 2. Sugar Feedstocks The two most common bioen- ergy feedstocks used for their starch and sugar content are corn and sugar cane. Over 90 percent of ethanol (or bioethanol as it is sometimes called) is still made from corn in the United States. The world’s largest producer of ethanol is Brazil. Brazil uses sugar cane as its primary feedstock. Because fermentation producesRelated ATTRA alcohols, the higher the yield ofpublications fermentable sugars in the feed-Biochar and Sustain- stock, the higher the yield of alco-able Agriculture hols. Since fermentation can pro- cess almost any starch into sugar, The geographic range of some bioenergy crops. Source: ORNL.Oilseed Processing for other feedstocks may include bar-Small-Scale Producers ley, milo, wheat, potatoes, sugar beets, cheese information on the best rotations for soil-build-Biodiesel Use, Han- whey, brewery and beverage waste and many ing, water needs and pest management. See thedling, and Fuel Quality others. Many of these feedstocks serve multiple ATTRA publication Biodiesel: The Sustainability functions as either food or fuel sources. Dimensions for more information about oilseedAgriculture, Climate feedstocks.Change and CarbonSequestration Oilseed FeedstocksRenewable Energy Plants that have oil-rich seeds, frequently Cellulosic FeedstocksOpportunities on referred to as oilseeds, can be a sustainable Feedstocks from cellulose (the primary com-the Farm source of bioenergy. Common American oilseed ponent in the cell walls of plants) such as pop- crops include soybeans, canola, sunflower, cam- lars, willows and switchgrass are creating a lotBiodiesel: The elina, and safflower and cottonseed. Camelina is of excitement among farmers, scientists andSustainability Dimen- a short-season crop that is well-suited for dou- the public. These fibrous and generally ined-sions ble cropping and grows well in cooler climates ible parts of plants are abundant and can be col-Biodiesel: Do-it-your- lected from diverse regions or grown directly by such as the northern Midwest. In comparison,self production basics farmers. Although there is currently a very lim- many varieties of sunflower are well-suited forEthanol Opportunities warmer Southern climates. Canola (one cultivar ited market for cellulosic bioenergy feedstocks inand Questions of rapeseed) is particularly well-suited for cooler the United States, some companies are currently regions, with varieties that are adapted for both purchasing cellulosic biomass for pellets andSwitchgrass as a spring and fall planting to achieve multiple oil- for cofiring (burning biomass with coal). A fewBioenergy Crop seed harvests. Your state agricultural experiment companies intend to begin commercial produc-Micro-Scale Biogas station, Cooperative Extension Service or the tion of cellulosic ethanol. Demand for cellulosicProduction: A begin- biomass is expected to expand market opportu- Natural Resources Conservation Service (NRCS)ner’s guide nities in the near future. may have information on specific oilseed crops that are well-adapted to your location and Energy crops can be grown on farms using prac- tices similar to those used with other agricul- tural crops. Trees and grasses, particularly those that are native to a region, can be sustainably produced when grown with minimal inputs such as water, fertilizer and chemicals. Trees that will regrow after each harvest may be cop- piced (repeatedly cut off at ground level), allow- ing them to be harvested multiple times. WoodyCanola (rapeseed) being varieties that regrow quickly without beingharvested for oil. Photo replanted are called short-rotation woody crops.courtesy NREL. Perennial varieties of grasses and legumes arePage 2 ATTRA An Introduction to Bioenergy: Feedstocks, Processes and Products
  3. 3. also being tested and used as feedstocks. Manyenergy crops are being researched for their bio- The Productionenergy potential. of Bioenergy Feedstocks require a conver- sion process in order to takeAgricultural Residues raw materials and turn themResidues left over from forest products and farm- into useful bioenergy such asing may also be used as cellulosic feedstocks. The electricity, biodiesel, ethanol,U.S. Department of Energy has estimated that biobutanol, methane, heatbetween 581 and 998 million dry tons of agri- and other bioenergy products.cultural residues such as corn stover and wheat Keep in mind that harvesting,straw (the stalks and leaves left on a field after a drying to the correct moisture content, trans- Short-rotation hybridharvest) could be harvested for biofuels by the porting to the necessary location and supplying poplar trees. Photo cour-middle of the 21st century (DOE, 2005). How- a sufficient quantity of biomass are important tesy NREL.ever, research has also shown that less than 25 considerations that are only briefly mentionedpercent of some agricultural residues could be in this introduction to bioenergy. Each type ofsustainably harvested under current agriculture feedstock may require a slightly different conver-practices, because crop residues are critical to E sion process, but many feedstocks can be con-soil fertility (Graham et al., 2007). Study results verted using similar processes and technologies. ach type ofvary widely on the quantity of agricultural resi- feedstockdues that may be sustainably harvested. What iscertain is that when left in the field, agriculture Thermochemical Conversion may require aresidues help restore soil tilth, protect agricul- Heating biomass assists a chemical reaction (a slightly different con-tural soils and sequester carbon. The removal of thermochemical process) and creates useful bio- version process, butagricultural residues is unlikely to be sustainable energy products such as gases, liquids and heat. many feedstocks canunless agricultural best management practices Electricity generated from biomass is referred to as be converted usingsuch as cover crops, no-till production and better biopower, and the combination of both heat andfertilizer management are fully adopted, among power is commonly referred to as cogeneration or similar processes andother practices (Marshall and Zugg, 2008). combined heat and power (CHP). The overall effi- technologies. ciency of these integrated systems is significantly higher than either of the systems alone.Animal ManureManure is used for feedstocks in anaerobicdigesters primarily to produce gas burned to Combustion in a Direct-fired orgenerate electricity. Although there are substan- Conventional Steam Boilertial environmental and welfare issues associated The burning of feedstocks for energy has beenwith confined animal feeding operations, these practiced for many years. One of the oldestlarge operations are increasingly using manure commercial methods of producing electricitydigestion to control a variety of environmental is through the burning of wood or charcoal toproblems, reduce odors, generate bioenergy for produce steam. The steam is piped into a tur-the farm and provide additional income through bine that spins a generator used to make elec-the sale of power. tricity, or biopower. A problem with burning feedstocks in a steam boiler is that that a great deal of energy is lost in the conversion process. Pre-processing biomass by pelletizing, torre- faction (superheating in a low-oxygen environ- ment) or making condensed biomass briquettes has helped improve the efficiency of burning woody biomass. These processes are expensive and not always economical given current fossil fuel prices. This 21-megawatt direct-fired biopower plant uses wood residues discarded from orchards and industrial operations. Photo courtesy ATTRA Page 3
  4. 4. Cofiring feedstocks into useful intermediates to be used as energy later (Sadaka, 2010). Gasification Cofiring woody biomass and high-fiber grasses exposes the feedstock to some oxygen, but not with coal can reduce carbon dioxide emissions enough to allow the feedstock to burn. The con- compared to burning coal alone. Many plant- version efficiency of gasification systems is high, based feedstocks have lower sulfur contents than typically between 80 and 85 percent efficiency coal, reducing sulfurous gases including sulfur in taking a raw feedstock and converting it into dioxide. Cofiring plant-based feedstocks has producer gas (NREL, no date). Controlling the been successfully demonstrated to replace up to temperature, pressure, feedstock characteristics 20 percent of the coal used in the boiler, accord- and other aspects changes the energy density ing to the Federal Energy Management Program and makeup of the producer gas. (2004). However, the economics of cofiring have generally not been favorable with historical fos- More on gasification can be found on the Sun sil fuel prices. You should carefully consider the Grant BioWeb Web site at http://bioweb.sungrant. market opportunities in your local area if you are org/General/Biopower/Technologies/Gasification/ planning to produce feedstocks for cofiring, and Default.htm. you should pursue long-term supply contracts. BioWeb is a non-commercial, educational WebG More information on cofiring and other bio- site that provides current information about bio- asification power technologies can be found at the U.S. mass resources for bioenergy and bioproducts. converts Department of Energy’s Distributed Energy feedstocks Program’s website, Pyrolysisinto combustible biomass_power.html. Pyrolysis is derived from the Greek words pyro,gases called syn- meaning fire, and lysys, meaning decomposi-thesis gas (syngas) Thermal Process Heat tion. Pyrolysis is a method of producing syngasthat can be used to and Space Heat and biocrude, also known as bio-oil or pyroly- Burning biomass directly can be used to produce sis oil. Pyrolysis uses thermal decomposition byproduce heat, motor heating biomass at temperatures usually greater both process heat and space heat. Process heatfuels, biopower, is vital to many manufacturing processes and than 400 degrees F (204 degrees C). Biocrudechemicals and for is used in a variety of agricultural applications is formed when syngas produced during pyroly-other purposes. including grain and crop drying. Space heat- sis is re-condensed into liquid biocrude. There ing is the most common use. Both large boil- are few opportunities to use unrefined biocrude ers in manufacturing facilities and small stoves in directly on the farm and a limited market. Bio- shops are frequently used for space heat. Wood, crude can be refined into high-quality hydrocar- wood chips and hay can be used for both process bon fuels such as diesel, gasoline and jet fuel. heat and space heat, and are readily available on These liquid fuels can be used in internal com- the farm. bustion engines as a chemically identical substi- tute to petroleum fuels. Thermal Gasification Pyrolysis is often the first process that occurs Gasification converts feedstocks into combusti- during the burning of solid fuels including ble gases called synthesis gas (syngas) that can wood. Pyrolysis releases gases that are visible be used to produce heat, motor fuels, biopower, as yellowish and orange flames. If you were to chemicals and for other purposes. Syngas is also stop burning these gases and condense them, sometimes referred to as producer gas, wood you would have a form of biocrude. Next, the gas and town gas. Synthesis gases are generally solids (charcoal) left behind are burned but upgraded to other fuel products such as etha- have no visible flame. Instead of letting these nol, methanol, hydrogen and ammonia using solids burn, they can be converted into bio- char. Using modern pyrolysis for energy stops processes such as the Fischer-Tropsch process. the burning of both gases and solids short. These fuels and process will be discussed later in this publication. Gasification occurs at tempera- tures generally between 1,202 and 1,832 degrees Pyrolysis variables such as temperature, pres- Fahrenheit (650 to 1,000 degrees Celsius) and sure, reaction rates and other factors produce a deliberately limits burning in order to convert wide variety of gas, liquid and solid intermedi- ates. However, generally pyrolysis processes withPage 4 ATTRA An Introduction to Bioenergy: Feedstocks, Processes and Products
  5. 5. higher temperatures and more rapid reaction Wind electricity mayrates are most efficient at producing biocrude. be used to electrolyze water and produceThe pyrolysis process known as fast or high- hydrogen, a key com-temperature pyrolysis has higher reaction rates ponent of ammonia.(greater than 1,000 degrees F or 538 degrees C). Photo courtesy Uni-This process can be used to optimize biocrude versity of Minnesotaor char production. Low-temperature pyroly- Renewable Energysis processes are generally used to produce char. Center.Pyrolysis and gasification are both complex pro-cesses that require laboratory-like conditions toconsistently produce bioenergy products.Biochar is a type of charcoal that is high in wind, solar, water, biomass and other renewableorganic carbon and is a coproduct of pyrolysis resources. Instead of using natural gas or coal toof biomass. Char has many potential benefits in produce hydrogen, biopower is used to electro-agriculture (International Biochar Initiative, no lyze water and produce hydrogen. This offers thedate). Biomass pyrolysis systems for biocrude benefit of releasing fewer carbon dioxide emis-and biochar production are available in smaller sions, but has normally required large amounts Bdemonstration units at this time, but some of energy and remains cost-prohibitive because iochar is alarger-scale facilities are being built. For more of low-cost natural gas and coal. type of char-information on biochar, see the ATTRA publi-cation Biochar and Sustainable Agriculture. coal that is Ammonia high in organicMore on pyrolysis can be found on the Sun Ammonia produced during the Haber-BoschGrant BioWeb Web site at http://bioweb.sungrant carbon and is a process can be run in modified internal bustion engines as an alternative liquid fuel. coproduct of pyrolysisDefault.htm. Ammonia has about half the energy of gasoline of biomass. and can be generated from a variety of renewableFischer-Tropsch Process energy sources. Farmers who have experienceThe Fischer-Tropsch process converts syngas with ammonia application know there are manyusually produced during gasification into unre- hazards associated with the handling and use offined liquid fuels such as biocrude. The Fischer- ammonia. The broad use of ammonia as a liquidTropsch process usually takes place in a pres- fuel for vehicles will require substantial invest-surized and high-temperature environment. ments in safe storage and handling, and requireThis process chemically converts a gas generally improvements in transportation infrastructure.composed of carbon monoxide and hydrogeninto liquid fuels or oils that can then be burned Methanolin an internal combustion engine and used to Methanol or wood alcohol is usually producedmake other fuels. Fischer-Tropsch liquids can be from methane during steam-methane reform-refined further into hydrocarbon fuels such as ing of natural gas and coal. Methane producedgasoline and diesel and used as a direct replace- from anaerobic digestion of manure (discussedment for petroleum-derived fuels. next) may also be an option but is usually cost- Methanol and ethanol prohibitive. Methanol can be used as a substi- pumps. Photo courtesyHaber-Bosch Process tute for gasoline with some engine modifica- NREL.The Haber-Bosch process is a synthesis reaction tions but has only aboutbetween nitrogen gas, hydrogen gas and an iron half the energy density ofcatalyst. The Haber-Bosch process is often used gasoline. Methanol can alsoin sequence with steam reforming of natural gas be converted into syntheticor coal into gaseous hydrogen to produce ammo- fuels such as dimethyl ethernia. The entire process of producing ammonia (DME) to be used as a die-is often referred to as the Haber-Bosch process. sel substitute with signifi- cantly lower emissions andGaseous hydrogen for the Haber-Bosch pro- with about half the energycess can be produced using electricity from density of diesel. ATTRA Page 5
  6. 6. is already commonly used in the transesterifi- cation process of producing biodiesel, which we will discuss later. Biochemical ConversionA Bacteria, yeasts and other living enzymes fer- naerobic ment material such as sugars and proteins and digesters convert them into useful alcohols or other liquid break down fuels. These processes are known as biochemi-(or digest) organic cal conversion processes. Corn ethanol andmatter without oxy- other grain alcohols are some of the most com- Anaerobic digestion creates a variety of nutrient-rich mon fuels produced in this way. Other meth- liquids and solids that can be used on the farm. Photogen (anaerobic) to ods include capturing methane produced when courtesy USDA ERS.produce methane bacteria break down manure from livestock andand other gases and poultry production, human sewage and landfill natural gas (LNG) in automobiles, among other waste to burn it for heat and biopower. uses. The byproducts from anaerobic digestioncoproducts that are can be used as soil amendments and liquid fer-useful on the farm. tilizers. For more information, see the ATTRA Anaerobic Digestion publication Anaerobic Digestion of Animal Wastes: Anaerobic digesters break down (or digest) Factors to Consider. organic matter without oxygen (anaerobic) to produce methane and other gases and coprod- ucts that are useful on the farm. This gas mixture Fermentation (for Ethanol) is commonly referred to as biogas or digester gas. Ethanol, a fuel alcohol, is made from biologi- Biogas is a combustible and normally consists of cal sources and usually is produced through the 50 to 60 percent methane. Biogas can be burned fermentation of plant starches and sugars. In the in an engine to generate biopower and thermal United States, corn is the most common source energy or processed further into other fuel types of starch converted into ethanol, while barley, such as methanol. Refined biogas can be used milo, wheat starch, potatoes, cheese whey and as compressed natural gas (CNG) and liquefied brewery and beverage waste make up a smaller share of production. Ethanol can also be pro- duced from sugarcane, which has a high content of the sugars needed for fermentation. Accord- ing to the Renewable Fuels Association, the United States produced 9 billion gallons of eth-Cellulosic biofuels anol in 2008 and 22 million metric tons of dis-and the carbon cycle. tillers grains were sold from the ethanol makingSource: US DOE. process (2008). For more information, see the ATTRA publication Ethanol Opportunities and Questions. Ethanol from corn and other grains can be made using either a dry milling or wet milling process. The dry milling process uses the whole corn ker- nel, which is ground into a powder, mixed with water to form a mash and then cooked with added enzymes that turn the liquefied starch to glucose (sugar). After cooling, the mash is fer- mented with a second enzyme (yeast) and finally distilled further to separate the alcohol from the solids and water. Coproducts of the dry milling process include distillers grain, which is used as animal feed (also known as distillers dried grain with solubles or DDGS) and carbon dioxide.Page 6 ATTRA An Introduction to Bioenergy: Feedstocks, Processes and Products
  7. 7. The wet milling process involves soaking the energy density that is 10 to 20 per-corn kernel in water and sulfurous acid before cent lower than gasoline and slightlygrinding the kernels into a mash. This soaking higher than ethanol. The Environ-separates the germ (oil), fiber, gluten (protein) mental Protection Agency allowsand starch components. The starch is fermented biobutanol to be blended with gas-into ethanol and then distilled further, corn oil oline up to 11.5 percent. Higheris extracted from the germ and both fiber and blends have greater restrictions andother starch components are separated. While may require modifications to inter-dry milling provides valuable coproducts such nal combustion engines (DOE, noas DDGS, the wet mill process is also used to date). Biobutanol can be deliveredproduce corn oil, corn gluten and meal. to the end user with existing pipe- line and storage infrastructure inAs with ethanol produced from starch grains, many cases. However, biobutanol isprocessing cellulosic feedstock for ethanol aims toxic to humans and is water solu-to extract fermentable starch from the feedstock. ble, which means it may easily findHowever, the starches found in cellulose are its way into water sources.hard to extract because they are locked in com-plex carbohydrates called polysaccharides (long Biodiesel is blended withchains of simple sugars). To produce ethanol Transesterification for Renew- petroleum-based die- sel to produce B99 andfrom cellulose efficiently, these chains of simple able Diesel Fuels lower blends. Photo bysugars must be broken up prior to fermentation. Transesterification is a chemical process that Leif Kindberg.Fermenting sugars from cellulose into ethanol reacts an alcohol with the triglycerides con-is less efficient than fermenting sugars directly, tained in vegetable oils and animal fats to pro-although ethanol from either source is chemi- duce biodiesel and glycerin. This process iscally identical. commonly used to produce B100 biodiesel, orThe conversion of cellulose to sugar is gener- 100-percent biodiesel to be blended with petro-ally accomplished through one of two processes. leum diesel. Biodiesel is essentially permanentlyThe first uses acid hydrolysis (a method of split- thinned plant oil or animal fat, with a viscos-ting water molecules) to break complex carbo- ity approximating that of standard No. 2 petro-hydrates into simple sugars. The second uses a leum-based diesel fuel. Biodiesel is chemicallycombination of pre-treatment to break apart the different from petroleum-based diesel because it Bfeedstock cell structure and enzymatic hydro- contains oxygen atoms and is not a pure hydro- iobutanol islysis for the production of fermentable sugars. carbon. For more information about biodiesel, very similarCellulosic ethanol may also be produced from see the ATTRA publication Biodiesel Use, Han-gasification, which is a thermochemical process. dling and Fuel Quality. to gasoline and is produced in Another type of renewable diesel known asBiobutanol green diesel or hydrogenation-derived renewable much the same wayBiobutanol is very similar to gasoline and is diesel is more like petroleum-based diesel, but as ethanol.produced in much the same way as ethanol. uses many of the same plant oil and animal fatBiobutanol is produced by Acetone-butanol- feedstocks used in making biodiesel. Green die-ethanol (ABE) fermentation. Biobutanol has an sel is produced using a chemical reaction known as hydrocracking or hydrotreating. Hydrocrack- ing is a process in which hydrogen is added to organic molecules under pressure and heat. An important advantage of green diesel is that it can be produced as a chemically identical replace- ment to petroleum diesel. A ButylFuel vehicle was driven across the United States on 100 percent biobutanol. Photo courtesy ButylFuel, LLC. July 18, ATTRA Page 7
  8. 8. An important part of bioenergy production is the net energy balance (also referred to as the energy balance). The energy balance is a lifecycle method of accounting for the amount of energy needed to make a unit of bioenergy versus the amount of usable energy produced. Therefore, the lifecycle energy balance of bioenergy will include inputs required to plant, cultivate, fertilize, harvest, trans- port, dry and process the feedstock and convert it into a useful bioenergy form. Said another way, the energy balance is the difference between the energy produced and the energy needed to pro- duce that given unit of energy. The complexity involved in accurately calculating the energy balance of bioenergy makes the calcu- lations almost impossible to conduct at this point. The methods used to produce an energy crop on one farm, for example, may be somewhat or significantly different on the next. An example of this could be intercropping nitrogen fixers and perennial grasses without the use of herbicides on one farm versus using alternative nutrient and weed management practices on the next farm. Straight Vegetable Oil (SVO) to consider when thinking about biomass and bioenergy production on the farm. The viscosity (thickness) of straight vegetable oilW hen may cause buildup when burned in an unmodi- Some things to consider include: biodie- fied engine. However, engines that burn straight • Is there a local market for my feedstock sel from vegetable oil are available and modification kits or fuel or can I use it on the farm to off-oilseeds is burned, are available as well. With the correct filter- set energy costs?carbon dioxide and ing, heating and conversion of a diesel engine, straight vegetable oil offers a partial alternative to • Will the quantity of fertilizer and energyother emissions are bio-based or No. 2 petroleum-based diesel fuel. used during the production of myreleased back into feedstock be positive or negative for thethe air and are taken For more information about straight vegetable oil, see the ATTRA publication Biodiesel Use, environment?up again by nextyear’s energy crop, Handling and Fuel Quality. • Will converting my land, once out ofthus completing the agricultural production, into productioncarbon cycle. Conclusion (indirect land use change) create addi- tional greenhouse gases? Through its role in the carbon cycle, bioen- • How much energy will be consumed ergy can reduce direct emissions such as car- during transportation of feedstocks? bon dioxide (CO2) when compared with petro- leum-based energy. For example, when biomass • How much energy will be used during feedstocks are grown, they pull carbon dioxide feedstock conversion? from the air and make stems, roots, leaves and • Will bioenergy provide net positive ben- seeds. When biodiesel from oilseeds is burned, efits to my farm and the environment carbon dioxide and other emissions are released when all the economic, energy and envi- back into the air and are taken up again by next ronmental costs are added up? year’s energy crop, thus completing the carbon This publication did not provide answers to all cycle. In comparison, when fossil fuels such as these questions and is meant as a starting point coal or petroleum-based fuels are burned, all of for learning about bioenergy. It is not a com- the carbon dioxide released adds additional car- plete reference guide and we encourage you to bon dioxide into the air (NREL, 2008). How- explore all of the additional publications and ever, not all bioenergy is equally good at reduc- resources provided by ATTRA and in the Fur- ing emissions. There are many complex factors ther Resources that follow.Page 8 ATTRA An Introduction to Bioenergy: Feedstocks, Processes and Products
  9. 9. Further Resources Additional Online Resources National Biodiesel BoardBioenergy Feedstock www.biodiesel.organd Production Resources Renewable Fuels AssociationFor an extensive list of bioenergy equipment, designers, and www.ethanolrfa.orgtechnical assistance please visit the ATTRA Directory of The Ammonia Fuel NetworkEnergy Alternatives at a glossary of bioenergy terms see the National Renew- International Biochar Initiativeable Energy Laboratory at www.biochar-international.orghtml. U.S. Department of EnergyThe Alternative Fuels and Advance Vehicles Data Center Energy Efficiency and Renewable Energyprovides information on the production, distribution and of biobutanol, biodiesel, ethanol, hydrogen, metha-nol, natural gas, propane, ultra-low sulfur diesel, biogas, Sun Grant Initiativep-series fuels and much more. The AgSTAR ProgramJourney to Forever is a small, non-government organization in Japan and involved in Third World rural develop-ment work. The Web site also offers a lot of information BioCycle Magazineabout biofuels and other appropriate technologies. www.biocycle.net Home Power MagazineThe Sun Grant BioWeb provides both non-technical and www.homepower.comtechnical information on biomass, bioenergy conversion Roundtable on Sustainable Biofuelstechnologies, biomass economics, and related policy. Bioenergy Feedstock Information Network (BFIN) is a Referenceshelpful gateway to biomass resources from the U.S. Depart- Bergman, Patrick C.A and Jacob H.A Kiel. 2005. Torrefac-ment of Energy, Oak Ridge National Laboratory, Idaho tion for biomass upgrading. 14th European Biomass Con-National Laboratory, National Renewable Energy Labora- ference & Exhibition. Accessed July 2009.tory and other research organizations. %20for%20biomas%20upgrading%20-2005.pdfThe Agricultural Marketing Resource Center provides Department of Energy. 2005. Biomass as Feedstock for aresources on value-added agriculture including bioenergy Bioenergy and Bioproducts Industry: The Technical Feasi-feedstocks. bility of a Billion-Ton Annual Supply. p. 23. Accessed 2009.The National Renewable Energy Lab (NREL) is a learning covering biofuels, biopower, bioproducts and other Department of Energy (DOE). No Date. What is Biobuta-energy technologies for farms and ranches. nol? Alternative Fuels & Advanced Vehicles Data Accessed June 2009. ATTRA Page 9
  10. 10. Energy Information Administration (EIA). 2009. Renew- National Renewable Energy Laboratory. 2008. Biodieselable Energy Consumption and Electricity Preliminary 2008 Handling and Use Guide. 4th Ed. p. 7. Accessed July 2009.Statistics. Accessed October 2009. National Renewable Energy Laboratory (NREL). No Date.rea_prereport.html An Overview of Biomass Gasification. p. 2. Accessed MayFederal Energy Management Program (FEMP). 2004. Bio- 2009. Cofiring in coal-fired boilers. DOE/EE-0288. Wash- overview_biomass_gasification.pdfington, D.C. U.S. Department of Energy. Accessed May Persson, Kristoffer et al. No date. Biomass Refinement by2009. Torrefaction. Energy Technology and Thermal Chemistry. Umea University. Accessed August 2009.Graham, R. L. et al. 2007. Current and Potential U.S. Corn Supplies. American Society of Agronomy - Agron- Torrefaction.pdfomy Journal. p. 10 Renewable Fuels Association. 2008. Ethanol Industry Sta-International Biochar Initiative. No Date. Biochar: A Soil tistics. Accessed May 2009.Amendment that Combats Global Warming and Improves Sustainability and Environmental Impacts. p. 2. Sadaka, Samy. 2010. Potential Bioenergy Production Thermochemical Processes. Webinar for Energy Traininginformationaboutbiochar.html for Agriculture Professionals. September.Marshall, Liz and Zugg, Zachary. 2008. Finding Balance:Agricultural Residues, Ethanol, and the Environment.World Resources Institute. WRI Policy Note. No. 3. p. 1.NotesPage 10 ATTRA An Introduction to Bioenergy: Feedstocks, Processes and Products
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  12. 12. An Introduction to Bioenergy: Feedstocks, Processes and Products By Leif Kindberg NCAT Farm Energy Specialist © 2010 NCAT Holly Michels, Editor Robyn Metzger, Production This publication is available on the Web at: or IP359 Slot 357 Version 102010Page 12 ATTRA