Carbon/Solar Cycle
The electric power sector comprises electricity-only and
combined-heat-power (CHP) within the North American Industry
Classification System (NAICS) 22 category whose primary business is
to sell electricity, or electricity and heat, to the public. b
Agriculture byproducts/crops, sludge waste, tires, and other
biomass solids, liquids and gases. c Ethanol primarily derived from
corn. P = Preliminary. Note: Data revisions are discussed in the
Highlights section. Totals may not equal sum. of components due to
independent rounding. Sources: Table 2 of this report.
Biomass ResourcesBiomass resources include any organic matter
available on a renewable basis, including dedicated energy crops
and trees, agricultural food and feed crops, agricultural crop
wastes and residues, wood wastes and residues, aquatic plants,
animal wastes, municipal wastes, and other waste materials.
Material handling, collection logistics and infrastructure are
important aspects of the biomass resource supply chain.
ResourcesHerbaceous Energy Crops Herbaceous energy crops are
perennials that are harvested annually after taking two to three
years to reach full productivity. These include such grasses as
switchgrass, miscanthus (also known as Elephant grass or e-grass),
bamboo, sweet sorghum, tall fescue, kochia, wheatgrass, and others.
Woody Energy Crops Short-rotation woody crops are fast growing
hardwood trees harvested within five to eight years after planting.
These include hybrid poplar, hybrid willow, silver maple, eastern
cottonwood, green ash, black walnut, sweetgum, and sycamore.
Industrial Crops Industrial crops are being developed and grown to
produce specific industrial chemicals or materials. Examples
include kenaf and straws for fiber, and castor for ricinoleic acid.
New transgenic crops are being developed that produce the desired
chemicals as part of the plant composition, requiring only
extraction and purification of the product. Agricultural Crops
These feedstocks include the currently available commodity products
such as cornstarch and corn oil; soybean oil and meal; wheat
starch, other vegetable oils, and any newly developed component of
future commodity crops. They generally yield sugars, oils, and
extractives, although they can also be used to produce plastics and
other chemicals and products. Aquatic Crops A wide variety of
aquatic biomass resources exist such as algae, giant kelp, other
seaweed, and marine microflora. Commercial examples include giant
kelp extracts for thickeners and food additives, algal dyes, and
novel biocatalysts for use in bioprocessing under extreme
environments. Agriculture Crop Residues Agriculture crop residues
include biomass, primarily stalks and leaves, not harvested or
removed from the fields in commercial use. Examples include corn
stover (stalks, leaves, husks and cobs), wheat straw, and rice
straw. With approximately 80 million acres of corn planted
annually, corn stover is expected to become a major biomass
resource for bioenergy applications. Forestry Residues Forestry
residues include biomass not harvested or removed from logging
sites in commercial hardwood and softwood stands as well as
material resulting from forest management operations such as
pre-commercial thinnings and removal of dead and dying trees.
Municipal Waste Residential, commercial, and institutional
post-consumer wastes contain a significant proportion of plant
derived organic material that constitute a renewable energy
resource. Waste paper, cardboard, wood waste and yard wastes are
examples of biomass resources in municipal wastes. Biomass
Processing Residues All processing of biomass yields byproducts and
waste streams collectively called residues, which have significant
energy potential. Residues are simple to use because they have
already been collected. For example, processing of wood for
products or pulp produces sawdust and collection of bark, branches
and leaves/needles. Animal Wastes Farms and animal processing
operations create animal wastes that constitute a complex source of
organic materials with environmental consequences. These wastes can
be used to make many products, including energy.
http://www.eere.energy.gov/RE/bio_resources.html
The dry, fibrous residue remaining after the extraction of juice
from the crushed stalks of sugar cane, used as a source of
cellulose for some paper products. Switchgrass (Panicum virgatum),
also called Tall Panic Grass, is a warm-season plant (C4 carbon
fixation) and is one of the dominant species of the central North
America tallgrass prairie. Switchgrass can be found in remnant
prairies, along roadsides, pastures or as an ornamental in
gardens.This hardy, perennial grass begins growth in late spring.
It can grow up to 1.8-2.2 m in height, but is typically shorter
than Big Bluestem Grass (Andropogon gerardii) or Indiangrass
(Sorghastrum nutans). The leaves are 30-90 cm long with a prominant
midrib.Its flowers have a well-developed panicle often up to 60 cm
in length and bears a good crop of fruits, which are 3 to 6 mm long
and up to 1.5 mm wide. The fruits are developed from a
single-flowered spikelet. Both glumes are present and well
developed. When ripe, the seeds sometimes take on a pink or
dull-purple tinge, and turn golden brown with the foliage of the
plant in the fall.Switchgrass is a short rhizomatous plant that
tends to resemble a bunch grass. As an ornamental grass, it is
easily grown in average to wet soils and in full sun to part shade.
It is very drought resistant. Establishment is recommended in the
spring, at the same time as maize is planted.Switchgrass is grazed
by all kinds of animals. Grazing sheep and horses on monoculture
switchgrass stands should be avoided. Due to its hardiness and
rapid growth, switchgrass is often considered a good candidate for
farming as feedstock or for biofuel production (for example,
ethanol). It was in this capacity that President George W. Bush
mentioned it in his 2006 State of the Union address. Many farmers
already grow switchgrass, either as forage for livestock, in
wildlife areas, or as a ground cover, to control
erosion.Switchgrass has the potential to produce the biomass
required for production of up to 1000 gallons of ethanol per acre.
A high yield like this makes it a very attractive crop to grow as
the value by far exceeds any other crop. Yet, some studies claim
that switchgrass is not a viable alternative, requiring 45 percent
more fossil energy than the fuel produced. It's possible that with
research, the conversion process might become more efficient.Other
common names for this grass include Wobsqua grass, lowland
switchgrass, blackbent, tall prairiegrass, wild redtop, and
thatchgrass.
http://en.wikipedia.org/wiki/Switchgrasshttp://www.eia.doe.gov/cneaf/solar.renewables/page/mswaste/msw.jpghttp://www.eeingeorgia.org/eic/images/landfill.jpgWhat
Is a Biorefinery? A biorefinery is a facility that integrates
biomass conversion processes and equipment to produce fuels, power,
and chemicals from biomass. The biorefinery concept is analogous to
today's petroleum refineries, which produce multiple fuels and
products from petroleum. Industrial biorefineries have been
identified as the most promising route to the creation of a new
domestic biobased industry.By producing multiple products, a
biorefinery can take advantage of the differences in biomass
components and intermediates and maximize the value derived from
the biomass feedstock. A biorefinery might, for example, produce
one or several low-volume, but high-value, chemical products and a
low-value, but high-volume liquid transportation fuel, while
generating electricity and process heat for its own use and perhaps
enough for sale of electricity. The high-value products enhance
profitability, the high-volume fuel helps meet national energy
needs, and the power production reduces costs and avoids
greenhouse-gas emissions.
Conceptual BiorefineryNREL's biorefinery concept is built on two
different "platforms" to promote different product slates. The
"sugar platform" is based on biochemical conversion processes and
focuses on the fermentation of sugars extracted from biomass
feedstocks. The "syngas platform" is based on thermochemical
conversion processes and focuses on the gasification of biomass
feedstocks and by-products from conversion processes.
http://www.nrel.gov/biomass/biorefinery.html
----------------------------------Integrated BiorefineriesIn
addition to reducing dependence on foreign oil, fostering a
domestic biorefinery industry modeled after petrochemical
refineries is a primary objective of the Biomass Program. Existing
industries such as wet-mill corn processing and pulp and paper
mills fit the multiple-products-from-biomass definition of a
biorefinery, but the goal is to foster new industries converting
lignocellulosic biomass into a wide range of products, including
ones that would otherwise be made from petrochemicals. As with
petrochemical refineries, the vision is that the biorefinery would
produce both high-volume liquid transportation fuel (meeting
national energy needs) and high-value chemicals or products
(enhancing operation economics).Sugar Platform Biorefineries would
likely break biomass down into different types of component sugars
for fermentation or other biological processing into various fuels
and chemicals. Thermochemical biorefineries would likely convert
biomass to synthesis gas (hydrogen and carbon monoxide) or
pyrolysis oil, the various components of which could be directly
used as fuel or converted to other fuels and chemicals by chemical
catalysis.
http://www1.eere.energy.gov/biomass/integrated_biorefineries.htmlBiochemical
Conversion Technologies - Projects Biochemical conversion
technologies involve three basic steps: (1) converting biomass to
sugar or other fermentation feedstock (NREL's process design uses
dilute acid pretreatment followed by enzymatic hydrolysis); (2)
fermenting these biomass intermediates using biocatalysts
(microorganisms including yeast and bacteria); and (3) processing
the fermentation product to yield fuel-grade ethanol and other
fuels, chemicals, heat and/or electricity.Researchers are working
to improve the efficiency and economics of the biochemical
conversion process technologies by focusing their efforts on the
most challenging steps in the process. The major thrusts of the
advanced R&D on biochemical conversion technologies are
currently improving pretreatment technology, for breaking
hemicellulose down to component sugars and developing more
cost-effective cellulase enzymes, for breaking cellulose down to
its component sugar.Researchers are also working to demonstrate
biochemical conversion processes in real-world applications.
Integration and production activities involve industrial partners
and focus on developing valuable products from sugars and on
relatively large integrated projects that seek to improve the
commercial viability of biochemical conversion
technologies.Advanced Biochemical Conversion R&D
ProjectsResearchers are working to improve the efficiency and
economics of the biochemical conversion process technologies by
focusing their efforts on the most challenging steps in the
process. The major thrust of the advanced R&D on biochemical
conversion technologies is on pretreatment, cellulase enzymes, and
catalyst development for products from sugars.
http://www.nrel.gov/biomass/proj_biochemical_conversion.html
Thermochemical Platform
Biomass combustion, such as burning wood, has been one of man's
primary ways of deriving energy from biomass from prehistoric times
to the present. It is not, however, very efficient. Converting the
solid biomass to a gaseous or liquid fuel by heating it with
limited oxygen prior to combustion can greatly increase the overall
efficiency, and also make it possible to instead convert the
biomass to valuable chemicals or materials. U.S. Department of
Energy Biomass Program researchers help lead a national effort to
develop thermochemical technologies to more efficiently tap the
enormous energy potential of lignocellulosic biomass. In addition
to gasification, pyrolysis, and other thermal processing, program
research focuses on cleaning up and conditioning the converted
fuel, a key step for effective commercial use of thermochemical
platform chemicals.
Biomass GasificationWhen biomass is heated with no oxygen or
only about one-third the oxygen needed for efficient combustion
(amount of oxygen and other conditions determine if biomass
gasifies or pyrolyzes), it gasifies to a mixture of carbon monoxide
and hydrogensynthesis gas or syngas.Combustion is a function of the
mixture of oxygen with the hydrocarbon fuel. Gaseous fuels mix with
oxygen more easily than liquid fuels, which in turn mix more easily
than solid fuels. Syngas therefore inherently burns more
efficiently and cleanly than the solid biomass from which it was
made. Biomass gasification can thus improve the efficiency of
large-scale biomass power facilities such as those for forest
industry residues and specialized facilities such as black liquor
recovery boilers of the pulp and paper industryboth major sources
of biomass power. Like natural gas, syngas can also be burned in
gas turbines, a more efficient electrical generation technology
than steam boilers to which solid biomass and fossil fuels are
limited.Most electrical generation systems are relatively
inefficient, losing half to two-thirds of the energy as waste heat.
If that heat can be used for an industrial process, space heating,
or another purpose, efficiency can be greatly increased. Small
modular biopower systems are more easily used for such
"cogeneration" than most large-scale electrical generation.Just as
syngas mixes more readily with oxygen for combustion, it also mixes
more readily with chemical catalysts than solid fuels do, greatly
enhancing its ability to be converted to other valuable fuels,
chemicals and materials. The Fischer-Tropsch process converts
syngas to liquid fuels needed for transportation. The water-gas
shift process converts syngas to more concentrated hydrogen for
fuel cells. A variety of other catalytic processes can turn syngas
into a myriad of chemicals or other potential fuels or
products.
The award-winning gasifier is located at the McNeil Generating
Station in Burlington, Vermont, which uses wood from nearby
forestry operationsforest thinnings and discarded wood palletsto
generate electric power for the citys residents. The gasifier can
convert 200 tons of wood chips each day into a gaseous fuel that is
fed directly into the McNeil Station boiler to generate 8 MW of
electricity. Wood fuel in the gasifier is surrounded by sand heated
to 18001900F, which breaks down the biomass into gas and residual
char in a fluidized-bed reactor at 15001600F. Sand is used to carry
the biomass and the char and to distribute the heat. Using sand as
a heat carrier keeps out air, which results in a better quality
fuel gas. The biomass gasifier enables the use of advanced power
systems based on gas turbines and combined cycles that will nearly
double the efficiency of todays biopower industry.
http://www.nrel.gov/docs/fy00osti/28330.pdf
http://www1.eere.energy.gov/biomass/pyrolysis.html
Pyrolysis and Other Thermal ProcessingSolid biomass can be
liquefied by pyrolysis, hydrothermal liquefaction, or other
thermochemical technologies. Pyrolysis and gasification are related
processes of heating with limited oxygen. Conditions for producing
pyrolysis oil are more likely to include virtually no oxygen.
Pyrolysis oil or other thermochemically-derived biomass liquids can
be used directly as fuel, but also hold great promise as platform
intermediates for production of high-value chemicals and
materials.PyrolysisFast pyrolysis is a thermal decomposition
process that occurs at moderate temperatures with a high heat
transfer rate to the biomass particles and a short hot vapor
residence time in the reaction zone. Several reactor configurations
have been shown to assure this condition and to achieve yields of
liquid product as high as 75% based on the starting dry biomass
weight . They include bubbling fluid beds, circulating and
transported beds, cyclonic reactors, and ablative reactors. Fast
pyrolysis of biomass produces a liquid product, pyrolysis oil or
bio-oil that can be readily stored and transported. Pyrolysis oil
is a renewable liquid fuel and can also be used for production of
chemicals. Fast pyrolysis has now achieved a commercial success for
production of chemicals and is being actively developed for
producing liquid fuels. Pyrolysis oil has been successfully tested
in engines, turbines and boilers, and been upgraded to high quality
hydrocarbon fuels although at a presently unacceptable energetic
and financial cost. In the 1990s several fast pyrolysis
technologies reached near-commercial status. Six circulating
fluidized bed plants have been constructed by Ensyn Technologies,
with the largest having a nominal capacity of 50 t/day operated for
Red Arrow Products Co., Inc. in Wisconsin. DynaMotive (Vancouver,
Canada) demonstrated the bubbling fluidized bed process at 10 t/day
of biomass and is scaling up the plant to 100 t/day. BTG (The
Netherlands) operates a rotary cone reactor system at 5 t/day and
is proposing to scale the plant up to 50 t/d. Fortum has a 12 t/day
pilot plant in Finland. The yields and properties of the generated
liquid product, bio-oil, depend on the feedstock, the process type
and conditions, and the product collection efficiency.Biomass
Program researchers use both vortex (cyclonic) and fluidized bed
reactors for pyrolyzing biomass. The fluidized bed reactor of the
Thermochemical Users Facility at the National Renewable Energy
Laboratory is a 1.8 m high cylindrical vessel of 20 cm diameter in
the lower (fluidization) zone, expanded to 36 cm diameter in the
freeboard section. It is equipped in a perforated gas distribution
plate and an internal cyclone to retain entrained bed media
(typically sand). The reactor is heated electrically and can
operate at temperatures up to 700C at a throughput of 15-20 kg/h of
biomass.Recently, a catalytic steam reformer was coupled to the
pyrolysis/gasification system. Like the pyrolyzer, the reformer is
an externally heated fluidized bed reactor that will be used to
produce hydrogen from pyrolysis gas and vapors generated in the
first stage of the process and to clean the gas from tars.Biomass
Program micro-scale pyrolysis systems include externally heated
different types reactors coupled to the molecular-beam
mass-spectrometer (MBMS). These systems are very efficient tools,
especially for studying mechanisms of thermal and catalytic
processes and to optimize process conditions for different products
from variety of feedstocks. For example, the ongoing research
sponsored by Philip Morris resulted in understanding the chemical
processes of biopolymer pyrolysis and oxidation leading to aromatic
hydrocarbon formation.
http://www1.eere.energy.gov/biomass/pyrolysis.html
Pyrolysis and Other Thermal ProcessingSolid biomass can be
liquefied by pyrolysis, hydrothermal liquefaction, or other
thermochemical technologies. Pyrolysis and gasification are related
processes of heating with limited oxygen. Conditions for producing
pyrolysis oil are more likely to include virtually no oxygen.
Pyrolysis oil or other thermochemically-derived biomass liquids can
be used directly as fuel, but also hold great promise as platform
intermediates for production of high-value chemicals and
materials.PyrolysisFast pyrolysis is a thermal decomposition
process that occurs at moderate temperatures with a high heat
transfer rate to the biomass particles and a short hot vapor
residence time in the reaction zone. Several reactor configurations
have been shown to assure this condition and to achieve yields of
liquid product as high as 75% based on the starting dry biomass
weight . They include bubbling fluid beds, circulating and
transported beds, cyclonic reactors, and ablative reactors. Fast
pyrolysis of biomass produces a liquid product, pyrolysis oil or
bio-oil that can be readily stored and transported. Pyrolysis oil
is a renewable liquid fuel and can also be used for production of
chemicals. Fast pyrolysis has now achieved a commercial success for
production of chemicals and is being actively developed for
producing liquid fuels. Pyrolysis oil has been successfully tested
in engines, turbines and boilers, and been upgraded to high quality
hydrocarbon fuels although at a presently unacceptable energetic
and financial cost. In the 1990s several fast pyrolysis
technologies reached near-commercial status. Six circulating
fluidized bed plants have been constructed by Ensyn Technologies,
with the largest having a nominal capacity of 50 t/day operated for
Red Arrow Products Co., Inc. in Wisconsin. DynaMotive (Vancouver,
Canada) demonstrated the bubbling fluidized bed process at 10 t/day
of biomass and is scaling up the plant to 100 t/day. BTG (The
Netherlands) operates a rotary cone reactor system at 5 t/day and
is proposing to scale the plant up to 50 t/d. Fortum has a 12 t/day
pilot plant in Finland. The yields and properties of the generated
liquid product, bio-oil, depend on the feedstock, the process type
and conditions, and the product collection efficiency.Biomass
Program researchers use both vortex (cyclonic) and fluidized bed
reactors for pyrolyzing biomass. The fluidized bed reactor of the
Thermochemical Users Facility at the National Renewable Energy
Laboratory is a 1.8 m high cylindrical vessel of 20 cm diameter in
the lower (fluidization) zone, expanded to 36 cm diameter in the
freeboard section. It is equipped in a perforated gas distribution
plate and an internal cyclone to retain entrained bed media
(typically sand). The reactor is heated electrically and can
operate at temperatures up to 700C at a throughput of 15-20 kg/h of
biomass.Recently, a catalytic steam reformer was coupled to the
pyrolysis/gasification system. Like the pyrolyzer, the reformer is
an externally heated fluidized bed reactor that will be used to
produce hydrogen from pyrolysis gas and vapors generated in the
first stage of the process and to clean the gas from tars.Biomass
Program micro-scale pyrolysis systems include externally heated
different types reactors coupled to the molecular-beam
mass-spectrometer (MBMS). These systems are very efficient tools,
especially for studying mechanisms of thermal and catalytic
processes and to optimize process conditions for different products
from variety of feedstocks. For example, the ongoing research
sponsored by Philip Morris resulted in understanding the chemical
processes of biopolymer pyrolysis and oxidation leading to aromatic
hydrocarbon formation.
"Biogas Platform" Decomposing biomass with natural consortia of
microorganisms in closed tanks known as anaerobic digesters
produces methane (natural gas) and carbon dioxide. This
methane-rich biogas can be used as fuel or as a base chemical for
biobased products. Although the Biomass Program is not currently
doing much research in this area, a joint Environmental Protection
Agency/Department of Agriculture/Department of Energy program known
as AgStar works to encourage use of existing technology for manures
at animal feedlots.
http://www1.eere.energy.gov/biomass/other_platforms.html
"Carbon-Rich Chains Platform" Natural plant oils such as
soybean, corn, palm, and canola oils are in wide use today for food
and chemical applications. Transesterification of vegetable oil or
animal fat produces fatty acid methyl ester, commonly known as
biodiesel. Biodiesel already provides an important commercial
air-emission reducing additive or substitute for petroleum diesel,
but it, its glycerin byproduct, and the fatty acids from which it
is made could all be platform chemicals for biorefineries.
http://www1.eere.energy.gov/biomass/other_platforms.html
BiofuelsA variety of fuels can be made from biomass resources
including the liquid fuels ethanol, methanol, biodiesel,
Fischer-Tropsch diesel, and gaseous fuels such as hydrogen and
methane. Biofuels research and development is composed of three
main areas: producing the fuels, applications and uses of the
fuels, and distribution infrastructure. Biofuels are primarily used
to fuel vehicles, but can also fuel engines or fuel cells for
electricity generation. For information about the use of biofuels
in vehicles, see the Alternative Fuel Vehicle page under
Transportation. See the Transportation page for information about
the biofuels distribution infrastructure. See the Hydrogen page for
more information about hydrogen as a fuel. FuelsEthanol Ethanol is
made by converting the carbohydrate portion of biomass into sugar,
which is then converted into ethanol in a fermentation process
similar to brewing beer. Ethanol is the most widely used biofuel
today with current capacity of 1.8 billion gallons per year based
on starch crops such as corn. Ethanol produced from cellulosic
biomass is currently the subject of extensive research, development
and demonstration efforts. Biodiesel Biodiesel is produced through
a process in which organically derived oils are combined with
alcohol (ethanol or methanol) in the presence of a catalyst to form
ethyl or methyl ester. The biomass- derived ethyl or methyl esters
can be blended with conventional diesel fuel or used as a neat fuel
(100% biodiesel). Biodiesel can be made from soybean or Canola
(rapeseed) oils, animal fats, waste vegetable oils, or microalgae
oils. Biofuels from Synthesis Gas Biomass can be gasified to
produce a synthesis gas composed primarily of hydrogen and carbon
monoxide, also called syngas or biosyngas. Hydrogen can be
recovered from this syngas, or it can be catalytically converted to
methanol. It can also be converted using Fischer-Tropsch catalyst
into a liquid stream with properties similar to diesel fuel, called
Fischer-Tropsch diesel. However, all of these fuels can also be
produced from natural gas using a similar process. Conversion
ProcessesBiochemical Conversion Processes Enzymes and
microorganisms are frequently used as biocatalysts to convert
biomass or biomass derived compounds into desirable products.
Cellulase and hemicellulase enzymes break down the carbohydrate
fractions of biomass to five and six carbon sugars, a process known
as hydrolysis. Yeast and bacteria ferment the sugars into products
such as ethanol. Biotechnology advances are expected to lead to
dramatic biochemical conversion improvements. Photobiological
Conversion Processes Photobiological processes use the natural
photosynthetic activity of organisms to produce biofuels directly
from sunlight. For example, the photosynthetic activities of
bacteria and green algae have been used to produce hydrogen from
water and sunlight. Thermochemical Conversion Processes Heat energy
and chemical catalysts are used to break down biomass into
intermediate compounds or products. In gasification, biomass is
heated in an oxygen-starved environment to produce a gas composed
primarily of hydrogen and carbon monoxide. In pyrolysis, biomass is
exposed to high temperatures in the absence of air, causing it to
decompose. Solvents, acids and bases can be used to fractionate
biomass into an array of products including sugars, cellulosic
fibers and lignin.
http://www.eere.energy.gov/RE/bio_fuels.html"Plant Products
Platform
Selective breeding and genetic engineering can develop plant
strains that produce greater amounts of desirable feedstocks or
chemicals or even compounds that the plant does not naturally
produce getting the biorefining done in the biological plant rather
than the industrial plant.
http://www1.eere.energy.gov/biomass/other_platforms.html
Economic IssuesSustainable Development Biomass technologies are
one approach to moving our economy to a more sustainable basis
because they move us away from fossil fuels. One of the biggest
impediments to sustainable development is our economic system that
places little value on the environment or on the future. Energy
Security As a domestic energy source, biomass can substantially
reduce dependence on imported crude oil. Biomass is more evenly
distributed over the earth's surface than other finite energy
sources and therefore provides opportunities for local, regional,
and national energy self-sufficiency. Rural Economic Growth
Producing biomass and using agricultural residues for biomass
technologies will stimulate rural development efforts in farming,
forestry, and associated service industries by creating new
products, markets, and jobs. Land Use Our nation's arable lands
must be used in balanced ways, supporting agricultural and forestry
production, environmental preservation, human and wildlife
habitats, as well as biomass production.
http://www.eere.energy.gov/RE/bio_integrated.htmlSwitchgrass
Economics Using inputs advised by the Crop and Soil Sciences
department at the University of Georgia an enterprise budget was
constructed for Switchgrass production. The University has three
test plots growing Switchgrass and have tested the best possible
combinations of methods and ingredients to receive the best yields.
These results allow the budget to be realistic. The variable cost
associated with growing Switchgrass amounted to approximately $260
per acre. The fixed cost, including machinery cost for the
enterprise, amounted to $82 per acre. Adding a return to management
at 5% of the variable cost and the pre-harvest interest of the same
amount, the total cost per acre is $395. (Refer to budget in
appendix) The test plot yielded from 2 to 8 tons per acre, so for
this study an average yield of 6 tons per acre was chosen. The
breakeven price needed for various tons appears in the chart below
This table indicates that even with 10 tons per acre the total cost
for the farmer to grow Switchgrass is around $40 per ton. The
average tons per acre based off all known test plots were 6 tons.
Given this, the farmers will need to earn $66 per ton to cover the
costs. Each ton of Switchgrass is assumed to produce 80 gallons of
ethanol. Using the above cost for growing Switchgrass, one can
establish the ethanol price necessary to cover the cost of
Switchgrass as an input. When an acre yields 6 tons of Switchgrass,
the minimum price of ethanol to cover Switchgrass is $.82. This
chart simply shows that to cover the Switchgrass cost the ethanol
price per gallon has to be at the above price. This does not
include any of the other costs needed in producing ethanol. One
problem with Switchgrass is the transportation and shrinkage
factor. Presently little testing has been done on what the actually
shrink amount in the grass may be. Researchers suggest anywhere
from 10% to 40% basing this off forage shrinkage rates. So, when
the shrink factor and transportation are added to the equation for
the average yield of 6 tons at 30% shrinkage the breakeven become
$81.25. (Refer to chart in appendix)
http://www.agecon.uga.edu/~caed/Pubs/switchgrass.htmlEnvironmental
IssuesBiomass technologies are friendlier to the environment than
conventional energy technologies, which rely on fossil fuels.
Fossil fuels contribute significantly to many of the environmental
problems we face today greenhouse gases, air pollution, and water
and soil contamination. Biomass technologies could help us break
our conventional pattern of energy use to improve the quality of
our environment. Air Quality Biomass alternatives can reduce the
emission of nitrogen oxides, sulfur dioxides, and other air
pollutants associated with fossil fuel use. Global Climate Change
Increased emissions of greenhouse gases from use of fossil fuels,
especially carbon dioxide, has created an enhanced greenhouse
effect known as global climate change or global warming. Biomass
technologies produce very low or no amount of carbon dioxide
emissions. Soil Conservation Soil conservation issues associated
with biomass production include soil erosion control, nutrient
retention, carbon sequestration, and stabilization of riverbanks.
Water Conservation Biomass technology life cycles may have impacts
on watershed stability, groundwater quality, surface water runoff
and quality, and local water use for crop irrigation and/or
conversion facility needs. Biodiversity and Habitat Change
Biodiversity is the genetic and species diversity of living things
in a defined area or region. Altered land use to support increased
biomass production may result in changes in habitat and levels of
biodiversity.
http://www.eere.energy.gov/RE/bio_integrated.htmlIssuesBiomass
Production Improvements Improvements in agricultural practices will
lead to increased biomass yields, reductions in cultivation costs,
and improved environmental quality. Key elements include new plant
genetics and breeding technology, new analytical techniques and
evaluation techniques, and the development of tools to enable
precision agriculture, such as remote sensing and geographic
information systems (GIS). Biomass Material Handling Materials
handling systems for biomass constitute a significant portion of
the capital investment and operating costs of a biomass conversion
facility. Requirements depend on the type of biomass to be
processed as well as the feedstock preparation requirements of the
conversion technology. Biomass storage, handling, conveying, size
reduction, cleaning, drying, and feeding equipment and systems are
included. Biomass Collection Logistics and Infrastructure
Harvesting biomass crops, collecting biomass residues, and storing
and transporting biomass resources are critical elements in the
biomass resource supply chain.
http://www.eere.energy.gov/RE/bio_resources.htmlNathaniel Greene et
al., Growing Energy, How Biofuels Can help end Americas oil
dependence,
www.bioproducts-bioenergy.gov/pdfs/NRDC-Growing-Energy-Final.3.pdf.
Professor Lee Lynd, Big or Little Potatoes? Role of Biomass in
Americas Energy Future, Feb. 2004,
http://thayer.dartmouth.edu/thayer/rbaef/.
Fermentation is the biochemical process that converts sugars
into ethanol (alcohol). In contrast to biogas production,
fermentation takes place in the presence of air and is, therefore,
a process of aerobic digestion. Ethanol producers use specific
types of enzymes to convert starch crops such as corn, wheat and
barley to fermentable sugars. Some crops, such as sugar-cane and
sugar beets, naturally contain fermentable sugars.
Most of the ethanol produced in the United States today comes
from grain (predominantly corn). In the wet mill process, grain is
steeped and separated into starch, germ and fiber components. In
the dry mill process, grain is first ground into flour and then
processed without separation of the starch.Wet milling is more
common. After the grain is cleaned, it is steeped and then ground
to remove the germ. Further grinding, washing and filtering steps
separate the fiber and gluten. The starch that remains after these
separation steps is then broken down into fermentable sugars by the
addition of enzymes in the liquefaction and saccharification
stages.To produce ethanol, yeast is added to a slurry (or "mash"),
which is a solution of fermentable sugars and water. The yeast
ferments the sugars, producing a solution called beer. The beer
solution contains about 10-percent to 12-percent ethanol. The rate
of the conversion process depends on the amount of water in the
slurry and its acidity, temperature and oxygen content. Up to a
third of the original dry weight of the feedstock leaves the
fermentation process as carbon dioxide. The solids that remain
after the mash has fermented still contain nutrients suitable for
use as livestock feed. Distilling the beer produces a solution of
80-percent to 95-percent ethanol.Producers can use several methods
of dehydration to purify the ethanol solution further to
100-percent (200-proof) alcohol for use as a motor
fuel.Cellulose-to-ethanol technology converts lignocellulosic
feedstock (LCF) into component sugars, which are then fermented to
ethanol. This technology is currently in an early stage of
commercial development. However, as early as 1945, Oregon pioneered
cellulose-to-ethanol technology. At that time, Dr. Raphael Katzen
designed, built and operated a 17 million-gallon-per-year ethanol
plant in Springfield, Oregon, that used woodfeedstockAll LCF
materials are made of cellulose, hemicellulose and lignin. Lignin
acts like glue in plant material. It holds the other components
together and gives trees and plant stalks their strength. The
lignin removed in pretreatment is itself a biomass fuel. Burning
the lignin produces heat, useful for other steps in the
cellulose-to-ethanol conversion process.Several methods are
available to breaking down the chemical bonds of cellulose and
hemicellulose and to remove the lignin. Methods include dilute and
concentrated acid hydrolysis and enzymatic hydrolysis. Hydrolysis
releases fermentable sugars from cellulose and hemicellulose. This
stage is sometimes called saccharification.Fermentation, the next
stage of the process, uses enzymes to convert the sugars into
ethanol. As with the grain-to-ethanol process, the final stage is
distillation of the fermented beer into ethanol that is about
95-percent pure.Biomass BasicsBiomass (organic matter) can be used
to provide heat, make fuels, chemicals and other products, and
generate electricity. Wood, the largest source of bioenergy, has
been used to provide heat for thousands of years. But there are
many other types of biomasssuch as wood, plants, residue from
agriculture or forestry, and the organic component of municipal and
industrial wastes can now be used to produce fuels, chemicals and
power. In the future, biomass resources may be replenished through
the cultivation of energy crops, such as fast-growing trees and
grasses, called biomass feedstocks. Unlike other renewable energy
sources, biomass can be converted directly into liquid fuels for
our transportation needs. The two most common biofuels are ethanol
and biodiesel. Ethanol, an alcohol, is made by fermenting any
biomass high in carbohydrates, like corn, through a process similar
to brewing beer. It is mostly used as a fuel additive to cut down a
vehicle's carbon monoxide and other smog-causing emissions.
Biodiesel, an ester, is made using vegetable oils, animal fats,
algae, or even recycled cooking greases. It can be used as a diesel
additive to reduce vehicle emissions or in its pure form to fuel a
vehicle. Heat can be used to chemically convert biomass into a fuel
oil, which can be burned like petroleum to generate electricity.
Biomass can also be burned directly to produce steam for
electricity production or manufacturing processes. In a power
plant, a turbine usually captures the steam, and a generator then
converts it into electricity. In the lumber and paper industries,
wood scraps are sometimes directly fed into boilers to produce
steam for their manufacturing processes or to heat their buildings.
Some coal-fired power plants use biomass as a supplementary energy
source in high-efficiency boilers to significantly reduce
emissions. Even gas can be produced from biomass for generating
electricity. Gasification systems use high temperatures to convert
biomass into a gas (a mixture of hydrogen, carbon monoxide, and
methane). The gas fuels a turbine, which is very much like a jet
engine, only it turns an electric generator instead of propelling a
jet. The decay of biomass in landfills also produces a
gasmethanethat can be burned in a boiler to produce steam for
electricity generation or for industrial processes. New technology
could lead to using biobased chemicals and materials to make
products such as anti-freeze, plastics, and personal care items
that are now made from petroleum. In some cases these products may
be completely biodegradable. While technology to bring biobased
chemicals and materials to market is still under development, the
potential benefit of these products is great.
http://www.eere.energy.gov/RE/bio_basics.htmlBiopowerBiopower
technologies are proven electricity generation options in the
United States, with 10 gigawatts of installed capacity. All of
today's capacity is based on mature, direct-combustion technology.
Future efficiency improvements will include co-firing of biomass in
existing coal fired boilers and the introduction of high-efficiency
gasification combined-cycle systems, fuel cell systems, and modular
systems. TechnologiesDirect Combustion Direct combustion involves
the burning of biomass with excess air, producing hot flue gases
that are used to produce steam in the heat exchange sections of
boilers. The steam is used to produce electricity in steam turbine
generators. Co-firing Co-firing refers to the practice of
introducing biomass in high-efficiency coal fired boilers as a
supplementary energy source. Co-firing has been evaluated for a
variety of boiler technologies including pulverized coal, cyclone,
fluidized bed and spreader stokers. For utilities and power
generating companies with coal-fired capacity, co-firing with
biomass may represent one of the least-cost renewable energy
options. Gasification Biomass gasification for power production
involves heating biomass in an oxygen-starved environment to
produce a medium or low calorific gas. This "biogas" is then used
as fuel in a combined cycle power generation plant that includes a
gas turbine topping cycle and a steam turbine bottoming cycle.
Pyrolysis Biomass pyrolysis refers to a process where biomass is
exposed to high temperatures in the absence of air, causing the
biomass to decompose. The end product of pyrolysis is a mixture of
solids (char), liquids (oxygenated oils), and gases (methane,
carbon monoxide, and carbon dioxide). Anaerobic Digestion Anaerobic
digestion is a process by which organic matter is decomposed by
bacteria in the absence of oxygen to produce methane and other
byproducts. The primary energy product is a low to medium calorific
gas, normally consisting of 50 to 60 percent methane. Market
IssuesGreen Power Marketing Green power marketing provides choices
in restructured electricity markets for electricity consumers to
purchase power from renewable or environmentally preferred sources,
such as biomass. Green pricing allows customers to support a
greater level of investment in renewable energy technologies by
paying a premium on their electric bill to cover the incremental
cost of the additional renewable energy. Both approaches can
contribute to the growth of the biopower industry. Combined Heat
and Power (CHP) Much of today's biopower is provided by CHP
facilities located at forest product industry sites. CHP, also
called cogeneration, achieves high efficiencies by using both the
power and the excess heat from burning the biomass. Modular Power
Systems These small energy systems can be used in farm systems and,
more generally, to provide power at or near a customer's site a
concept known as distributed generation.
http://www.eere.energy.gov/RE/bio_biopower.htmlIntegrated Biomass
Systems and AssessmentsBiorefineries The vision for biorefineries
mirrors the development of petroleum refineries, which began with
simple refineries making a few basic fuel products from crude oil.
Biorefineries of the future will have started simply as the
petroleum refinery did, making a few basic products from biomass,
and will expand into highly sophisticated multi-product operations
that maximize the use of biomass resources. Life Cycle Assessments
Life cycle assessments (LCA) employ systematic analytical methods
to identify, evaluate, and help minimize the impacts of a specific
process or to compare competing processes. Material and energy
balances are used to quantify resource depletion, emissions, and
energy consumption of all process steps from developing the raw
materials, producing useful products, and final use or disposal of
all products and byproducts.
http://www.eere.energy.gov/RE/bio_integrated.htmlBiomass
ResourcesBiomass resources include any organic matter available on
a renewable basis, including dedicated energy crops and trees,
agricultural food and feed crops, agricultural crop wastes and
residues, wood wastes and residues, aquatic plants, animal wastes,
municipal wastes, and other waste materials. Material handling,
collection logistics and infrastructure are important aspects of
the biomass resource supply chain. ResourcesHerbaceous Energy Crops
Herbaceous energy crops are perennials that are harvested annually
after taking two to three years to reach full productivity. These
include such grasses as switchgrass, miscanthus (also known as
Elephant grass or e-grass), bamboo, sweet sorghum, tall fescue,
kochia, wheatgrass, and others. Woody Energy Crops Short-rotation
woody crops are fast growing hardwood trees harvested within five
to eight years after planting. These include hybrid poplar, hybrid
willow, silver maple, eastern cottonwood, green ash, black walnut,
sweetgum, and sycamore. Industrial Crops Industrial crops are being
developed and grown to produce specific industrial chemicals or
materials. Examples include kenaf and straws for fiber, and castor
for ricinoleic acid. New transgenic crops are being developed that
produce the desired chemicals as part of the plant composition,
requiring only extraction and purification of the product.
Agricultural Crops These feedstocks include the currently available
commodity products such as cornstarch and corn oil; soybean oil and
meal; wheat starch, other vegetable oils, and any newly developed
component of future commodity crops. They generally yield sugars,
oils, and extractives, although they can also be used to produce
plastics and other chemicals and products. Aquatic Crops A wide
variety of aquatic biomass resources exist such as algae, giant
kelp, other seaweed, and marine microflora. Commercial examples
include giant kelp extracts for thickeners and food additives,
algal dyes, and novel biocatalysts for use in bioprocessing under
extreme environments. Agriculture Crop Residues Agriculture crop
residues include biomass, primarily stalks and leaves, not
harvested or removed from the fields in commercial use. Examples
include corn stover (stalks, leaves, husks and cobs), wheat straw,
and rice straw. With approximately 80 million acres of corn planted
annually, corn stover is expected to become a major biomass
resource for bioenergy applications. Forestry Residues Forestry
residues include biomass not harvested or removed from logging
sites in commercial hardwood and softwood stands as well as
material resulting from forest management operations such as
pre-commercial thinnings and removal of dead and dying trees.
Municipal Waste Residential, commercial, and institutional
post-consumer wastes contain a significant proportion of plant
derived organic material that constitute a renewable energy
resource. Waste paper, cardboard, wood waste and yard wastes are
examples of biomass resources in municipal wastes. Biomass
Processing Residues All processing of biomass yields byproducts and
waste streams collectively called residues, which have significant
energy potential. Residues are simple to use because they have
already been collected. For example, processing of wood for
products or pulp produces sawdust and collection of bark, branches
and leaves/needles. Animal Wastes Farms and animal processing
operations create animal wastes that constitute a complex source of
organic materials with environmental consequences. These wastes can
be used to make many products, including energy. U.S. Department of
Energy - Energy Efficiency and Renewable Energy Biomass
ProgramSugar PlatformThe vast bulk of plant material consists of
cellulose, hemicellulose, and lignin (as opposed to starch and
sugar that industry currently converts to ethanol and uses to make
food and feed products). The U.S. Department of Energy's Biomass
Program is at the forefront of a national effort to develop
technology to break cellulose and hemicellulose down into their
component sugars. Anticipated biorefineries will then be able to
biologically process these sugars to fuel ethanol or other building
block chemicals. Lignin can either be burned to provide process
heat and electricity or can itself be converted to fuels and
chemicals.This lignocellulosic biomass technology will enable the
development of biorefineries that produce an array of valuable
chemicals and products together with bulk biofuels needed for the
transportation sector to alleviate dependence on foreign oil,
reduce net greenhouse gas emissions, and mitigate other
environmental problems. There are a variety of technologies for
hydrolyzing biomass breaking it down into its component sugars.
Although other hydrolysis technologies such as concentrated acid
and dilute acid have long industrial histories, the Biomass Program
focuses on enzymatic hydrolysis as the most promising for reducing
the cost of producing fuel ethanol and enabling biorefinery
development.
After mechanical milling, the Biomass Program process design for
the sugar platform starts with dilute-acid thermochemical
pretreatment. This hydrolyzes the hemicellulose, breaking it down
into its component sugars (xylose and others). It also solubilizes
some of the lignin. Because cellulose is naturally wrapped in a
sheath of hemicellulose and lignin, both of these actions make the
cellulose more accessible to further action. The cellulose is then
enzymatically hydrolyzed to release its sugars (glucose). The
biomass sugars so produced are then available for fermentation to
fuel ethanol or to bio/catalytic processing to other products, and
the residue lignin is available for catalytic conversion to other
products, gasification, or combustion to provide heat and power for
the plant's operation or export. At the more basic research end of
the spectrum, the Biomass Program also researches the scientific
fundamentals underlying sugar platform technology, as well as new
concepts that hold promise to greatly improve overall processing
economics. At the applied end of the spectrum, the Program's sugar
platform integration efforts seek to resolve practical challenges
involved in industrial scale application of sugar platform
technology. The program also works extensively to develop "bridges"
between future biomass-to-ethanol technology and the current
ethanol industry, to exploit the many opportunities that exist for
adopting or advancing cellulosic ethanol production or other sugar
platform technologies.The U.S. Department of Energy (DOE) Biomass
Program develops technology for conversion of biomass
(plant-derived material) to valuable fuels, chemicals, materials
and power, so as to reduce dependence on foreign oil and foster
growth of biorefineries. Biomass is one of our most important
energy resources. The largest U.S. renewable energy source every
year since 2000, it also provides the only renewable alternative
for liquid transportation fuel. Biomass use strengthens rural
economies, decreases America's dependence on imported oil, avoids
use of MTBE or other highly toxic fuel additives, reduces air and
water pollution, and reduces greenhouse gas emissions. Today's
biomass uses include ethanol, biodiesel, biomass power, and
industrial process energy.
http://www1.eere.energy.gov/biomass/Other PlatformsA number of
technologies have been identified as having significant potential
for expanding use of biomass energy. Particularly important for
reducing fossil fuel use and imports and for promoting new domestic
industry are those for development of biomass-derived "platform
chemicals." From such platforms, "biorefineries" could make a
variety of fuels, chemicals, products, and power, much as is done
with petroleum and petrochemicals today. The Biomass Program is
currently focusing on the Sugar Platform and the Thermochemical
Platform, but there are several other interesting possibilities
including the following."Biogas Platform" Decomposing biomass with
natural consortia of microorganisms in closed tanks known as
anaerobic digesters produces methane (natural gas) and carbon
dioxide. This methane-rich biogas can be used as fuel or as a base
chemical for biobased products. Although the Biomass Program is not
currently doing much research in this area, a joint Environmental
Protection Agency/Department of Agriculture/Department of Energy
program known as AgStar works to encourage use of existing
technology for manures at animal feedlots."Carbon-Rich Chains
Platform" Natural plant oils such as soybean, corn, palm, and
canola oils are in wide use today for food and chemical
applications. Transesterification of vegetable oil or animal fat
produces fatty acid methyl ester, commonly known as biodiesel.
Biodiesel already provides an important commercial air-emission
reducing additive or substitute for petroleum diesel, but it, its
glycerin byproduct, and the fatty acids from which it is made could
all be platform chemicals for biorefineries."Plant Products
Platform" Selective breeding and genetic engineering can develop
plant strains that produce greater amounts of desirable feedstocks
or chemicals or even compounds that the plant does not naturally
produce getting the biorefining done in the biological plant rather
than the industrial plant.
http://www1.eere.energy.gov/biomass/other_platforms.htmlDirect
Hydrothermal LiquefactionDirect hydrothermal liquefaction involves
converting biomass to an oily liquid by contacting the biomass with
water at elevated temperatures (300-350C) with sufficient pressure
to maintain the water primarily in the liquid phase (12-20 MPa) for
residence times up to 30 minutes. Alkali may be added to promote
organic conversion. The primary product is an organic liquid with
reduced oxygen content (about 10%) and the primary byproduct is
water containing soluble organic compounds. Hydrothermal treatment
is based on early work performed by the Bureau of Mines Albany
Laboratory in the 1970s. Developers include Changing World
Technologies (West Hampstead, NY), EnerTech Environmental Inc
(Atlanta, GA), and Biofuel B.V. (Heemskerk,
Netherlands).http://www1.eere.energy.gov/biomass/thermochemical_platform.html
Thermochemical Process R&DNREL's researchers have
investigated the thermochemical conversion of renewable energy
feedstocks since the lab's inception. Researchers have focused on
developing gasification and pyrolysis processes for converting
biomass and its residues to fuels, chemicals, and
power.Gasification R&D is working to produce biosyngas with
characteristics suitable for commercial applications. One major
part of this effort is the development of biomass gasification
combined cycles. Integrated biomass gasification with combined
cycles can be used to generate synthesis gas that can be burned in
gas turbines or used in fuel cells to produce electricity at high
efficiency. The methods developed by NREL researchers for
analyzing, cleaning, and conditioning product gas to meet
prime-mover (e.g., spark-ignited internal combustion engines,
turbines, etc.) requirements are critical to making this technology
commercially viable.Fundamental work is also being conducted at
NREL that provides a solid understanding of the chemistry of
biomass pyrolysis, including stabilization and upgrading of
bio-oil, the potential applications of pyrolysis liquids, and the
requirements for engineering systems that can produce fuels and
chemicals via biomass pyrolysis on a large scale.
http://www.nrel.gov/biomass/thermochemical_conversion.html
