Posts Tagged ‘biomass’
BIOMASS TO ETHANOL
BIOMASS TO ETHANOL: HYDROLYSIS AND
FERMENTATION
Sugars are the essential raw material for a range of
biobased products from ethanol to bioplastics. In the
case of ethanol, sugar is converted into alcohol through
fermentation. Both corn grain and cellulosic feedstocks,
such as corn stover, straw and wood, are composed of
about 70 percent sugars, making them good candidates
for ethanol production. The challenge lies in extracting
the sugars from these agricultural feedstocks.
In corn grain, the sugars are all of the same variety (6-
carbon molecules of glucose), joined together with
relatively simple bonds to form starch. These simple
bonds can easily be broken using commonly available
amylase enzymes and water in a process called hydrolysis.
Isolating the sugars in cellulosic biomass is a
considerably more complicated task. Cellulosic biomass is
composed of a mixture of 6-carbon glucose sugars in the
form of cellulose and 5-carbon pentose sugars linked to
other 6-carbon sugars in the form of hemicellulose, all
held together by complex chemical bonds bound with a
stiff, fibrous substance called lignin. The biomass must
first be pre-treated to separate the lignin and loosen the
chemical bonds. Cellulase enzymes can then be used to
break the sugar-to-sugar bonds via hydrolysis.
Recent biotech advances have made significant
improvements in cellulase enzymes and pentoseprocessing
microbes, closing the gap on making cellulosic
biomass conversion to ethanol economical. As
commercialization proceeds, further gains will help ensure
sustainable feedstock platforms for fuels and chemicals.
Sugar
content
70% as starch. 30-50% as cellulose.
25-32% as hemicellulose.
Conversion
to individual
sugars
Straightforward conversion
to sugars via amylase
enzymes.
Current starch to sugar
conversion cost 3¢ to
5¢ per gallon ethanol.
Challenge to convert to sugars.
Cellulose to glucose with muchimproved
enzymes approaching
10¢ per gallon.
Current
ethanol
yield
105 to 120 gallons
per dry ton (2.5 to 2.8
gallons ethanol per
bushel).
80 to 90 gallons per dry ton feedstock.
Pentose fermentation to alcohol
still an evolving technology.
Energy crops
A research commitment on Renewable Biomass Energy & Global Warming by using Nature’s own Power Plants! Read the full article here In unique public and industry research and commercial demonstration partnerships, the Common Purpose Institute is working with the University of Florida, Florida Energy Office, U.S. Department of Energy, U.S. Department of Agriculture, Farmers, Power Providers, Industrial & Manufacturing Companies, Ethanol Biofuel Producers, and others to grow, harvest, and use fast growing crops (called energy crop or closed loop biomass) and also biomass waste streams (e.g., clean yardwaste, crop residues, etc.) as renewable energy biofuel or feedstocks for:
Biomass Energy & Global Warming: By remembering the basic science of photosynthesis, a key aspect of our biomass research effort can be easily understood. Since plants and trees absorb and store atmospheric carbon as they grow, growing and using biomass energy crops reduces the level of CO2 emissions into the atmosphere — which may be creating Global Warming Climate Change on our planet.
The science behind this Strategy to reduce greenhouse gas levels is accomplished in two ways: First, biomass energy from crops is “carbon cycle neutral” just like other forms of renewable energy such as wind or solar power. Second, growing energy crops creates a “carbon sink” through terrestrial carbon sequestration by storing carbon underground through root systems and soil chemistry management practices (e.g., recycling bagasse). Because of this creation of a “carbon sink” (a component which solar and wind energy do not have), we believe that bioenergy from closed loop energy crops represents the most effective choice in “alternative energy” options to address Global Warming.
Also, it’s important to note that our biomass research and commercial demonstration is using environmentally damaged lands, such as closed mining sites. According to NASA Scientists, one-fifth of the carbon dioxide released annually from fossil-fuel emissions could be “sequestered” by planting energy crops on marginal lands of this type. Hopefully, our work can help create a “Global Model”, where thousands of acres now largely considered wastelands can have productive agriculture and environmental use.
For marginal lands such as mining (phosphate, coal, etc.), pre-mined lands were most likely in native forest for hundreds/thousands of years. As such, these sites’ soils were probably at carbon saturation. After mining however, empirical research is clear that post-mined lands often have little soil carbon.
Thus, any incremental build-up of carbon from post-mined sites (starting from a low percentage close to zero) to a carbon saturation level (present before mining) would be creating a permanent carbon sink. This concept of “incremental build-up” of carbon levels on mined lands is illustrated in the yellow bar of the graph below.
Carbon Saturation Levels of Pre and Post Mined Soils
Biomass Energy & Pollution: Because energy crop fuel contains almost no sulfur and has significantly less nitrogen than fossil fuels — reductions in pollutants causing acid rain (SO2) and smog (NOx) may be realized — improving our air quality. An additional environmental benefit is in water quality, as energy crop fuel contains less mercury than coal. Also, energy crop farms using environmetally pro-active designs will create water quality filtration zones, uptaking and sequestering pollutants such as phosphorus from soils that leach into water bodies.
Biomass Energy & Agriculture: What if the next big oil or natural gas field wasn’t in places like the Middle East or Venezuela — but fields of energy crops (trees, sorghum, switchgrass) grown in Florida and the Southeastern U.S.?
In ongoing research and commercial demonstration (best management agricultural and environmental practices) efforts, an “energy crop farm” of non-invasive eucalyptus trees and various row crops (e.g., soybeans, sweet sorghum, sweet potatoes, energycane) has been established on closed phosphate mining marginal lands (non-irrigated) in central Florida.
The Project reflects decades of tree research conducted by the University of Florida and Shell Energy to produce “Super Trees” which may grow 20 feet a year (yielding 32 green tons and 16 dry tons per acre per year).
Also, significant collaboration is occuring with sorghum seed companies in the development of varieties (hybrids, cultivars) producing high yields (~30 green tons per harvest) and high Brix (sugar content) that can be grown year-round in Florida’s warm climate.
Another important aspect of “Energy Crops” is that they can also represent a sustainable renewable energy resource — since our trees and certain row crops like sugarcane will re-grow after each harvest (coppice, ratoon) — allowing multiple harvests without having to re-plant (called short rotation crops).
A key aspect of our agriculture research and demonstration efforts is the development of Strategies to vertically integrate Farming into Bioenergy projects — allowing Farmers to participate in a profitable “process end” (e.g., biofuel ethanol production) of agriculture rather than just selling a commodity based raw product (e.g., corn, soybeans, etc.). All of these Strategies have a common nexus to create “value added” products and services to become a low cost Producer.
If our team of scientists, engineers, farmers, and environmentalists are successful, energy crops could provide:
platforms) and biodiesel.
Biomass Energy Engineering: The power plant engineering behind the project is also innovative, using an approach called biomass co-firing. With co-firing, an existing power generation facility is modified to allow use of energy crop fuel — changing the fuel mix from a current 100% dependence on fossil fuels (such as coal, oil, natural gas) to approximately 5% biomass fuel and 95% fossil fuels.
While displacing relatively small percentages of fossil fuel use with biomass energy crops may not sound like much, it is very significant when recognizing the tremendous size of electricity generation facilities. For example, co-firing energy crops at just one medium size power plant would be the equivalent of installing over 41,000 large solar panels — or in reducing CO2 emission levels, by removing approximately 17,000 cars off the road.
Co-utilizing “Energy Crop Fuel” especially with coal is both effective and economically promising because it doesn’t require major changes in existing technology at power plants.
Instead of building new power generating facilities, which would ultimately result in higher costs to the consumer, we are working with scientists and engineers to change the fuel blend. It’s a novel approach to creating Renewable Energy, and if it works, there’s potential for immediate commercial use by electric utilities offering their customers a low cost option to purchase “Green Energy”.
In biomass co-firing, there are three primary approaches to biomass fuel delivery into the existing power plant: Solid Fuel Blending; Solid Fuel Direct Injection; and External Gasification.
Examples include: (1) Blending coal and biomass fuel together for a cyclone coal unit; (2) Directly injecting only biomass fuel through dedicated fuel ports into a pulverized coal unit; (3) Creating biogas in an external gasifier and then piping the hot gas into an existing coal, oil, or natural gas boiler.
An intriguing aspect of this third option is the potential to use the biogas high in the boiler’s re-burn zone — possibly avoiding the need to install costly pollution control equipment (e.g., Selected Catalytic Reduction or SCR) at a coal unit. Engineering research suggests that the “hot tar” fraction in the “hot raw” biogas is particulary reactive and may reduce NOx emissions between 50% and 70%.
Working with Electric Utilities, U.S. Department of Energy Labs (NETL, NREL, ORNL), the Electric Power Research Institute (EPRI) and Others — we have performed biomass co-firing engineering research (called “test burns”) on all major combustion technologies of cyclone, pulverized coal, and combined cycle gasification (IGCC) units.

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The Biorefinery Concept: In addition to the above electric utility power plant project work, we are working with Industrial Companies to integrate a variety of biomass raw feedstocks (e.g., cellulose, sugar/starch crops or waste streams) and conversion processes (e.g., biotechnology) into a single facility called a biorefinery at an existing “host” industrial plant:
Our approach in creating a biorefinery is fundamentally the same as the approach used with electric utility power plant co-firing — where an existing industrial “host” facility is modified for biomass applications utilizing as much of the existing engineering infrastructure as possible (e.g., avoiding high capital costs of a new stand alone bioenergy or biorefinery facility).
From an industrial company’s perspective, the large economic incentive with this approach is the displacement of high cost natural gas (and in Florida, also oil) with lower cost biogas in the generation of steam/power (i.e., cogeneration) and/or process heat (i.e., product drying) for the industrial company’s “core market” products. An example would be the installation of a new external biomass gasifier to an existing industrial natural gas boiler package at a citrus juice processing plant — resulting in lower cost steam and power for both “core market” (e.g., juice processing) and biorefinery products (e.g., pyrolytic liquids).
Biomass Energy & Native Habitats: Also included in this Research Effort are special project advisors from leading environmentalists, such as the Sierra Club, Audubon Society, and the Florida Fish & Wildlife Conservation Commission — ensuring that natural wildlife habitats are preserved and enhanced. A key aspect of this environmental habitat work effort is using energy crops as “Bridge Crops” to reclaim/restore severely damaged closed phosphate mining sites.
Biofuels Initiative
Biofuels Initiative
The Office of Energy Efficiency and Renewable Energy’s Office of the Biomass Program has implemented the Biofuels Initiative (BFI), with the goal of reducing U.S. dependence on foreign oil by meeting the following targets:
- To make cellulosic ethanol (or ethanol from non-grain biomass resources) cost competitive with gasoline by 2012.
- To replace 30 percent of current levels of gasoline consumption with biofuels by 2030 (or 30×30).
Background and Basis for the BFI
During the 2006 State of the Union Address, the President announced the Advanced Energy Initiative (AEI). The AEI aims to reduce the nation’s reliance on foreign sources of energy by addressing two areas: 1) Changing the way we fuel our vehicles, and 2) Changing the way we power our homes and businesses.
The AEI goals that address the way we fuel our vehicles are:
- Develop advanced battery technologies that allow a plug-in hybrid-electric vehicle to have a 40-mile range operating solely by battery charge.
- Foster the breakthrough technologies needed to make cellulosic ethanol cost competitive with corn-based ethanol by 2012.
- Accelerate progress towards the President’s goal of enabling large numbers of Americans to choose hydrogen fuel cell vehicles by 2020.
The Biomass Program adopted the President’s goal to make cellulosic ethanol technologies cost competitive by 2012. To assess the impact it could have in contributing to reducing dependence on foreign sources of energy, it analyzed the biomass resource potential identified in the DOE/USDA Billion Ton Study (PDF 8.5 MB). Based on that analysis, the Biomass Program set a goal to reduce 30 percent of our current transportation fuel usage by 2030. This goal is equivalent to 60 billion gallons of ethanol.
Implementing and Achieving the BFI
The Energy Policy Act of 2005 required the Department of Energy to solicit proposals for the demonstration of commercial scale integrated biorefineries that convert cellulosic biomass resources into fuels, chemicals, and power. These projects will be play a large role in developing and validating the technology required to meet the 2012 goal of making cellulosic ethanol technologies cost competitive.
The Biomass Program has also undergone a number of planning efforts that will help contribute to meeting both the 2012 cost target and the 2030 volumetric target. In August 2006, the Program hosted the “30×30 Workshop”, during which input was collected from industry, academic, and other external stakeholders for the technology, policy, and infrastructure needs required to meet both goals.
In November 2006, the Program hosted the National Biofuels Action (NBA) Plan Workshop, during which representatives from all Federal agencies involved in biomass-related work came together to identify areas of overlap or gaps in their work. The Program is currently working with these agencies to develop the NBA Plan that will outline the strategy for meeting the goals of the BFI. The Interagency Biomass R&D Board will be primarily responsible for implementing the plan.
Many states have begun their own initiatives creating state incentives and actually funding projects. Here is a great example of a State program.
The Tennessee Biofuels Initiative
A Model for Tennessee’s Economic & Environmental Sustainability
Increased energy independence, economic development and environmental sustainability are the goals of a new initiative that is gaining traction across the state.
The Tennessee Biofuels Initiative is a research and business model presented by the University of Tennessee that may position the state as a leader in the nation’s efforts toward reduced dependence on petroleum.
The plan proposes the construction and operation of a pilot biorefinery to demonstrate and refine biofuels production technology as well as to work out issues related to continuous production streams, transportation of feedstocks like switchgrass, and distribution of products. The principal product of the refinery will be Grassoline™ – ethanol derived from cellulosic biomass. With continued improvements in production technology and economics, it is expected that government and private partners would invest in multiple commercial-scale biorefineries across the state.
Potential benefits from commercial implementation of the business model include:
- 4,000 new jobs in rural Tennessee counties
- $400 million in new state and local taxes annually
- Satellite plants creating an additional 3,000 jobs and $1 billion in annual revenue from chemical coproducts useful in other manufacturing processes.
- $100 million annually in new farm revenue to about 20,000 of the state’s producers
- 1 billion gallons of Grassoline™ annually at a potential wholesale price of $1.20 per
- gallon. This level of production would displace approximately 30 percent of Tennessee’s present petroleum-based consumption.
Principal feedstocks for cellulosic ethanol are switchgrass and woody biomass. Economists,
agronomists, and biochemists with the UT Institute of Agriculture and the Oak Ridge National Laboratory are leaders in cellulosic production and conversion research, and Tennessee has an ideal climate for production of the feedstock commodities. The state’s extensive transportation system will also contribute to the development of commercial facilities. The Tennessee Biofuels Initiative outlines tremendous economic potential for the state. The vision is a vibrant, sustainable bioeconomy for Tennessee and the nation.
Switchgrass Establishment
| by John Guretzky |
As a leader in bioenergy research and development, the Noble Foundation is evaluating the agronomics and economics of switchgrass as a bioenergy crop. Switchgrass is a native range and pasture grass that has been identified by state and national leaders as a potential crop to be grown, harvested and converted into ethanol. Slow seedling establishment has previously limited adoption of switchgrass in forage production. Presently, scientists in the Noble Foundation’s Agricultural and Forage Improvement divisions are researching ways to improve switchgrass establishment. Here is what we know, and don’t know, about the process.
Seed Selection and Quality
Two types of switchgrass, lowland and upland, are available for planting. Lowland types tend to grow taller and more rapidly than upland types. Lowland cultivars adapted to the southern plains include Alamo and Kanlow. Adapted upland cultivars include Blackwell and Cave-In-Rock. Although forage quality differences may exist, all varieties are suitable for hay or pasture.
When choosing a variety, it is important to purchase high quality, certified seed. Freshly harvested seed can have a high percentage of dormancy. Seed dormancy is typically reduced if the seed is properly aged for one year. Seed older than two years may become less viable and have poor seedling vigor under field conditions. Check with seed companies on availability and quality of their seed before making purchases.
Planting Date and Methods
Current research shows that spring is the best time to plant switchgrass in Oklahoma. The average date of the last spring freeze in southern Oklahoma typically falls between March 22 and March 31. Switchgrass will germinate at soil temperatures of 50°F, although seedling growth is best when air temperatures reach 75°F to 85°F. When soil moisture and temperatures are good, average emergence will be 10-21 days after planting.
Planting methods include drilling or broadcasting into either tilled or no-tilled seedbeds. Drilling involves planting in rows using either a conventional or no-till drill. Broadcast seeding refers to techniques where seed is spread uniformly across the soil surface. Regardless of method, switchgrass should be planted at shallow depths, 0.25 to 0.5 inches, in seedbeds that are firm enough to allow good seed-to-soil contact, but not so much as to restrict root growth.
Research shows that switchgrass produces similar yields across a range of seeding rates and row spacings. At lower plant population densities, individual plants are able to exploit more space and soil resources, attain greater size and maintain biomass yields equivalent to those grown at higher plant population densities. Recommended seeding rates of switchgrass range from two to 10 pounds of pure live seed (PLS) per acre, with the higher rates applied to sites with poorer growing conditions. Generally, four pounds PLS per acre is sufficient. Second year stands of one to 1.5 plants per square foot (43,000 to 65,000 plants per acre or more) would be considered fully successful stands. Stands with less than 0.5 plants per square foot (22,000 plants per acre) may require partial reseeding to maximize biomass yields.
Soil Fertility and Weed Control
As with planting any crop, soils should be tested and phosphorus and potassium deficiencies be corrected before seeding. Lime is typically not required unless pH drops below 5.5. Because of slow seedling growth, nitrogen fertilizer should not be applied during the seeding year as it enhances weeds over that of switchgrass. Fifty to 150 pounds of nitrogen per acre typically maximize biomass yields of fully established second year stands. Currently, there are not proven weed control methods that consistently allow switchgrass stand development. The best form of weed control is to delay planting until “grassy” weeds emerge so they can be sprayed with glyphosate before planting. Broadleaf weeds can generally be controlled with 2, 4-D amine after switchgrass reaches the four-leaf stage.
Virtual Farming
Perennial Grasses for Bioenergy
| by John Guretzky |
In the 2006 State of the Union Address, President George W. Bush proposed the Advanced Energy Initiative to reduce U.S. dependence on foreign oil through accelerated development of domestic, renewable alternatives to gasoline and diesel fuels. A goal of the initiative was to make ethanol derived from cellulosic biomass (crop residues, fast-growing trees and grasses) cost competitive with grain ethanol by 2012. Transportation fuels derived from cellulose – the fibrous material of plants – offer an attractive alternative as an abundant, domestic and renewable resource.
The U.S. Department of Energy identified switchgrass as a model cellulosic crop because it combined more attributes desirable for bioenergy production than other grasses. Among these attributes, switchgrass was a seeded, perennial grass native throughout North America. It was widely distributed and productive across a wide geographical range.
In research at Ardmore, we have found biomass yields of switchgrass (cultivar “Alamo”) to average 6.5 tons per acre. Multilocation experiments were initiated in 2007 to evaluate the response of switchgrass to nitrogen, phosphorous and potassium fertilization rates, and biomass harvesting. Data is limited or sometimes nonexistent on biomass yields of other perennial grasses for bioenergy production in Oklahoma.
A number of perennial grasses can be produced in Oklahoma that may provide substantial net benefits to the national goal of making cellulosic ethanol cost competitive. These grasses include, among others, giant reed, weeping lovegrass, miscanthus, Indiangrass, big bluestem, bermudagrass and Johnsongrass. In some trials conducted in Europe and North America, biomass yields of miscanthus have averaged 10 tons per acre compared to 5 tons per acre for switchgrass. Research in Alabama has reported biomass yields of giant reed to reach 15 tons per acre. Giant reed frequently can be found growing as an ornamental in residential neighborhoods in Oklahoma. Indiangrass and big bluestem, in addition to switchgrass, are tall, perennial grasses native to Oklahoma. They are characteristic of productive rangelands. Weeping lovegrass is a perennial, warm-season grass adapted to Oklahoma that grows particularly well on sandy soils.
A number of concerns exist while evaluating any of these grasses as a bioenergy feedstock. First and foremost, the grasses will have to produce a lot of biomass at a low cost. Large biomass yields are necessary to reduce transportation distances and improve the economy of scale for a biorefinery. A second concern is their nitrogen fertilizer and water use efficiencies. As nitrogen fertilizer costs continue to rise and water supplies increasingly become limited, it will be important that these feedstocks produce biomass with less water and nitrogen. Third, establishment costs need to be low. Switchgrass has an advantage because seed is generally available. We have found establishment costs of switchgrass to range from $75 to $150 per acre. A disadvantage of miscanthus and giant reed is that they must be propagated vegetatively. Planting of root, rhizome and stem cuttings to achieve stands has been estimated to increase establishment costs to $350 to $500 per acre.
Additional concerns with these grasses are their invasiveness and resistance to pests. Johnsongrass is commonly considered a weed. Some have expressed concerns about miscanthus and giant reed escaping managed croplands to become weeds in natural lands. Another concern that exists with any of the grasses is their resistance to disease and other pest outbreaks when planted as a monoculture crop. Being clones and having less genetic diversity, miscanthus and giant reed may be susceptible to increased risk from disease and insect pressures.
Colorado Corn Stover
Corn Stover is the residue left in the field after the corn has been harvested. Corn stover is the other half of the corn plant that remains on the surface aside from the corn kernels. The stover is 50% stalks, 22% leaves, 15% cob, and 13% husk. Stover does not include the crown and its surface roots. Most of the time with Till farming this residue is left in the field to be tilled into the ground to provide nutrients and erosion protection.
About one ton of corn stover is produced for every one ton of corn grain. Corn grain yields per acre have increased by 60 percent from the early 1970s, from about 85 bushels per acre nationwide to about 135 today. Corn stover yields have increased proportionately. About 250 million dry tons of stover are produced each year.
Some surface residue—a minimum of 30 percent coverage—is required by USDA guidelines for erosion protection. Relating mass to soil cover is guess work. The actual amount of stover that must remain to prevent soil erosion varies greatly, depending on local conditions such as soil type, slope of the field, length of slope, tillage practice and crop rotation. With no-till cultivation, about 150 million dry tons could be taken off the land. For no-till fields with slopes less than 4%, the required cover varies from 0.5 to 1.5 tons/acre. So if the yield is 180 bu/acre (5 tons/acre), 3.5 to 4.5 tons can be removed while complying with Best Management Practices (BMPs) for residue set down by the USDA. For mulch till, the required cover amount is about doubled to 1 to 3 tons/acre, leaving 1 to 2 to 3 tons/acre available for removal. Generally, no stover can be removed from conventional tilled fields and still comply with BMPs.However as the practice of no till continues to grow in Colorado this resource is available as biomass to produce bioenergy. It is estimated that there is 2,524,000 dry tons per year available in the state of Colorado, this number includes wheat residues as well.
There are many research studies that are ongoing into the economical recovery of this valuable by product. Many have shown that at $50 per dry ton it is both profitable for the farmer and practical for biomass energy.
Colorado Bioenergy
Currently, perennial grass and woody crops have an average yield of about 5 dry tons per acre. Ethanol yield from a dry ton of biomass is about 67 gallons, so today we can obtain roughly 335 gallons of ethanol from an acre of bioenergy crops. If average biomass yields of about 10 to 15 dry tons per acre and ethanol yields of 80 to 100 gallons per dry ton of biomass could be achieved, an acre of bioenergy crops could generate 800 to 1500 gallons of ethanol.
Colorado has a vast amount of biomass that is capable of being converted into cellulose ethanol however there has not been any formal studies to confirm the actual amount of available biomass.
We need the state of Colorado and C2B2 to invest in research to figure out what amount of biomass is available in the state of Colorado.

