Energy Crops — Sugar from Cellulosic Biomass

2.7 pounds of sugar contains as much energy as 1 pound of crude oil

America has more Sugar than the Middle East has oil.

How can this be?

When people are asked where sugar comes from they will most likely answer sugar cane or sugar beets because that is what most people are familiar with. Yet, sugar is the basic molecular building block within all plant life on Earth. Carbohydrates are made of sugar molecules. All plants, including trees and grasses, are made of carbohydrates, combined with lignin and a small percentage of oils and proteins (although some plants and vegetables are known for their high percentage of oil or protein, they are the exception).

America can grow more plants and trees—the desert sands of the Middle East cannot grow more oil.

Carbohydrates are made of carbon, hydrogen, and oxygen with a ratio of two hydrogen atoms for every oxygen atom. Carbohydrates are produced by photosynthesis—a natural process that takes place chemically within plants and trees. Photosynthesis uses the energy of sunlight to remove carbon from CO2, which the plant absorbs from the atmosphere and combines the carbon with hydrogen and oxygen taken from water drawn from the plant’s roots, creating carbohydrate molecular chains to grow the plant’s cells, and releasing free oxygen molecules back to the outside air. In this way, plants and trees create the oxygen animals and humans need to breathe.

The name carbohydrate means “watered carbon” or carbon with attached water molecules.

Carbohydrates take the form of natural sugars, starches, cellulose, and hemicellulose. The natural sugars are called simple carbohydrates, or simple sugars (monosaccharides). The starches, cellulose, and hemicellulose are called complex carbohydrates, also known as complex sugars (polysaccharides).

Because of modern technology, all biomass (plants and trees) is a source of sugar and energy. Modern technology can break down the long molecular chains that form the complex carbohydrates within the plants and free the sugar molecules for conversion to usable forms of energy such as renewable ethanol.

Picture in your mind’s eye the trees and plants that cover the United States. Imagine how vast this is. The energy locked inside the sugar molecules created by the huge amount of new plant growth each year within the U.S. is far more than the energy contained within the crude oil the U.S. imports each year.

With Cellulosic Ethanol, There is
No Food vs. Fuel Debate

Bruce Dale
Dr. Bruce Dale

Ethanol made from cellulosic materials, rather than corn grain, renders the food vs. fuel debate moot, according to research by Michigan State University ethanol expert.

As more and more corn grain is diverted to make ethanol, some groups have become concerned about food shortages. Dr. Bruce Dale, Michigan Agricultural Experiment Station (MAES) chemical engineering and materials science researcher, has used life cycle analysis tools, which include agricultural data and computer modeling, to study the sustainability of producing biofuels — fuels such as ethanol and biodiesel that are made from renewable resources.

“We grow animal feed, not human food in the United States,” Dale said. “We could feed the country’s population with 25 million acres of cropland, and we currently have 500 million acres. Most of our agricultural land is being used to grow animal feed. It’s a lot simpler to integrate animal feed production into cellulosic ethanol production than it is to integrate human food production. With cellulosic ethanol, the ‘food vs. fuel’ debate goes away.”

Dale, who also serves as associate director of the MSU Office of Biobased Technologies, presented his findings on March 27, 2007, at the American Chemical Society annual meeting in Chicago

Cellulosic ethanol is made from the stems, leaves, stalks, and trunks of plants, none of which is used for human food production. Dale, who has studied ethanol for more than 30 years, said that as the country moves toward large-scale cellulosic ethanol production, the yield of so-called energy crops—grasses and woody materials grown for their energy content—also will dramatically increase.

“This will reduce pressure on our land resources,” Dale said. “We’ll be able to get more raw material out of one acre of land.”

Dale also pointed out that many of these energy crops will be grown on land that isn’t prime agricultural acreage, but rather on marginal land that isn’t growing a commercial crop right now.

“The evidence indicates that large-scale biofuel production will increase, not decrease, world food supplies by making animal feed production much more efficient,” Dale said.

Sustainability Analyses of the Biobased Economy — The biobased economy will grow rapidly during the 21st century. A combination of low-cost plant raw materials and gradually improving biorefinery process technologies for converting these raw materials into a variety of fuels, chemicals, materials, foods and feeds will drive the adoption of the biobased economy. The biological sciences will have a particularly powerful impact on both the raw materials and the processing technologies underlying the biobased economy… Our sustainability analysis efforts are intended to outline how this new industry can achieve both environmental and economic sustainability. For perhaps the first time, humanity can design and develop a new industry, the biorefining industry, to achieve both economic and environmental goals. —Bruce E. Dale

     Relief from soaring prices at the gas pump could come in the form of corncobs, corn stalks, switchgrass, and other types of biomass, according to a joint feasibility study for the departments of Agriculture and Energy.
     The recently completed Oak Ridge National Laboratory report outlines a national strategy in which 1 billion dry tons of biomass – any organic matter that is available on a renewable or recurring basis – would displace 30 percent of the nation’s petroleum consumption for transportation.
     “One of the main points of the report is that the United States can produce nearly 1 billion dry tons of biomass annually from agricultural lands and still continue to meet food, feed, and export demands,” 
said Robin Graham, leader for Ecosystem and Plant Sciences in ORNL’s Environmental Sciences Division.—Growth in biomass could put the U.S. on road to energy independence

Ethanol and Net Energy

There is much discussion, or argument, about Ethanol: Does it take more energy to make it than you can get back from it?

The argument focuses on the energy consumed by the tractors and the farm equipment, the trucks that transport the ethanol to market, and the fertilizer that is made from fossil fuels, as well as the amount of energy required to extract the sugar from corn starch (or cellulosic biomass) and convert it to ethanol.

Bruce Dale, Professor of Chemical Engineering at Michigan State University (MSU) provides some very important information about “Net Energy”.

Professor Dale tells us: “Net energy analysis is fundamentally wrong: it assumes that all BTU is equivalent. This is obviously untrue; otherwise, we would not pay over ten times as much for electrical energy derived from coal as we do for the energy in the coal itself. All energy conversion systems lose some quantity of energy in order to increase energy quality. Gasoline from petroleum actually has poorer net energy than ethanol from corn. The MOST RELEVANT measure of energy efficiency for biofuels is the liquid fuel produced per unit of PETROLEUM CONSUMED.”

Net Energy Basics: Rebutting Some Ethanol Myths —Debunking Pimentel and Patzek Studies    size: 200 Kb – 10 pages

Thinking Clearly about Biofuels: Ending the Irrelevant “Net Energy” Controversy
— By Bruce E. Dale, Ph. D. Professor of Chemical Engineering, Michigan State University
  size: 19 Kb – 2 pages

MIT ethanol analysis confirms the benefits of biofuels —Regardless of the energy balance, replacing gasoline with corn-based ethanol does significantly reduce oil consumption because the biomass production and conversion process require little petroleum. And further MIT analyses show that making ethanol from cellulosic sources such as switchgrass has far greater potential to reduce fossil energy use and greenhouse gas emissions.

Do we have enough land?

 Professor Dale gives us the answer: “The range of opinion on this subject varies enormously. A USDA-DOE study indicates that we can sustainably produce about 1.3 billion tons per year of cellulosic biomass, sufficient to produce at least 100 BILLION gallons/year of ethanol. I believe this estimate is conservative because 1) we have at least 800 million acres suitable for energy crops, 2) we have devoted very little attention to increasing energy crop yields, 3) we have not explored the opportunities for integrating food/feed production with energy crops, and 4) biomass conversion technology is very far from mature. Given proper emphasis to increasing energy crop yields, maturing biomass conversion technology, and integrating food/feed production with energy crops, it should be POSSIBLE TO PRODUCE SEVERAL HUNDRED BILLION GALLONS PER YEAR OF ETHANOL and other liquid fuels while simultaneously increasing food/feed supplies. We will not choose between food or fuel; we will produce food and fuel.”

Economic Viability? 

Professor Dale responds: “The United States has a serious problem. Our national and state economies are absolutely dependent on liquid fuels. The United States currently uses more than 140 billion gallons of gasoline and almost 40 billion gallons of diesel fuel annually. More than 60 percent of the petroleum we use is imported, and the percentage is rising. At $20 per barrel, oil is still cheaper to refine than biofuels are,” Dale explained. “But when oil costs $40 a barrel, biofuels are very competitive. At current corn prices, corn ethanol is competitive with gasoline when petroleum is about $45/barrel. When cellulosic biomass conversion technology is mature, we should be able to produce hundreds of billions of gallons of liquid biofuels at much less than $1 per gallon (energy equivalent basis) and be competitive with petroleum at about $25 per barrel. Hence it is critical that we do both the fundamental research and technology deployment at the scale required to rapidly develop mature biomass conversion technology.”
Everything Biomass-Dale Research Group —The Biomass Conversion Research Laboratory at Michigan State University.

Switchgrass is a promising energy crop one-acre plot of switchgrass can grow the energy equivalent of about 2-6 tons of coal per year. (Photo credits: Warren Gretz, DOE/NREL)
tall switchgrass

The American prairie—tens of millions of acres—was once covered with tall fast-growing native grasses that fed millions of bison. Switchgrass is one of America’s natural prairie grasses.

Switchgrass grows fast, capturing solar energy and turning it into chemical energy in the form of cellulose that can be harvested and converted to sugar.

Switchgrass reaches deep into the soil for water, and uses the water it finds very efficiently. The plant can thrive in climates and growing conditions spanning much of the nation.

Switchgrass can be cut and baled with standard farming equipment.

Many farmers are already experienced at raising switchgrass for forage or to protect soil from erosion. Switchgrass also restores vital organic nutrients to farmed-out soils.

The U.S. Department of Energy (DOE) believes that biofuels—made from crops of native grasses, such as fast-growing switchgrass—could reduce the nation’s dependence on foreign oil, curb emissions of the “greenhouse gas” carbon dioxide, and strengthen America’s farm economy. The Biofuels Feedstock Development Program (BFDP) at DOE’s Oak Ridge National Laboratory (ORNL), has assembled a team of scientists ranging from economists and energy analysts to plant physiologists and geneticists to lay the groundwork for this new source of renewable energy. Included are researchers at universities, other national laboratories, and agricultural research stations around the nation. Their goal, according to ORNL physiologist Sandy McLaughlin, who leads the switchgrass research effort, is nothing short of building the foundation for a biofuels industry that will make and market ethanol and other biofuels from switchgrass and at prices competitive with fossil fuels such as gasoline and diesel.

Test plots of switchgrass at Auburn University have produced up to 15 tons of dry biomass per acre, and five-year yields average 11.5 tons—enough to make 1,150 gallons of ethanol per acre each year.

— Scientists determine farm costs of producing switchgrass for ethanol (With the total farm costs of growing switchgrass known, scientists, have estimated the cost of producing cellulosic ethanol from switchgrass will be about $0.55 to $0.62 per gallon)  April 11, 2008

First, a distinction: switchgrass and your suburban lawn grasses—bluegrass and zoysiagrass—are about as similar as a shopping mall focus and an old-growth redwood. Switchgrass is big and it’s tough—after a good growing season, it can stand 10 feet high, with stems as thick and strong as hardwood pencils.

Switchgrass can be harvested using conventional farm equipment.

switchgrass harvest

But what makes switchgrass bad for barefoot lawns makes it ideal for energy crops: It grows fast, capturing lots of solar energy and turning it into lots of chemical energy— cellulose—that can be liquified, gasified, or burned directly. It also reaches deep into the soil for water, and uses the water it finds very efficiently.

And because it spent millions of years evolving to thrive in climates and growing conditions spanning much of the nation, switchgrass is remarkably adaptable.

Now, to make switchgrass even more promising, researchers across the country are working to boost switchgrass hardiness and yields, adapt varieties to a wide range of growing conditions, and reduce the need for nitrogen and other chemical fertilizers. By “fingerprinting” the DNA and physiological characteristics of numerous varieties, the researchers are steadily identifying and breeding varieties of switchgrass that show great promise for the future.

Many farmers already grow switchgrass, either as forage for livestock or as a ground cover, to control erosion. Cultivating switchgrass as an energy crop instead would require only minor changes in how it’s managed and when it’s harvested. Switchgrass can be cut and baled with conventional mowers and balers. And it’s a hardy, adaptable perennial, so once it’s established in a field, it can be harvested as a cash crop, either annually or semiannually, for 10 years or more before replanting is needed. And because it has multiple uses—as an ethanol feedstock, as forage, as ground cover—a farmer who plants switchgrass can be confident knowing that a switchgrass crop will be put to good use.

— Biofuels from Switchgrass: Greener Energy Pastures (Oak Ridge National Laboratory, Bioenergy Feedstock Development Program)

Research farms have demonstrated that switchgrass farming can yield about 1,000 gallons of ethanol per acre each year:

  • One thousand acres of switchgrass would yield about one million gallons of ethanol per year.
  • One million acres of switchgrass would yield about one billion gallons of ethanol annually.
  • One hundred million acres of switchgrass could produce about one hundred billion gallons of ethanol every year.

The deep Switchgrass root system could store tons of atmospheric carbon – removing the cause of global warming.
“Switchgrass could have a lot to do with carbon sequestration storage potential and for overall improvement of soil quality as well,” says Mark Liebig, a soil scientist at USDA’s Agricultural Research Service laboratory in Mandan.

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