Newswise — Two critically important energy problems face us at this early point in the 21st Century, and our best approach to dealing with each of them is likely to involve technology that resembles a lawn mower much more than it does an oil well.
Our increasing dependence on foreign energy supplies and the climate disrupting greenhouse effect are separate issues, but our search for effective ways to deal with these key challenges of our time may ultimately focus on two seemingly unlikely suspects: plants and enzymes.
There is an emerging consensus that alternative fuels will have to be developed to reduce our petroleum addiction, and the candidate that gets most of the attention today is ethanol produced from corn. However, the process for this transformation is not effective from an environmental, economic or energy perspective. Converting corn into ethanol requires the input of a great deal of fossil fuel energy, and this results in the emission of large amounts of climate disrupting carbon dioxide into the atmosphere. This energy can come from natural gas, petroleum or, worst of all, coal, but whatever the energy source, it will contribute to the perpetuation of our global warming crisis. The energy requirements of the corn-to-ethanol process have been the subject of many studies, and these studies have shown that, at best, a twenty-five percent net energy gain is realized when the energy required to form corn from ethanol is compared to the energy released when that ethanol is burned as a fuel.
Using corn as a major alternative fuel source would require that much of our productive farmland be used for this purpose. This must result in a decreased availability of farmland for growing other crops as well as increased prices for these crops, and for corn itself. The cost of meats would also increase sharply since about twenty percent of the U.S. corn crop is currently used for animal feed.
At best, this major disruption of our agricultural system would afford only minor relief from our petroleum dependency. Expert studies conclude that if we were to use all of our available cropland to grow corn for conversion into ethanol, the resulting ethanol would replace only about ten percent of the fuel we currently use for our vehicles.
In reality, the corn to ethanol process is probably only viable today because it is supported by Federal subsidies and tax breaks resulting from the political support of farm belt congressional representatives and from an intense advertising and lobbying campaign carried out by politically powerful farming organizations and major agricultural corporations. The most valuable outcome of our current fascination with the conversion of corn to ethanol is that it may prove to be a stepping-stone along a path leading us to a far more promising energy future, one that will provide us with increased home-based energy supplies and significantly reduce our input of carbon dioxide into the atmosphere.
When corn is converted to ethanol today, only the corn's kernels are used; the stalks and husks are largely considered to be waste. This is because, as every moon shiner knows, only corn kernels contain sugars that can be fermented and distilled to make ethanol. But corn stalks and husks are made of cellulose, a polymer that is made up of many sugar molecules strung together. If cellulose is treated with an appropriate catalyst, an enzyme capable of breaking it down into the sugars from which it is formed, these sugars can then be fermented and distilled to form alcohol. This change would make the corn to ethanol process far more efficient since it would also allow the corn kernels to continue to be used as food, avoiding the otherwise inevitable steep increase in agricultural prices that would occur as corn became a fuel supply source.
The conversion of corn husks and stalks to ethanol is only one specific example of the great potential that will be unleashed as we learn how to efficiently convert cellulose into biofuels. Cellulose is the most abundant organic chemical that exists. Trees, leaves, grass, and virtually all plant materials contain large amounts of cellulose. Both major chemical manufacturers and promising small startup companies have recognized this potential and are beginning to develop novel processes to convert cellulosic materials into biofuels. Britain's BP Corporation has joined forces with the U.S. chemical giant Dupont to use cellulosic materials to manufacture butanol. Butanol is an alcohol that is more similar to gasoline than ethanol. In Ottawa, Canada, a relatively tiny company, Iogen is currently making ethanol from cellulosic wheat straw and using waste formed in their process as fuel to power it.
The key to the success of all such processes, however, is the availability of effective enzymes, biocatalysts, that can break cellulose down into its component sugars. The Allies found themselves in a similar situation during World War II. Penicillin had only recently been discovered and could only be made in small amounts. An enzyme capable of forming the antibiotic efficiently and in large quantities was desperately needed. Scientists were sent all over the globe in search of such an enzyme. They found it, ironically, in a supermarket in Peoria, Illinois, and large-scale, efficient penicillin production was soon booming. Today, a comparable search is underway to find "bugs" that that can effectively break cellulose down into its component sugars. This search is also succeeding.
A fungus used to give blue jeans that valued "softened look" has been found to effectively break down cellulose. It is currently being used to make biofuel in a plant in Nebraska. During World War II, the army was plagued with a fungus that fed on and decomposed its cotton tents. Today, that same fungus is being studied intensely for its ability to decompose other cellulosic materials as well as cotton. Termites have been found in Costa Rica that can digest cellulose efficiently. They too are now being studied as cellulose decomposing biofuel producers.
Agricultural crops such as corn and soybeans currently receive most of the attention directed at potential biofuel sources, but they are by no means the most efficient source of materials for this purpose. Plants exist today that are capable of growing at rates far faster than those attained by anything commonly grown in North America. Studies conducted at the University of Illinois on a perennial grass called miscanthus have shown that it can be grown under Midwest climate conditions and have established that it can be used for energy production. Miscanthus grows very rapidly, requires little water or fertilization and can supply up to a massive fifteen tons per acre. It can be burned to supply heat, and can serve as a source of cellulose for conversion into biofuels.
A still more prolific source of cellulosic materials usable for heat generation or for conversion into biofuels is the giant reed arundo donax, trade named E-Grass. E-Grass grows so densely that a person cannot walk through a field of it. It reaches heights taller than a one-story house. Amazingly, it does this while requiring only small amounts of water and fertilizer. A Florida based company, BioMass Investment Group, or BIG, currently has a project underway using E-Grass to supply fuel to a power plant that will provide electrical energy for 80,000 homes. Perhaps most importantly though, BIG claims that this can be done without adding any net carbon dioxide to the atmosphere.
To understand the basis for BIG's claim, we must recall that all of today's fossil fuels were formed from plants that captured carbon dioxide from the atmosphere by photosynthesis hundreds of millions of years ago. These ancient plants grew, died, were buried, and, over vast geologic time, decomposed under heat and pressure to form the petroleum, natural gas, and coal that we use today. When we burn these fuels, we release carbon dioxide that was captured from the ancient earth's atmosphere over long periods of time many millennia ago, and we do so in less than a geologic eye-blink. This rapid release of long sequestered carbon dioxide is the major cause of today's greenhouse gas emission problem. However, our nascent cellulose to biofuel technologies stand on the verge of dramatically improving this seemingly insoluble environmental problem.
Both miscanthus and E-Grass can act as carbon dioxide neutral fuels because of their ability to use carbon dioxide highly efficiently in photosynthesis. As these plants grow they remove carbon dioxide from the air so effectively that when they are used to supply energy, little, if any, more carbon dioxide is returned to the atmosphere than was removed from it by the growing plants. The result is a stable, steady-state situation: the amount of carbon dioxide that is added to the atmosphere when the plants are used to produce energy is approximately equal to the amount of carbon dioxide that is removed from the atmosphere by the growing plants.
Great advantages await us as we move into a cellulose based biofuel future. A highly favorable carbon dioxide balance, and the resulting positive impact on our global warming crisis; a markedly decreased dependence on uncertain petroleum sources from the middle east and elsewhere; and stable food prices for consumers are some of them. These benefits will accrue not only to U.S. consumers, but also to people throughout the world. How can we afford not to pursue this uniquely promising "growing" energy future?
Frank J. Dinan, PhDProfessor of Chemistry/BiochemistryCanisius CollegeBuffalo, New York
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