Ethanol and Cellulosic Ethanol Ethanol and Cellulosic Ethanol

It's self-evident, these days, that society's reliance on nonrenewable energy sources presents a serious problem as far as future sustainability is concerned. Oil, for instance, is at the heart of the modern economy, yet the world's oil supplies are ever dwindling while demand only increases. Its usage demands a high price: Reliance on importation from some of the world's most unstable regions, environmental damage ranging from the smog-filled metropolis to concern over global warming, the list goes on. Other nonrenewable forms of energy, from coal to natural gas, engender similar concerns.

Given these pressing energy issues, ethanol has been busy earning itself continued attention as an energy source with the potential to serve as a cleaner, renewable, easily produced alternative to the fossil-fuel staples. Ethanol is an alcohol product produced from corn, potatoes, wheat, sugar cane and other plants, even biomass such as cornstalks and vegetable waste. It can be used as a fuel additive—when combined with gasoline, it increases octane levels while also promoting more complete fuel burning—or as a fuel source by itself.

Two Types

There are two basic categories of ethanol, both fundamentally different in their means of production. The first, ethanol as it's traditionally conceived, is derived from fruits and seeds of various plants (typically from the kernels of corn), the raw material being sugars and starches. The second is cellulosic ethanol, derived from a wide range of biomass, often waste from urban, agricultural or forestry sources, the raw material being (as the name would suggest) cellulose.

Cellulosic ethanol has a number of advantages, as a source of energy, when compared to corn ethanol. Rather than having to grow crops for conversion purposes—of which only a small part of the plant is used—industrial waste and organic matter can be utilized as a base. Not only does the celluosic process save significantly on land usage and act as a means to rid ourselves of waste products, but moreover its efficiency as a renewable source of energy is far greater than that of corn ethanol. Cellulosic ethanol production promises to consume less petroleum and produce fewer greenhouse gases as compared to corn ethanol (of course, both improve greatly on nonrenewable sources).

Unfortunately, the technology for producing cellulosic ethanol is as of yet in its infancy stages. While various cutting-edge companies have established initial test facilities, large-scale production is currently only 'in the works'. The technology for corn ethanol production, on the other hand, has been well-established since the 1980s; the infrastructure and means for large scale operations are in-place and cost effective.

Either method has significant benefits, certainly. Aside from reducing dependence on nonrenewable sources and all that such would entail, there are significant environmental positives: Notably, according to the US Department of Energy, corn ethanol reduces greenhouse gas emissions by up to 30% as compared to gasoline; Cellulosic ethanol by up to 85 percent.

Ethanol vs. Biodiesel

Another popular renewable energy source with much potential is "Biodiesel." This is a type of diesel-equivalent fuel derived from biological sources, either a fat or some sort of oil (often vegetable), through a process called transesterification, where glycerin (the fuel source) is separated from the fat/oil.
Biodiesel offers a number of benefits: compared to gasoline, the advantages are similar to those of ethanol. But compared to corn ethanol, biodiesel appears superior in a number of manners. Whereas corn ethanol production offers about 25 percent more energy than it consumes, biodiesel production can yield up to 90% and up more energy than it consumes. And burning biodiesel fuel offers even greater reductions on greenhouse gas emissions.

However, unless one already owns a vehicle with a diesel engine, ethanol-blended gasoline is likely the best option for renewable fuel use. While Biodiesel is technically superior, it works only in diesel engines and has the marked disadvantage of being dependent on the availability of fat/oil products (compared to ethanol, which has components available in near unlimited supply). Biodiesel, however, could provide a great environmental benefit to trucking and shipping fleets, as they typically consist entirely of vehicles with diesel engines.

Future Direction

The future for ethanol fuel alternatives appears promising. Corn ethanol has well-established, refined technology and a widely available raw material. Cellulosic ethanol promises even greater returns, once the technology is developed and refined; with cellulose essentially the main component of plants, available raw material is in seemingly endless supply.

Indeed, cellulosic ethanol would seem to be an ideal candidate for an alternate fuel source. Not today, though: In June of 2006, a U.S. Senate hearing determined that the current cost of producing cellulosic ethanol is US 2.25 per gallon, a price which is simply too high when distribution costs are factored in. Science and industry are optimistic, though. The US Department of Energy has requested that research funding for the technology be doubled, and scientists expect to reduce the cost of production to US 1.07 per gallon by 2012.

If the industry has its way, we'll all be driving on discarded plant matter within the decade. And it will be good.

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