Cellulosic ethanol fuels environmental concerns
mongabay.com
August 6, 2006


In recent months, high fuel prices and national security concerns have sparked interest in biofuels. Cellulosic ethanol, which can be derived from virtually any plant matter including farm waste, looks particularly promising. The U.S. Department of Energy projects that cellulosic conversion technology could reduce the cost of producing ethanol by as much as 60 cents per gallon by 2015. Green groups see cellulosic ethanol as a carbon neutral energy source that could be used to fight the build up of atmospheric carbon dioxide responsible for global warming.



Nevertheless, there are worries that cellulosic conversion technology could have severe environmental consequences.

In an editorial published in the April 10, 2006 issue of Forbes ("The Forest Killers"), Manhattan Institute senior fellow Peter Huber argued that cellulosic ethanol could hasten the conversion of forestlands and other wilderness into a fuel source.


The above figure from the U.S. Department of Energy explains plant cell wall structure (biomass) and some of the issues preventing their efficient conversion to ethanol. Click here for a full size image with explanation.

Earlier this year the DOE announced the goal of making ethanol a practical and cost-competitive alternative by 2012 (at $1.07/gal) and displacing 30% (60 billion gallons) of gasoline by 2030. The United States now produces 4.5 billion gallons of (corn-grain) ethanol per year, a fraction of the 140 billion gallons of transportation fuel used annually.



Huber said that the development of efficient cellulose-splitting enzymes to convert plant structural materials into sugars then alcohols could "quickly turn a hundred pounds of wood chips or grass into a gallon of diesel." The origin of this biomass could be farm waste or, in a tropical developing country, it could be freshly cut from a rainforest teeming with biodiversity. Cellulosic conversion technology could easily drive deforestation, especially in poorer parts of the world where converting natural systems to fuel would be easier than planting potential fuel-crops like oil palm, sugar cane, soybeans, or corn.

"History has already taught us what a carbohydrate energy economy does to a rich, green landscape--it levels it," wrote Huber. "The carbon balance goes sharply negative, too, when stove or cow is fueled with anything but waste or crops from existing farmland. It's pleasant to imagine that humanity might get all its liquid fuels from stable, legacy farms or from debris that would otherwise end up as fungus food. But that just isn't how humans have historically fed whatever they could feed with cellulose.

"From the perspective of all things green, cellulose-splitting enzymes are much the same as fire or cow, only worse. Fire and cow consume cellulose, but the process is generally messy and inconvenient, which is a big advantage, from the plant's perspective. To improve on wood-burning fires, or grass-eating cows, perfect the cellulose-splitting enzyme. Then watch what 7 billion people will do to your forests and your grasslands," he concludes.

While Huber's concerns are valid, it seems likely that profit motives would push any private developer of cellulose-splitting technology to keep close-tabs on their intellectual property and not freely disseminate it in the developing world. As such, the scenario where rural villages melt down local forests to power their motorbikes seems somewhat remote.

RELATED

High oil prices fuel bioenergy push High oil prices and growing concerns over climate change are driving investment and innovation in the biofuels sector as countries and industry increasingly look towards renewable bioenergy to replace fossil fuels. Bill Gates, the world's richest man, has recently invested $84 million in an American ethanol company, while global energy gluttons ranging from the United States to China are setting long-term targets for the switch to such fuels potentially offering a secure domestic source of renewable energy and fewer environmental headaches.

Why is oil palm replacing tropical rainforests? Recently much has been made about the conversion of Asia's biodiverse rainforests for oil-palm cultivation. Environmental organizations have warned that by eating foods that use palm oil as an ingredient, Western consumers are directly fueling the destruction of orangutan habitat and sensitive ecosystems. So, why is it that oil-palm plantations now cover millions of hectares across Malaysia, Indonesia, and Thailand? Why has oil palm become the world's number one fruit crop, trouncing its nearest competitor, the humble banana? The answer lies in the crop's unparalleled productivity. Simply put, oil palm is the most productive oil seed in the world. A single hectare of oil palm may yield 5,000 kilograms of crude oil, or nearly 6,000 liters of crude according to data from JourneytoForever. For comparison, soybeans and corn—crops often heralded as top biofuel sources—generate only 446 and 172 liters per hectare, respectively.

Scientists closer to understanding key to cellulosic biofuels Cellulose -- a fibrous molecule found in all plants -- is the most abundant biological material on Earth. It is also a favored target of renewable, plant-based biofuels research. Despite overwhelming interest, scientists know relatively little about how plant cells synthesize individual cellulose fibers.





This article uses quotes from a Forbes article.




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CITATION:
mongabay.com (August 06, 2006).

Cellulosic ethanol fuels environmental concerns.

http://news.mongabay.com/2006/0806-cellulosic.html