ethanol and water scarcity

Ethanol: Environmental Trade – offs of Biofuels

One of the major incentives in developing and increasing biofuel production is its environmental benefits, including the potential to reduce green house gas emissions. It is estimated that around 25 percent of man-made global carbon dioxide emissions, a leading green house gas, comes from our road transport. Global road transport has grown rapidly over the past 40 years and it continues to increase, especially in countries that are currently undergoing rapid economic growth, middle-class expansion, and urbanization. Biofuels provide an alternative to gasoline because while they also give off CO2 when burned, it is carbon neutral. Gasoline and other fossil fuels increase the supply of CO2 in the atmosphere by giving off CO2 absorbed and trapped in plant material millions of years ago. On the contrary, biofuels release CO2 that has been recently absorbed from the atmosphere by the crops used to produce them. However, along side this important advantage, biofuel technologies carry a number of environmental disadvantages that need to be carefully analyzed to determine whether the trade off is worth it for us a global community in the long run.

Life-Cycle Analysis

When you examine the production and processing of the feedstock into fuel and not just combustion, this “life-cycle” analysis makes the initial advantage of biofuel less obvious. Research indicates that the net energy balance of biofuels is positive (energy output is greater than energy input), but these estimates vary. Net balances are small for corn ethanol and more significant for biodiesel from soybeans, as well as ethanol from sugarcane and cellulose. Biofuel with the highest net energy balance reduces green house gas the most when compared with that for gasoline.

Water Scarcity and Pollution

Another major concern is the fact that ethanol production apparently requires large amounts of water. In fact, ethanol production requires so much water, that this issue alone makes it a highly costly fuel, one that puts water scarcity on the other side of the trade off scale. For example, researchers at the Missouri University of Science and Technology report that ethanol derived from corn grown in Nebraska, requires 50 gallons of water per mile driven, when all the water needed in irrigation of crops and processing into ethanol is considered. Deriving fuel from sorghum requires even more water to produce – as much as 115 gallons per mile!

Another issue is that increasing production of biofuels from row crops may cause more water pollution due to soil erosion and the increased use of pesticides to grow enough crops to meet US federal mandates for more biofuels. To mitigate this problem researchers suggest that using drought-tolerant, high-yield plants grown on little irrigation water to produce biofuel would have less impact on water resources. One such plant is miscanthus, a fast-growing perennial grass that grows an impressive 9-10 feet a year. However, currently there is no technology that could convert the cellulosic biomass of miscanthus into biofuel and produce it in large quantities.

Issues with Land

Not be overlooked is the environmental concern of the potential land requirements, if biofuels become a more mainstream fuel. According to the University of Minnesota, devoting all U.S. corn and soybean acreage to ethanol and biodiesel production would offset only 12 percent and 6 percent of gasoline and diesel consumption for transportation fuel, respectively. These numbers are even smaller when adjustments are made for the fossil fuel requirements for producing the biofuel. These statistics point to the fact that it does not seem to be economically savvy or sustainable to to use so much land to meet a relatively small share of transportation fuel demand. The resource commitment to meet domestic fuel demand would be less in lower income economies of countries in Asia Africa and Latin America. However, in many countries like Indonesia, Malaysia, and Brazil, expanding feedstock production in way that would encroach on rain forest areas and wildlife habitats is a grave environmental concern.

What is next?

It is clear that at the present stage of biofuel technology there are many negative environmental trade-offs to massive biofuel production that greatly decrease its potential to downgrade oil’s dominance in the world. This means that as a global community, we need to make a commitment to continue investing, researching and developing alternative biofuel production crops and processes that will optimize biofuel production and minimize its adverse environmental impacts.