In previous posts we’ve expressed concern – to put it mildly – over the role emerging biofuel markets are having in accelerating tropical deforestation. In our posts “Deforestation and Global Warming,” “Biofueled Ethanol,” “Reforest the Tropics,” “IPCC 2007 & Deforestation,” “Is Biofuel Carbon Neutral?,” “Biofueled Global Warming,” and many others, we make the case that tropical deforestation is the most significant cause of desertification and droughts on earth, it is a major cause of extreme weather, and, along with other changes in land use, may actually have as much or more to do with global warming than industrial CO2 emissions.
Now we have a story in the St. Louis Post, dated April 15, 2007, entitled “Ethanol Plants Come With Hidden Costs: Water,” which surveys the impact ethanol refineries may have on fresh water supplies. Here’s an excerpt:
“The ethanol industry says it takes about 3 gallons of water on average to produce a gallon of ethanol and that recycling and other water-saving innovations will reduce that amount. Sometimes that consumption is understated: In Minnesota, one of the few states that require reporting of water use, a state study in 2005 found that ethanol plants used an average of 4.5 gallons for every gallon of ethanol. The water drawn for ethanol is a cost borne by communities — or whole regions — and a price sometimes ignored in the planning stages for new plants, experts say.”
Not mentioned in this story, of course, is the cost in water to irrigate the corn to produce the feedstock – the 3.0 to 4.5 gallons of water required for ethanol refining doesn’t include the water required to grow the corn, and corn is a relatively water-intensive crop.
Another cause of global warming we believe to be grossly understated to-date by climate scientists is the impact of depleted water tables, which increases the thermal conductivity of any land where the water tables have dropped significantly. Notwithstanding the potential global warming impact of depleted aquifers, the health of aquifers is an important and under-recognized factor influencing general environmental health, imperiling springs that feed aquatic ecosystems, as well as supplies of water for people. And often once these aquifers are depleted too much, it becomes difficult if not impossible to replenish them.
Ethanol proponents have correctly debunked the notion that ethanol is not energy-positive. While not as energy-positive as sugar cane, corn ethanol does embody more energy than is required to make it. But the impact of ethanol production on land use, the impact of ethanol production on water consumption, and the impact of ethanol production on water tables and aquifer health is not sufficiently understood.
Many forms of ethanol and biofuel production in general are very promising – but environmentalists are way behind in developing proper certification for biofuel crops, and as a result, for now it is probably accurate to say that biofuel mania is doing more harm than good to our global environment.