Slashdot Mirror
Biofuels Make Greenhouse Gases Worse
vortex2.71 sends us to the Seattle Times for an account of two studies published in the prestigious journal Science pointing to the conclusion that almost all biofuels used today cause more greenhouse-gas emissions than conventional fuels if the full emissions costs of producing these "green" fuels are taken into account. "The benefits of biofuels have come under increasing attack in recent months, as scientists took a closer look at the global environmental cost of their production. These plant-based fuels were originally billed as better than fossil fuels because the carbon released when they were burned was balanced by the carbon absorbed when the plants grew. But that equation proved overly simplistic because the process of turning plants into fuels causes its own emissions — for refining and transport, for example. These studies... for the first time take a detailed, comprehensive look at the emissions effects of the huge amount of natural land that is being converted to cropland globally to support biofuels development."
One thing that immediately jumps out at me:
"Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%."
Huh? Why would you grow switchgrass on corn lands? The whole point of switchgrass it that you can grow it on marginal lands, freeing croplands for food production. On crop lands, cellulosic ethanol is to be made from corn stover and the like.
Here's an interesting analysis of the studies from a member of the UC Davis faculty. He strongly disagrees with the methodology used.
Well, either way, I think we can all agree that corn ethanol from the corn itself is lousy, cellulosic ethanol from waste streams is good, and everything else is up in the air.
Margaret Thatcher died the other day. It was a sad day, but I like to think that she's looking up at us right now."
Blame the environmentalists too. They're even worse than politicians when it comes to misunderstanding science. Their ideology causes them to discount any evidence contrary to their preconceived view of how the world should work. They're backtracking and spinning now, but a few years ago they were all gung-ho about biofuel farming.
Don't blame me, I didn't vote for either of them!
The key discussion is the current primary biodiesel production is on crop land. They're right. We're going to be needing all our crop land to grow food to feed a rapidly growing population.
Biodiesel production from high oil content algaes doesn't need to use crop land. From a University of New Hampshire study...
"...NREL's research focused on the development of algae farms in desert regions, using shallow saltwater pools for growing the algae. Using saltwater eliminates the need for desalination, but could lead to problems as far as salt build-up in bonds. Building the ponds in deserts also leads to problems of high evaporation rates. There are solutions to these problems, but for the purpose of this paper, we will focus instead on the potential such ponds can promise, ignoring for the moment the methods of addressing the solvable challenges remaining when the Aquatic Species Program at NREL ended.
NREL's research showed that one quad (7.5 billion gallons) of biodiesel could be produced from 200,000 hectares of desert land (200,000 hectares is equivalent to 780 square miles, roughly 500,000 acres), if the remaining challenges are solved (as they will be, with several research groups and companies working towards it, including ours at UNH). In the previous section, we found that to replace all transportation fuels in the US, we would need 140.8 billion gallons of biodiesel, or roughly 19 quads (one quad is roughly 7.5 billion gallons of biodiesel). To produce that amount would require a land mass of almost 15,000 square miles. To put that in perspective, consider that the Sonora desert in the southwestern US comprises 120,000 square miles. Enough biodiesel to replace all petroleum transportation fuels could be grown in 15,000 square miles, or roughly 12.5 percent of the area of the Sonora desert (note for clarification - I am not advocating putting 15,000 square miles of algae ponds in the Sonora desert. This hypothetical example is used strictly for the purpose of showing the scale of land required). That 15,000 square miles works out to roughly 9.5 million acres - far less than the 450 million acres currently used for crop farming in the US, and the over 500 million acres used as grazing land for farm animals.
The algae farms would not all need to be built in the same location, of course (and should not for a variety of reasons). The case mentioned above of building it all in the Sonora desert is purely a hypothetical example to illustrate the amount of land required. It would be preferable to spread the algae production around the country, to lessen the cost and energy used in transporting the feedstocks. Algae farms could also be constructed to use waste streams (either human waste or animal waste from animal farms) as a food source, which would provide a beautiful way of spreading algae production around the country. Nutrients can also be extracted from the algae for the production of a fertilizer high in nitrogen and phosphorous. By using waste streams (agricultural, farm animal waste, and human sewage) as the nutrient source, these farms essentially also provide a means of recycling nutrients from fertilizer to food to waste and back to fertilizer. Extracting the nutrients from algae provides a far safer and cleaner method of doing this than spreading manure or wastewater treatment plant "bio-solids" on farmland.
These projected yields of course depend on a variety of factors, sunlight levels in particular. The yield in North Dakota, for example, wouldn't be as good as the yield in California. Spreading the algae production around the country would result in more land being required than the projected 9.5 million acres, but the benefits from distributed production would outweigh the larger land requirement. Further, these yield estimates are based on what is theoretically achievable - roughly 15,000 gallons per acre-year. It's important to point out that the DOE's ASP that projected that such yields are possible, was never able to come close to achieving such yields. Thei