Watering Down Biofuels
The ineffectiveness of biofuels—ethanol and biodiesil—has been much in the news lately, with reports from the EPA, California's CARB and the EU's joint Research Council claiming that biofuels pollute more than the fossil fuels they are supposed to replace. Still, this has not prevented the biofuels industry from receiving big government subsidies. Now a new report discloses another reason to shun biofuels, one that has nothing to do with CO2 and everything to do with H2O. When the water use of biofuel feedstock crops is analyzed, the water footprint (WF) ranges from 1,400 to an astounding 20,000 gallons of water for each gallon of biofuel produced.
Even if you do not believe that carbon dioxide is ravaging our planet by causing global warming or that the EPA and CARB decisions to include all production emissions when evaluating biofuels are fair; even if you think the study from the Carnegie Institution's Department of Global Ecology that says if is better to burn crops than turn them into biofuels is wrong, there is one thing that cannot be overlooked—the world is running out of fresh water. Agriculture already consumes 70% of all global freshwater withdrawn worldwide, depleting soil nutrients, draining underground aquifers and promoting desertification.
In the US, a rainy spring is finally bringing relief to the parched Southern states that have been under drought conditions for several years. During the drought, several states began to squabble over the rights to water flowing through the region's rivers. This is nothing new for residents of the American Southwest, where water rights disputes go back more than 100 years. Things are getting so bad in California—one of the nation's premier agricultural areas—that even Hollywood celebrities are getting involved. Move star Cameron Diaz recently shared her prescription for saving toilet water in Vogue: “If it’s yellow let it mellow, if it’s brown flush it down.” (I hope Ms Diaz doesn't have pets that occasionally take a drink from the porcelain spring.)
Nor is this strictly an American problem. According to the UN, the world faces a bleak future over its dwindling water supplies. The warning from the UN is based on a comprehensive assessment of the state of the world's fresh water, which involved some 24 UN agencies. “Today, water management crises are developing in most of the world,” says the 3rd World Water Development Report. The demand for water is increasing rapidly because of industrialization, rising living standards and changing diets that include more foods—primarily meat—that require larger amounts of water to produce.
“The result is a continuously increasing demand for finite water resources for which there are no substitutes,” it says, predicting that by 2030, nearly half of the world's population will be living in areas of high water stress. The UN is worried that squabbles over water in politically unstable areas are increasingly driving conflicts and that water shortages are beginning to constrain economic growth. The report cites a lack of water as a threat to growth in parts of China, India and Indonesia, and commercial centers in Australia and the western United States.
What does water have to do with biofuels? A paper, soon to be published in the Proceedings of the National Academy of Sciences (PNAS), reports that crops raised for ethanol and biodiesil production can be incredibly inefficient users of water. The article, titled “The water footprint of bioenergy,” gives an overview of water footprints (WFs) of bioenergy from 12 crops that currently contribute the most to global agricultural production: barley, cassava, maize, potato, rapeseed, rice, rye, sorghum, soybean, sugar beet, sugar cane, and wheat. In addition, this study includes jatropha, currently being touted as the energy crop of the future.
The WF of a biofuel product is defined as the volume of freshwater used for its production at the place where it was actually produced. The actual water content of such products is negligible compared with their WF. It is the water use in making the product—dominated by the agricultural production stage—that are so large they cause concern. As the paper's authors, Winnie Gerbens-Leenesa, Arjen Y. Hoekstraa and Theo H. van der Meerb, explain:
The WF consists of 3 components: the green WF, the blue WF, and the gray WF. The green WF refers to rainwater that evaporated during production, mainly during crop growth. The blue WF refers to surface and groundwater for irrigation evaporated during crop growth. The gray WF is the volume of water that becomes polluted during production, defined as the amount of water needed to dilute pollutants discharged into the natural water system to the extent that the quality of the ambient water remains above agreed water quality standards.”
The goal of this study was to provide a global overview of the WFs of the main crops that can be used for bioenergy. In theory, any crop can be used for bioenergy, but in practice a limited number of crops dominate global production: sugar cane, sugar beet, maize (called corn in the US), rapeseed, and soybeans. In all, it includes the 12 crops that contribute 80% of total global crop production. Additionally, the study includes jatropha curcas, a tree species with seeds from which oil can be extracted.
Weighted global average WF for 10 crops providing ethanol and for 2 crops providing oil for biodiesel.
The table above shows the results of the study, given in cubic meters per giga-Joule of energy produced (m3/GJ). One cubic meter (m3) is equal to 264 US gallons and a giga-Joule (1,000,000,000 Joules) is the equivalent of 278 kilowatt hours of electrical energy. For comparison, an average home uses a total of about 30 kilowatt hours a day during the summer, and about 50 kilowatt hours a day during the winter (this can vary widely, depending on location).
There are large differences among the 10 crops used to produce ethanol. Currently, sugar beets are the most favorable ethanol crop and sorghum the worst, with a seven fold difference in WF volume between them. Just because one crop is more efficient in terms of WF than another doesn't mean every country should try to grow the more efficient crop. When data for the two main ethanol producing countries, Brazil and the US, are compared, Brazilian ethanol from sugar cane is more efficient than from maize (99 vs 140 m3/GJ ethanol). however, in the US, maize is more attractive than sugar cane (78 against 104 m3/GJ ethanol).
The chart above shows the distinction between green and blue water. In terms of global averages, the blue WF of cassava is smallest, with sugar beet, potato, maize, and sugar cane shown to be relatively efficient crops. In terms of blue water for ethanol, sorghum is the most unfavorable feedstock, but it is not as bad as soybeans and rape, both used to make biodiesil. Blue water volume is amplified in many areas when crops inappropriate for the local climate are used, promoting heavy irrigation.
As I have previously reported in this blog, an article, published in the online edition of Science, showed that the best use of biomass is to convert it to electricity, rather than ethanol. They calculate that, compared with ethanol used for internal combustion engines, bioelectricity used for battery-powered vehicles delivers more miles of transportation per acre of crops. Similarly, the WF of bioelectricity is smaller than that of biofuels because it is more efficient to use total biomass (e.g., for electricity or heat) than a fraction of the crop (its sugar, starch, or oil content) for biofuel.
No pot of gold at the end of this rainbow.
The WF of ethanol appears to be smaller than that of biodiesel. For electricity, sugar beets, maize, and sugar cane are the most favorable crops, coming in at around 50 . Rapeseed and jatropha, typical energy crops, are disadvantageous (400 m3/GJ). For ethanol, sugar beet, and potato (60 and 100 m3/GJ) are the most advantageous, followed by sugar cane (110 m3/GJ); sorghum (400 m3/GJ) is the most unfavorable. For biodiesel, soybean and rapeseed show to be the most favorable WF (400 m3/GJ). Jatropha, the new wonder plant, has an adverse WF (600 m3/GJ). Here is how the study author's summed up their findings:
The WF of bioenergy is large when compared to other forms of energy. In general, it is more efficient to use total biomass, including stems and leaves, to generate electricity than to produce a biofuel. For most crops, the WF of bioelectricity is about a factor of 2 smaller than the WF of bioethanol or biodiesel.
IEEE Spectrum published an online article titled “Burning Biomass to Charge Electric Vehicles Beats Fueling Cars with Ethanol.” They quote J. Elliott Campbell, a professor of environmental science and engineering at the University of California and the study’s lead author, as saying there is no level of efficiency for converting biomass to ethanol achievable in the near future where bioelectricity-powered electric vehicles don’t win. “Even when we’re considering an ideal scenario—where roughly 41 percent of the energy content of the biomass ends up in the fuel tank—the results seem to favor the biomass-to-electricity pathway,” he states. Now it seems that we can add profligate water use to the already high price of biofuels.
Not only are biofuels a bad idea in terms of energy efficiency, pollution and water use, they threaten to ravage the natural world by almost eliminating unmanaged forests and wild areas. At the same time they will bring increasing preasure on world food prices. In a study reported in Science, Marshall Wise et al., plotted the course of future land use based on a number of different energy pollicies. Their conclusions for the scenario most favorable to biofuels is as follows: “The substantial increase in demand for purpose-grown biomass (four times as much as the reference scenario in Year 2095) intensifies its competition with food and fiber crops for the best cropland, pushing crops and biomass growth beyond traditional croplands and into lands that are inherently less productive. As a result, the relative increase in land required for biomass and other crops exceeds the relative increase in demand.” This can be seen more dramatically in the plot below, taken from the paper:
Overall, here is how biofuels stack up:
- Produce little or no additional energy.
- Can damage vehicle engines not designed to run on ethanol.
- Result in greater CO2 emissions than fossil fuel.
- Causes rising food prices either directly or by competing with food crops.
- Encourage clearing of forest lands.
- Increase use of fertilizer leading to greater runoff and NOx emissions.
- Produce less energy than simply burning the biomass to produce electricity.
- Will consume large amounts of already scarce freshwater.
- Are only commercially viable with government subsidies and forced use mandates.
How can this be made any clearer? Biofuels are a bust, a scam, a swindle created by muzzy headed greens, big agri-business, and government officials who are either industry lackeys, just plain ignorant or both. In the US this stuff is being pushed by corn belt politicians who are using it as a new form of agricultural subsidy. Whether you believe in global warming or not, the threat of water shortages is undeniably real and growing. Already the world's remaining rain forests are being cleared to raise feedstock crops for ethanol and biodiesil. Biofuels will not make the environment cleaner or our nations energy independent, they only make fat cats rich. We need to STOP BIOFUELS NOW! The only proper place for ethanol is in your favorite adult beverage.
Be safe, enjoy the interglacial and stay skeptical.
Eat them, feed them to animals but don't make them into fuel.