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The Water Requirements of Biofuels
Volume 13, Number 34: 25 August 2010

In a paper recently published in AMBIO: A Journal of the Human Environment, Mulder et al. (2010) assess the connection between water and energy production by conducting a comparative analysis for estimating the energy return on water invested (EROWI) for several renewable and non-renewable energy technologies using various Life Cycle Analyses. This approach mirrors the energy return on energy investment (EROEI) technique that has been used to determine the desirability of different forms of alternative energy, with the technique's most recent application being adjusted to also consider the global warming potentials of the different forms of non-fossil-fuel energy and the greenhouse gases emitted to the atmosphere in the process of obtaining them and bringing them to the marketplace.

The reason for bringing water into the equation derives from the facts, as noted by Mulder et al., that (1) "water withdrawals are ubiquitous in most energy production technologies," (2) "several assessments suggest that up to two-thirds of the global population could experience water scarcity by 2050 (Vorosmarty et al., 2000; Rijsberman, 2006)," (3) "human demand for water will greatly outstrip any climate-induced quantity gains in freshwater availability (Vorosmarty et al., 2000; Alcamo et al., 2005)," and (4) the increased need for more freshwater "will be driven by the agricultural demand for water which is currently responsible for 90% of global freshwater consumption (Reault and Wallender, 2006)."

So what did the analyses of Mulder et al. reveal?

The three U.S. researchers say their results suggest that "the most water-efficient, fossil-based technologies have an EROWI one to two orders of magnitude greater [italics and bold added] than the most water-efficient biomass technologies, implying that the development of biomass energy technologies in scale sufficient to be a significant source of energy may produce or exacerbate water shortages around the globe and be limited by the availability of fresh water."

These findings will not be welcomed by those who promote biofuel production as a means of combating what they call "the threats posed by 'climate refugees' and 'climate conflict' to international security," as recently discussed by Hartmann (2010) in the Journal of International Development, where she identifies some of the principals in the spreading of what she calls this "alarmist rhetoric" to be various United Nations agencies, NGOs, national governments, security pundits, the popular media and -- quite specifically -- the Norwegian Nobel Committee of 2007, which, as she describes it, "warned that climate-induced migration and resource scarcity could cause violent conflict and war within and between states when it awarded the Nobel Peace Prize to Al Gore, Jr. and the Intergovernmental Panel on Climate Change."

Hartmann goes on to suggest that "this beating of the climate conflict drums has to be viewed in the context of larger orchestrations in U.S. national security policy." And in this regard it doesn't take a genius to realize that the promotion of biofuels to help resolve these concerns will only exacerbate them in one of the worst ways imaginable, providing a "cure" that is worse than the disease.

So why is it, as Hartmann notes, that "in the United States, members of Congress eager to pass climate legislation -- which will likely mandate the use of more biofuels -- have resorted to the security threat argument as a way to win support on Capitol Hill"? She answers with the remark that "according to the New York Times (2009), 'many politicians will do anything for the Pentagon'."

Clearly, there are way too many ulterior motives involved in the debate over possible CO2-induced climate change and what to do about it. So what is our solution? Let simple facts prevail, realizing that one of those facts is that there simply is not enough freshwater on the face of the earth to make the production of biofuels a viable and significant alternative to the mining and usage of fossil fuels.

Sherwood, Keith and Craig Idso

Alcamo, J., van Vuuren, D., Ringler, C., Cramer, W., Masui, T., Alder, J. and Schulze, K. 2005. Changes in nature's balance sheet: Model based estimates of future worldwide ecosystem services. Ecology and Society 10:

Hartmann, B. 2010. Rethinking climate refugees and climate conflict: Rhetoric, reality and the politics of policy discourse. Journal of International Development 22: 233-246.

Mulder, K., Hagens, N. and Fisher, B. 2010. Burning water: A comparative analysis of the energy return on water invested. Ambio 39: 30-39.

New York Times. 2009. The climate and national security. Editorial, 17 August. Available at:

Renault, D. and Wallender, W. 2006. Nutritional water productivity and diets. Agricultural Water Management 45: 275-296.

Vorosmarty, C.J., Green, P., Salisbury, J. and Lammers, R.B. 2000. Global water resources: Vulnerability from climate change and population growth. Science 289: 284-288.