June 2007, Vol. 19, No.6


‘Virtual Water’ Innovator Awarded 2008 Stockholm Water Prize

Professor John Anthony Allan of King’s College London and the School of Oriental and African Studies has been named the 2008 Stockholm Water Prize Laureate. Allan pioneered the development of key concepts in the understanding and communication of water issues and how they are linked to agriculture, climate change, economics, and politics, according to a news release from the Stockholm (Sweden) International Water Institute (SIWI).

In 1993, Allan introduced the “virtual water” concept, which measures how water is embedded in the production and trade of food and consumer products. Behind that morning cup of coffee are 140 L of water used to grow, produce, package, and ship the beans, according to the SIWI release. That is roughly the same amount of water used by an average person daily in England for drinking and household needs. A hamburger requires an estimated 2400 L of water.

Virtual water has major impacts on global trade policy and research, especially in water-scarce regions, and has redefined discourse in water policy and management. By explaining how and why nations such as the United States, Argentina, and Brazil “export” billions of liters of water each year, while others, such as Japan, Egypt, and Italy, “import” billions, the virtual water concept has opened the door to more productive water use. National, regional, and global water and food security, for example, can be enhanced when water-intensive commodities are traded from places where they are economically viable to produce to places where they are not. While studying water scarcity in the Middle East, Allan developed the theory of using virtual water import, via food, as an alternative water source to reduce pressure on the scarcely available domestic water resources there and in other water-scarce regions.

Allan has authored or edited seven books and has published more than 100 papers in political science, natural resource management, and interdisciplinary water journals, the press release says. He also also educated more than 1100 current or future water professionals. He has worked for more than 35 years in the Middle East and North Africa. He also served as editor of the scientific journal Water Policy and as a consultant for numerous governments, the World Bank (Washington, D.C.), and the European Union, according to the press release.

The $150,000 Stockholm Water Prize will be presented Aug. 21

How Much Water Does It Take To Power a Light Bulb?

Virginia Polytechnic Institute and State University (Virginia Tech; Blacksburg, Va.) professor Tamim Younos and undergraduate student Rachelle Hill are researching the water efficiency of some of the most common energy sources and power-generating methods.

Younos and Hill have analyzed 11 types of energy sources, including coal, fuel ethanol, natural gas, and oil; and five power-generating methods, including hydroelectric, fossil-fuel thermoelectric, and nuclear methods. According to a Virginia Tech news release, the most water-efficient energy sources are natural gas and synthetic fuels produced by coal gasification. The least water-efficient energy sources are fuel ethanol and biodiesel.

In terms of power generation, Younos and Hill have found that geothermal and hydroelectric energy types use the least amount of water, while nuclear plants use the most.

Hill took the study one step further and calculated how many gallons of water are required to burn one 60-W incandescent light bulb for 12 hours a day over the course of 1 year. She found that the bulb would consume between 11,355 and 22,710 L (3000 and 6000 gal) of water, depending on how water-efficient the power plant is that supplies the electricity.

Hill said the results are estimates of the water consumption based on energy produced by fossil-fuel thermoelectric plants, which produce about 53% of the power used in the United States. “The numbers are even more staggering if you multiply the water consumed by the same light bulb by the approximately 111 million U.S. homes,” Hill said. “The water usage then gets as high as 655 billion gallons [2.48 billion m3] of water a year.”

By contrast, burning a compact fluorescent bulb for the same amount of time would save about 7570 to 15,140 L (2000 to 4000 gal) of water per year, according to the release.

The study is part of a multicollege partnership at Virginia Tech led by Younos that proposes a unique approach to managing water and energy resources, called the Decentralized Energy and Water Systems. Another research theme under scrutiny by the Decentralized Energy and Water Systems scientists is to study rainwater harvesting as an alternative to using water from the public system for nonpotable uses, and the impact of rainwater harvesting on water and energy conservation and stormwater management.

Switching to Ethanol

Following up on a net-energy study published in the January Proceedings of the National Academy of Sciences, a team of U.S. Agricultural Research Service (ARS) and University of Nebraska–Lincoln (UNL) scientists have reported the on-farm economic costs of producing switchgrass to make cellulosic ethanol.

In their energy-analysis paper, the team reported that switchgrass, when used for cellulosic ethanol, yielded more than five times more energy than required to produce the fuel. In the March edition of BioEnergy Research, the team describes their study’s second part, which examined the farm-scale production costs of switchgrass. Richard Perrin of UNL and Ken Vogel, Marty Schmer, and Rob Mitchell — all in the ARS Grain, Forage and Bioenergy Research Unit at Lincoln — conducted the studies, an ARS news release says.

Perrin and Vogel say this study is the most comprehensive one completed to date assessing the economic costs of producing switchgrass biomass on commercial fields, according to the news release. The team contracted with 10 farmers in Nebraska, North Dakota, and South Dakota to grow switchgrass commercially for 5 years, starting in 2000 and 2001. Throughout the study, the farmers recorded all costs for producing switchgrass biomass, from seed and fertilizer expenses to equipment and labor costs. Total baled biomass yields were recorded for each farm.

On average, switchgrass production costs were $66/Mg ($60/ton), the news release reports. Two farmers with previous experience growing switchgrass were able to limit production costs to $43/Mg ($39/ton). They were among a group of five farmers whose production costs were $55/Mg ($50/ton) or less.

Perrin and the ARS agronomists expect production costs will also decline as new, “ethanol-friendly” cultivars are developed, the news release says.

Mining Manure for Phosphorus

U.S. Agricultural Research Service (ARS) soil scientists Ariel Szogi, Matias Vanotti, and Patrick Hunt have found a way to “mine” the phosphorus in poultry manure. Their method — dubbed “Quick Wash” — consists of rapid removal and recovery of phosphorus in solid form, according to an ARS press release. ARS has applied for a patent on this process.

The process selectively removes up to 80% of the phosphorus from poultry litter while leaving the nitrogen. The washed poultry litter can be applied to farm fields as a balanced fertilizer or used again as a bedding material, according to the release. It can also serve as a feedstock for bioenergy production.

U.S. farmers use 1.7 billion kg (3.7 billion lb) of phosphorus in annual crop production, the release says. But poultry and other livestock produce about 453 million kg (1 billion lb) more phosphorus than livestock producers can use.