The Energy-Water Nexus
Every day the United States withdraws more than 200 billion gallons of water to cool the power plants that give us electricity. That’s more water than we use to irrigate the land. Meanwhile, about 13 percent of the electricity produced in the United States is used to bring us water for domestic purposes, including pumping it from the ground, transporting it to our homes, and heating it for our showers.
It takes a great deal of water to produce energy, and a great deal of energy to produce clean water. And these relationships will become more significant as the world’s growing population demands more of each resource. Global warming further complicates the situation, changing the availability and therefore politics of water around the globe as some areas receive more rain and others become more arid.
A new research effort organized by the MIT Energy Initiative aims to help the world better understand the relationships between water and energy both now and in the future. The multidisciplinary, MIT-led study, which involves 16 researchers on 5 teams, is part of a broader, multi-institutional program on energy sustainability sponsored by BP.
Ahmed Ghoniem leads an MIT group examining how much water it takes to produce energy globally. John Lienhard and a colleague are examining how much energy it takes to provide clean water. For the past year, Lienhard and Ghoniem have been collecting data to establish the technical foundation for the study. Lienhard, the Samuel C. Collins Professor of Mechanical Engineering, is currently putting the “sheer morass of information we have” into a rigorous framework to make it accessible to others.
Ghoniem’s team, which is also compiling data, has developed a physics-based model to better understand the use of water in producing energy. “Our model can estimate the water use at a given power plant with a reasonable degree of accuracy from readily available data sources like weather conditions. We think it will help fill in gaps in the field data available,” says Ghoniem, the Ronald C. Crane Professor of Mechanical Engineering.
Further, the model will help scientists and policymakers explore hypothetical situations like the effect on water withdrawal of adding a new technology for capturing carbon dioxide to a power plant. It could also help evaluate tradeoffs involved in not only producing power and conserving water, but minimizing environmental impacts. (Both Ghoniem and Lienhard note that withdrawing large amounts of water from, say, a river can affect the ecosystem of that river, and such environmental impacts are becoming ever more important.)
Ghoniem and Lienhard’s data will now be used to inform a suite of other cross-disciplinary MIT projects involving additional faculty from several schools and departments. For example, Professor Dara Entekhabi of civil and environmental engineering is examining the risks surrounding various sources of water supply.
“The challenge of water supply is one that we can meet,” says Lienhard, adding that the whole problem and its solutions are multidisciplinary. “It’s not just about technology, but also about economics and governance, and it’s going to take careful effort on the part of the leadership of countries.”