The links between water and energy

By Chris Burroughs

Water and energy are inextricably linked. It takes large volumes of water to produce energy and lots of low-cost energy to treat and distribute water. But the planning and management of these fundamental resources have historically been done in isolation. Such lack of coordination could lead to inefficiencies, conflict, and unnecessary stress on natural resources and the environment.

With power demands in the U.S. expected to increase 30 percent by 2025, researchers question how existing water supplies could accommodate new power generation. Future U.S. growth will likely also occur in the Southwest, a region with an already limited water supply.

Sandia's computer modeling initiative — drawn on the Labs' expertise in energy, water, and optimization — might provide some answers to these types of complex issues.

Vince Tidwell, Sandia principal investigator, says researchers face three problems — the coupling of complex systems, the integration of processes over disparate time and length scales, and the analysis and optimization of these models.

Tidwell also says electrical power generation nation wide requires about 140 billion gallons of water per day. Power generation accounts for more than 40 percent of all freshwater withdrawals in the United States. Although only a small fraction of the water withdrawn for power production is actually consumed (3.3 billion gallons per day), withdrawals taken from waterways and aquifers can lead to overdraft conditions while return flows introduce unwanted heat to the watershed that can pose problems.

Sandia’s model demonstrates possible energy and water shortfall scenarios for particular regions. Such shortfalls lead to tough and sometimes complex choices among future needs for energy, water, and environmental balance.

"Our model allows energy and water producers, resource managers, regulators, and decision makers to look at the different tradeoffs of water use and energy production caused by uncertainties in population, energy demand, climate, and the economy," says Tidwell.

The research is in its second year of three-year funding through Sandia’s internal Laboratory Directed Research and Development (LDRD) program.

Researchers will also create models and tools to assist in siting power plants and balancing the energy portfolio (e.g., fossil, nuclear, renew-ables). Decisions might be based on concerns such as cost, availability of water, availability of fuels, access to transmission lines, and greenhouse gas emissions.

"Users will be able to run hundreds of scenarios and see the effects in graphs and tables of their water and energy choices a year from now or decades away," Tidwell says.

The model, which will run on a standard PC, uses readily available software and provides rapid feedback.

Energy modeler Len Malczynski says the model will allow users to tailor their investigations to examine specific concerns. For example, they can get results on energy and water scenarios at the national, state, or local levels and will be able to look at specific watersheds. Such models would help determine water-energy trends in states like New Mexico where most of the power it generates leaves the state.

When the project is completed, researchers hope to make the model available to water and energy utilities, regulators, and decision makers.