Jan 28 2008
Water and energy are inextricably linked. It takes large volumes of water to produce energy and significant amounts of low-cost energy to treat and distribute water.
But the planning and management of these fundamental resources have historically been done independently of one another.
A Sandia National Laboratories research team is attempting to remedy the situation by developing interactive computer modeling tools that integrate the two for planning and management purposes.
“Our model will allow 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 Vince Tidwell, principal investigator.
Specifically, the model will help answer questions dealing with possible energy and water shortfall scenarios for particular regions; tradeoffs between alternate energy futures to meet projected shortfalls; tradeoffs between alternate water allocation schemes; economic and environmental consequences of these alternative futures; and potential consequences of alternative energy, environmental, and/or water policies.
The research is in its second year of three-year funding through Sandia’s internal Laboratory Directed Research and Development (LDRD) program.
Sandia is a National Nuclear Security Administration (NNSA) laboratory.
The idea for the modeling program grew out of the Energy-Water Roadmap Development exercise conducted by Sandia and several other entities that addressed major energy- and water-related issues facing the country. The roadmap, which is under review by the Department of Energy, shows that energy and water utilities usually don’t work together to resolve joint issues. This lack of coordination could lead to inefficiencies, conflict, and unnecessary stress on natural resources and the environment.
Tidwell says that currently, electrical power generation requires about 140 billion gallons of water per day, accounting for more than 40 percent of all freshwater withdrawals in the nation. That means thermoelectric generation withdrawals alone are almost equal to those for irrigated agriculture. However unlike agriculture, only a small fraction of the water withdrawn for power production is actually consumed (3.3 billion gallons per day). Nevertheless, withdrawals taken from waterways and aquifers can lead to overdraft conditions while return flows represent a source of thermal pollution.
With power demands expected to increase 30 percent by 2025, Vince questions where the water is going to come from to accommodate new power generation. Related to this is the fact that much of the growth in the US is occurring in the Southwest, a region that already has limited water.
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.
In developing the water-energy model, Tidwell says, the researchers face three problems — the coupling of complex systems, integration of processes over disparate time and length scales, and the analysis and optimization of simulation results.
Concurrent with the energy-water modeling, the research team will put together an optimization toolbox that will assist in data analysis. Specifically, optimization will be used to help in the siting of power plants, balancing the energy portfolio (e.g., fossil, nuclear, renewables) to keep pace with growing power demands, and decisions concerning when to build the next power plant. Such decisions might consider 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.
Sandia researcher Len Malczynski, who is doing energy modeling, says the team is now compiling data to go into the program. The model will allow users to tailor their investigations to meet specific needs. 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. This would be particularly helpful in determining water-energy trends in states like New Mexico where most of the power is generated at in-state plants but used by people from out of state.
“Energy data is provided by DOE, and water information is coming from different agencies,” says Peter Kobos, who is also doing energy modeling at Sandia. “The challenge will be to have enough data to tell a story. We think we do. If not, we’ll identify gaps and address them as the project progresses.”
When the project is completed, the researchers expect the model will be available to water and energy utilities, regulators, and decision makers.