Research: Water supply more limiting than intermittent renewables
Currently, 97 percent of the nation's electricity comes from thermoelectric or hydroelectric generators, which rely on vast quantities of water to produce electricity, according to a report prepared by Synapse Energy Economics for the Civil Society Institute (CSI). Comparing the production of coal-fired electric, nuclear and natural gas to the likes of intermittent wind and solar resources, the report asks the question, "What will happen when the water doesn't flow?"
Water is increasingly becoming a limiting factor on U.S. energy production and a key obstacle to maintaining both electricity output and public health and safety. The constraints range from insufficient water supplies to meet power plants' cooling and pollution control needs to the high costs of energy-related water contamination and thermal pollution.
The amount of water available to serve diverse needs is a growing concern across the country, from the arid western states to the seemingly water-rich Southeast. The report finds that thermoelectric plants withdraw 41 percent of the nation's fresh water -- more than any other sector. Thermoelectric generation compounds the stress already faced by numerous watersheds and adds future risk.
On an average day, water withdrawals amount to an estimated 85 billion gallons for coal plants, 45 billion gallons for nuclear plants, and 7 billion gallons for natural gas plants; coal mining consumes between 70 million and 260 million gallons per day; and natural gas fracking requires between two and six million gallons per well for injection purposes, according to the research. Additional water is required to extract, process, transport, and store fuel, and this water is often degraded in the process.
If current trends continue, water supplies will be unable to keep up with growing demands. Factors that are likely to exacerbate the problem include climate change, water shortages, and carbon capture and sequestration (CCS). CCS is projected to increase water consumption rates for existing coal plants by 83 percent and natural gas plants by 91 percent, according to the report. Failure to address these constraints will lead to forced plant shutdowns that will jeopardize electricity production and constrain economic growth in the future, CSI contends.
"Continued reliance on water-intensive electric generation technologies puts consumers and regional economies at risk of interruptions in electricity supply or on the hook for costly infrastructure investment," said CSI Senior Energy Analyst Grant Smith. "To ensure a reliable, cost-effective supply of energy, these water-related risks must be fully accounted for in energy planning and regulation. Once the environmental costs of conventional fuels are recognized, it becomes clear that energy efficiency and renewable energy are bargains by comparison. These clean alternatives cause little if any harmful environmental impacts. On a full-cost accounting basis, clean energy would win out as the least-cost solution and solution that harbors the least risk, as our energy system would no longer threaten, or be vulnerable to, the quantity and quality of our water."
- see the report