Nearly half of all water withdrawn in the U.S. is used to cool thermoelectric power plants, ensuring they operate safely and efficiently: On average a kilowatt-hour of electricity requires 25 gallons of water to be withdrawn from rivers and lakes. However, changes in precipitation, increased risk of drought, reduced snowpack and changes in the timing of snowmelt will impact the availability of water for electricity production.
Reduced water availability has led to some power stations turning to groundwater resources to supplement already stressed surface water supplies: The Department of Energy estimates that currently around 13% of thermoelectric cooling systems use groundwater but 30% of planned cooling systems are expected to use groundwater in the future. This will lead to some regions withdrawing more water from aquifers than is replenished.
Demand management reducing energy-water nexus pressures
With regions of the U.S., and overseas, facing decreased water availability for electricity production energy utilities have implemented, or are planning to implement, a range of demand management tools to reduce total energy usage and increase energy efficiency, which in turn lowers water demand.
Pricing to reduce peak demand: Duke Energy’s North Carolina Residential-Time Of Use (R-TOU) program encourages customers to shift their energy use away from high-demand on-peak hours. Under this program customers pay a higher rate during times of the day when demand for electricity is higher, however eligible customers pay off-peak rates for the remaining hours of the day, including all weekends and holidays.
Financial incentives for retrofits: Con Edison offers its customers numerous financial incentives for energy efficient technologies that helps improve operational performance of buildings and reduce peak energy demand during the summer months.
Energy audits: Australian energy utility AGL provides customers with a DIY home energy checklist allowing homeowners to assess their ‘building envelope’ (the structure and everything on the outside of the home that can affect energy consumption). The check includes a hot water check as heating water can account for up to a quarter of a household’s energy consumption.
Voluntary reductions: Pacific Power operates a voluntary load curtailment program, for large electricity users, where the utility posts on the Energy Exchange website a price for each hour it needs a reduction in energy use. Enrolled customers then make a pledge to reduce energy usage over certain hours with the utility calculating the actual reduction in energy use and making payment for curtailment delivered.
Energy conservation tips: TXU Energy has partnered with local youth groups and senior volunteer organizations to form the TXU Energy Home Makeover program to promote energy conservation awareness and help low-income customers in need of energy assistance. The program involves TXU Energy employees and volunteers providing customers with simple and affordable energy conservation tips that anyone can implement to save energy and reduce electricity bills.
To reduce energy-water nexus pressures, utilities can use a range of demand management tools to reduce total energy usage and increase energy efficiency, which in turn lowers demand for scarce water.