Editor’s note: Water sufficiently cool to cool equipment at conventional and nuclear power plants is in shorter supply than the industry admits and the problem is likely to exacerbate as hot summers continue. This executive summary from a report by the Union of Concerned Scientists details some of the problems, and in doing so, highlights the greater advantage of wind power — it needs no cooling water.
Power plant dependence on water creates many problems, including for the plants. They have recently run into three challenges: incoming cooling water that is too warm for efficient and safe operation, water that too hot for safe release into rivers or lakes, and inadequate water supplies. In response, operators must reduce discharge hot water, at times when demand for electricity is high and rivers and lakes are already warm.
The heat waves and drought that hit the United States in 2011 and 2012 shined a harsh light on the vulnerability of the U.S. electricity sector to extreme weather. During the historic 2011 drought in Texas, power plant operators trucked in water from miles away to keep the plants running, and disputes deepened between cities and utilities seeking to construct new water-intensive coal plants.
In 2012, heat and drought forced power plants, from the Gallatin coal plant in Tennessee to the Vermont Yankee nuclear plant on the Connecticut River, to reduce their output or shut down altogether. That summer, amid low-water levels and soaring water temperatures, operators of other plants—at least seven coal and nuclear plants in the Midwest alone—received permission to discharge even hotter cooling water, to let the plants keep generating.
These consecutive summers alone revealed water-related electricity risks across the country. The power sector has historically placed large demands on air and water. In 2011, electricity generation accounted for one-third of U.S. heat-trapping emissions, the drivers of climate change. Power plants also accounted for more than 40% of U.S. freshwater withdrawals in 2005, and are one of the largest “consumers” of freshwater—losing water through evaporation during the cooling process—outside the agricultural sector.
The electricity system our nation built over the second half of the 20th century helped fuel the growth of the U.S. economy and improve the quality of life of many Americans. Yet we built that system before fully appreciating the reality and risks of climate change, and before converging pressures created the strain on local water resources we see today in many places. This system clearly cannot meet our needs in a future of growing demand for electricity, worsening strains on water resources, and an urgent need to mitigate climate change.
We can, however, use fuel and technology options available now to design an electricity future that begins to shed some of these risks. We can also expand our options by making strategic investments in energy and cooling technologies. The key is to understand what a low-carbon, “water-smart” electricity future looks like—which electric sector decisions best prepare us to avoid and minimize energy-water collisions, and to cope with those we cannot avoid—and to make decisions that will set and keep us on that path.
This report is the second from the Energy and Water in a Warming World Initiative (EW3), organized by the Union of Concerned Scientists to focus on the water implications of U.S. electricity choices. The first, Freshwater Use by U.S. Power Plants, documented the energy-water collisions already occurring because of the dependence of U.S. power plants on water. In that research, we found that past choices on fuel and cooling technologies in the power sector are contributing to water stress in many areas of the country.
Like the first report, this one stems from a collaboration among experts from universities, government, and the nonprofit sector. Water-Smart Power reflects comprehensive new research on the water implications of electricity choices in the U.S. under a range of pathways, at national, regional, and local levels. The report aims to provide critical information to inform decisions on U.S. power plants and the electricity supply, and motivate choices that safeguard water resources, reduce carbon emissions, and provide reliable power at a reasonable price—even in the context of a changing climate and pressure on water resources.
The challenges
Our examination of today’s electricity-water landscape reveals prominent challenges:
• Energy-water collisions are happening now. Because of its outsized water dependence, the U.S. electricity sector is running into and exacerbating growing water constraints in many parts of the country. The reliance of many power plants on lakes, rivers, and groundwater for cooling water can exert heavy pressure on those sources and leave the plants vulnerable to energy-water collisions, particularly during drought or hot weather. When plants cannot get enough cooling water, for example, they must cut back or completely shut down their generators, as happened repeatedly in 2012 at plants around the country.
• As the contest for water heats up, the power sector is no guaranteed winner. When the water supply has been tight, power plant operators have often secured the water they need. In the summer of 2012, for example, amid soaring temperatures in the Midwest and multiple large fish kills, a handful of power plant operators received permission to discharge exceptionally hot water rather than reduce power output. However, some users are pushing back against the power sector’s dominant stake. In Utah, for example, a proposal to build a 3,000-MW nuclear power plant fueled grave concerns about the impact of the plant’s water use. And in Texas, regulators denied developers of a proposed 1,320-MW coal plant a permit to withdraw 8.3 billion gallons (25,000 acre-feet) of water annually from the state’s Lower Colorado River.
Climate change complicates matters
Energy-water collisions are poised to worsen in a warming world as the power sector helps drive climate change, which in turn affects water availability and quality. Climate change is already constraining or altering the water supply in many regions by changing the hydrology. In the Southwest, for example, where the population is growing rapidly and water supply is typically tight, much of the surface water on which many water users depend is declining. Scientists expect rising average temperatures, more extreme heat, and more intense droughts in many regions, along with reductions in water availability. These conditions—heightened competition for water and more hydrologic variability—are not what our power sector was built to withstand. However, to be resilient, it must adjust to them.
Change is under way
Building an electricity system that can meet the challenges of the twenty-first century is a considerable task. Not only is the needed technology commercially available now, but a transition is also under way that is creating opportunities for real system-wide change.
The U.S. power sector is undergoing rapid transformation. The biggest shift in capacity and fuel in half a century is under way, as electricity from coal plants shrinks and power from natural gas and renewables grows. Several factors are spurring this transition to a new mix of technologies and fuels. They include the advanced age of many power plants, expanding domestic gas supplies, and low natural gas prices, state renewable energy and efficiency policies, new federal air-quality regulations, and the relative costs and risks of coal-fired and nuclear energy.
Read the rest of the executive summary here:
http://www.ucsusa.org/assets/documents/clean_energy/Water-Smart-Power-Executive-Summary.pdf
Filed Under: News, Policy
It is actually quite simple. 1 Kg of water is heated by about 1050 Kcal. addition by coal/nuclear heating, to be supplied as
steam into the TURBINE. Typical turbine efficiencies are 33%, which means at least 600-700 kacl/kg needs to be withdrawn.
This is done in cooling towers etc. but at 540 Kcal/kg of latent heat, obviously more water has to be evaporated into
air.
We have to move on to CPV /PV and similar sources with V2O5 batteries for bulk power storage, if we want to go for sustainable
power production.