Last year we told you about the under appreciated link between water and energy. In fact, we devoted an entire issue to it. (One of the main links, in case you’ve forgotten, is that about 40 percent of all water withdrawn in the United States is used to cool nuclear and fossil-fuel fired generators.) We looked at several spots where water availability was a serious constraint on electricity generation, but one of the places we didn’t detail, but maybe should have, was Texas. (We did touch on it later in a podcast, though.)
Texas is in the throes of its worst drought in more than 40 years. It’s already cost the state’s agriculture $1.2 billion since November 2010 according to Texas officials and the damage could hit $4 billion if conditions don’t change in June. According to the US Drought Monitor, the entire state is experiencing at least “abnormally” dry conditions and 82 percent of the state has hit the “exceptional drought” mark, the second worst of five categories.
So what’s all this done to electricity generation in Texas? You might think that with livestock dying, cotton fields turning to dust, and suburbanites unable to water their lawns that electricity generators would be in trouble too.
Not so, according to Michael Webber, assistant professor of mechanical engineering at University of Texas, Austin and a leading expert on what water wonks call the water-energy nexus. So far he hasn’t heard of any Texas power plants having to throttle back because of drought. But “that doesn’t mean it’s not going to happen,” he adds.
Why no power outages? Well it has to do with water rights. Water law in the western United States works on the principal of seniority. Basically, if you made the first claim of rights to 1000 megaliters of water from a stream and your neighbor made the second claim for the same amount, you get yours first no matter what. So if there is only 1500 ML in the stream one year, you get 1000 ML and your neighbor gets just 500 ML. Power plants in Texas tend to hold senior rights, so they get what they need.
Webber points out that there is still a danger to generators. Firstly, even these senior rights would be strained if the drought continues too long. Secondly, with the hot Texas summer coming, what water is left might become so hot that its ability to cool the power plants would diminish. Heat waves have repeatedly throttled many French nuclear plants.
What can help? There are less water-intensive forms of generation, such as wind power and photovoltaics, but these are generally intermittent sources—less useful for supplying a grid’s baseload power. There are even ways to minimize water use in nuclear and other thermal power plants such as, using dry cooling systems (essentially a really big radiator) or water-efficient hybrid systems. But the latter are less efficient in hot climates like Texas, and the former are costly compared to the price of water. Coastal power plants could also make use of seawater cooling, but that makes plants vulnerable to natural disasters (Fukushima Dai-1 and to a much lesser extent, the Diablo Canyon jellyfish attack) and man-made ones (the Deepwater Horizon spill).
No matter what you do, understanding the real risk will help. Webber would like there to be detailed assessment of the risk of drought to individual power plants in Texas. Right now, he says, “that’s sort of an unknown.”
Samuel K. Moore is the senior editor at IEEE Spectrum in charge of semiconductors coverage. An IEEE member, he has a bachelor's degree in biomedical engineering from Brown University and a master's degree in journalism from New York University.