Reducing Reliance on Coal Power Could Save City of Austin One Billion Gallons of Water

Not many people think about energy conservation as a way to boost water supplies but the potential is huge. Roger Duncan, General Manager of Austin Energy in Austin, TX, recently explained to City Council members in the drought-stricken city that they could save upwards of a billion gallons of water by 2020 simply by reducing the electricity received from a local coal-fired power plant by just one-third.

An artricle written by Marty Toohey in the Austin American-Statesman describes Mr. Duncan's remarks:

A sign that Austin’s drought is on everyone’s mind: Austin Energy, in pitching its idea to phase out the coal-fired Fayette Power Plant, is emphasizing water.

Austin Energy General Manager Roger Duncan is proposing the utility cut the power it gets from Fayette by a third by 2020. That in turn would save a billion gallons of water in 2020, according to a report from Duncan to the City Council.

Thermoelectric power generation currently accounts for 39% of all freshwater withdrawals in the United States--equivalent to the amount of water used for agriculture. If saline withdrawals are included, the energy sector's share of water use jumps to 48% making it the largest overall water-using sector in the U.S. Of course, much of this water is used for once-through cooling and is returned to or near the source but its often at a hotter temperature or degraded quality. Furthermore, fish and other aquatic organisms can get caught in the massive intake structures--some of which withdraw a whopping 500 million gallons of water per day!

Energy efficiency and a switch to clean, non-water-intensive energy sources offers the best opportunities to begin reducing the energy sector's outsized water demands. Of course, knowing which power options are the best from a water perspective is easier said than done.

We all know that biofuels are a renewable, supposedly clean source of energy that has huge water impacts, however, solar power and wind are largely considered "good" from a water-perspective.

But its more complicated than that and with regards to solar, one must differentiate from photovoltaic (PV) solar, the relatively small installations found on rooftops and street signs, from concentrating solar power (CSP), the big arrays of mirrors out in the desert. PV solar requires a lot of water to manufacture (although I have yet to come across anythings saying exactly how much) but virtually no water at all to operate. On the other hand, CSP currently requires as much or more water per kWh of produced electricity than conventional thermoelctric power, although new technologies are reducing CSP's water demands.

Wind might be the safest bet from a water perspective: a relatively new report from the Department of Energy describes how a shift to 20% wind power in the U.S. could save a total of 4 trillion gallons of water by 2030. As the DOE report 20% Wind Energy by 2030 explains:

Wind energy does not require the level of water resources consumed by many other kinds of power generation. As a result, it may offer communities in water-stressed areas the option of economically meeting growing energy needs without increasing demands on valuable water resources. Wind energy can also provide targeted energy production to serve critical local water system needs such as irrigation and municipal systems...Wind energy has the potential conserve billions of liters of water in the interior West, which faces declining water reservoirs.

For more information on the water embedded in the production of energy, check out the DOE's Energy Demands on Water Resources or the National Renewable Energy Laboratory's Consumptive Water Use for U.S. Power Production(PDF).