This year, residents of Austin, Texas celebrated their 4th of July with plenty of beer and BarBQ – but there were no fireworks over Lady Bird Lake as a burn ban prohibited even sparklers from being sold in the area. Texas has just moved through its driest 8-month period on record. The lack of rain, coupled with record-breaking spring heat waves, has created a reality where some Texas towns might not have enough water to last through the summer. While residents hope for a wet hurricane season to end the drought, they have found a way to conserve water to the tune of millions of gallons per day. By using the wind to offset fossil fuels for electricity generation, the Lone Star State has shown how going green can help when regions struggle to balance water supply and demand.
In the United States each of us use, on average, almost 36,000 gallons of water a year for activities like showering and flushing the toilet. This does not include our indirect water use for growing the food that we eat or for generating the electricity that keeps our lights on. In the face of a drought, these simultaneous demands can lead to struggles in determining where the water should go.
For every kilowatt-hour (kWh) of electricity generated in the United States, 2 gallons of water are consumed due to evaporation. This means that the average U.S. resident indirectly consumes more than 9,400 gallons of water per year to run the power plants that generate electricity for their home. When you include the number of gallons of water used (though not consumed – also called “pass-through” water use) to generate this electricity, this number jumps by an order of magnitude or more.
This water is used primarily to cool thermoelectric (for example – coal, natural gas, and nuclear) power plants. Heat is generated in these plants by combusting fossil fuels or using nuclear fission. This heat is then used to boil water to generate steam, which turns a turbine connected to a generator that produces electricity. Cooling is needed throughout this process, not only to protect the boilers where the steam is produced, but also to cool the hot water that exits the turbines before it is discharged into cooling ponds or other waterways. In the United States thermoelectric power plants consume, on average, 0.47 gallons of water for every kilowatt-hour (kWh) that they produce.
To supply the nation’s total electricity demand, thermoelectric power plants use more than 200 billion gallons of water for cooling – EVERY DAY. While the majority of this water can be reused at these facilities, approximately 5 billion of these 200 billion gallons will be lost through evaporation. Texas is responsible for 6%, or 12 billion gallons, of these water withdrawals for a daily consumption rate of 300,000 million gallons of water.
But, Texas has managed to decrease the amount of water needed to generate electricity in the state by using the wind to supply a portion of the state’s electricity needs. While we might typically think of Texas in terms of its rich oil and gas resources (good ol’ Texas Tea), the state also has extensive renewable electric energy resources including solar, wind and geothermal (the new Texas ‘E’). Over the past decade, the state’s renewable portfolio standard (RPS) has driven Texas to become the nation’s leader in wind generation. Today, Texas has more than 10,000 megawatts(MW) of wind capacity installed - more than the next three-largest wind generating states (Iowa, California, and Minnesota) combined.
Over the course of a year, these wind turbines supply around 7% of Texas’s electric power needs. They also save the state millions of gallons of water because wind turbines require virtually no water to generate electricity. Alternatively, hundreds of gallons of water would have been consumed if a megawatt-hour from wind power was instead generated using natural gas (223 gallons/MWh), coal (426 gallons/MWh) or nuclear (600 gallons/MWh) power.
This summer, amid the heat and extreme drought, Texas set a new record for wind generation. At 10:26pm on June 19, 2011, the Electric Reliability Company of Texas (ERCOT) recorded 7,355 megawatts (MW) from wind generation – the most “Wind-Watts” that had ever been generating power on the Texas grid. This wind power represented 14.58% of the 50,447 MW load at the time. It also represented a savings potential of more than 2.4 million gallons of water per hour compared to thermoelectric alternatives. And, this number is likely conservative, as it does not include water consumption at the state’s hydroelectric facilities.
Power generation in hydroelectric facilities uses water directly in order to spin turbines connected to generators to produce electricity. Water is pooled to create a “head” and is then allowed to flow through the dam using gravity, being released on the other side at a lower elevation. While we can argue over the amount of water used by these dams (versus for recreational activities on the lakes and rivers that they connect to), we can certainly say that the increased surface area of the dammed water way leads to increased evaporation rates. According to the United States Geological Survey, hydroelectric power plants consume 18 gallons of water for every kilowatt-hour that they produce – more than 30 times their thermoelectric power counterparts.
This year, along with most of the southern United States, Texans are faced with extreme drought and the growing concern of what will happen if rain doesn’t come soon. Through investments in wind power, they have conserved millions of gallons of water, helping them to bide their time until the rain falls again. For Texans, as described in Bob Dylan’s 1963 lyrics, one “answer is blowin’ in the wind” .
- "Blowin' in the Wind", written by Bob Dylan, released on his album The Freewheelin' Bob Dylan in 1963
For a list of calculations used in the writing of this post, please go here.
[Photo of wind farm and oil derrick © Copyright Mary Christenberry Lott and used with permission]