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The Energy-Water Nexus, Southern Rivers & Us

September 3, 2010

In early 2010, winter rains and snow put a lot of water in the Tennessee River.  With all that extra water, the Tennessee Valley Authority’s (TVA) 29 hydroelectric facilities were generating more energy than normal.  And as a result, energy prices in TVA markets dropped 15 percent below comparable regional averages.  Customers were happy.

Too Hot in the Hot-tub: Then, by July things took a turn for TVA and their customers, according to this story and many others.  Summer air temperatures soared into the 90s for days, leading to increased energy demands from consumers running more air conditioners and fans.  Electrical rates also spiked upward.  So what does this have to do with water?  TVA’s Browns Ferry Nuclear Power Station had to reduce production by 50 percent to comply with an Alabama state regulation requiring the Tennessee River’s water temperature to remain below 90 degrees.  In order to serve their customers, TVA had to turn to the open market to purchase replacement power – and this led to increased energy costs for consumers.  TVA estimates it lost over $50 million in power generation due to reduced production.

Energy-Water Nexus.  The Tennessee River situation is a prime example of the energy-water nexus, and is representative of a problem the American South faces in the near future according to this excellent Circle of Blue report.  All energy companies need water to produce electricity.  Regardless of how they do so – in coal, natural gas, or nuclear plants – energy companies consume water to power your computer, keep your smart phone charged, and cool your house.  Without getting into the different generation technologies or cooling systems, all you need to know is that power plants consume river water to cool their equipment.  If you are a visual learner, visit the Southern Company’s interactive site to see how water can make electricity.  But in order to produce energy, water has to be available and at the right temperature.

Energy companies use millions and millions of gallons of river water in evaporators and condensers every day.  As water circulates through these systems to cool the equipment, cold water either picks up heat before re-circulating or it evaporates into the atmosphere.  At some plants, such as Browns Ferry, the heated water is piped back into the Tennessee River.  And the hot water – well it’s no good for anybody.  It’s not good for trout and other aquatic organisms that need cool water to survive.  Hot water is also no good for other downstream power plants that also need water for cooling purposes.

River Systems, Energy Systems.  TVA claims that some technical fixes at Browns Ferry would reduce water temperatures in the Tennessee River.  That’s great, but if you look at the whole river, you can see that any technological fix might be a short term fix.  Why?  Like nearly every other major southern river (the Coosa, Chattahoochee, Catawba, etc), there are multiple energy plants up and down the corridor.  On the Tennessee, TVA operates at least three fossil fuel plants upstream and two downstream from Browns Ferry, as well as two existing upstream nuclear stations (plus TVA has proposed a third).  There is only so much heat the river can withstand and shed.  Cooling the water for each plant matters, but in the long run, it will not if global temperatures increase, precipitation decreases, or both happen.  What we really need are energy systems that are not dependent on river systems.

IBT Dead in the Water.  One last thing.  Remember that Georgians with parched throats looked longingly at the Tennessee River as a water source for metro Atlanta during the recent epic drought.  However, if TVA is currently having a hard time managing water temperatures, I cannot imagine they want to see any water leave the Tennessee River basin via an interbasin transfer (IBT) into Georgia.  Might we eliminate this “highly contentious” IBT option identified by the Water Contingency Task Force in 2009 (see slide 124 & 129) from the public discussion?

-Chris Manganiello

5 Comments leave one →
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