Water–A Potential Threat to Reliable Power

I read an article last week in the Austin-American Statesman about water use and the potential shortages Texas may face in the all-too-near future, with conditions being exacerbated by the current drought [1]. The article brought to my attention the vulnerability of not only the availability of clean drinking water but of power as well. According to the article, water may become a new limiting factor for power production.

Electricity generation requires water for a variety of reasons, steam production, cooling, equipment cleaning, and other purposes; requirements for each technology or fuel source vary [2]. “Approximately 89% of the energy produced in power plants is generated by thermoelectric systems” [3]. Although a great majority of this water is reused or put back into the original water source, a portion of that water is evaporated or consumed; a 2003 study from NREL determined that in Texas, approximately 0.44 gallons of water are consumed per kWh produced [3].

With energy consumption rising exponentially, water consumption will continue to rise as well, and in semi-arid, highly populous regions like we see in Texas, this can potentially create a huge problem. So, putting the water consumption used during extraction or production of the fuel aside (i.e. hydraulic fracturing for natural gas, corn for ethanol), how can we make these power plants more efficient by using less water?

One option is a dry cooling system. These systems reduce water consumption by more than 90%, however, there is a loss in efficiency, as heat transfer by air is not as effective as with water; an estimated 1.5% of power generated through a dry cooling system goes to powering additional fans needed to facilitate the air-cooling process alone [4]. Furthermore, a study done by the DOE found that dry cooling systems can be three to four times as expensive as the traditional wet cooling system as well [4]. Because of these current limitations, this technology is rarely seen in the US. The system is not a complete bust though; one opportunity that has been mentioned is retrofitting older wet cooling systems, adding a dry cooling component; this would allow the plant to switch over to the dry cooling system during colder months, when the system is most efficient (less additional power is needed to cool) [4]. I think this option sounds very promising. At least it could be a step forward toward more water-conscious power plants, while in the mean time more R&D can go into developing technologies that can help to further mitigate this problem.

  1. Mashood, Farzad. “Texas in Drought: Rethinking How We Get, Use Water.” Austin-American Statesman. 29 January 2012.
  2. http://www.epa.gov/cleanenergy/energy-and-you/affect/water-resource.html
  3. http://www.nrel.gov/docs/fy04osti/33905.pdf
  4. http://www.world-nuclear.org/info/cooling_power_plants_inf121.html
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2 Comments

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2 responses to “Water–A Potential Threat to Reliable Power

  1. johnpmaxwell

    This is a very interesting topic, not only for power supply but a water quantity supply issue in general. The Texas State Comptroller’s Office recently released a report with three contingencies for precipitation and drought impact. Scenario 1 is adequate water supply. Scenario 2 and 3 are drought conditions with varying degrees of magnitude. The report notes the most impacted industry under the drought conditions is agriculture. As of 2010, 56% of the total demand of water in the state was used by irrigation while electric steam generation used just over 4%. Under both the severe drought and mega drought conditions in the estimate, it appears that agriculture would almost disappear in the semi-arid regions of Texas.

    Source of data: The Impact of The 2011 Drought and Beyond
    Susan Combs
    Texas Comptroller of Public Accounts

    http://www.window.state.tx.us/specialrpt/drought/pdf/96-1704-Drought.pdf

  2. energiaypolitica

    MPL and John, thanks for the article/report. One more thing I noticed when reading the report John cited is that 16% or 11,000 MG of ERCOT’s power resources depend on “on cooling water from sources at historically low levels” [1]. Not receiving the necessary water by May, 2012 could put more than 3,000 MW, or around 4% of ERCOT’s Capacity Demand and Reserves at risk. To put it in perspective, 1 MW can be used to power “500 average homes under normal conditions” or 200 during hot weather [2]. So that’s power for about 600,000-1,500,000 homes depending on the time of the year.

    Fortunately, ERCOT predicts that this shortage in power generation will not cause huge impacts on the grid in 2012 because even with this power shortage we will still be able to meet the forecasted demand. However, if rainfal conditions do not improve, we will not only see a more severe impact in agriculture but also on electric power availability in Texas in 2013 [3]. I wonder how industries in Texas that depend on a steady supply of electricity will respond to the possible shortage in power they’ll experience due to the drought.

    [1] http://www.window.state.tx.us/specialrpt/drought/pdf/96-1704-Drought.pdf
    [2] http://ercot.com/news/press_releases/show/459
    [3] http://www.ercot.com/content/news/presentations/2012/DOGGETT%20-%20Senate%20BC%20Hearing%201-10-12.pdf

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