Climate change, water and energy

A July 2013 report by the US Department of Energy details many of the interconnections between climate change and energy.[1] These include:

• Increasing risk of shutdowns at coal, gas and nuclear plants due to decreased water availability which affects cooling at thermoelectric power plants, a requirement for operation;
• Higher risks to energy infrastructure located along the coasts due to sea level rise, the increasing intensity of storms, and higher storm surge and flooding. A 2011 study evaluated the flood risk from coastal storms and hurricanes for the Calvert Cliffs nuclear plant (Maryland) and the Turkey Point nuclear plant (Florida). Under current conditions, storm surge would range from 0.6 metres for a Nor'easter to 3.7 metres for a Category 3 hurricane, causing no flooding at Calvert Cliffs but "considerable flooding" at Turkey Point (which would be inundated during hurricanes stronger than Category 3);
• Disruption of fuel supplies during severe storms;
• Power-plant disruptions due to drought; and
• Power lines, transformers and electricity distribution systems face increasing risks of physical damage from the hurricanes, storms and wildfires that are growing more frequent and intense. For example, in February 2013, over 660,000 customers lost power across eight states in the US Northeast affected by a winter storm bringing snow, heavy winds, and coastal flooding to the region and resulting in significant damage to the electric transmission system.

Many incidents illustrate the connections between climate, water and nuclear power in the US:

• From February 8−11, 2013, Winter Storm Nemo brought snow and high winds to 19 nuclear energy facilities in the Northeast and mid-Atlantic − 18 facilities operated continuously at or near full power throughout the storm while Entergy's Pilgrim 1 reactors in Massachusetts safely shut down on February 9 due to a loss of off-site power (restored the following day).[6]
• In October 2012, ports and power plants in the Northeast were either damaged or experienced shutdowns as a result of Hurricane Sandy. More than eight million customers lost power in 21 affected states.[1] Hurricane Sandy affected 34 nuclear energy facilities in the Southeast, mid-Atlantic, Midwest and Northeast. Twenty-four nuclear energy facilities continued to operate throughout the event. Seven were already shut down for refueling or inspection. Three reactors shut down: Salem 1, New Jersey, was manually shut down due to high water at its outside circulation water pumps; Indian Point 3, New York, automatically shut down due to external power grid disruption; Nine Mile Point 1, New York, automatically shut down due to external power grid disruption. Exelon declared an alert due to the high water level at the cooling water intake structure of its Oyster Creek, New Jersey nuclear plant; the alert ended after 47 hours when the water level dropped.[6]
• In August 2012, Dominion Resources shut down one reactor at the Millstone Nuclear Power Station in Connecticut because the temperature of the intake cooling water, withdrawn from the Long Island Sound, was too high. Water temperatures were the warmest since operations began in 1970. No power outages were reported but the two-week shutdown resulted in the loss of 255,000 megawatt-hours of power, worth several million dollars.[1]
• In August 2012, Entergy's Waterford 3 reactor, Louisiana, was temporarily shut down as a precaution due to projected high winds (Hurricane Isaac).[6]
• In July 2012, four coal-fired power plants and four nuclear power plants in Illinois requested permission to exceed their permitted water temperature discharge levels. The Illinois Environmental Protection Agency granted special exceptions to the eight power plants, allowing them to discharge water that was hotter than allowed by federal Clean Water Act permits. [1]
• In July 2012, the Vermont Yankee had to limit output four times because of low river flow and heat; and FirstEnergy Corp's Perry 1 reactor in Ohio dropped production because of above-average temperatures.[2]
• In September 2011, high temperatures and high electricity demand-related loading tripped a transformer and transmission line near Yuma, Arizona, starting a chain of events that led to the shut down of the San Onofre nuclear plant with power lost to the entire San Diego County distribution system, totaling approximately 2.7 million power customers, with outages as long as 12 hours. [1]
• On 27−28 August 2011, Hurricane Irene affected 24 nuclear power plants along the East Coast. Eighteen reactors remained at or near full power throughout the storm. Power output from four reactors was temporarily reduced as a precaution. One plant temporarily shut down as a precaution − Constellation Energy declared an unusual event when the Calvert Cliffs 1, Maryland, reactor automatically shut down due to debris striking an external electrical transformer.[6]
• On 27 April 2011, three Browns Ferry reactors, Alabama, automatically shut down when strong storms knocked out off-site power. Emergency diesel generators were used for just over five days.[6]
• On 16 April 2011, Dominion Resources' two Surry reactors, Virginia, automatically shut down after a tornado damaged a switchyard and knocked out off-site power.[6]
• In the Summer of 2010, the Hope Creek nuclear power plant in New Jersey and Exelon's Limerick plant in Pennsylvania had to reduce power because the temperatures of the intake cooling water, withdrawn from the Delaware and the Schuylkill Rivers respectively, were too high and did not provide sufficient cooling for full power operations. [1]
• On 6 June 2010, DTE Energy's Fermi 2 reactor, Michigan, automatically shut down after a tornado knocked out off-site power to the site. The tornado caused some external damage.[6]
• On 1 September 2008, Entergy's River Bend reactor, Louisiana, was manually shut down ahead of the approach of Hurricane Gustav. The shut down proceeded safely as designed but the hurricane caused some external damage.[6]
• In 2007, 2010, and 2011, the Tennessee Valley Authority's (TVA) Browns Ferry Nuclear Plant in Athens, Alabama, had to reduce power output because the temperature of the Tennessee River was too high to discharge heated cooling water from the reactor without risking ecological harm to the river. TVA was forced to curtail the power production of its reactors, in some cases for nearly two months. While no power outages were reported, the cost of replacement power was estimated at US$50 million. [1] From August 5−12, 2008, the TVA lost a third of nuclear capacity due to drought conditions; all three Browns Ferry reactors were idled to prevent overheating of the Tennessee River.[2]
• On 20 August 2009, lightning struck transmission lines knocking out off-site power to the Wolf Creek reactor, Kansas, and the plant automatically shut down.[6]
• In August 2006, two reactors at Exelon's Quad Cities Generating Station in Illinois had to reduce electricity production to less than 60% capacity because the temperature of the Mississippi River was too high to discharge heated cooling water. [1] The Dresden and Monticello plants in Illinois cut power to moderate water discharge temperatures from July 29 to August 2.[2]
• In July 2006, one reactor at American Electric Power's D.C. Cook Nuclear Plant in Michigan was shut down because the high summer temperatures raised the air temperature inside the containment building above 48.9°C, and the temperature of the cooling water from Lake Michigan was too high to intake for cooling. The plant could only be returned to full power after five days.[1]
• On 28 August 2005, Hurricane Katrina knocked out off-site power to Entergy's Waterford 3 reactor, Louisiana, and a manual shut down proceeded. Emergency diesel generators were used for 4.5 days.[6]
• On 24 September 2004, Hurricane Jeanne prompted a manual shut down of NextEra Energy's St. Lucie 1, 2 reactors, Florida, then caused loss of off-site power. Emergency diesel generators functioned as designed.[6]
• In 2003, Hurricane Charley led to a shut-down of the Brunswick 1 reactor in North Carolina due to loss of off-site power because of a trip of the station auxiliary transformer. The transformer trip was due to an electrical fault on a transmission system line. Operators manually shut down the reactor.[7]
• On 24 June 1998, FirstEnergy's Davis Besse reactor, Ohio, received a direct hit by an F2 tornado. The plant automatically shut down and emergency diesel generators (EDG) provided back-up power.[6] One EDG had to be started locally because bad switch contacts in the control room prevented a remote start. Then, problems due to faulty ventilation equipment arose, threatening to overheat the EDGs. Even with the EDGs running, the loss of offsite power meant that electricity supply to certain equipment was interrupted, including the cooling systems for the onsite spent fuel pool. Water temperature in the pool rose from 43°C to 58°C. Offsite power was restored to safety systems after 23 hours just as one EDG was declared inoperable.[7]
• On 24 August 1992, Category 5 Hurricane Andrew knocked out off-site power to NextEra Energy's Turkey Point 3, 4 reactors, Florida, and damaged electrical infrastructure. Manual plant shut down proceeded and emergency diesel generators were used for six days, 10 hours.[6] All offsite communications were lost for four hours during the storm and access to the site was blocked by debris and fallen trees. The nuclear power station's fire protection system was also destroyed.[7]
• In 1988, drought, high temperatures and low river volumes forced Commonwealth Edison to reduce power by 30% percent or in some cases shut down reactors at the Dresden and Quad Cities plants in Illinois. "That was the first wake-up call that plants would be vulnerable in a climate-disrupted world," said David Kraft, director of the Nuclear Energy Information Service.[2]

Of course, the problems are not unique to the US. A few examples:

• In July 2009, France had to purchase power from the UK because almost a third of its nuclear generating capacity was lost when it had to cut production to avoid exceeding thermal discharge limits.[2]
• In 2003, France, Germany and Spain had to choose between allowing reactors to exceed design standards and thermal discharge limits and shutting down reactors. Spain shut down its reactors, while France and Germany allowed some to operate and shut down others.[2] The same problems occurred in the Summer of 2006.[3]
• On 8 February 2004, both Biblis reactors (A and B) in Germany were in operation at full power. Heavy storms knocked out power lines. Because of an incorrectly set electrical switch and a faulty pressure gauge, the Biblis-B turbine did not drop, as designed, from 1,300 to 60 megawatts, maintaining station power after separating from the grid. Instead the reactor scrammed. When Biblis-B scrammed with its grid power supply already cut off, four emergency diesel generators started. Another emergency supply also started but, because of a switching failure, one of the lines failed to connect. These lines would have been relied upon as a backup to bring emergency diesel power from Biblis-B to Biblis-A if Biblis-A had also been without power. The result was a partial disabling of the emergency power supply from Biblis-B to Biblis-A for about two hours. Then, the affected switch was manually set by operating personnel.[7]

A study by researchers at the University of Washington and in Europe, published in Nature Climate Change, found that generating capacity at thermoelectric plants in the US could fall by 4.4−16% between 2031 and 2060 depending on cooling system type and climate change scenarios.[4]

Prof. Dennis Lettenmaier, one of the authors of study, told InsideClimate News the problems will be two-fold.[5] First, water temperatures will be higher because of raised air temperatures, and will be too high at times to adequately cool the plant. Secondly, there may simply not be enough water to safely divert the flow and return it to the waterway. Climate models project a greater probability of low river levels due to a more variable climate. Lower river or lake levels would mean there would be less water available to diffuse the warmth that is returned. Plants currently have discharge restrictions to prevent ecological damage from downstream thermal pollution. With lower water levels, the plants would be forced to shut down more often.

Lettenmaier said the study's findings might discourage operators from applying for relicensing of ageing facilities, because of the expensive upgrades that would be required. "That could be the last nail in the coffin," he said. (For example the the Oyster Creek (NJ) plant will close in 2019 in part because the utility prefers closure instead of installing a state-mandated cooling tower to minimise damage to Barnegat Bay.) Plants using cooling towers rather than once through cooling will also be affected by climate change, but not nearly as much.

The impacts of climate change could be even bigger in Europe, according to the Nature Climate Change study. Power production in European thermoelectric plants could drop by 6.3−19% between 2031 and 2060 due to increased shut-downs.

The Nature Climate Change article states: "In addition, probabilities of extreme (>90%) reductions in thermoelectric power production will on average increase by a factor of three. Considering the increase in future electricity demand, there is a strong need for improved climate adaptation strategies in the thermoelectric power sector to assure future energy security."

References:
[1] Department of Energy, July 2013, 'U.S. Energy Sector Vulnerabilities to Climate Change and Extreme Weather' http://energy.gov/downloads/us-energy-sector-vulnerabilities-climate-cha...
[2] Robert Krier, 15 Aug 2012, 'Extreme Heat, Drought Show Vulnerability of Nuclear Power Plants', InsideClimate News, http://insideclimatenews.org/news/20120815/nuclear-power-plants-energy-n...
[3] Susan Sachs, 10 Aug 2006, 'Nuclear power's green promise dulled by rising temps', www.csmonitor.com/2006/0810/p04s01-woeu.html
[4] Michelle T. H. van Vliet et al., June 2012, 'Vulnerability of US and European electricity supply to climate change', Nature Climate Change, Vol.2, pp.676–681, www.nature.com/nclimate/journal/v2/n9/full/nclimate1546.html
[5] Robert Krier, 13 June 2012, 'In California, No Taboos Over Coastal Climate Threats', InsideClimate News, http://insideclimatenews.org/news/20120613/nuclear-power-plants-united-s...
[6] Nuclear Energy Institute, 'Through the Decades: History of US Nuclear Energy Facilities Responding to Extreme Natural Challenge', www.nei.org/Master-Document-Folder/Backgrounders/Fact-Sheets/Through-the...
[7] Hirsch, Helmut, Oda Becker, Mycle Schneider and Antony Froggatt, April 2005, 'Nuclear Reactor Hazards: Ongoing Dangers of Operating Nuclear Technology in the 21st Century', Report prepared for Greenpeace International, www.greenpeace.org/international/press/reports/nuclearreactorhazards

Further reading:
Section D.2 of the Greenpeace report cited immediately above addresses the following topics:

• Consequences of Climate Change for NPP Hazards
• Examples of Flooding
• Examples of Storm Events
• Vulnerability of Atomic Power Plants in the Case of Grid Failure
• Vulnerability of Atomic Power Plants in the Case of Flooding
• Vulnerability of Nuclear Power Plants by Other Natural Hazards
• Possible Counter-measures