Heat Waves Putting Pressure on Nuclear Power's Outdated
May 4, 2011
Power generated from coal, natural gas and nuclear withdraws
more freshwater per year than the entire agricultural
sector; nuclear uses the most
By Lisa Song, SolveClimate News
The scramble to cool the Fukushima Daiichi nuclear complex
with seawater in the aftermath of Japan's disastrous
accident put a spotlight on just how much cold water an
atomic reactor needs to function — and not just in a crisis.
All existing nuclear plants use vast amounts of water as a
coolant. But in recent years — often far from the public eye
— hot river and lake temperatures have forced power plants
worldwide to decrease generating capacity.
Experts say the problem is only getting worse as climate
change triggers prolonged heat waves, prompting calls for
changes in siting processes.
"As a long-range strategy, [the industry] might change where
we site new plants to have better use of water resources,"
Gary Vine, an independent consultant, told SolveClimate
News. Vine has worked in the nuclear industry for decades
and is a former employee of Electric Power Research
Institute, a utility group.
There is also hope that new technologies will help mitigate
The U.S. Department of Energy is part of an international
team working to design the next generation of nuclear plants
— some of which will use less water than traditional plants.
But the project faces numerous challenges such as cost and
implementation barriers, and the DOE anticipates that the
generation IV reactors will not be commercially available
for at least two decades.
In the meantime, the scope of the problem is still not
Preliminary data from the Union of Concerned Scientists (UCS),
an environmental and nuclear watchdog group based in
Cambridge, Mass., shows that seven nuclear units at five
facilities had to reduce generating capacity due to warm
waters on at least 15 occasions between May and September
2010. The plants were in New Jersey, Pennsylvania, Illinois
and Georgia. While such incidents didn't affect plant
safety, they posed economic risk and decreased power
In one case, which did not appear in the UCS database, the
Tennessee Valley Authority's Browns Ferry station near
Athens, Ala., lost over $50 million dollars when it was
forced to run at half capacity for eight weeks last summer,
passing the price surge to customers.
During a blistering heat wave in Europe in 2003, France cut
4,000 megawatts of nuclear power — the equivalent of
shutting down four power plants — at a time when demand for
air conditioning was at its highest.
Figuring Climate Impacts Into Siting
Of the 104 nuclear plants in the U.S., over 30, or about
one-third, are located in the Southeast where they are
especially vulnerable to heat waves. In part because the
region's wind energy resource lags behind much of the
nation, nuclear is seen as an attractive emissions-free
Nuclear accounts for about a quarter of the region's
electrical generation, compared with 20 percent for the
nation as a whole. As of March, the Nuclear Regulatory
Commission had received 16 license applications for building
new nuclear units in the Southeast. The projects closest to
construction are units 3 and 4 of Southern Company's Vogtle
plant in Burke County, Georgia.
Sara Barczak, a program director for the Knoxville,
Tenn.-based Southern Alliance for Clean Energy, said climate
effects must figure into utilities' decisions to build new
nuclear facilities, especially since it can cost up to $10
billion per reactor and each is designed to last for 60
Climate change studies published in research journals such
as Science and the Journal of Climate project longer and
more intense heat waves over the next century worldwide,
adding constraints to water-intensive power systems.
According to the U.S. Geological Survey, thermoelectric
generation in the U.S. from coal, natural gas and nuclear
withdraws more freshwater per year than the entire
agricultural sector. Overall, nuclear plants consume up to
25 percent more water than fossil fuel plants.
David Lochbaum, director of the Nuclear Safety Project at
UCS, said regulators should be more forward-thinking in
When deciding where to build new reactors, officials "look
backwards for [records of] earthquakes and rainfall patterns
but never look forward," he said. "It's always struck me as
ironic that the industry touts nuclear as part of the
solution for climate change but they don't consider climate
change" in their planning.
Ray Golden, a spokesperson for TVA, said the last time the
utility licensed a nuclear plant was in the 1980s, at a time
when climate science was "less" available.
TVA has no plans to expand its nuclear fleet beyond its
three existing plants. But if it did, Golden said, it would
"be looking at all scientific evidence as part of the
environmental review, including the potential that global
warming might impact river temperatures in the future."
South Carolina Electric & Gas (SCE&G), a utility currently
licensing two new nuclear units, did not include
climate-related impacts in its recent siting discussions,
according to spokesperson Eric Boomhower.
Boomhower said the utility has never had to reduce nuclear
capacity because of water temperatures. SCE&G currently gets
19 percent of its electricity from its single nuclear plant
near Jenkinsville, South Carolina, some 25 miles northwest
of Columbia. The two proposed units will be built at the
Southern Co. did not respond to requests for comment by
'Glorified Way to Boil Water'
All thermoelectric plants operate on the same principle.
Water gets heated by a fuel source — coal, natural gas or
nuclear reactions — to create steam that drives a turbine to
In a nutshell, nuclear power is just "a glorified way to
boil water," said Barczak.
After steam is created, it must be condensed back into water
and recycled through the nuclear plant to be boiled again.
In a process known in the industry as "once-through"
cooling, the plant pumps in cold water from a river, lake or
ocean. This water pulls heat from the steam, and then it is
returned to where it came from, 10 to 20 degrees warmer.
Overheating occurs during the summer months, when outdoor
water temperatures are already high. Environmental
regulations prevent power plants from discharging the heated
water back into the river when temperatures reach a certain
point and could harm fish. When that happens, nuclear
operators have to decrease their generating capacity.
These regulations vary from state to state. In Alabama, for
instance, once the river hits 90 degrees Fahrenheit, power
plants cannot discharge any water that's warmer than the
river's ambient temperature, TVA's Golden said.
Fossil fuel plants are also vulnerable to such heat impacts,
though nuclear is more water-hungry. In once-through cooling
systems, nuclear reactors withdraw 25 to 60 gallons of water
for every kilowatt-hour of electricity, while coal uses 20
to 50 gallons per kilowatt-hour.
TVA spokesperson Barbara Martocci said the utility must
derate some of their coal plants every year. "It's unusual
if it doesn't happen." Sometimes the utility has enough
reserve power to make up for the lost capacity; in other
instances they have to buy power on the open market. When a nuclear plant reduces capacity, it tends to grab more
headlines than similar shutdowns at a coal-fired power
plant, explained Vine, the independent consultant. One
reason is that nuclear plants are larger: In the U.S., each
unit generates about 1,000 megawatts of electricity, at
least twice as much as individual fossil plants.
Cooling Towers: A False Solution?
Nearly 80 percent of the nation's nuclear facilities are
sited inland, relying on rivers and lakes, which heat up
more quickly than seawater.
However, operators of these facilities have another option
for cooling steam: Instead of cycling cold water through the
plant, they can build cooling towers that use air to
evaporate steam. Plants with cooling towers use 90 percent less water than
once-through cooling, said Lochbaum of UCS. But they
ultimately consume more.
In once-through cooling, power plants return the water they
use to the lake or river. When cooling towers are used,
steam is evaporated and lost to the atmosphere, so
additional water must be brought in and boiled for steam.
Cooling towers are usually restricted to inland plants, said
Vine, because saline water causes corrosion and
environmental problems like salt drift in the towers.
For him, the "megatrend" of siting nuclear plants inland is
unfortunate. Only 22 nuclear complexes are located next to
an ocean, estuary or tidal river. The top reasons are the
high cost of coastal real estate iand stringent
environmental regulations for saltwater ecosystems, Vine
High-Tech Fixes in the Works
Technologies on the horizon could mitigate future climate
The power company Dominion, which operates two nuclear units
near Virginia's Lake Anna in Louisa County, plans to add a
third unit at the same location. The proposed plant would
include a hybrid cooling tower capable of removing heat
without evaporating water.
The tower incorporates wet and dry cooling technology in a
way that's been used on nuclear plants in Europe but not in
the U.S., said Richard Zuercher, a spokesperson for
Zuercher emphasized, however, that the tower's design isn't
final and nothing will be decided for sure until Dominion
completes the licensing process in 2013 or 2014.
Looking far into the future, nuclear engineers are designing
new reactors that use less water for cooling. In some cases,
hot gas will be used in place of steam to drive the
turbines. Another design uses more efficient condensers that
require less cooling water.
However, these reactors won't be
ready until between 2030 and 2040, experts say.
TVA isn't waiting for that day to come. The utility has a
three-year plan to address water issues, said Golden. Unlike
most nuclear plants, Browns Ferry has a unique hybrid
design. The reactor uses once-through cooling with
additional helper towers that cool the water before it's
discharged into the river.
TVA will refurbish the station's six existing towers and
build a new one by 2013. Golden called the $160 million
dollar project an "adaptation plan" to help TVA avoid a
repeat of summer 2010.