Wednesday, June 06, 2012

Revisiting Nuclear Energy and Cooling Water

Earlier this week, the journal Nature Climate Change published a study concerning how warmer weather and reduced river flows might impact electricity generation at nuclear and coal-fired power plants. Here's how Reuters reported the findings:

In a study published on Monday, a team of European and U.S. scientists focused on projections of rising temperatures and lower river levels in summer and how these impacts would affect power plants dependent on river water for cooling.

The authors predict that coal and nuclear power generating capacity between 2031 and 2060 will decrease by between 4 and 16 percent in the United States and a 6 to 19 percent decline in Europe due to lack of cooling water.
The nuclear energy industry isn't unfamiliar with the topic. Here at NEI Nuclear Notes, we first dealt with the issue during the Summer of 2006 when a heat wave struck Europe and forced a number of nuclear plants to reduce power.

Back then, our points were pretty clear: the industry was well aware of the situation and that there were a number of adaptations that could be implemented in order to mitigate it. When we revisited the issue in response to a study by the Union of Concerned Scientists back in November 2011, I turned to one of our policy experts, Bill Skaff, to handle the question. I spoke with Bill again this week about the latest study, and he passed along the following note to me:
Environmentally conscious regulators and companies are already taking into account flow, discharge temperature, and intake temperature projections when locating and permitting new power plants and other industrial facilities. The Nature study’s time parameters remind us that gradual change allows time for adaptation. Additionally, there are engineering solutions being implemented today that can mitigate climate change impact. For instance, Browns Ferry is building small cooling towers to pre-cool discharge water.

Sustainable development will require electricity for quality of life and a mix of energy sources to generate that electricity—renewable, nuclear, and fossil. We must balance all environmental, social, and economic factors and make trade-offs when considering what energy source or cooling system to deploy at each of our diverse ecosystems around the country.

Wind and solar energy use very little water, but their electricity output is variable and intermittent. An electricity grid can only balance a limited amount of these electricity shortfalls, limiting how much renewable energy can be accommodated by a grid before it becomes unstable and black outs occur. Moreover, the variable, intermittent output of these renewables is usually balanced by fossil plants, which emit carbon dioxide and air pollutants.

The electricity grid requires steady, reliable baseload electricity—the output of nuclear and fossil plants. Nuclear power plant water use is comparable to coal plants. Natural gas uses less water, but produces half as much carbon dioxide as a coal plant as well as nitrogen oxides, which contribute to ground level ozone formation, a cause of respiratory ailments. By contrast, nuclear power plants produce no greenhouse gases or air pollutants during operations.
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EPRI, Water & Sustainability, Vol. 3 U.S. Water Consumption for Power Production, 2002, p. viii. National Energy Technology Laboratory (G. J. Stiegel, J. R. Longanbach, M. D. Rutkowski, M. G. Klett, N. J. Kuehn, R. L. Schoff, V. Vaysman, J. S. White), Power Plant Water Usage and Loss Study, August 2005, revised May 2007, p. xiii.

3 comments:

Kit P said...

One of the recommendations in the report is making natural gas plants more efficient. So how do we do that?

Inefficient SSGT are made more efficient CCGT by using cooling water to condense steam. There you have it; the solution becomes part of the problem.

Colin Megson said...

Let coal decline - we all want it to. But for nuclear, the answer is so simple - generate our electricity and process heat using high temperature reactors which, if the 'waste' heat can't be put to a useful purpose, can be air cooled.

However, high temperature 'waste' heat can be used to desalinate, to produce vast quantities of potable water from brackish groundwater and seawater. It can also be used to implement a hydrogen economy, whereby all liquid fuels can be made carbon neutral, by using atmospheric CO2 in their production. Likewise carbon-neutral ammonia can be made from atmospheric N2 and used as feed stock for fertilisers, to maintain agricultural production to feed 9 billion people.

There is one outstanding reactor that can do all of this and also is inherently safe - it shuts down according to the laws of physics, even if all safety systems and all electrics are lost. The fuel in the reactor core starts life in the molten state, so no more TMI or Fukushima-Diiachi style meltdowns. It operates at atmospheric pressure, so there is no high powered 'driver' available to expel radiotoxic substances upwards and outwards into the environment. Also, its fuel is thorium - 3½ X more common than uranium and in sufficient abundance to be economically available until the end of time.

This silver-bullet answer to the most significant problems facing humankind, is the Liquid Fluoride Thorium Reactor (LFTR). Google: LFTRs to Power the Planet for all of the benefits.

Anonymous said...

I think it would be very smart if the cooling plants employed solar power in addition to generator and battery power to help the plants keep running better during a nuclear crisis. This would give the plant an infinite amount of time to cool the water down after a SCRAM - reducing the chances of a complete meltdown considerably. Thanks for listening. Steve Wise - Colorado Springs, Colorado