Thirsty Nukes Can't Take the Heat
by Lloyd Alter, Toronto on 06.23.07
As John noted earlier, President Bush has suggested that ""Nuclear power helps us protect the environment" and wants to build new plants. However, there is a problem that John posted about last year and that raised its head again: water, and the huge amounts needed to keep reactors operating at safe temperatures. David Lochbaum, a nuclear engineer with the Union of Concerned Scientists, told the International Herald Tribune:
"We're going to have to solve the climate-change problem if we're going to have nuclear power, not the other way around. As the climate warms up, nuclear power plants are less able to deliver."
In the French 2003 killer heat wave, 17 reactors had to be cut back or turned off because of the rapid rise in river temperatures. In Germany and Spain, reactors were dialled back as temperatures rose. In the US, the group Public Citizen reported a shutdown last year at a plant in Michigan, and slowdowns at plants in Minnesota, Illinois and Pennsylvania, because of hot conditions.
So build them on the coasts and cool them with seawater or don't expect much out of them when you need them most- when it is hot outside. ::International Herald Tribune
Coal plants also use HUGE amounts of water for cooling and scrubbers.
Actually, the same article applies to fossil generation plants as well. You can think of the modern large power plant as having two parts: the first makes the steam and the second uses it to create electricity via a turbine/generator. The second part for fossil and nuclear are roughly the same - high temperatures at their ultimate cooling source (oceans, rivers, etc.) effect power output. The more recent plants cool their output water via cooling towers (like the giant hourglass cooling towers noted above) but that isn't a complete solution. I suspect from my experience that nuclear plants are a bit more sensitive to river/lake/ocean temperatures because they are best run both stable and at high power and their input temperature limits are a bit more constrained because they wish to avoid having an emergency shutdown whenever possible (to protect the expensive turbine/generator equipment and because they take longer to restart.) But hotter water temperatures are not exclusively a nuclear power problem in the energy biz.
Regards, James Aach, author of "Rad Decision", the first insider novel of nuclear power. Available at no cost at my website http://RadDecision.blogspot.com and also in paperback. I believe we'll make better decisions about our energy future if we first understand our energy present (and I don't know what that energy future should be.)
"I'd like to see Rad Decision widely read." - Stewart Brand, noted futurist and founder of "The Whole Earth Catalog".
I should have put a link in the article but we wrote about the problems of water for conventional plants here
This is a dumb article.
The same precludes Geothermal and Solar Thermal all the same.
The issue with warm water discharge is a common issue shared by all steam turbine power plants, so the fact the the article targeted nuclear is really pointless.
How about using large Stirling engines in stead of steam turbines? Stirling engines don't use up any water, but use the temperature difference to generate motion.
Anyone know if this would be a serious option to large nucleair/coal/gas fired plants?
Stirling engines still have to operate between a high temperature source and a low temperature heat sink, like all heat cycle engines. You can use the atmosphere instead of water as the heat sink but you can do that with turbine cycles also. This requires what is known as a dry condenser, which is essentially a huge radiator that allows air cooling. These can be and have been used with any type of power plant - coal, gas, nuclear, etc.
google "Gen IV nuclear reactors" or "Air Cooled Heat Exchangers". I worked on a project determining HX's to be used for cooling down a nuclear test reactor in west Texas (no water). There are only two designs of reactors that acutally use water;' Boiling Water Reactors and Pressurized Water Reactors. Liquid Sodiium and Pebble Bed Reactors do not.
KenG: thanks for the info. I knew Stirling engines are air cooled (or liquid cooled but then you'd have to cool the liquid with air anyway). But big steam turbines too? Interesting.
So why isn't it being used more? Poor economics? Too much maintenance? Not as energy-efficient?
Sounds like the water use problem is technical ie can be fixed.
But nucleair has other problems which may prove difficult to solve...