Op-ed: Nuclear power and economics
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Mr. Stossel's nuclear engineer who provided most of the input for his column needs a refresher course in thermodynamics and economics. His main concern was radiation and how little damage occurred at Three Mile Island.
Nuclear fission reactors that provide heat for steam turbine generated electricity operate at 33% efficiency. Big costs for utilities are refueling and relicensing nuclear reactors. Utilities maximize shareholder profit by using the highest efficiency electric generating plants since electricity prices are fixed. Modern coal fired electric generating stations have efficiencies of 40%. It is no surprise that utilities would shut down nuclear power plants and buy grid electricity generated by coal fired power plants or build new coal fired power plants. Then came climate change/global warming.
Mr. Stossel claims nuclear power is "clean" because it does not pfoduce CO2, a greenhouse gas. Another cause of global warming is inefficiency in thermal electricity generating systems be they nuclear or coal fired. For nuclear power plants, that means that 67% of the fission reaction energy goes to warming the environment either air or water. For fossil fuel fired boilers the value is 60%. Skeptics only have to look at the cooling towers associated with these power plants. The News and Sentinel has pictures of the Pleasants generating station at part load, and a Georgia unit at full load -- both from 2025. The white cloud over the cooling tower, water below its dew point, is unrecoverable energy from generating electricity. Fact checkers can find this information on the internet and Power magazine.
Stossel's source claims modular fission reactors will be safer than existing ones due to smaller size/less fissionable material with fewer containment issues. A different fuel configuration may improve fuel efficiency, but the upper limit is 40%. Containment is still a design requirement because energy transfer between the fission reactor and steam boiler is done with molten salt or lead at temperatures between 750 and 1000 degrees F. Design errors for these modular fission reactor containment systems would be less severe than for large power stations. Manufacturers of these modular reactors are aiming for the chemical plant market, which utilizes electricity to run pumps and steam to heat reactors and distillation columns.
This is called cogeneration, and it boosts the thermal efficiency from 40% to 80-90%. The plant I retired from had a thermal efficiency of 90% using a gas turbine to generate electricity and exhaust gas heat recovery to make steam. Data centers do not lend themselves to cogeneration, so modular nuclear reactors at data centers will contribute to global warming.
Engineers always try to make electricity generation more thermally efficient. This lowers fuel costs -- shareholders and ratepayers like this -- and lowers CO2 and heat discharge to the environment -- global warming/climate change.
The latest efforts are combined cycle systems. Typically, these are gas turbine powered generators with exhaust gas heat recovery powering steam turbine driven generators. These have thermal efficiencies of 55-60%. When these plants come online, 40% efficient coal fired power plants get relegated to peak operations, of 47% onstream, when grid electrical prices peak. Gov. Morrisey's demand they run full time means higher costs for ratepayers or reduced value for shareholders. Replacing the gas turbine with a diesel could up the efficiency to 75%.
Ultimate thermal efficiency in electricity generation are water and wind turbines at 93%. The downside of wind turbines and solar power are abrupt changes in weather. Battery backup is a possible solution. I don't think its response is quick enough to prevent a grid shutdown.
Grid shutdowns are real. One caused power loss in Spain, Portugal and southern France for three days. This was attributed to a large number of renewable power generating systems on this grid. General Electric and Siemens engineers developed a "synchronous capacitor" to address the problem. This consists of a large generator electrically connected to the grid and mechanically connected to a giant fly wheel.
I do not deny the effect of CO2 and greenhouse gases on climate change. Increasing the efficiency of fossil fuel systems for electricity generation will reduce greenhouse gas. I have not seen any studies that compare greenhouse gas effects and thermal inefficiencies on climate change. More study is needed.
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Gregory Cigal, of Parkersburg holds a masters of science in chemical engineering.