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Comment by gpm

2 days ago

I don't have numbers to quote at you, but I would assume not. Fundamentally coal, nuclear, and gas-boiler (but not gas-turbine) power plants work the same way - you heat up water until it boils, and run the steam through a turbine to turn that heat into mechanical energy. I.e. the "cooling" is also the electricity generation mechanism. As a result same amount of heat should result in the basically same amount of electricity for each process, and since the water is being used in the same way they should be pretty much equal in water (use or consumption)/electricity output efficiency assuming they were built with the same era of technology...

I was mentally referring to this article. It mentioned that natural gas plants only used one tenth that of coal. I assumed this is because natural gas plants are newer etc.

https://www.eia.gov/todayinenergy/detail.php?id=50698

      Natural gas-fired generation uses a more energy-efficient technology to produce electricity than coal and has a lower water withdrawal intensity than coal. Natural gas combined-cycle generation had an average water withdrawal intensity of 2,793 gal/MWh in 2020, compared with 21,406 gal/MWh for coal.

  • Yeah, that's the gas turbine thing. The first-stage (which generates the majority of the power) isn't boiling water, but extracting energy directly from pressure from burning the gas in a jet-engine like fashion.

    The coal/nuclear like natural gas is what is labelled as "Steam Turbine" in the chart in this article: https://www.eia.gov/todayinenergy/detail.php?id=61444

    Looks like it's already a small minority.

    • Coal and natural gas also emit some of their waste heat in the outgoing exhaust gases. Nuclear doesn't have exhaust gases (aside from evaporated cooling water) to carry away waste heat.

      The big difference is the much lower thermal efficiency of LWR power plants.