How Much Water is Required to Cool a Recirculating Coal Plant Generator?
It takes 3 tons to 4.2 tons of steam at typical pressures and temperatures to generate 1 MWh of electricity with a steam generator. That's 720 to 1,000 gallons of makeup water per MWh.
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However 17x this amount 12,000 to 17,000 gallons per MWh is needed to cool the plant.
There's also the water consumed in the production and transport of the coal. A smaller but measurable amount.
How much is consumed depends on the details of the design. So water use depends on the type of coal fired plant. There are three types;
- Once through 20,000 cool- 300 makeup 53% of all plants.
- Recirculating 700 cool - 700 makeup 40% of all plants
- Dry 0 cool 0 makeup. 1% of all plants.
Now all three have added water usage when there's a blowdown prior to maintenance or the water used to mine and transport coal attributed to the plant operation.
Usage can change as well per MWh if the plant is operating under rated capacity more than doubling water use.
Clearly operating all plants at peak capacity and retrofitting recirculating technology in the once through plants would cut out 2/3 of coal plant water usage. Using excess power at peak use times to make hydrogen from electricity and water then use peaking turbines running on hydrogen to do load matching would set the stage for eventual transition to hydrogen economy.
William Mook, Linkden