The water cost of electricity

Embodied water it’s called – meaning how much water was used, or consumed, to make something.

A rule of thumb for water consumed in a constructing a building is: embodied water equals ten times the volume of the building. For example, a one cubic meter building will have consumed ten cubic meters of water in all the processes and materials involved in its construction. Makes you feel good about your renovation…

Producing electricity requires water, especially steam based generation – coal, nuclear, and solar thermal. The study used for this article comes from Arizona in the US, revised in 2008. “The Water Costs of Electricity in Arizona, Martin J. Pasqualetti, Ph.D. School of Geographical Sciences, Arizona State University.

Nuclear generation uses 2971 litres per megawatt hour, coal 1930 l/MWh and natural gas 1570 l/MWh. This study also estimated water lost in evaporation and seepage form hydro-electric scheme dams and arrived at a figure of 113 857 litres per megawatt hour.

One megawatt is a 1000 kilowatts, so 1 kilowatt hour consumes 1.93 litres of water in coal based generation, and 2.97 litres in nuclear generation.

Figures for Victorian generation range between 1.3 and 2.5 litres per kilowatt hour.

So if you run a 1000 watt (1 kilowatt) heater for one hour about two litres of water is consumed – counting a bit for electricity transmission loss. A hundred watt globe on for five hours will use up one litre. Gone.

So in a dry climate like Arizona, or Australia, steam based generation meets real limits. You can have as much brown coal or uranium as you like, but getting enough water without killing a river is a problem. Basically electricity generation is competing with other water uses like agriculture and environmental flows, and in a dry this is a real problem.

We opted for wind power under our greenpower scheme as it has low embodied water – a little would be used in the construction and installation of turbines.

When options for alternative electricity generation in Australia are discussed nuclear power often comes up, especially as it has lower carbon emissions than brown coal.

But given the environmental limitations i.e. not enough water, is nuclear generation an option for Australia? No.

We should be able to catch up to Germany in the use of solar power! There are alternatives working here right now and distributed generation makes great sense (and use of the grid) as a robust energy system.

Water we don’t have, so coal and nuclear are out.

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