Which power source is the most water efficient?

As we all know Australia is a very dry country where water is one of our most valuable resources.

So how much water do we need to generate our electricity?

The generation of 1 kWh of electricity by way of nuclear power uses 2.3 litres of water.

By contrast, coal is slightly more efficient as coal power requires only 1.9 litres of water per kWh.

Even solar thermal power (not solar pv), although one of the greenest forms of energy out there, still requires a great deal of water, about 3.6 litres per kilowatt hour.  But it does have a saving grace in that solar thermal power plants re-use as much water as possible in a trough system.  The solar power is used to heat and boil the water, which in turn makes steam spin a turbine which then generates electrical power.

A solar thermal plant in Israel is taking the hot water after it has spun the turbines and is feeding it to homes and factories for heating. Nice idea.

The renewable energy source that uses the least amount of water is wind power which uses a minuscule four millilitres per kilowatt hour. It is only used to clean the turbines.

The other technology which consumes very little water is solar power in the form of solar PV panels which uses about 110 millilitres per kilowatt hour.