Shadow Minister, a clarification. I was not saying that "hot dry rocks" have been proven, rather is was correcting the view that the heat comes from magma which it does not. Other forms of geothermal are well proven and operate around the world, including Birdsville here in Australia.

I am not sure where you get the figures on water usage. I would be interested to see your source for this claim.

Byork - "the beauty of nuclear fusion is that it can generate all of humanity's energy needs for thousands of years" - billions in fact. We already have one, it is called the sun. Far better to work on solar thermal and pv to use what we already have than invest money duplicating what nature already provides.

"Solar cannot, as yet, provide primary base load power to run industry." Who says it has to? As I have pointed out many times, we have other options. Solar and wind tend to dominate the renewables discussion on these pages, but mini-hydro, geothermal, sewer gas and biomass are examples of other options. You should also not forget energy efficiency measures and smart grids that optimise what we already have.

The only site that deals with water loss in detail is the company running the test site in Germany.

The information is available on the Australian site, but the water losses are only mentioned in passing, but don't differ significantly per cycle from the German plant.

The German plant has easy access to large quantities of fresh water, the Australian site does not. This is a game changer in itself.

SM

Perhaps I needed to be more specific with my question. I am aware of at least three types of geothermal energy of which hot dry rocks is only one. My question related to your comment that geothermal uses three times as much water as nuclear. I find this difficult to believe and was wondering where you got your data.

Loxton, you are simply being obtuse.

There is only one type of geothermal energy in Aus that can make more than a tiny scratch on CO2 emissions.

The hot rocks requires water to be injected at high pressure into fractures in the granite, and retrieved at a higher temperature from another well.

The losses per cycle are between 10-15% per cycle in extracting the heat. So even when the generation is air cooled, the losses are significant, especially given the comparatively low temperature and energy generated per cycle.

Nuclear and coal power stations are also capable of air cooling thus using almost no water. Kendal power station near Johannesburg does this for about 3GW of generating capacity.

This is generally mentioned in the footnotes, but can be found on the Geodynamics website or the German Landau website.

Loxton,

What I find so amusing about SM is his myopic fixation on electricity generation. This is a handicap not suffered by Amory Lovins, of www.rmi.org, one of the world's most respected energy policy analysts.

By all means fossick through the footnotes on SM's biblical references, but don't forget to have a look at the wikipedia article on geothermal energy. It makes points which resonate with the article I mentioned above,

http://www.rmi.org/cms/Download.aspx?id=1802&file=ForgetNuclear.doc&title=Forget+Nuclear

about cogeneration and direct supply of electricity and low grade heat.

Energy lost through transmission from a centralised power station is energy and money wasted. That is why efficiency measures, "negawatts", are the clever way to assure electricity availability.

Thinking outside the electricity box, the Wikipedia article notes that, for low-grade heat applications,

"Direct heating is far more efficient than electricity generation and places less demanding temperature requirements on the heat resource. Heat may come from co-generation via a geothermal electrical plant or from smaller wells or heat exchangers buried in shallow ground. As a result, geothermal heating is economic at many more sites than geothermal electricity generation."

http://en.wikipedia.org/wiki/Geothermal_energy

Sir Vivor,

Piped hot water has been used for many years in Europe for house heating in winter, supplied from geothermal, gas and coal power stations.

Due to the high energy consumption of pumping water this is restricted to houses relatively close to the source of heat.

Given the generally warm climate in Aus and the large distances from the heat sources, this is completely irrelevant to the discussion.