Renewables, a realistic vision for Australia

The last couple of blogs have discussed a way out of our Green House Gas producing dilemma. Sticking to Australia for an example, there is progress on the green energy front; as I said we have the ability to become a leader in this area in Australia, the choice is ours.

Geothermal. There, I’ve said it. This is one golden key to the future!

What Geothermal is in Australia you say?!!? But the country is not volcanic, unstable like New Zealand where Geothermal sources abound. The process is simple. The centre of the earth is super hot metal and it’s surrounded by molten rock. All we need to do is get some of that awesome power up to the surface. In some places that happens naturally. New Zealand where there are pools of water boiling just under the surface the tapping of this energy has been in place for some time. In locations like NZ you can see the steam come out. And you can smell the sulphur gas that comes with it. Smells like rotten eggs. While it might put you off your lunch, this sort of geothermal energy is pretty useful. The steam can spin turbines which create electricity. There's hardy any harmful emissions, and it can make power all day every day.
So, traditional Geothermal energy is energy from the molten rocks heat close to the surface of the earth. It has been used for thousands of years in some countries for hot water, cooking and heating. Well, Geothermal now has a new and interesting twist.

Hot Dry Rocks:
In Australia, the main types of geothermal energy are to be found in hot dry rocks (HDR) and hydrothermal reservoirs (hot groundwater that has been heated by hot rocks). Currently, these are being used for heating applications and tested for electricity generation in various States. Harnessing HDR energy typically involves drilling into and fracturing hot basement rocks, so that water can be circulated via deep injector wells into the heat source. This heated fluid is recovered from deep production wells and circulated to the surface to a heat exchanger and used to generate electricity. The fluid is then recirculated. Project are ready to run in other countries.
In Australia, the potential to produce electricity is being tested in South Australia and the Hunter Valley Region in New South Wales.

Let’s take the Cooper Basin, in South Australia example. At about four and a half km under the surface there's 1000 square kilometers of hot granite. It’s hot because of the slow decay of potassium, thorium and uranium, which generates temperatures as high as 300 degrees. The granite is hot because of the natural nuclear activity in there - it's actually green nuclear! At this temperature it's more than hot enough to boil water.

A great little Aussie company, Geodynamics, is trail blazing the way. It is planning to use the hot rocks as a big underground kettle. They're drilling holes into the rock and making cracks in the hard granite below. Water is sent down the hole and through the cracks where it heats up. The water turns to steam and pours out of another hole where it spins turbines to create electricity. The water then cools and is sent back down the hole to make more steam so if it works properly nothing should be wasted. So far Geodynamics has produced some pretty impressive steam. The pressure in the Copper Basin test holes is actually high enough to force the water 3.5km into the air. The company says there enough hot rock down there to power the whole of Australia for well over 100 years. The setting that up will cost many millions of dollars. But, given that the previous government spent $200M to try to produce clean coal based energy, I think this technology deserves a little bit of effort too. Hot rock supporters recognise the one glitch. The transmission lines are not in place. Before deregulation of generation and the break of transmission system, the government paid for power lines from fossil fuel plants when they were built. So, it should help geothermal companies now just as they helped the coal fired plants in the past.

This is a promising technology, proven at a test well in Cooper Basin; and ready for commercialisation now (unlike clean coal).

Hydrothermal Power:
Harnessing hydrothermal energy usually involves accessing deep hot water reservoirs and circulating the water to the surface where a heat exchanger is used to generate electricity. The water is then recirculated. Hydrothermal energy can also be used for non-electricity producing activities such as temperature regulation (eg heating) and greenhouse warming. Hot groundwater has been used on a small scale in South Australia, Queensland and Victoria. For example, at Portland, naturally hot groundwater from the Portland area was used from 1985 until recently to heat municipal buildings, the town swimming pool and a motel.
Advantages of using geothermal energy
· It's free once built.
· It is renewable (ie. it won't run out).
· It does not take up very much land, and does not spoil the landscape.

Renewables and Baseload

Baseload power is the energy that supports the 24 hour 7 day a week consumption at the bottom of the demand curve. Unfortunately much of the renewable sources of energy (wind and solar) don’t have a 24X7 baseload supply capability. They come and go with the wind and the sun. Back to Geothermal as a source of power… This has the same capability as a coal fired power station. It will continue to supply a constant source of power at the rated capacity of the generation plant. This makes geothermal an important element in the portfolio of renewable generation capacity in any countries fight to reduce GHG emissions. In Australia we have the capacity, innovation and tenacity….. do we now have the political will and support?