Australia Pushes Geothermal Energy

_martini_ writes writes to tell us Reuters is reporting that several Australian firms are experimenting with taking geothermal energy mainstream. Geodynamics Ltd. will be making an investment decision on their first geothermal power station in early 2006. From the article: "Mother Nature has been kind to us. Australia could be the world leader within the next couple of years given the geological anomalies present in South Australia," says Peter Reid, chief executive of another explorer, Petratherm Ltd."

Comments

Re:Isn't This Dangerous

[HotNeedleOfInquiry]

No. It's not dangerous and it's not new technology. I know firsthand that it is used in California and the Sierra Madres of Mexico. Most of the homes in Klameth Falls, Oregon are heated via geothermal energy. I'm sure it's used in a lot of other places, so I'm a little surprised this is even news. I've not heard of any sort of accident or danger, other than the possible release of poisionous hydrogen sulfide gas, and that only during the exploration stage.

There are issues, but nothin insurmountable.

Re:Isn't This Dangerous

[palndrumm]

Will it effect the ground in any way?

Not really, no. We're talking about big solid lumps of granite, which at the sort of temperatures they're at to start with won't undergo any significant thermal contraction even if cooled to atmospheric temperature. Plus we're only able to extract a relatively small proportion of the overall amount of heat in these deposits, so the overall temperature of the rock won't change a whole lot.

Re:Geothermal Is Expensive

[ian_mackereth]

This is quite different to most geothermal installations, though. Most of them utilise vulcanism, with all the attendant sulfur and such to cause the corrosion and scaling. This scheme is in granite that contains low-level radioactivity and should be relatively clean to pump water through. The basic idea is to force water/steam into one hole to open up some fissures, then pump water through those fissures to generate steam that goes up an outlet pipe to drive a turbine. The water's reclaimed and re-pumped down the feed bore.

Environmental impact should be minimal, and there's hardly any ecosystem there to affect anyway. This region was chosen for the Woomera rocket range for exactly this reason. Australia's about 90% of the area of the continental USA, and much of it looks exactly like this area; arid or semi-arid rocky plains.

There's a transcript of an article with quite some depth (ahem.) here. http://www.abc.net.au/rn/science/ockham/stories/s1 440622.htm

Re:Here on the Ring of Fire...

[nathanh]

I'm sure we can lend them some expertise -- NZ's first geothermal plant was commissioned in the '50s... (apparently, we get 18% of our primary energy from geothermal sources)

NZ has a different area of expertise. NZ has naturally occuring hot water springs. Tapping those is relatively easy. That's why NZ has had geothermal energy for so long. Iceland was in a similar fortunate position and they also have geothermal.

Australia is drier than Oscar Wilde's wit. There are no naturally occuring hot water springs. The technology being researched in Australia is Hot Dry Rock. The rocks are dry and you pump fluids down into the rocks. The water is forced through naturally occuring horizontal fissures in the rocks and collected by a second bore. This only works when there are insulating rocks above, below and around the fissures. Otherwise the fluid disperses and you never collect back enough water to make the system economical.

When it does work it's brilliant. The system powers itself and the only significant issue is dealing with scale buildup on the pipes. The energy output is enormous and the capital investment is modest. A single plant can power a small city with almost no pollution and no (as yet known) environmental impact.

Re:Geothermal Is Expensive

[Timbotronic]

There needs to be a distinction drawn between regular geothermal power from volcanic areas (such as Iceland, NZ, Yellowstone etc) and hot dry rock geothermal power which is what Geodynamics are pursuing.

HDR Geothermal works by passing water through hot, fractured granite. The granite is hot because of the radioactive decay of trace elements in the granite (too low in concentration for any radioactive waste concerns). A thick layer of sediment above the granite effectively creates a heat blanket, allowing the temperature to build to 200-300 hundred degrees C - ideal for heating water without building up extreme pressure.

I'm not a geologist, but I imagine that problems with pipe scaling would be much lower for HDR geothermal than in regular geothermal power, where you've got a lot of salts, sulphur and all sorts of muddy crap bubbling through. The water in HDR geothermal is kept in a closed loop so there's no waste to dispose of. The heat is extracted via a heat exchanger which boils a more volatile fluid such as ammonia and this fluid is used for the power generation. So you've got no impurities going through your generation facility.

Geodynamics say they have enough heat to power Australia at current levels of consumption for 70 years. Unlike solar or wind, the power is constant and can be ramped up or down at will. I'm surprised this has been off everyone's radar for so long.

Re:I'm a geothermal geek

[Anthony]

I am studying at the ANU dept of Earth and Marine Sciences that is doing a lot of the research in this. This is not hydrothermal. You are right, there are no active margins and no active hotspots. This is using 3-4km deep drill holes, injecting plentiful artesian water down, fracturing the rock at depth and the heated water returning. The anomaly is a large intrusion that is near enough to the surface to make the project feasible. Sorry I haven't the paper at hand. Look at Geodynamics or look for papers by Prame Chopra. The "limited life" they are projecting is 300 years.