Even "greenies" frac

FRACCINGis not confined to the oil and gas industries – it is also essential for geothermal energy drawn from hot rocks deep below the surface. In South Australia both Petrotherm and Geodynamics have already used the technique.

Hot rock geothermal essentially involves drilling two deep holes into the hot rock and fraccing the rock at the bottom of the wells so that water pumped down one well will flow through the cracks and up another well to where the heated water is used to generate electricity.

Petratherm is working at Paralana, east of the northern Flinders Ranges in South Australia’s outback. Its initial fraccing, in July 2011, created a “cloud” of fissures that stretched for more than a kilometre.

PTR fracc 1

Petratherm’s CEO, Terry Kallis, says the fraccing had been carefully monitored and there had been no ill effects.

“We are four kilometres down, several casing strings away from the aquifers, which are about 400 metres down,” he said.

The seismic array set up to monitor the 2011 fracc was still in place at Paralana. The largest tremor it had recorded was 2.7 on the Richter scale, “well below anything you can actually feel”.

“Fraccing is something that has been done as long as oil and gas has been in the game, it’s been done for several decades,” he said.

“As long as you are away from connections with aquifers it is a non issue. If you are away from built-up areas it is even better.”

At Paralana “we have steel and cement casing all the way through. We don’t actually connect with the rock until we are below 3,700 metres.”

He said the $13 mln grant was “a massive boost for the entire project and an important vote of confidence by the government in Petratherm’s capabilities and the geothermal energy sector in general”.

SA Greens leader Mark Parnell accepts that "Fracking for Geothermal energy does not represent the same risks to groundwater, farmland or the climate as fraccing for hydrocarbons. "

He has recently amended his Bill, which calls for a permanent ban on fraccing on farmland and near populated areas and a two-year moratorium everywhere else, to exclude geothermal.

He also accepts that "you could still have some adverse impacts in relation to geothermal and also that even without the presence of hydrocarbons, you still have the fracking chemicals to deal with, plus impacts on pressure and watertable levels".

His primary concern, however, was with the impact of gas on soil and groundwater, as well as the fugitive emissions (mainly leaking methane), which "when factored in can make gas as dirty as coal in terms of climate change".

A vote on Parnell's Bill in Parliament is expected later this month or in November.

The author owns Petratherm shares.

Article amended 30 September 2013

Adelaide Independent Reporter 2013