Petratherm hits the lists with a market capitalisation of $7.1 million and 35.6 million ordinary 20 cent shares on issue with an application pending for a $4 million Commonwealth R&D Start Grant.

"The Petratherm IPO offer period has coincided with surging investor interest in geothermal exploration for future energy needs, which now enables us to accelerate exploration work on our three South Australian projects," said Petratherm's chief executive officer Peter Reid.

"The immediate program involves a series of shallow depth wells to around 600-750m on which work will commence as soon as the company lists.

"These wells - by testing temperatures, stress environment and fracturing characteristics - will determine the ability of the various prospects to sustain economic geothermal energy through heat exchange."

Petratherm is the first company in the world to adopt an exploration model designed specifically to optimise the identification of the hottest rocks as near to the surface as possible.

The unique technology, developed in partnership with the University of Adelaide, allows economic evaluation of Hot Rock deposits without the need for deeper, more expensive drilling, and with a focus on exploring areas closer to commercial markets.

Petratherm plans to initially employ the technique over the next year to discover an economic geothermal hot rock source as part of a longer-term five-stage development program.

Successful assessment of hot rock depth limits will be followed by a series of test wells, evaluation of thermal reservoirs, the completion of injection and production holes, the establishment of a heat exchange system and a final additional drilling program on a grid spacing to establish a commercial power plant.

"Our aim is to establish large-scale, commercially sustainable, emission-free, renewable energy for power generation by identifying and developing hot geothermal source rocks at temperatures in excess of 220°C but no deeper than 3.5km," Reid said.

The company would then seek suitable partners to develop a base-load commercial power station supplying the national grid and remote mining operations such as Olympic Dam.

Petratherm's three Hot Rock energy projects are spread over 1500sq.km of northern South Australia at Ferguson Hill north of Olympic Dam, and Callabonna and Paralana near Mount Painter.

The tenements are thought to contain hot rocks at depths of between three and 3.5km, and at temperatures 8-25 times the heat of most granites, making it one of the most thermally active hot rock zones in the world.