Hot Rock Ltd closed its initial public share offering last week and aims to list on the Australian Securities Exchange later this month under the code HRL.

The public issue of 16 million shares at 25c each was oversubscribed. It adds to 45.2 million shares on issue before the IPO and was accompanied by 3 million options. The shares are expected to be listed on the ASX later this month

Confusingly, Hot Rock Limited is not what is generally referred to as a 'hot rocks' company.

It is not exploring for hot dry rocks and planning to develop and engineered reservoir; rather, the company is aiming at conventional, wet rock, geothermal targets.

Hot Rock's four tenements cover 18,294 square kilometres of the Victorian sector of the Otway Basin.

Previous drilling in the Otway Basin to depths of up to 3500m has recorded temperatures of up to 143C, according to managing director Dr Mark Elliott.

"Temperature of more than 120 degrees is commercially viable, depending on productiveness and depth of well and production pumping requirements," he said.

According to Elliott, 24 countries generate power from geothermal resources but the future potential is enormous, as it is estimated only some 10% of the global reserve of geothermal energy has yet been developed.

"We are now compiling and re-interpreting the extensive geological and geophysical data that exists on our areas, and we plan magneto-telluric geophysical soundings, traditional seismic, aeromagnetic and gravity surveys to help identify and define drilling targets," he said.

Unlike many Australian geothermal operators, Hot Rock Limited's acreage is close to power markets and the resource can be easily developed, Elliott said.

"Our tenements, surrounding the centres of Portland, Hamilton Warrnambool and Colac, are close to transmission lines, population centres, infrastructure and industry," he said.

"Hot wet rock resources can be developed at lower cost than hot dry rock, as they contain reservoir water, are naturally permeable, and are exploitable at shallower drilling depths."

Dr Elliott and non-executive chairman, Norm Zillman, have considerable experience in energy exploration and development.

The company is supported by Sinclair Knight Merz and two geothermal experts, Professor Jim Cull AM (PhD) and Dr Kerry Burns BSc (Hons) PhD.

Greenearth Energy

Meanwhile, Greenearth Energy - an affiliate of Lakes Oil and Victoria Petroleum - on Friday lodged a prospectus to raise up to $15 million in an initial public offering.

Lakes and VicPet shareholders will receive priority for $8 million of these shares.

Greenearth Energy holds three geothermal exploration permits in Victoria, based on heat data encountered by Lakes in the region.

Two of its permits cover the Latrobe Valley/Gippsland region, with the third covering the western part of Melbourne and Geelong.

Since that time, $1.8 million has been spent gathering heat information, including data from several of Lakes' existing wells and the recently-drilled Hazelwood-1 and Boola Boola-2 wells.

Most recently, Greenearth signed a memorandum of understanding with the Royal Melbourne Institute of Technology to develop new technologies for exploiting geothermal resources.