SANTA ROSA – Not immune to the stagnant economy, ThermaSource is no longer the fastest-growing company in Northern California, but after a tough quarter or two, it's on the move again, said company marketing specialist Patrick Hanson.

The Santa Rosa geothermal drilling company is still a force to be reckoned with, having ballooned from a three-man consulting firm in 2006 into the leading developer of geothermal wells in the world.

Founder and Chief Executive Officer Lou Capuano Jr., a 32-year veteran of the geothermal industry and before that an expert in oil drilling, led the company's rise.

The surge in interest in clean energy worldwide and, in California, a mandate for utilities to expand their clean, renewable energy portfolios have driven the growth of ThermaSource.

But investment in large energy-producing projects has dwindled with the economy. During the second quarter of 2009 ThermaSource was forced to shrink its work force from about 200 to 125 employees. That number has since risen to 180, said Mr. Hanson.

The company sold one of its nine massive drilling rigs but picked up a couple of labor contracts to take up the slack, he said.

"We have rigs at the Geysers, in El Centro and Utah and consulting contracts worldwide."

Equity firms and private investors poured more than $90 million into ThermaSource during 2007 and 2008 and have put in additional funding to support its rebound, he said.

The company supplies an umbrella to two acquisitions and one self-built subsidiary. In 2008, it acquired EGS Inc. of Santa Rosa, whose founder Paul Brophy is an expert in volcanology and geophysics, to aid in the analysis of heat and fluid migration paths, as well as expedite the permitting process, which can be lengthy.

Also in 2008, the company spun off ThermaSource Cementing, a well-lining team that's picked up its own jobs. And Tecton Geologic, a Windsor-based geothermal well logging company was acquired. Tecton provides on-site rig monitoring to the geothermal drilling industry.

Tecton also provides hydrogen sulfide detection and abatement to provide a safe drilling environment. Tecton's networked data acquisition system TopHand is able to measure a wide range of in-hole variables, giving an up-to-date view of the well.

With these capabilities, ThermaSource has built itself into a one-stop shop for countries, utilities and energy companies to develop geothermal resources wherever hot spots near the surface are detected or even just suspected.

Geothermal fields are found where deep rock fissures allow heat from the earth's core to rise toward the surface. Harnessing that energy requires water, superheated and captured in steam.

According to Mr. Capuano, there are potential steam fields in the Philippines, Nicaragua, Chile, Peru, Mexico (Baja), Panama, Iceland and the Caribbean islands.

New ways to inject water into wells are being developed, including a controversial technology that bores deep into the rocky mantle of the earth and causes fractures, releasing heat to a closed system of water pumped into them. A project by Alta Rock of Sausalito to bore fracture wells at The Geysers has been held up for further studies, as it may cause earthquakes.

"We support the Alta Rock project, but we're not the current drilling contractor with The Geysers project," said Mr. Hanson.

For more information, visit www.thermasource.com.