The first phase is 15MW. Financial details were not disclosed.
Qualibou, a US company based in Henderson, Nevada, has plans to generate an eventual 120MW of power from a geothermal resource located in Sulphur Springs on the island.
"The resource on St Lucia has proven reserves of 30MW and probable reserves of an additional 140MW, says Qualibou chief executive Stephen Baker.
He says production drilling plans are underway and a drilling schedule will be announced in the near future.
Exploratory