Magma Power Co., which earlier this year...

Magma Power Co., which earlier this year moved its accounting staff to Rancho Bernardo, will relocate the rest of its headquarters staff here during coming months, the company said Monday. About 15 of Magma’s 100 employees eventually will work in Rancho Bernardo.

Magma, which develops geothermal resources used to generate electricity, operates a geothermal plant near Niland that produces 34 megawatts of electric power that is sold to Southern California Edison. The company has begun construction on two more geothermal-powered electric plants near Niland and plans to build at least another at that site.

Magma plans to build four more geothermal plants at other locations in the Imperial Valley.

Last year, Magma acquired San Diego Gas & Electric’s Imperial Valley geothermal leaseholds in a deal that, depending upon how productive those holdings are, could be worth as much as $30 million. State regulators--who several years ago pushed SDG&E; to acquire the leases--last year ordered the utility to sell its leaseholds.

Magma is a publicly traded company. The over-the-counter stock that began trading five years ago at $3 per share recently has traded at $15.

During a special board meeting Friday, former Dow Chemical U.S.A. President Arnold L. Johnson was elected president and chief executive. Dow recently exercised two stock options that boosted the Midland., Mich.-based company’s interest in Magma to 38% from 26%. Dow also agreed to provide Magma with $40 million in cash and engineering services and to provide Magma with a $22-million letter of credit.