HILO » Puna Geothermal Venture celebrated yesterday its 15th anniversary of producing up to 30 megawatts of electricity for the Big Island while also looking forward to doubling that amount in the future.

Negotiations are under way between the geothermal company and Hawaii Electric Light Co., which distributes the power, to increase geothermal output by eight megawatts using heat that is now wasted, said company consultant Barry Mizuno, formerly manager of the company.

PGV has had permits since 2001 to increase power to 60 megawatts from the current 30, Mizuno said.

The company's plant uses steam from water heated underground by Kilauea volcano.

Lt. Gov. James “;Duke”; Aiona told about 200 guests celebrating the anniversary that the addition of 180 megawatts by 2025 is a practical possibility.

Geothermal's current contribution of 30 megawatts is part of the 195 megawatts the island now uses. But the total of power sources is now 270 megawatts, more than the island needs.

A number of factors make it favorable to replace some of that excess with geothermal, officials said.

One factor is that geothermal is “;base power,”; said HELCO President Jay Ignacio. That means that PGV produces power around the clock, while wind and solar are unpredictable from moment to moment.

Geothermal as base power had a drawback 15 years ago. Output could not be reduced or increased with sudden changes in customer demand.

New technology attached to the next eight megawatts will allow quick changes, Mizuno said.

The current way of smoothing out those ups and down is with supplementary oil-fired generators, which are like big locomotive engines that can speed up or slow down on command.

That versatility of oil-powered plants has kept HELCO tied to equipment that is decades old and decaying, and to the tremendous price fluctuations in oil seen recently.

Customers are looking for ways to become independent of HELCO, which is why the company knows buying more geothermal power at a stable price is to its advantage, Ignacio said.

Unlike the old system, which pegged the purchase of power from independent producers to the cost of oil, the price of the next eight megawatts will be “;de-linked”; from oil, Ignacio said.