Hawaii Electric Light Co. today told the state Public Utilities Commission it is ready to consider proposals for expanded geothermal development on the Big Island.

With the filing, the utility is seeking PUC approval of its proposal to add up to 50 megawatts of geothermal power to its Big Island grid.

It currently has contracts with Puna Geothermal Venture for 38 megawatts produced at PGV’s plant in Pohoiki in lower Puna.

The RFP filed today seeks geothermal energy that has both firm capacity and “dispatchable” electricity which HELCO could use as needed on its grid.

“This project combines our efforts to increase renewable resources on our island with a commitment to reduce costs for our customers,” Jay Ignacio, Hawaii Electric Light Company president, said in a statement. “We look forward to working with developers while ensuring our communities have a voice in energy planning for our island.”

HELCO’s filing of a “Request for Proposals” with the PUC comes 18 months after the Big Island utility formally requested information on expanding geothermal from developers, landowners and other interested parties.

HELCO received 20 responses to that “Request for Information” issued in June 2011.

According to HELCO, more than 40% of the Big Island’s electricity already comes from renewable resources including hydroelectric, wind, geothermal. Those resources also include a small thermal solar generating farm in Kona.

According to Curtis Beck, HELCO’s manager of energy services, if the power provided by residential rooftop photovoltaic net metering systems is factored in, the percentage increases to near 50%.

The request for proposals filed today is a draft document, HELCO said, and a final version of the geothermal RFP is expected to be issued in January. The utility said it would conduct a technical conference “webinar” to provide additional information to prospective bidders.

It is anticipated that PGV will be among those seeking to take part in the RFP.

The filing comes on the same day the Hawaii County Council is considering a bill that would ban nighttime drilling for geothermal wells.

A variety of geothermal consultants and organizations have provided testimony to the council saying that such a prohibition could have a chilling effect on the future of geothermal development on the Big Island.

They say the nighttime ban would dramatically increase drilling time and cost, and could compromise safety for both the plant operator and community.

It was not yet clear what impact such a ban would have on PGV, as that company has already obtained approvals needed to expand its production to 60 megawatts.