Hawaiian Electric Co.’s Hawaii island subsidiary has submitted a new plan to buy locally produced biofuel for electricity generation after a previous proposal was rejected by regulators as being too expensive.

HECO said the price of the biofuel in proposed 20-year contract between Hawaii Electric Light Co. and Aina Koa Pono would be about $125 million less than what was proposed the in the previous contract nixed by the Public Utilities Commission in September 2011.

Aina Koa Pono, which is building a biofuel processing facility in Pahala, would provide HELCO 16 million gallons of biofuel a year that would initially replace petroleum-based fuel burned by the utility at its Keahole Power Plant. An additional eight million gallons a year will be produced for sale to Mansfield Oil Co., an privately-owned fuel distributor.

Aina Koa Pono is investing $450 million to develop a renewable fuel using crops grown on more than 12,000 acres of private land. Company officials said they plan to use a process called microwave catalytic depolymerization to convert organic material into a liquid fuel.