Aina Koa Pono has hired a global engineering con­sultant to help develop a $350 million biofuel plant on Hawaii island.

Aecom Technology Corp. will provide engineering, procurement and construction management for the Kau project, which will convert invasive plants and other feedstocks into liquid fuel that can be used in a range of applications, including power plants and automobiles, AKP said Tuesday in a news release.

The Honolulu-based biodiesel supplier’s main customer will be Hawaiian Electric Co., which has signed an agreement to buy 16,000 gallons of biodiesel a year to burn in the Keahole power plant operated by its subsidiary, Hawaii Electric Light Co. HECO said biofuel would replace 100 percent of the petroleum-based diesel currently burned annually at the plant.

Aecom is based in Los Angeles and has two offices in Honolulu and one in Hilo.

When AKP unveiled the project in January, HECO said the biodiesel would cost more than petroleum-based diesel. At the time, HECO estimated that it would add from $1.55 to $1.86 a month to electricity bills if the premium were spread across ratepayers in Hawaii County, Maui County and Honolulu County.

The state Public Utilities Commission, however, rejected the cost-sharing mechanism, saying it would be unfair to charge utility customers whose electricity was not being generated using the biodiesel.

The PUC’s ruling prompted the Legislature to approve a bill signed by Gov. Neil Abercrombie that allows HECO to divide the renewable energy premium among ratepayers in the three counties even if the biofuel is only being used in Hawaii County.