Maui County is advancing plans to build a biogas facility to help power its wastewater treatment facility on the northern shore of Kahului.

On Friday the Maui County Department of Environmental Management opened up a 30-day public comment period and filed an environmental impact statement for a renewable energy conversion and sludge processing facility with the state. The project, which would capture methane produced by local crops to power the Wailuku-­Kahului Wastewater Reclamation Facility and dry sewage, is expected to be built before the end of 2019.

The county selected Anaergia Services LLC — which does business as Maui All Natural Alternative LLC — to design, build, own, operate and maintain a renewable energy and sludge drying project. Maui County chose the company after issuing a request for proposals in 2016 to build a project that would help reduce the amount of fossil fuel the wastewater treatment plant uses for its energy as well as reduce its electric bill.

According to the EIS, Maui County “expressed a long-term clean energy and electric grid independence strategy in moving toward the ultimate goal of utilizing 100 percent renewable energy. One step is to provide firm renewable power to meet the needs of the (Wailuku-Kahului Wastewater Reclamation Facility).”

If the EIS is approved, Maui All Natural Alternative will install an anaerobic digester — where solid waste is broken down by microorganisms and turned into the biogas — on the site of the wastewater treatment facility to process crops grown on former Hawaiian Commercial & Sugar Co. plantation lands. The crops used would be provided by Central Maui Feedstocks, a company created by the owner of the now closed sugar plantation, Alexander & Baldwin Inc.

The product of the anaerobic digestion process is renewable methane. The methane is then used to fuel a combined heat and power engine for electrical power generation. The EIS said the waste heat of the methane combined with other biogas will provide the required heat to dry the sludge produced on Maui. The EIS said the dried sludge will then become “Grade A” fertilizer that the county could sell.

The EIS said one alternative to building the biogas facility would be a solar and battery facility that is capable of providing roughly 1,800 kilowatts of combined energy and heat. The EIS said the land required for a facility of that size would be challenging to build because it would be near Kahului Airport and the Kahana Pond Wildlife Sanctuary.

Residents can send traditional mail or email to Maui County and Maui All Natural Alternative to comment on the project:

>> Maui County Department of Environmental Management, Director Stewart Stant, 2050 Main St. Suite 2-B, Wailuku 96793. Stant’s email is stewart.stant@co.maui.hi.us.

>> Maui All Natural Alternative, Jeff Walsh, 5780 Fleet St. Suite 310, Carlsbad, CA 92008. Walsh’s email is jeff.walsh@anaergia.com.

Public comments about the biogas facility are due by July 24.