LIHUE — Methane gas generated by the decay of organic matter in the Kekaha landfill could one day be used to power Kauai County’s public bus fleet.
The plan is part of a long-range strategy to reduce the island’s dependence on fossil fuels and move toward a more sustainable system.
The first step is to build a biogas collection system, which the county is already planning to do to meet federal Environmental Protection Agency guidelines. The county has allocated $5 million for that purpose in the Capital Improvement Projects budget for the 2016 fiscal year that begins on July 1.
According to Energy and Sustainability Manager Ben Sullivan, construction of the biogas collection system is scheduled to be completed by December of next year. At first, captured methane will be flared off in order to prevent the release of greenhouse gases into the atmosphere. Then, tests will be done to see if the quality and quantity of gas generated by the landfill is sufficient to move forward with the next phase of the plan.
“If after six months it looks good, then we can proceed to refining the gas,” Sullivan said.
The county would need to build a system to remove impurities and refine the captured methane into Compressed Natural Gas (CNG) that could then be used to power vehicles.
Conservative estimates based on models predict the county could capture and convert enough biogas to replace up to 1,000 gallons of diesel fuel per day, which is approximately double the amount currently used by the vehicle fleet.
Councilwoman JoAnn Yukimura supports the concept, but noted it is not clear whether the system will be feasible.
“The fossil fuel basis of the Kauai Bus is both a weakness and threat that we must address if we want our bus system to be sustainable into the future,” Yukimura said. “The methane gas at the landfill presents a possibility and opportunity of a renewable fuel for the Kauai Bus – for how long and how reliable have not been answered.”
No timetable has been set for when such a system could come online, nor are there any plans in place to purchase new buses that are capable of using CNG fuel.
The county recently purchased 20 new buses that will be used to replace older vehicles in the aging Kauai Bus fleet of 56 vehicles.
The expected lifespan of those buses is about 150,000 miles, which means it could be at least five to seven years until those buses are taken out of service and replaced with new ones that run on CNG.