With the closing of Hawaiian Commercial &Sugar Co. and the shutdown of its power-generating facility, Maui Electric Co. is losing an emergency backup power plant.

HC&S has its own power plant and, for decades, has sold the electricity not used on its site to Maui Electric. At its peak the sugar plantation could provide 16 megawatts of power, or about 4 percent of Maui’s need. Over the years HC&S has supplied as much as 10 percent of Maui’s electricity.

This year’s power supply contract with HC&S will end along with the sugar plantation’s operations.

The facility produces a portion of its energy from bagasse, the residual fiber of the sugar cane plant. HC&S also burns coal, diesel, fuel oil and recycled motor oil to generate power when bagasse is not produced in sufficient quantities. HC&S also generates a limited amount of hydroelectric power.

HC&S’s backup power was available to support Maui’s electrical system during emergency situations such as severe storms or hurricanes.

Maui Electric said it expects it will be able to absorb the loss of power generation through energy efficiency and renewable energy sources.

“We are exploring possible options to replace this generation support,” said Kau‘i Awai-Dickson, manager at Maui Electric.

The options include adding more rooftop solar panels, implementing programs to cut use at peak times and the use of emergency generators.

The amount of power the utility was purchasing from HC&S was phasing down before the announcement of the sugar plantation closing, Awai-Dickson said.

“Since October of last year HC&S has not exported any power to Maui Electric,” she said.

Much of the power HC&S sells to the utility is generated by burning coal.

HC&S and Maui Electric would not say what percentage of the power was from coal. Kyle Datta, general partner at the renewable-energy advocate Ulupono Initiative, estimated that HC&S used coal for 55 to 60 percent of its electric power generation.

In the last few years the plant’s use of coal was a problem for HC&S. In June 2014 the state Department of Health fined HC&S $1.3 million for more than 400 alleged violations of clean-air rules. The violations occurred from 2009 to 2013 and had to do with excess emissions.

In a 2014 annual financial report, Alexander &Baldwin Inc., owner of HC&S, said that the company would have to pay up to $2 million to get the necessary equipment to abide by Environmental Protection Agency standards on emissions.

Rick Volner, general manager of HC&S, said, “(Maui Electric) and HC&S mutually agreed to reduce the amount of firm power that HC&S supplied to the grid. Our reasons for the agreement include reducing our fossil fuels footprint by lowering the use of coal and other fossil fuels.”