Oahu households can expect to see a decline in their April electrical bills due largely to the resumption of production at a coal-fired plant that provides the island’s lowest-cost source of power, Hawaiian Electric Co. reported Friday.

The bill for a household using 600 kilowatt-hours of electricity a month will fall to $203.11 in April, a $15.64 decline from March, according to HECO. The rate per kilowatt-hour will drop to 32.4 cents from 34.9 cents.

Electricity prices on Oahu rose in February and March as the owner of the state’s only coal-fired power plant shut it down for scheduled maintenance. The 180-megawatt plant operated by independent power producer AES Corp. has the capacity to provide about 15 percent of the island’s peak electricity demand.

HECO pays AES about 9 cents a kilowatt-hour compared with the 22 cents a kilowatt-hour it costs to generate power at the oil-burning plants that provide nearly 80 percent of HECO’s electrical output, according to the utility. The AES plant, which went online in 1992, burns coal imported from Indonesia.

Although coal is by far HECO’s cheapest source of energy, concerns about greenhouse gas emissions prompted state officials as part of the Hawai‘i Clean Energy Initiative approved in 2008 to prohibit the construction of any new coal-fired generating plants in the state.

Jim Arcate, a Manoa resident who installed solar photovoltaic panels on his roof three years ago to cut his power bill, said he doesn’t believe adding more coal to the state’s energy mix is the answer to Hawaii’s high electrical rates.

"I don’t think we need more coal in Hawaii. I would prefer to see HECO use more LNG (liquefied natural gas)," said Arcate, a semiretired owner of a renewable-energy consulting company.

Arcate said his 2,250-watt rooftop PV system has nearly paid for itself as a result of the savings on his electricity bill.

"A lot of what motivated me was my green attitude. We started with solar water and then moved on to PV," he said. "Its just so cost-effective to have solar in Hawaii, even in the back of Manoa Valley where I live.

"But solar and wind aren’t going to be enough to meet our energy demands. That’s why LNG is a good option. It’s good for power production, but you can also use it for transportation," Arcate said, noting that some cities use compressed natural gas to power buses.

Hawai‘i Gas, the state’s sole natural-gas utility, last month began shipping in small quantities of LNG in specialized shipping containers to supplement the supply of synthetic natural gas it manufactures from petroleum-based naphtha. Hawai‘i Gas officials said they plan to eventually bring in larger quantities of LNG that could be used to generate electricity at a lower cost than the low-sulfur fuel oil currently burned by HECO.

Elsewhere in the state, electrical rates also will fall on Kauai this month but will rise on Hawaii island and in Maui County.

Maui Electric Co. customers will see their rate rise to 37.2 cents per kilowatt-hour this month from 37 cents in February. The typical Maui bill will go up $1.44, to $232.16.

Hawaii island’s residential rate will rise to 39.9 cents a kilowatt-hour from last month’s 39.7 cents. The typical bill will go up to $249.63 from $248.59.

The rate on Kauai will fall to 42.4 cents a kilowatt-hour from 44.8 cents.

Hawaii has the highest electrical rates in the nation. The statewide average of 37.9 cents a kilowatt-hour in January was more than triple the national average of 11.5 cents a kilowatt-hour, according to the most recent numbers available from the U.S. Energy Information Administration. North Dakota, which had the nation’s cheapest electricity at 7.7 cents a kilowatt-hour in January, generates 82 percent of its electricity from coal.