Rising fuel oil prices pushed residential electricity rates higher in April on all islands except for Hawaii island.

Hawaiian Electric Co. said a typical 600-kilowatt-hour bill for Oahu residential customers rose by 51 cents to $204.25 in April. The effective rate for electricity in Hono­lulu is 32.6 cents per kilowatt-hour, little changed from March.

On Maui, electric utility customers saw rates rise to 36.5 cents per kilowatt-hour this month from March’s 36.3 cents. The typical Maui bill rose by $1.30 to $226.76.

The residential rate on Kauai rose to 45.8 cents per kilowatt-hour in April, up from 42.6 cents charged by the Kauai Island Utility Cooperative last month.

On Hawaii island the typical bill fell by $6.28 to $252.91 as a ruling by the state Public Utilities Commission reduced the amount Hawaii Electric Light Co. had been allowed to collect under an interim rate hike. The rate per kilowatt-hour fell to 40.4 cents in April from 41.3 cents in March.

Hawaii consistently has the highest electricity costs in the nation, largely because of its dependence on expensive fuel oil for power generation.

Low-sulfur fuel oil, HECO’s primary source of power generation, cost the utility $138.78 a barrel in April, up from $109.38 the same month a year ago. Prices for LSFO began climbing sharply in the Pacific Basin last spring due to high demand from utilities in Japan. The country turned to oil-fired power plants to replace the generating capacity lost when it shut down many of its nuclear reactors following the devastating earthquake and tsunami there in March 2011.

Hawaii’s average statewide electricity rate was 36.25 a kilowatt-hour in January, more than three times the national average of 11.43 cents per kilowatt-hour, according to the U.S. Energy Information Administration.