Higher fuel prices continued to push up Hawaii’s electricity prices in August, with rates paid by residential customers on Oahu reaching their highest level in nearly two years.

The typical Hawaiian Electric Co. residential customer on Oahu using 600 kilowatt-hours per month will pay $160.41, up from $157.99 in July, HECO said. That’s the highest since November 2008, when the typical bill was $182.01, according to HECO.

The rate per kilowatt-hour on Oahu rose to 25.2 cents in August from 24.8 cents in July.

Residential bills also rose on the neighbor islands, with the typical Big Island customer paying the most at $215.03, or 34 cents per kilowatt-hour, up from $209.45 last month.

Crude oil prices, while fluctuating from month to month, have been on an upward trend during the past year. The benchmark contract on the New York Mercantile Exchange closed at $75.39 yesterday, up 7 percent from $70.52 in August 2009.

"Fortunately, the price of oil is well below the $147-a-barrel high of late summer 2008. But it is still high," said HECO spokesman Peter Rosegg. In September 2008 the electricity rate for Oahu was 32.5 cents per kilowatt-hour.

In addition to rising fuel prices, HECO’s Oahu customers have experienced two interim rate hikes since 2008, the first in August 2009 and the second in February.

Rosegg said HECO is asking its customers and those at its sister utilities on Maui and the Big Island to take steps to curb their electricity use, including setting their air conditioners a few degrees warmer and replacing incandescent bulbs with compact fluorescents.

Electricity prices in Hawaii, which are the highest in the country, are particularly sensitive to oil prices because petroleum-fired power plants supply more than three-fourths of the state’s electricity, according to the U.S. Energy Information Administration.

Increases in fuel oil costs are passed on to HECO consumers in something that’s called the Energy Cost Adjustment clause on its bills.

Rate increases varied on the neighbor islands, with Maui residents feeling the effect of an interim rate increase that went into effect Aug. 1.

The typical Maui household using 600 kilowatt-hours will pay $183.32, or $2.73 more than July. The effective rate rose to 29.1 cents per kilowatt-hour.

Residential utility customers on Kauai, who are customers of the Kauai Island Utility Cooperative, will be charged an effective rate of 44 cents per kilowatt-hour, up fractionally from 33.9 cents in July.