PU'UNENE, Maui — Hawaiian Commercial and Sugar Co. may build a plant to make ethanol and allow it to meet demand created by a state law mandating an ethanol blend for automobile fuel.

But several obstacles could prevent speedy construction.

The Maui-based company that produces 60 percent of the state's sugar would be able to supply about two-thirds of Maui's ethanol if it built a plant that would change molasses into ethyl alcohol.

The company would need to convert 65,000 to 70,000 tons of molasses to 5 million gallons of ethanol each year to meet that level of demand, said Steve Holaday, the company's general manager.

The sugar company could reap $15 million a year for processed ethanol instead of just $5 million a year for unprocessed molasses if the plant were built.

Hawaiian Commercial and Sugar, part of Alexander & Baldwin Inc., has not yet made a firm decision to build the plant. Construction would likely require an investment of several million dollars.

"The biggest unknown," said Holaday, is the putrid byproduct created when yeast digests molasses sugar and makes alcohol.

In Brazil, ethanol makers spread the substance on fields, said Lee Jakeway, the company's director of energy development and planning. But he doubts Americans would tolerate the smell so the plantation would need to build complex machinery to distill it.

Another potential obstacle is the likely need for the company to recruit some staff from off-island to run the plant.

Ethanol supervisors need microbiology or chemical engineering expertise. Holaday said he doubts people with such skills are available on Maui.

A molasses-to-ethanol plant would employ about 18 to 20 employees.

Hawaiian Commercial currently exports most of its molasses, a byproduct of refining sugar cane.

It also sells small amounts of molasses to local ranchers as feed supplements and even smaller amounts to Haleakala Distillers as a rum ingredient.

Holaday said the plantation would continue to sell to these customers even if it diverted most of its molasses to ethanol.

A state law went into effect April 2 requiring that 85 percent of gasoline contain at least 10 percent ethanol.

Many local producers are at least months away from being able to make ethanol, however, so oil companies are importing ethanol from elsewhere to obey the law.

In addition to sugar cane, ethanol can be made from corn, barley, wheat and such materials as waste paper and yard and wood waste.