NEW YORK -- High oil prices, worries over global warming and a resistance to outside investors are straining multinational companies' efforts to find ways into Brazil's booming market for biofuels.

The United States and other countries hope to substitute as much as 15 percent of domestic gasoline for ethanol over the next decade. With ample land, low production costs and ethanol-production experience, Brazil is viewed by many as the country best able to sate world demand, The Wall Street Journal reports.

A slew of potential investors have descended on the country but family-owned companies that largely control the ethanol industry are asking for sky-high prices for their businesses. Resistance to outsiders could affect how quickly larger amounts of cheap Brazilian ethanol can begin flowing into the world's auto fleet as bigger companies with access to credit and capital could help consolidate, modernize and expand Brazil's ethanol industry.

Many family-owned mills are in trouble. Brazil's domestic ethanol and sugar industry is informally regulated and highly fragmented, "making it less than ideal for outside investment," according to the newspaper.

Despite the hurdles, foreign biofuels companies like Archer Daniels Midland (ADM) believe that getting into Brazil is still a must. U.S. corn ethanol has been competitive with gasoline due to a 51-cent tax credit on each gallon. And both ADM and competitor Cargill Inc. faced narrowing profit margins in their U.S. ethanol operations last year.

Brazil has been using ethanol since the 1970s, when the government decided to support the fuel as a way to limit the country's reliance on Middle East oil.

Ethanol wins followers because it contributes less to global warming than gasoline. But the lengthy process of creating ethanol "green fields," sometimes up to six years, before the ethanol is fully flowing make the projects unattractive to investors.

ADM's chief strategist, Steve Mills, said his company needs to capture knowledge for growing and processing the sugar-cane ethanol in Brazil. "The one thing we do know is that we're going to have to acquire some expertise in the area," he said.