By MARIO PARKER

Over the last four years, the title of world’s top ethanol exporter has changed hands three times: The US took it from Brazil in 2011, lost it back a year later and retook it again in 2014.

The fourth title change -- back over to Brazil -- may be taking place already.

The soaring dollar is making US ethanol more expensive in overseas markets while a tumble in Brazil’s currency, the real, is giving a lift to exporters there. The South Americans are winning sales in the Middle East and Asia, two growing markets. The greenback has jumped as much as 24% against the real in 2015 to a 12-year high, and is currently up 16% at 3.074 reais.

“The dollar and the weakness in the real could wash out some of the exports from America,” said Jordan Fife, a trader at Biourja Trading LLC in Houston. “The Arabian Gulf is the biggest swing” market, he said.

Americans captured the export crown last year as the Brazilians, hobbled by a severe drought that hurt output, saw sales drop by more than 50%. Shipments abroad are key to US producers even though they made up only 5.9% of total sales in 2014 because domestic demand is stagnant.

US ethanol capacity has grown almost threefold in the last decade on the back of a 2005 law championed by then-President George W. Bush to use the fuel as a way to reduce dependence on foreign oil. The Renewable Fuels Standard has required refiners to blend increasing amounts of gasoline with ethanol.

Denatured ethanol for May delivery slipped 0.5 cent to $1.558/gal at 10:33 a.m. New York time on the Chicago Board of Trade.

Brazil, which uses sugarcane to make ethanol, increased exports 16% in January from December, while the US, which uses corn, saw sales decline 9%, according to government data.

Brazilians sent ethanol to the United Arab Emirates, the US’s third-largest market in 2014, and their exports to South Korea were triple the amount of US shipments to that country. Last year, the US exported 847.4 million gallons of the fuel additive, while the Brazilians shipped just 369 million.

Government estimates show the challenge facing US distillers. They’ll produce 14.4 billion gal of ethanol this year and next. Projected gasoline demand will be 139 billion gal in 2015 and 137.9 billion in 2016. That means when ethanol is blended at the 10% ratio to gasoline required by federal law, there will be at least 500 million gal of the additive left over each year.

The only way to avert a glut or to keep plants from shutting is for exports to make up the difference, Ann Duignan, an analyst at JPMorgan Chase & Co., wrote in a March report.

With 867 million gal of ethanol in storage, US inventories are about 29% higher than a year ago.

Now the strength in the dollar is making it harder to reduce the excess supply, said Will Babler, a broker at Atten Babler Risk Management in Galena, Illinois. Meanwhile, Brazil’s economic woes are creating the conditions that will help its ethanol producers ramp up exports.

With Brazilian growth sputtering and a political scandal deepening, the currency is likely to remain weak, making the country’s ethanol competitive for the foreseeable future, said Christoph Berg, managing director at F.O. Licht GmbH, in Ratzeburg, Germany.

Ethanol in Sao Paulo has fallen 19% in dollar terms this year, making it cheaper than in two of four key US regions, data compiled by Bloomberg show. The fuel cost $1.63/gal last week in Sao Paulo, 6 cents cheaper than ethanol on the US West Coast. Brazilian prices in March touched $1.58 a gallon, the lowest since July 2009.

America may still benefit from Brazil’s decision this year to boost the level of ethanol in its gasoline to 27% from 25% because more of it will be needed domestically, said Marcus Ludtke, vice president of Commodity Marketing Co., an Albert Lea, Minnesota-based brokerage.

The impact of the stronger dollar will be “minimal” in the export market because of Brazil’s increased domestic consumption and America’s cheaper cost of production, said Bob Dinneen, president of the Washington-based Renewable Fuels Association, which represents US ethanol-producing companies.

US ethanol export data for February and March aren’t yet available from the Energy Department. Brazilian figures show its shipments for February and March were 9% and 43% higher than a year ago, respectively.

Brazil may be poised to snatch the export lead back, said Jim Damask, a trader at StarFuels in Jupiter, Florida.

“Some of these guys in Brazil may be picking up the phone and saying, ‘Hey, we have some stuff sitting around, what price would you want to take it?’,” Damask said.