Commodity merchants and investment firms such as Citadel, Gunvor (GGL.UL) and Trafigura (TRAFGF.UL) are bolstering U.S. teams that specialize in trading renewable fuels as demand soars, according to people familiar with the matter.

Many trading firms already have an established presence in Europe, but the production of advanced biofuels that act as petroleum fuel substitutes has driven hiring in the United States in recent months, the sources said. Renewable fuels account for roughly 12% of U.S. energy consumption, according to government data, and are growing every year.

In April, hedge fund Citadel made its first entry in the U.S. renewable fuels trading space, a source close to the firm said. The firm brought in Jay McCall as head of North America Environmental Products Trading based in San Francisco, according to source familiar with the matter and his LinkedIn page. McCall previously was director of environmental commodities trading at DTE Energy Trading (DTE.N).

In the same month, commodities trader Gunvor hired Shane Foster to its renewable energy division based in New York, according to his LinkedIn profile.