Ames-based Renewable Energy Group Inc. reported a net loss of $38 million in the first quarter, despite a 27 percent increase in biodiesel gallons sold. The biodiesel and renewable chemicals company initiated a $30 million share buyback plan, and is recovering from a fire at its Geismar plant in Louisiana. Revenues were up 5.4 percent. “Our first-quarter results reflect the challenging market conditions experienced by our industry,” said Daniel Oh, president and chief executive officer. “We currently see that industry conditions are improving and are already taking advantage of better margins as energy prices have improved and feedstock prices continue to adjust. We remain committed to our long-term strategies and are executing on these daily.”