A new economic impact study reinforces the importance of continued federal support for renewable fuels, says Monte Shaw, executive director of the Iowa Renewable Fuels Association. The renewable fuels industry accounted for more than $5.5 billion, or about 4 percent, of Iowa's gross domestic product in 2013, according to a report released today during the association's annual meeting in Altoona. The study estimates that renewable fuels production generated $4 billion in income for Iowa households and supported more than 62,000 jobs.  If the U.S. Environmental Protection Agency moves forward with proposed lower blending requirements in the Renewable Fuels Standard, industry observers predict that 25 to 45 percent of U.S. biodiesel production will shut down, costing thousands of jobs, Shaw said.