The Environmental Protection Agency (EPA) supports a significant expansion of renewable fuels including corn ethanol and soy biodiesel. Corn ethanol is the most-popular renewable motor vehicle fuel in the United States; soy biodiesel is the second.

The EPA’s National Renewable Fuel Standard (RFS) program is designed to significantly increase the volume of renewable fuels in both highway and non-road gasoline and diesel vehicles.
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(The success of the biodiesel fuel industry relies heavily on biodiesel testing <http://www.youtube.com/watch?v=s32Ke2VzrqU>, not only at the production level but at the consumer level, where degraded fuel may cause engine failures.  Of major concern to diesel and biodiesel users is the very real possibility that water has contaminated their fuel. (See http://www.youtube.com/watch?v=0YcczdvPyAk).  The potential catastrophic impact of this problem is discussed at length  in this video at: http://www.youtube.com/watch?v=-lh4qhXc_5s&feature=youtube_gdata.
Fleet Fuel's  family of inexpensive biodiesel test kits  is just a click away on the internet at:
<http://fleetbiodiesel.com/biodiesel_testing_and_supplies.html>)