The fear is that such a big commitment to biodiesel would come at the expense of developing the next generation of the fuels that would be even cleaner.
Representative All Juhnke of Willmar says the biodiesel mandate would give a boost to the state's Soybean farmers, as did a similar rule for the use of corn-based ethanol.
Heavy trucks in Minnesota now burn a blend that contains 2 percent biodiesel. His bill would raise that to 20 percent by 2015, with some seasonal exceptions.
Alternative fuels experts point to research indicating that algae growing in waste water plants could be one of those cleaner, next-generation fuels.
The Senate is scheduled to vote on the biodiesel bill on Thursday. The bill includes $500,000 for the research into algae as fuel.