ST. PAUL, MN --- Freezing temperatures in Minnesota have led government leaders to stop enforcing the 5-percent biodiesel requirement that's part of the state's anti-global warming initiative. 

According to a report from Today's Trucking, the state is temporarily lifting the ULSD No. 1 requirement until April. The more common ULSD No. 2, which blends biodiesel with regular diesel and kerosene, is not affected. 

"The biodiesel and petroleum industries have been monitoring reports of very rare instances of filter clogging of storage tanks containing 5-percent biodiesel and pure kerosene (ULSD No. 1)," the Minnesota Biodiesel Council said. "These rare reports in Minnesota are occurring in extremely cold temperatures and only in tank dispensing filters with certain types of kerosene and some types of biodiesel." 

The Minnesota Department of Commerce opted to temporarily suspend the ULSD No. 1 rule after requests from the Minnesota Biodiesel Council and the Minnesota Petroleum Marketers Association. 

Extremely cold temperatures can cause the gelling of biodiesel, which can result in clogged filters. Older truck engines are especially susceptible to such clogging.