I guess I should have looked at the Toro website,
"For the past five years, Toro has conducted extensive equipment testing using bio-fuel and biodiesel blends. With kit modifications and an understanding of a few additional precautions customers can enjoy a more efficient, cleaner technology through biodiesel fuel blends of up to B20.
Biodiesel is an alternative fuel source derived from biological sources that are completely biodegradable and non-toxic. Emissions from bio-fuels and biodiesel blends are lower than petroleum-based diesel fuels making them more environmentally friendly. There are various levels of biodiesel fuels including B2, B5, B10, B20 and B100. For example, biodiesel fuels designated as B20 represent a mixture of 80 percent petroleum and 20 percent bio-fuel. "
Seems like they could run this on biofuels, its not like a tractor trailer.