The Canadian Renewable Fuels Association said five more plants would create hundreds of jobs, add hundreds of millions of dollars to the rural economy and produce cheaper, cleaner gas.
"We don't have large oilfields like Alberta but we can certainly produce renewable fuels here in Ontario," said executive director Kory Teneycke.
"It's the way of the future."
The Canadian Taxpayers Federation, however, predicted the cost of blended gas would go up by as much as a cent per litre.
Spokeswoman Tasha Kheiriddin called the province's plan an attempt to curry favour with the agricultural sector and derided the governing Liberals for providing businesses with a government subsidy.
"You should source that ethanol in the cheapest way possible," Kheiriddin said. "If it is cheaper to import it, then it should be imported and producers here should be more competitive to produce it at a lower cost."