US EPA mulls inclusion of sorghum oil in RFS

The US Environmental Protection Agency has proposed that sorghum, a fast growing, high-calorific crop, be mandated for use under the country’s Renewable Fuel Standard, in a move that could displace other biofuels.

The sorghum-producing lobby in the US said a mandate, if approved, would mean higher revenue for ethanol producers using sorghum and that producers could pass a portion of this premium along to sorghum growers.

In a statement published on 27 December, the EPA said its evaluation of the GHG emissions “indicates that producing biofuels from distillers sorghum oil results in no significant upstream agricultural GHG emissions due to the extraction of oil from sorghum at dry mill ethanol plants.”

It added that based on these results, biodiesel, renewable diesel, jet fuel, heating oil, naphtha and liquified petroleum gas (LPG) produced from distillers sorghum oil via a transesterification or hydrotreating process would meet the lifecycle GHG emissions reduction threshold of 50% compared with the baseline petroleum fuel they would replace.

This threshold is required for advanced biofuels and biomass-based diesel under the Renewable Fuel Standard program.

“Chemically, sorghum oil is very similar to other grain oils. This similarity makes it a drop-in replacement in most biofuel production processes,” John Duff, National Sorghum Producers' Strategic Business Director, told Energy Census.

The EPA has a 30-day comment period during which interested parties can register their opinions, after which the agency will likely introduce a final rule that will allow biofuel producers (mostly biodiesel and renewable diesel producers) to use sorghum oil as a feedstock.

Duff said sorghum ethanol producers only began extracting just a couple years ago, while others waited in the wings due to regional grain oil supply and demand factors. 

"EPA has not evaluated the feedstock until now for this reason," the lobby executive said.

Sorghum is a viewed as a crucial crop in regions that have to endure water and other environmental stress.

However, experts in the use of the crop say there are limitations to the widespread cultivation of sweet sorghum for ethanol use, as processing centres need to be built near production areas to reduce freight costs.

“Farmers are fast to switch crops that they grow depending on competing commodity prices.  If someone built an expensive processing facility and the prices of corn or soybeans jumped because of bad weather in South America, the local farmers probably would not plant sweet sorghum in their fields,” said Gene Stevens, professor of cropping systems at the University of Missouri

One solution could be the development of cooperatives where the farmers invest in a refining facility. 

“They would have an incentive to supply raw materials to keep the plant open even if prices of other crops goes up,” Stevens told Energy Census.