Posted Oct. 13, 2010

Researchers at the University of Connecticut have found that industrial hemp-based biodiesel has superior cold flow properties. According to UConn Professor Richard Parnas, incorporating hemp biodiesel may make the resulting fuel blend more amenable to cold weather usage.

While industrial hemp cannot be legally grown in the U.S., it is produced in many other areas of the world for the purposes of making rope, textiles and other products. "We thought the seeds generally would be thrown away or wasted [in these areas]," Parnas said. "That's not entire true, but in many cases it is true-and that oil could be a byproduct of the hemp industry that could then be made into a value-added product, like biodiesel. That was our initial interest."

The UConn research team produced a small, lab-scale batch of hemp biodiesel. "We used a subset of the ASTM tests in order to evaluate it," Parnas said. "One of the critical points of biodiesel is it doesn't have very good cold weather properties…A good biodiesel will have a cloud point in the vicinity of 0 degrees centigrade. What we found when we evaluated the cloud point of our biodiesel made from hemp using the standard measurement technique, we couldn't find a cloud point down to minus 20 degrees centigrade."

Due to the unusual-and amazing-cloud point results, Parnas said his team performed additional testing on the fuel. "At the University of Connecticut we have some more sensitive instrumentation that we can use to look at crystallization and other types of light-scattering events," he continued. "We used that more sensitive instrumentation, and we found what we call a weak cloud point at about minus 5.6 degrees centigrade."

"We think biodiesel from hemp is an easy biodiesel to make," said Parnus, noting that it doesn't require any special processing, and that the cold weather attributes are the most significant finding.

According to Parnas, hemp biodiesel could benefit the hemp industry by providing producers with an additional revenue stream. "For the biodiesel industry in general, it could provide a blending stock to lower the cloud point and improve the cold weather properties without going to any special effort," he continued. "If you've got a certain amount of hemp-based biodiesel, it might make a very nice winter blend."

Additional members of the UConn research team include graduate student Si-Yu Li; James Stuart, a member of the Department of Chemistry; and Yi Li, a member of the Department of Plant Sciences. Results of the team's research were recently published in Bioresource Technology.

According to Parnas, the team does not currently have plans to continue research on hemp biodiesel. "We showed that we could convert the hemp oil to biodiesel very straightforwardly," he said. "I'm not sure there is a whole lot of research issues as far as engineering issues go. I could imagine a lot of research issues in terms of industrial economics and optimization of crop yields and crop types." However, Parnas also noted it is unlikely for a U.S. entity to undertake that line of research on its own.

"There is such a negative attitude towards hemp in the United States, it would probably actually be very difficult to get research funding to do this [here]. I might be much more interesting to do it in collaboration with someone overseas, and we haven't made those connections yet, but it might come out of what we've been doing. I'm not sure."

In addition to the research on hemp-based biodiesel, UConn is actively engaged in other biodiesel research projects as well. Over the past few years, UConn researchers have patented a continuous biodiesel reactor that simultaneously results in a 99 percent conversion while removing 80 to 90 percent of glycerin all in one reaction vessel, Parnas said. "We also have a patent pending on a waste oil pretreatment process," he continued. "We recently received a DOE grant that will enable us to by the industrial versions of this equipment, so we can set up a pilot-scale production facility." That facility, if run at full commercial capacity, would be able to produce 200,000 gallons of biodiesel annually.

"As part of the pilot plant, we're also going to be installing some new types of bioreactors to convert the glycerol waste product into high value products," Parnas said, noting that he is not currently able to disclose more information on what products, due to the fact that the process might be subject to additional patent applications. "The main points of our pilot-scale project will be to test our patented and patent-pending technologies in an industry operation, and also to test some new technologies for handling the glycerol waste stream." According to Parnas, the pilot scale facility could be operational in late 2011.