INSIGHT: US REG developing crude glycerine fermentation

By Al Greenwood

HOUSTON (ICIS)–US-based Renewable Energy Group (REG), the country’s largest biodiesel producer, is developing strains of E coli that can produce fatty alcohols by fermenting various sugars  – including crude glycerine and those found in biomass.

If successful, this would not only give REG an alternative feedstock, it would also give the company another stream of products, many of which would earn higher margins than biodiesel.

Moreover, it could give REG another use for its crude glycerine. Many of REG’s biodiesel plants rely on waste oils, and this produces a crude-glycerine by-product that is used mostly as animal feed or in industrial applications.

Eric Bowen, the head of the company’s Life Sciences subsidiary, talked about these and other projects recently in an interview with ICIS. REG Life Sciences is in charge of developing such new technologies.

One way to boost margins would be to find a better use for the large amounts of crude glycerine that REG makes as a by-product in its biodiesel plants. Typically, such plants produce 1 lb (0.45 kg) of crude glycerine for every gallon (3.785 litres) of biodiesel.

Crude glycerine commands little in the market because of its impurities. In addition to glycerine, it contains salts, residual amounts of methanol and organic compounds other than glycerine.

REG, though, is developing strains of E coli that can ferment crude glycerine to directly produce detergent-range fatty alcohols with chain lengths of 12 to 14 carbon atoms, known in the industry as C-12 to C-14.

Once REG proves this technology, it will use it to make other products, such as fatty alcohols with longer lengths, Bowen said.

So far, REG’s E coli can tolerate most of the impurities in the company’s crude glycerine. It has too little methanol to threaten the E coli, Bowen said. In fact, REG tries to extract as much methanol out of its crude glycerine as possible because it is a feedstock for biodiesel.

Likewise, the other organic compounds in the crude glycerine are being tolerated well by REG’s E coli. However, it does pass through the fermentation process, so these compounds will either need to be removed at the beginning – when it is still mixed with the crude glycerine – or at the end – when it is appears with the final product. 

The salts pose the only possible problem – but only when their concentrations are too high. The ways around the salt problem include removing it before fermentation, developing E coli strains that can tolerate higher concentrations and diluting the fermentation mix to lower the salt levels, Bowen said. REG is looking at all three options.

Currently, REG is running tests on various crude glycerines to understand how they work as a fermentation feedstock, Bowen said. The company is using that information to determine how to optimise its strains of E coli so they can ferment the wide variety of crude glycerine produced at the company’s plants.

The company has been transferring the strains of E coli to its demonstration plant in Okeechobee, Florida, Bowen said. Later this year, the company plans to run fermentation tests at the plant using the E coli strains.

“The potential from my perspective is huge. It is very, very attractive,” Bowen said. Since REG is the largest biodiesel producer in the US, it is also the country’s largest crude-glycerine producer.

Crude glycerine is not the only fermentation stock being developed for REG’s E coli. It is developing other strains that can consume C-5 sugars. Such sugars make up hemicellulose, which, along with cellulose and lignin, make up biomass.

The cellulose portion of biomass has not posed a problem, since it is a polymer of glucose, a sugar that is readily fermented. However, the C5 sugars in hemicellulose are not so easy to ferment.

“That’s one of the great advantages of our technology,” Bowen said. “E coli likes to eat everything.”

However, for such a route to be profitable, there needs to be a large spread between sugar and biodiesel prices. Because oil prices are so low, that spread currently is not large enough to justify sugar fermentation via E coli. As such, REG is concentrating on E coli strains that can ferment sugars and produce fatty alcohols, since these can fetch higher margins.

That leads to the other products being developed by REG. Because of their margins, REG is also developing strains of E coli that can ferment sugars to produce intermediates for flavours and fragrances, Bowen said.  This is getting very close to becoming ready for commercialisation, he said.

Similarly, REG is also developing intermediates used to make plastics. Bowen would not say much more about this project because he did not want to tip off competitors about which products REG plans to bring to the market.

Pursuing such alternative routes for these intermediates could also provide customers with a more stable source of feedstock than petroleum-based sources, Bowen said.

“There are a lot of customers who limit their use of certain products because of price volatility,” he said. In fact, because of this volatility, some companies are reluctant to introduce new uses for their products because of this underlying volatility.

The intermediates REG is developing are drop-in molecules, so downstream producers can use them without altering processes or equipment.

For both the plastic and flavour and fragrances intermediates, the goal is to produce substitutes at a cost lower than those for petroleum or palm-oil products.

“It is much harder today to economically produce products that are substitutes for things coming out of the petrochemical process made from crude petroleum or natural gas or things coming out of the oleochemical process made from palm oil,” Bowen said.

“Crude oil, natural gas and palm oil reach are at much lower prices than they were five years ago,” he said. “That certainly limits the opportunities to go after commodities.”