Industrial Biotechs Accelerate Drive to Leverage Glycerin

Producing additional amounts of ethanol from glycerin in whole stillage may boost plant revenue.
By David J. Gaskin | September 15, 2009
Glycerin is at the forefront of a mobilization to improve the production yields of ethanol plants. Ethanol fermentation produces glycerin as a by-product and emerges from the distillation columns in whole stillage. In 2008, 170 dry-mill plants in the U.S. producing a combined 9.23 billion gallons of ethanol, generated more than 350 million gallons of glycerin. Researchers in the biotechnology industry are well aware of this situation and have recently invested in the means to develop technologies to convert glycerin to ethanol and a portfolio of other end-products.

Squeezing the Most from Grains
Industrial biotechnology company Glycos Biotechnologies Inc. (GlycosBio) of Houston, Texas, has recently developed a biotransformation technique that directs the glycerin in stillage into ethanol at high yield efficiency. Using microorganisms as biocatalysts - enzymes or microbes that initiate or accelerate chemical reactions - that provide a route for the production of ethanol from glycerin, GlycosBio makes possible for the first time, to conversion of a disadvantaged byproduct of dry milling into its primary product. In this way, ethanol producers can tap thin stillage streams exiting the distillation and centrifuge units to maximize the production of ethanol and improve the value of its coproducts.

What does this mean for the ethanol industry? This new biological process enables owners of grain-fed plants to use glycerin streams within their plants to both increase production efficiency and provide revenue management flexibility. If both the residual C5 and C6 sugars and glycerin present in the stillage are converted to ethanol, average production yield could rise from 2.85 gallons per bushel to 3.05 gallons per bushel. Translating this into dollars, a 100 MMgy plant producing approximately 320,000 tons of dried distillers grains can churn out 7.4 million extra gallons of ethanol by mining carbon sources internally, or $13.32 million at today's prices.

The science begins by modifying the metabolic pathways of selected microorganisms to digest glycerin and ensuring that growth conditions and metrics are met by the cultured strains. From there, only strains that consume large amounts of glycerin with a minimum of interfering, coproducts are selected. High-throughput screening expedites the selection of characteristics based on glycerin consumption, conversion yield, and minimizing competing metabolites. Exclusive production of ethanol is key. Successful strains are introduced into fermentation reactors containing thin stillage with two goals in mind: minimize reaction time and select strains for actual process stream conditions.

Big Possibilities
Experts believe that the glycerin-to-ethanol production technology will align well with next-generation cellulosic ethanol technology. As cellulosic ethanol phases into production, these by-product conversion technologies can serve the same purpose that they do with today's grain-fed plants. Until then, the technology can utilize the glycerin in dry-mill plants or the corn oil in wet-mill plants, imparting biorefinery process advantages to both.

By harnessing processed components within thin stillage, these new microbial biocatalysts make possible higher yield productivities, lower operating costs, and greater product renewability (sourcing secondary carbons internally improves overall renewability). That is something that ethanol producers recognize and have expressed anticipation to possess. Large producers such as Poet LLC and Hawkeye Energy Holdings LLC, engineering, procurement and construction firms such as ICM Inc. and Delta-T Corp., and agricultural majors Archer Daniels Midland Co. and Cargill Inc. all have large strategic resources that present a compatible need for such integrated biorefinery tools.

Earlier this year, GlycosBio validated its ability to co-ferment C5 and C6 sugars, alongside glycerin, to produce ethanol. Scientists have since doubled the production tier of ethanol, while both increasing the rate kinetics and glycerin consumption of the strain. By integrating all underutilized carbon components within a plant, additional capacity is made available to diversify co-product areas. Converting glycerin and residual sugars to ethanol has the potential to capture 18 percent more operating margin, taking into account recaptured savings in heat and electricity and current prices for corn and ethanol.

The technology makes sense wherever ethanol prices happen to be. When ethanol prices drop, the flexibility is there to drive more feed co-products. Furthermore, downswings in ethanol prices summon a larger disruptive capability of the technology, - whereby a flexible technology (i.e., the ability to biologically ferment glycerin into higher value biochemicals) can provide revenue and profit diversity during periods of lower ethanol crush spreads. That is the concept of a biorefinery - for example, in a petroleum refinery, several strata of liquid fuels, chemicals and energy are produced. A biorefinery accomplishes this with biological reactions, chemical and biochemical processes.

ADM, Cargill and other traditional grain suppliers are among the most heavily involved in chemical production from biomaterials. Cargill owns the massive NatureWorks biopolymeric plastics and resins operation in Nebraska. ADM formed its industrial chemicals unit in 2007, with the intent to produce USP-grade propylene glycol among other renewable chemicals. DuPont-Tate & Lyle BioProducts has been successful in its joint venture to produce and market 1,3-propanediol, a clear liquid used as a building block in the production of polymers. Other companies including Green Biologics Ltd. in the UK, Arkema SA in France and Myriant Technologies in Quincy, Mass., are also developing processes around glycerin as a viable starting material for diverse chemicals such as butanol, acetone and acrylic acid.

Advent of the Biorefinery
At the heart of the matter is the rising cost of traditional feedstocks and the saturated nature of their land-use complexities. Grain-based ethanol, the largest and most fungible of bio-based chemicals, is center stage at the economic, environmental and policy debates that surround biofuels. Several biotech companies are positioning themselves for the ethanol industry of 2020. The more prominent technologies are using a combination of synthetic biology and thermochemical approaches to convert second-generation - mostly non-food biomass - feedstocks into ethanol.

But Genencor, a division of Danisco AS and Iogen Corp. as well as smaller players such as BioEnergy International LLC and Integrated Genomics have their sights set on a projected $215 billion bio-based chemicals market. Management consulting firm McKinsey & Co. predicts that sales of chemicals from renewable biobased sources will consume 10 percent of worldwide chemical sales in 2012. It is not a new idea, but the U.S. DOE is betting that these chemicals and other products will service biofuel plants as more profitable coproduct alternatives to livestock feed and glycerin.

For these tremendous bio-based chemical markets, the pool of potential feedstocks increases by an order of magnitude. From algae systems to waste starches to fatty acids, using these materials is so new that it's often enough work for a new start-up to figure out the scientific and commercial pathways from one of these feedstocks.

The successful approach will be to develop strains that metabolize high levels of glycerin to ethanol quickly, with additional capabilities and breakthroughs and follow-up research into systems that will produce chemical intermediates to replace petroleum-derived chemicals, such as dimthylsuccinate and propylene polyols. In fact, many companies in this field are pursuing the blue ocean of bio-derived solvents, monomers and chemical intermediates. According to McKinsey, biofuels will account for $91 billion of these sales. By 2020, most chemical manufacturers will have significant capacity devoted to bio-processed fuels and chemicals. EP

David Gaskin is director of planning for Glycos Biotechnologies, Inc. Reach him at