Green Biologics Ltd.: Commercialising bio-n-butanol

ABE history

The acetone-butanol-ethanol (ABE) fermentation industry has a long and turbulent history. During the development of industrial biotechnology (known then as zymotechnology) in Europe in the late 20th century, a number of biological processes for chemical production were being discovered and developed [1]. Pasteur first described the production of butanol via fermentation in 1861, with acetone production being reported in 1905 [2]. By the early 20th century a shortage of rubber led to a search for biotechnological routes to butanol; meanwhile the British need for acetone to produce cordite during World War I also accelerated development. Groups at the Pasteur Institute in Paris (Fernbach and Schoen) and the University of Manchester in England (Chaim Weizmann) led the search for solvent producers [2]. The war effort accelerated development and in 1915 Weizmann patented his process using Clostridium acetobutylicum. During the early development of the process commercial production was successful in two sites in the UK, and in 1916, to secure sufficient feedstock, a commercial plant was commissioned in Toronto, Canada [1] (Figure 1). A plant also operated in France and in Terre Haute, Indiana, in the USA, but these all stopped production at the end of the war. The ABE industry was revived by the increasing need for butanol as a component of lacquers for paints in the growing automobile industry, and between the wars there was significant production in Terre Haute; Peoria, Illinois and elsewhere. Starch and subsequently molasses were used as the feedstocks for these processes, and although acetone production from oil began to offer competition in the 1930s, this was a time of growth worldwide for the Weizmann process and fermentations using a wide range of Clostridium species with plants built in Japan, India, Australia, South Africa, Taiwan, Russia and in smaller quantities elsewhere [2]. During World War II the ABE process was again given priority due to its importance to the war effort. The cost of feedstocks and the advent of cheap oil in the 1950s caused the decline of the ABE industry and by 1960 it was essentially dead in the USA and UK. Local economic, feedstock and political drivers allowed the process to survive in locations such as South Africa and Russia, but by the 1980s the industry was in decline globally, superseded by cheaper, chemically produced solvents.

Figure 1

Fermenters in the British Acetones Toronto ABE plant, 1916. Picture courtesy of the City of Toronto Archives.

However, ever changing global drivers mean that the ABE story is not complete. Spurred by the need to import solvents and a desire to be more self-sufficient, China encouraged the production of solvents internally in the early 21st century and this led to the development of a number of ABE production plants scattered throughout the country (Figure 2). Mostly based on a Russian process, all of these plants suffered from high feedstock prices and reduced butanol values in the global economic downturn of the late 2000s and most had stopped production by 2011. In the West, increased desire for renewable chemicals, biofuels and reduced carbon footprints in manufacturing led to an increased focus on the ABE process and a number of academic groups and companies have increased attention on the process, applying modern techniques to solve the problems of the past and finally reintroduce microbial solvent production as a global industry.

Figure 2

Modern ABE plant in Jilin, China; bioreactors and purification (inset).

Company history

Green Biologics Ltd. (GBL) was founded in Oxford, UK in 2003 by Dr Edward Green to develop and commercialize advanced microbial technology for the production of renewable chemicals and biofuels. In 2005, GBL moved from an incubator site in Oxford to its current location in Milton Park, Abingdon. Today, GBL has state-of-the-art lab and pilot plant facilities in the UK and US, with strong collaborations across the globe (Figure 3). We have built an experienced team of employees and advisors, many of whom have advanced degrees in microbiology, biochemistry or biochemical engineering.

Figure 3

Green Biologics pilot plant in Gahanna, Ohio, USA.

GBL has raised significant equity financing from angel investors and venture capital firms, including ConVergInce Holdings, Capricorn Venture Partners, Oxford Capital Partners, the Carbon Trust and Morningside Ventures. GBL has been recognized with numerous awards in Europe and in the US, including the Cleantech 100 list for 4 years running (2008–2011), the Clean Connect 30 list (2009), the 30 Most Transformative Technologies of 2010 list, and the coveted New Energy Pioneer Award from Bloomberg News in 2011.

In December 2011, GBL merged with butylfuel™ LLC, (BF) a US based biobutanol technology company. BF was founded in 1991 by David Ramey, a biobutanol pioneer and champion of using biobutanol as an advanced biofuel. GBL’s strengths in biobutanol technology complement BF’s strengths in the design, build and operation of large scale bioprocessing facilities, particularly in the US market. Post-merger, the combined entity is a global leader in biobutanol and other C₄ chemicals, with established skills and assets spanning microbiology and metabolic engineering through advanced fermentation and process commercialisation.

Today, the company has commercial projects underway in China and is developing several commercial options in India, Brazil and the US.

Market and strategy

GBL is currently focussing on acetone and butanol produced in the ABE process. There are established and accessible markets for these chemicals.

The worldwide market for n-butanol is around 4.5 million tonnes per year valued at over $10 billion, and growing at a rate of 3.2% per year through 2025. Global demand is split between the US, Europe and Asia (driven largely by China). Major global producers include Dow Chemical, BASF, Oxea, Sasol and Eastman Chemical. Butanol is a building block chemical in the $85 billion paints and coatings market, and as acrylates and plasticizers, is used in the $700 billion polymers and plastics market. Butanol is used to produce key derivatives, including acrylates, acetates and glycol ethers. It is also used as an intermediate in butyl phthalate plasticizers, amino resins and butyl amines. GBL’s biobutanol is chemically identical to n-butanol derived from fossil fuel and can be used as a direct substitute.

In the short term GBL will sell product into the chemicals and chemical derivatives market, which represents higher value. However, there is an opportunity to access larger biofuel markets as technology advancements push down the cost of production. Biobutanol is a high value biofuel that can be used as a blend stock with other fuels (gasoline and diesel), or can be used as a ‘drop in’ fuel itself. It can also be upgraded to jet fuel. The current market opportunity for biobutanol for blending into existing fuels is 40 billion gallons per year (BGPY) with an estimated value of over $80 B. The total hydrocarbon fuel opportunity is 900 BGPY. Virtually all of the demand for biofuels today is met by ethanol and biodiesel.

Due to its unique advantages, biobutanol has the potential to capture a significant share of the biofuels market for both gasoline and diesel applications over the next 10 years. The key to unlocking this market is lowering the cost of production. Our focus at GBL is on driving down the cost of production through innovation.

Acetone is another global market of 7 million tonnes with an estimated value of well over $5 B. For every 3 tonnes of biobutanol, we generate 1 tonne of acetone co-product. Major global producers include Dow, Shell, Ineos, and Sunoco. Acetone is currently produced from fossil fuel-derived cumene, which is made from propylene and benzene. GBL acetone is chemically identical to acetone derived from fossil fuel and can be used as a direct substitute.

GBL technology

Technology development is underpinned by an extensive proprietary culture collection containing historical commercial production strains, culture collection strains from around the world, environmental strains isolated by GBL scientists and strains developed internally. Through strain evaluation, GBL has identified biocatalysts that exceed the performance of traditional commercial ABE strains, especially with respect to solvent ratio, where GBL production strains have butanol ratios that are more than the 60% of the solvent mix seen with culture collection strains such as C. acetobutylicum ATCC824.

Strain improvement utilises both classical mutagenesis and molecular biology methods. An extensive comparative genomics programme is being used to analyse historical strains and selected mutants with positive phenotypes to identify novel SNPs and other genetic changes. These targets are introduced into production strains which are assessed for performance. In addition to a team of talented molecular biologists experienced in Clostridium genetic modification, GBL has collaborative projects with world renowned Clostridium and anaerobic biologists at British, European and American institutions. Strain development focusses on developing strains that perform optimally in the GBL production processes.

One of the biggest challenges in the ABE process is product (especially butanol) toxicity which leads to low titres [3]. A two-stage fermentation process, where solvents are produced as the bacteria enter stationary phase, limits productivity [2]. Strain modification to improve butanol tolerance and to de-link solvent production from growth phase has been attempted with limited success. GBL is developing strains with these characteristics but is also developing fermentation process technology that solves these issues. Batch, fed-batch and continuous processes are being developed with a variety of methods for cell growth and for handling the products. GBL has a fermentation research group at the laboratories in Milton Park, Oxfordshire and also a pilot plant at the facilities in Columbus, Ohio where processes are developed and then validated at the pilot scale. The current manufacturing process has allowed a step-change in productivities when compared to the commercial processes of the 20th century.

With optimized strains and production, the missing part of the puzzle for re-commercialization of the ABE process is cheap and sustainable feedstocks. Feedstock costs can account for as much as 80% of the production costs. GBL has production economics that allows starch, molasses and other waste sugars to be used for solvent production, given good local economics. However, the long-term focus is on the use of lignocellulosic feedstocks especially agricultural wastes (e.g. wheat straw, corn stover), municipal wastes and woody biomass. GBL does not develop biomass hydrolysis methods but works with feedstock and biomass hydrolysis partners to produce sugar streams suitable for fermentation. GBL’s commercial strains have a broad substrate profile that makes the fermentation very versatile. This includes the ability to process certain sugar polymers. Sugars from all major plant sources have been successfully fermented at yields close to theoretical and equivalent to sugars from simple sugar/starch feedstocks.

Process commercialization

The combination of strain development, process development and a focus on cheap feedstocks has already led to a dramatic reduction in process economics. GBL is now scaling processes up through pilot and demonstration scale and is working on plans to retrofit uneconomic ethanol plants to produce solvents. The first plants to produce GBL produced solvents are expected to come online in 2015. The GBL engineering team has experience building and operating ethanol plants and bring a wealth of process experience to the company as it works toward scale up.

GBL is also operating in China, Brazil and India. In China, commercial scale trials were completed in 2012, with >80 tonnes of solvents produced from corn stover and cobs at the Laihe Rockley Chemical company in Jilin province. This represents the first cellulosic butanol produced at commercial scale globally. Fifty tonnes of butanol were shipped to the USA to allow potential clients to test the product for quality and to run the company Smart car (Figure 4).

Figure 4

Edward Green, founder with the Green Biologics Smart car, run exclusively on n-butanol.

Conclusions

GBL is a 10-year-old industrial biotechnology company that has spent the first decade developing technology for re-commercialization of solvent production through the Clostridial ABE process. The company is now ready to deliver that technology in commercial production projects. The Company has the requisite technical, engineering and commercial personnel in place and delivered superior technology that offers a step change in process economics. GBL is currently demonstrating technology improvements at scale and plans to commercialise advanced fermentation technology over the next couple of years using a capital light retrofit model. Butanol production will be rolled out first in North America and then globally as it seeks to become the largest producer of renewable butanol and other C4 chemicals from biomass feedstocks.