Synthetic biology begins to spawn biofuels

Biofuels fell from grace in 2008 when perverse tax incentives prompted food crops to be diverted to biofuel production. At the same time, falling oil prices removed the economic incentive to develop alternatives to fossil fuels. Yet, behind closed doors scientists haven’t given up. Synthetic biologists have been focusing their research on advanced biofuels that do not depend on food crops as the feedstock. So could the future of energy be in test tubes?

Global Bioenergies, Europe’s first company to attempt to apply synthetic biology to produce biofuels would like to think so. Founded one year ago at the Génopole science park in Evry, in the south of Paris, the 17-strong start-up is following the trail being blazed by ten or so American counterparts and few global corporations. Global Bioenergies’ aim is to create new metabolic pathways in bacteria and yeast so they will transform the sugar they eat into hydrocarbons that are chemically identical to those distilled from oil.

Twice as much energy per litre

In her lab, Macha Anissimova, the Russian-born research manager of Global Bioenergies explains the company’s approach. “Philippe Marlière, a leader in organic chemistry and co-founder of the company, started to design the ideal metabolic pathway to get to the targeted end product: isobutene. This is a hydrocarbon gas that is easily converted into isooctane, the best high-octane gasoline, also known as ‘Super 100’,” she says.

“As there is no organism able to produce this molecule naturally, we have programmed the pathway, first at the level of individual genes and then going through the different biological stages. This enables micro-organisms en masse to turn glucose into isobutene in the restricted environment of a bioreactor. We are currently selecting the most effective modified yeast and bacteria.”

In his office, Marc Delcourt, the company’s other co-founder, explains the advantages of this “living” approach. “Unlike ethanol, the main existing biofuel, our process does not require distillation, meaning that you skip various expensive heating phases. Then, the hydrocarbon [we will produce] can be directly blended into the existing infrastructures, from pipelines to engines, as well being used in petrochemicals. Finally, as for other hydrocarbons, the energy intensity is 50 per cent higher than with ethanol. It means you drive 50 per cent further with the same tank.”

Global Bioenergies raised about €4 million for its R&D work and is now about to disclose its results. Next, it is planning to build a pilot plant in order to prove its discovery can be scaled into mass production. This is the stage its American competitors have also reached.

For example, Amyris Biotechnologies has managed to modify the metabolic pathway that enables certain micro-organisms to produce cholesterol. This modification drives these organisms to turn sugar into diesel. The company has raised $244 million from venture capitalists, and is now building a pilot unit in Brazil in collaboration with some of the country’s largest sugar producers.

With backing from the oil company Chevron and consumer products giant Proctor and Gamble, another advanced biofuels start-up, LS9, is in the process of setting up a pilot plant in Florida to scale its technology for producing diesel. The company is using industrial microorganisms it has designed to express metabolic pathways that convert fatty acid intermediates to a range of petroleum products with greater than 90 per cent energy efficiency.

Meanwhile, Massachusetts-based Joule Technologies is building a plant in Texas to test a process that captures CO2 from industrial flues and transforms it into hydrocarbons using modified algae. Gevo, in partnership with French oil company Total, and Butamax, a joint venture of BP and Dupont, are using similar technologies to produce isobuthanol, an intermediate product between alcohol and hydrocarbon. Butamax is currently building a pilot plant near Sheffield in the UK. Other companies, including Sequesco, Promethegen and GlycoBio are also developing advanced biofuels.

Don’t drown the baby in the bathwater

Despite the progress being made by the US companies – with Codexis recently becoming the first advanced biofuels company to complete an initial public offering on Nasdaq – Global Bioenergies does not believe any of them have tackled one of the key challenges of producing hydrocarbons directly in micro-organisms.

As winemakers have known for centuries, when a certain level of alcohol is reached (around 16 per cent) during fermentation, that same alcohol becomes toxic to the yeast that produce it. This is why distillation is needed to increase the percentage of alcohol.

In the case of hydrocarbons, the toxicity of these products to the micro-organisms that produce them is even greater. Which is why Marliere and Anissimova came up with the idea of generating a gas and not a liquid.  Volatile isobutene will be extracted continuously as it is generated, so that the amount of hydrocarbon in the bioreactor remains below toxic levels. While downstream liquefaction will be required, this is a well-established and cheap process.  

Enzymes in Ferrari’s tank

For Global Bioenergies and its competitors, the ability to almost double energetic output by producing hydrocarbons rather than ethanol, puts them well on the way to ending the food versus fuel crops controversy. Now, other research is maturing that will make plant matter from non-food crops suitable for use as feedstock, and the issue will become irrelevant.

Glucose is not only to be found in sugarcane, or wheat and corn. It is abundant in the cellulose of any plant waste, such as straw, wood pulp or corn stalks, and in dedicated biofuel plants such as switchgrass.

Before it can be transformed into glucose, cellulose must be separated from lignose, the molecule that gives plants their rigidity. But thanks to biotechnology this is now possible. Enzymes cocktails such as those developed by the Danish company Novozymes do exactly that job. These technologies are now so mature that Shell has just introduced an ethanol produced using these enzymes in the blend used to fuel Ferrari Formula 1 racing cars.

With enzymes upstream and modified micro-organisms downstream, advanced biofuels hold the potential to replace more than 20 per cent of the global oil market within the next ten years. The life sciences are about to beat geology by some millions of years in transforming biomass into fuels. And with fossil resources fast depleting, that cannot happen a moment too soon.