L'Ombre de l'Olivier

The Shadow of the Olive Tree

being the maunderings of an Englishman on the Côte d'Azur

17 August 2007 Blog Home : August 2007 : Permalink

Small Scale Biofuel

Via slashdot and Baen's Bar I've come across a company that plans to genetically engineer bacteria to make hydrocarbons from vegetable matter. There are two article as Technology Review (here and here) that describe the business. From the first link:

...the company began speaking more openly about what it has accomplished: it has genetically engineered various bacteria, including E. coli, to custom-produce hydrocarbon chains.

To do this, the company is employing tools from the field of synthetic biology to modify the genetic pathways that bacteria, plants, and animals use to make fatty acids, one of the main ways that organisms store energy. Fatty acids are chains of carbon and hydrogen atoms strung together in a particular arrangement, with a carboxylic acid group made of carbon, hydrogen, and oxygen attached at one end. Take away the acid, and you're left with a hydrocarbon that can be made into fuel.

"I am very impressed with what they're doing," says James Collins, codirector of the Center for Advanced Biotechnology at Boston University. He calls the company's use of synthetic biology and systems biology to engineer hydrocarbon-producing bacteria "cutting edge."

There is in fact a second company that is working on a similar idea (earlier TR article) and there may be others. Currently these various companies are working on relatively costly food sources but they intend to find cheaper ones to use waste biomass:

LS9's current work uses sugar derived from corn kernels as the food source for the bacteria--the same source used by ethanol-producing yeast. To produce greater volumes of fuel, and to not have energy competing with food, both approaches will need to use cellulosic biomass, such as switchgrass, as the feedstock. Del Cardayre estimates that cellulosic biomass could produce about 2,000 gallons of renewable petroleum per acre.

As I commented at Baen's Bar, the great advantage about the modified E.Coli sort of approach is that it tends to scale down well. As in you can have one running in your back yard in a barrel sort of scale down. Now there is clearly a good deal of work to be done before we're at the final stage but eventually everyone ought to be able to take all the lawn cuttings and leaves and turn them into petrol.

Of course the problem is that you really really want such a system to not function at all at standard temp, pressure and atmostphere because if it does then a spill means a heap of E coli turning all the vegetable matter in the vicinity into oil. this is known as a Bad ThingTM, however it is highly likely that any process will actually be a multistage one with one bacterium doing a first stage breakdown and the second (or third) preducing the petrol or diesel you want at the end.

The catch so far seems to be in the cellulose breakdown part and anyone who can get a bacterium, yeast or other microorganism to take arbitrary cellulose and lignins and turn them into something softer (glucose for preference) in a simple manner is going to get very rich - assuming he isn't murdered by the Saudis or the Iranians first...

The obvious way to do this is to replicate the process that ruminants (cattle etc.) use in some artificial manner, possibly with a mechanical preprocessing stage act as more efficient teeth. The ruminant system would presumably also be a good source of biogas because, as I'm sure we're all aware, cows and other ruminants are a major source of methane. Whether the methane would be used to power the system or storred for some other function would clearly depend on how much is generated but either way the system ought not to generate more than just petrol. The propblem of course is that the ruminant system is a complex collection of protozoa, bacteria so it would be better if a simpler system could be found.