December 26, 2013 § Leave a comment

The next Big Thing in biofuels has always been just around the corner (the “are we there yet” refrain never far from the public mind).  A recent news story raises my own optimism significantly.  So, first the road we have travelled.  In the beginning there was ethanol from switchgrass and the like (the beginning after the ethanol from corn policy debacle).  Clean energy investors dived into that pool, led largely by Vinod Khosla, who made his money with the famed Kleiner Perkins investment firm.  Biochemical methods such as those used with corn have to date proven stubbornly resistant to cost reduction.  Then the wonder seed crop that did not compete with food, jatropha, burst into our consciousness.  The early excitement produced a review in the prestigious journal Nature.   Most recently there has been jet fuel from algae.  We discuss below each of these newer developments, including the latest piece of excitement linked above.

Jatropha plant

Fuel from Algae:
When I first heard of this source I was captivated. It grew in salty water useless for other purposes. It consumed carbon dioxide. Many varieties contained quantities of lipids, the building block of hydrocarbons. So, what was not to like? Just two characteristics: shallow ponds took up a lot of land and more importantly economical harvesting was challenging. Into this world stepped Craig Venter and his San Diego startup Synthetic Genomics. Venter led the successful mapping of the human genome and is quite possibly the best known gene sequencing expert. He targeted genetic manipulation of algae to directly attack the harvesting issue. The public details are sketchy but my take is that they are targeting producing the lipid precursor to hydrocarbons without going through the plant formation stage. More than likely this is intended to be a continuous process as in a chemical reactor. As of 2011 ExxonMobil, arguably the most conservative oil company had invested $300 million in the venture. The biofuels grapevine indicates that commercial scale operations are still in the future.
The promise of Jatropha (pictured above) has largely been centered on two considerations. One is that it is an oily seed, with as much as 40% oil depending upon the strain. Unlike corn, soy beans, canola and other seeds, jatropha is not also a food source. The second point may however be the key. It can grow in non-arable soil with very little water usage. But the fact that it is drought resistant does not mean that it does not grow better with more water. It does. But optimal water consumption is not known and likely varies with species. Consequently, a farmer with access to water will use it, especially because in most countries, including the US, water for agriculture is priced very low. In India there is a push to grow it in non-arable areas without irrigation, coincident in many cases with poverty.

Against this backdrop is another problem.  All strains currently being grown are wild type; none has been domesticated.  Therefore the yields are unpredictable.  It is hard to size a conversion plant to uncertain yields.  This is the problem being addressed by SGB in San Diego.  According to the linked story they are trying to create a strain with predictably high yields and other valuable characteristics.  In so doing they are using a relatively new and powerful technique known as High Throughput Screening (HTS).  This robotically controlled process allows tens of thousands of experiments to be conducted very rapidly.  It also allows one to zero in on the promising subset and quickly perform further optimization on just that subset.  The technique has been around for a while but has recently become dramatically cheaper.
But HTS has caused an explosion in data generated and needing rapid analysis. Fortunately, this happened coincidentally with new computational schemes to handle this onslaught. The associated field of Data Analytics is fast growing and the colloquialism Big Data applies to it in many fields including drug discovery and rapid diagnosis of genetic defects.
SGB claim to be zeroing in on productive strains. They conduct HTS mediated deciphering of strains with known phenotypes (the physical manifestation of a genetic propensity) such as yield and drought tolerance. While wild type bushes produce only about 6 to 8 fruits to a cluster, some SGB strains produce over 35. The varieties with the best phenotypes are combined to produce new strains. These strains are produced with standard grafting techniques, so would not fall in the class of Genetically Modified crops.
India has always welcomed jatropha because it is indigenous and because the country is incredibly diesel dependent. The country burns 325 million barrels of diesel, compared to only 95 million barrels of gasoline. Much of this is in public transport, especially trains. The significance of this statistic is that jatropha is most easily converted to diesel or jet fuel using the process known as transesterification. This is the same process used for processing canola oil to diesel. Interestingly, this can be done economically on a small scale, practically a garage operation. This has considerable appeal for producing fuel in each village cluster for local consumption. Currently a high fraction of villages have no electricity grid; any meagre electric power is from burning diesel. A viable local fuel has huge significance.
Some processes are uniquely suited to small scales. Photovoltaic solar is one such. We need to embrace these for what they are and resist the temptation to scale up. Sometimes smaller is simply better. In any case where energy is concerned the small scale and large scale will coexist, one is not necessarily better than the other. Horses for courses. Some horses run some courses better than others. Ask Kentucky Derby winners about the Belmont.
Vikram Rao


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