Solutions

Our project solutions

There is a growing industry surrounding renewable fuel. This industry is anticipated to supplement and ultimately replace non-renewable fuels. However, biofuel production is still in its early stages and is nowhere close to achieving such an ambitious goal.

Currently, the biofuel in highest production is corn-based ethanol, or first generation biofuel, which only accounted for 2.7% of transportation fuel in 2010. Ethanol, however, is quite expensive to produce, very corrosive to combustion engines, and is not nearly as efficient as gasoline or diesel fuel. It is also not a viable long-term solution because it would require a huge percentage of the world's landmass would have to be covered in corn, which in turn could not be utilized as food.

Second generation biofuels, those derived from lignocellulosic biomass, are the most abundant carbon fuel source. Unfortunately, they, like first generation fuels, require land, energy, and nutrient investment. A low cost, low input way to create renewable biofuel is still being sought after.

But there is hope for such a fuel source within third-generation biofuels: those produced by photosynthetic microbes, like cyanobacteria. To produce biofuel through this method, only sunlight and adequate growing conditions are needed. The microbes do not need much space or require nutrient input to create fuel. However, biofuel output through this method is relatively low.

Another thing to consider is the type of fuel to be replaced. The three petroelum fuels in greatest use are gasoline, diesel fuel, and jet fuel.

Diesel fuel is used in compression engines. An alternative would need a comparable freezing temperature, vapor pressure, and cetane number, so something like a fatty acid methyl esters, fatty alcohols, alkanes, and linear/cyclic isoprenoids could be used.

Jet fuel, used in gas turbines, requires much more advanced biofuels to replace because it requires comparable net heat of combustion, low freezing temperature, and a high energy density. Only fatty-acid and isoprenoid-based biofuels show any potential to replace it.

Gasoline, the fuel used in combustion engines, could be replaced by something with comparable energy content, transportability, and octane number. This limits a replacement to short-chain alcohols and alkanes.

With the exception of jet fuel, alkanes seem to be a common denominator. That's where our project comes in. Within cyanobacteria is a fatty-acid pathway stemming from pyruvate at the end of glycolysis. This pathway ends with the production of an alkane. Alkane output is very insignificant currently, but our project hopes to change that.

By genetically modifying cyanobacteria to over-express pyruvate kinase, we hope to increase pyruvate production from phosphoenolpyruvate (PEP) within the cell. This should allow for an increase in activity within the alkane fatty-acid pathway. This increase in alkane production could significantly increase the viability of third-generation biofuels in the global market.