Cellulosic ethanol is one of the most promising developments in the bio-fuel arena that large fleets have the potential to cultivate. Unlike other bio-fuels, such as corn or soy-based ethanol, which according to a recent EPA report may in fact create larger carbon footprints than conventional petroleum gasoline, cellulosic ethanol has the potential to yield up to 200% more biodiesel oil than soy-based alternatives. One of the least-developed bio-fuels, cellulosic ethanol is derived from algae in a process that extracts biodiesel from the fats in the algae material. See the diagram below for a more detailed explanation of the extraction process:
This makes cellulosic ethanol one of the most carbon-efficient fuel options on the market apart from the more unlikely hydrogen fuel-cell options. According to Evergreen Fleets, cellulosic ethanol represents an 85% reduction in net carbon emissions per gallon than conventional petroleum gasoline. Unfortunately, the algae-growing operations necessary to produce commercially viable quantities of cellulosic ethanol have not been established to a sufficient scale for fleets to purchase large amounts of this new fuel.
Current research at Sandia National Laboraties (begun in 2007) has focused on breeding the optimal strains of algae that have the highest fat ratios. According to Ali Kriscenski at Inhabitat, “the biggest challenge is to make algae biocrude within a fraction of the time that nature’s biomass decomposition occurs and to do it economically, for less than $60 a barrel.”
Most university research has focused on creating apparatuses that will do exactly that: create a pressure-cooker environment to extract fats from the algae and convert it to biodiesel in an economical timeframe.
One such project at the University of Illinois at Champaign-Urbana, titled“BioGrow”, uses old computer parts to create such a vessel for algae production. Using an Apple G4 CPU tower, PVC pipes, acrylic panels, an Apple iMac CRT, and high density foam for insulation, graduate students modified the old computer to allow the iMac CRT to turn on different light spectrums and to adjust the temperature. The makeshift tank contains a water pump that aerates the algae for a faster energy conversion process. The byproducts can be used for feedstock, fertilizer and high-end pharmaceuticals because algae is so rich in protein and nutrients. In addition, this method helps alleviate the problem of electronic waste, which often leach toxic heavy metals into the soil and groundwater when they end up in landfills.
Another group of scientists at Stanford University attempted a slightly different method by inserting electrodes directly into algae pools, attempting to intercept the electron flow that occurs during the natural process of photosynthesis. This method is a type of photosynthetic electrolysis that produces no emissions other than oxygen, distinguishing it from the more mainstream production method of cellulosic ethanol. However, this experiment was not able to produce enough energy per algae cell to be commercially viable for mass production.
At the University of Michigan, researchers have also been experimenting with a pressure-cooker apparatus that will reduce the time and money needed to convert algae into biodiesel. According to Sarah Parsons (also of Inhabitat),
“The pressure cooker works by heating microalgae up to about 300 degrees, forming an algae soup. The high temperatures combined with the pressure breaks the plants down, releasing the native oil and causing proteins and carbohydrates to decompose, adding to the fuel yield. Cooking the “soup” for 30 minutes to an hour yields a crude bio-oil, which can then be converted to fuel.”
This process has the advantage of eliminating the need for high-oil content strains of algae, allowing microscopic and less-oily species of algae to be used and removing the need for drying out the algae outdoors. An indoor production mechanism of cellulosic ethanol, rather than drying out algae in vast outdoor pools, has the potential to be widely cultivated, assuming reasonable installation costs, even by individual fleets themselves.
Claiming to reach fuel efficiencies of 150 miles per gallon on a fuel blend of 5% cellulosic ethanol, the company outfitted a plug-in hybrid Toyota Prius to run across the country on 25 gallons alone! The possible fuel economies of future cellulosic ethanol vehicles is staggering if you imagine how efficient the models would be if, instead of a 5% blend, an E85 or B40 blend were produced, as has already been manufactured for corn and soy-based biodiesel.