With the uncertainty about supply of crude oil, as well as high prices, other sources of fuel are now a hot topic. An interesting option is ethanol, currently made from plants such as corn and sugar cane. Companies and universities are working to develop a process for producing ethanol from many other types of plant material; which may significantly increase the amount of ethanol available as fuel. Nanotechnology may be of help in this effort.
Currently ethanol used in gasoline in the US (about 5 billion gallons a year) is produced from corn. The starch in the corn kernels is converted to sugar using enzymes. This starch is then fermented to make ethanol. However in order to make a useful reduction in the US consummation of crude oil, we need to up that production significantly. The goal set recently by the US government is to produce 35 billion gallons of ethanol a year within the next ten years.
The corn stalk is composed of a material called cellulous which is not converted to sugar by the enzymes used in the current ethanol producing process. To increase production of ethanol several companies and universities are trying to use the cellulous portions of the corn plant, such as the stalk, along with other plants that are currently thrown away. Nanotechnology is helping this effort by allowing researchers to study the molecular structure and function of bacteria and enzymes. This enables them to either select enzymes capable of converting cellulous to sugar or to modify enzymes to make them useful in the conversion process. Being able to use cellulous material such as wood chips, grasses, and corn stalks (in fact, most plant material) would increase the amount of feedstock available for ethanol production.
In another proposed method cellulous is heated and converted into carbon monoxide and hydrogen gas. A bacteria is then used as a catalyst in the conversion of the gas to ethanol. Nanotechnology may help this process both through genetic engineering of the bacteria to improve its performance as a catalyst and by providing alternative catalysts. For example, researchers have found that carbon nanotubes containing rhodium (Rh) nanoparticles act as very effective catalysts for the conversion of the gas to ethanol.
The US Department of Energy is a believer in cellulous feedstock for ethanol production. It has provided grants to six companies to help fund pilot production plants for the conversion of cellulous feedstock to ethanol using both the methods described here.
Researchers at Michigan State University are trying a neat trick. They are genetically engineering corn to include the needed enzyme. The plan is to make the enzyme inactive until triggered by high temperatures. When the cellulous part of the corn, such as the stalk, is processed, the high processing temperatures would activate the enzyme and convert the cellulous to starch. This would avoid the added cost of producing the enzyme separately.
Researchers at the University of Rochester are studying how bacteria chooses a particular enzyme, or enzymes, to break down at particular type of plant or other bio mass. They hope to generate enzymes that can convert cellulous to ethanol in one step, rather than the two steps used by the existing processes.
There are obvious cost savings of using yard waste to fuel our cars, and ethanol has a head start as an alternative fuel in that over 5 million cars in the US have already been equipped by the vehicle manufacturer to run either on regular gasoline or an 85% ethanol/15% gas mixture. These so-called Flex Fuel vehicles represent a portion of cars manufactured over the last several years. Manufacturers have done this in exchange for being allowed to produce other vehicles with low gas mileage. If cellulous-based ethanol production is shown to be economical, there are already cars on the road that could use the fuel.
The advantage of cars that can be filled up with either gasoline or ethanol has been demonstrated in Brazil which uses much of its sugar cane crop to produce ethanol. Drivers with Flex Fuel cars are able to chose their fuel depending upon which is less expensive at the time, and most cars sold in Brazil are capable of using either fuel.
Using nanotechnology/genetic engineering to produce ethanol from cellulous has the potential to make a serious dent in our consumption of crude oil. However we do need to keep an eye on some safety issues. For example precautions must be taken to insure that a built-in enzyme is only activated in the processing plant, not while the crop is in the field, and that corn with the special enzyme is not mixed with crops grown for human consumption. We can hope that corporations and universities will make public the steps they take to insure that the methods they use to simplify the conversion of cellulous to ethanol do not endanger food crops or forests.
To learn more about how nanotechnology can improve fuel availability visit my Nanotechnology and Fuel page.