Science

Pennies instead of petroleum!

• Ingenious
• Fascinating
• Relevant

The Problem – The use of non-renewable fuels is the cause of a number of geopolitical and environmental problems.  In the United States, ethanol produced from corn (maize) has been promoted as an alternative fuel that can ease the demand for petroleum, especially in transportation.  Although ethanol can be produced from a variety of crops, corn offers some advantages, especially for farmers in the United States.  Farmers in large areas of the United States already have the knowledge and equipment to grow and harvest corn/maize, so additional infrastructure is not required.  There are also vast areas of North America and other parts of the world that can support corn production.  Some other ethanol-crops such as sugar cane have a much more limited growing region, so expansion of ethanol based upon these crops may not be practical.

Although corn ethanol is an effective fuel, there are a number of significant disadvantages to its continued and expanded use.  First, corn is a food crop.  If significant amounts of corn are grown solely for the production of fuel ethanol, there will be less acreage for production of food.  Second, current technology only produces ethanol from the corn kernels.  A significant amount of energy is expended by both the plant and the farmer to produce parts of the plant that are not used in the production of ethanol; this decreases the overall efficiency of corn-based ethanol.  For these and other reasons, we must develop new technologies for the production of ethanol.

The Solution – Virtually all plant fiber is made up of sugar building blocks.  In most plants, these long chains of sugar molecules (cellulose and hemicelluloses) make up 50+% of the plant’s biomass and can be fermented to form ethanol after the chains are broken into individual sugar molecules by hydrolysis.  Producing ethanol from cellulose means that virtually all parts of any green plant could be used.  This would allow non-food crops to be used in ethanol production as well as the non-food components of food crop plants.  The first hurdle to the use of cellulose is that most of it is locked away by the rigid lignin structure in plant cell walls.  Lignin provides rigidity to the plant, but is difficult to break down.  Current methods for breaking down the lignin cage involve harsh acids and can be very energy-intensive, so finding alternative ways to break down lignin is a critical step in producing ethanol from the cellulose locked within this lignin prison.  Oxidation catalysts can be tailored to react with the chemical bonds that hold lignin molecules together, and catalysts that contain transition metals can be both effective and relatively inexpensive to produce and use.

Inspired by Nature – Natural catalysts in biological systems are called enzymes, and those which contain metals are called metalloenzymes.  Metalloenzymes can be found which contain a wide variety of transition metals including iron, manganese, zinc, copper, cobalt, nickel and vanadium.  Of these metals, copper is an attractive option because it has fewer undesirable side reactions than some of the others and the shape of copper complexes are more amenable to catalytic reactions.  Using the natural copper complexes found in natural enzymes as a model, this project will design new copper complexes and test their ability to oxidize lignin molecules.  In some cases, oxidation catalysts can also catalyze hydrolysis, so the copper complexes will also be tested for their ability to hydrolyze cellulose. 

Use of Funds – The contributions to this project will be used for routine lab chemical and supplies, testing and analysis of samples at external facilities, and may be used for travel and expenses related to the Spring 2012 National Meeting of the American Chemical Society in San Diego, CA, USA.  Significant individual contributions ($2000+) will permit purchase of a new balance, a portable gas chromatogram, a computer for the research lab, or other substantial equipment.  Any contribution at this level will earn the contributor naming rights for that piece of equipment which will include a small engraved plaque with the donor’s name on the equipment and a framed photo of the equipment in use after installation.

Pennies instead of petroleum! is part of the #SciFund Challenge.  Helping fund scientific research since 2011.