Alternative Energy

Biomass fuel is liquid, solid, or gaseous fuel produced by conversion of biomass. They are actually organic materials produced by plants, animals, or microorganisms. Those plants animals or microorganisms can be burned directly as a heat source or they can be converted into a gaseous or liquid fuel. Scientists are looking to biomass for sources of alternative fuels. Biomass can be directly converted to energy (not appealing for an environmentalists or non compatible to modern day living) or converted to liquid or gaseous fuels such as ethanol, methanol, methane, and hydrogen.

Los Alamos National Laboratory researchers have discovered the secret of hardness of plant cell walls. They have discovered the fact why cell walls of some plants are so tough. This peek into the toughness of plant material could lead to a cost-effective and energy-efficient strategy for turning biomass into alternative fuels. Los Alamos researchers have published two papers separately in Biophysical Journal and recently in an issue of Biomacromolecules, These scientists have recognized the potential weaknesses among sheets of cellulose molecules comprising lignocellulosic biomass. That is the fibrous material being derived from plant cell walls. The material is the magical substance because it is the abundant source of sugar that can be used to brew batches of methanol or butanol, and ultimately can be converted into biofuels.

How cellulose is synthesized into plant cells? It is the result of polymerization. In polymerization, molecules of glucose (a simple sugar) join into long chains. The plant is known to assemble these chains of cellulose into sheets. The sheets are held together by hydrogen bonds. Hydrogen bonds are mainly an electrostatic attraction of a positive portion of a molecule to a negative portion of the same or neighboring molecule. These cellulose sheets stack atop one another. Stacks join with one another by other bonds that are weaker than hydrogen bonds. The plant then spins these sheets into high-tensile-strength fibers of material.

The bondings between these fibers are extremely strong, but they are incredibly resistant to the action of enzymes called cellulases. The main work of cellulases is to crack the fibers back into their simple-sugar components. Here lies the key to future biomass fuels. Because here we can easily crack up the cellulose into sugars then the sugars can be used to create alternative fuels. The firmness of cellulose fibers is the main hurdle in converting them into simple sugars. United States presently lacks an energy-efficient and cost-effective method for turning inedible biomass such as switch grass or corn husks into a sweet source of biofuels. Researchers are tirelessly working to find a crack into the armor of plants firmness.

Los Alamos researcher Paul Langan is working in collaboration with researchers from the U.S. Department of Agriculture and the Centre de Recherches sur les Macromolécules Végétales in France. They are making use of neutrons to investigate the crystalline structure of highly crystalline cellulose – the same way a doctor uses an X-ray to find out the anomalies in our body. Langan and his colleagues found that although cellulose generally has a well-ordered network of hydrogen bonds holding it together, the material also displays significant amounts of disorder, creating a different type of hydrogen bond network at certain surfaces. These differences make the molecule potentially vulnerable to an attack by cellulase enzymes.

Tongye Shen and Gnana Gnanakaran discusss in Biophysical Journal, about a new lattice-based model of crystalline cellulose. The model exhibits that how hydrogen bonds in cellulose shift to remain stable under a wide range of temperatures. This plasticity permits the material to exchange different types of hydrogen bonds but also restrains the molecules. This way molecules form bonds in the weaker configuration described by Langan and his colleagues. Most important aspect of Shen and Gnanakaran’s model is that hydrogen bonds can be manipulated via temperature differences. This manipulation works to make the material more susceptible to attack by enzymes that can crack the fibers into sugars for biofuel production.