Sunday, December 14, 2008

Charcoal - a value added biomass

One of the methods of value addition of biomass is the production of charcoal for fuel, soil conditioner, water purification and other purposes and at the same time,contributing to carbon sequestration or CO2 emission reductions. Charcoal is usually produced by slow pyrolysis and the resulting soft, brittle, lightweight, black, porous material resembles coal with 85% to 98% carbon and the remainder consisting of volatile chemicals and ash. Charcoal is cleaner, easier and less smoky and smelly than other biomass fuels. Charcoal is a very stable substance and the half-life of charcoal (carbonized in 1000 degree Celsius) is reported to be around one thousand years. Gross heating value is estimated to be within the range of 28-30 MJ/kg. Charcoal carbonized under lower temperature is more stable under the higher concentration of ozone in the air. Charcoal can hold pure carbon inside it for a long time and can be a carbon sink. In the carbonization process (pyrolysis), considerable amount of carbon goes to the air and CO2 emission from charcoal production must be minimized. Burying char, known as black carbon sequestration enhances soils, helping future crops and trees grow even faster, thus absorbing more carbon dioxide in the future. Researchers believe that the char, an inert and highly porous material, plays a key role in helping soil retain water and nutrients, and in sustaining microorganisms that maintain soil fertility. It has been estimated that as much as 9.5 billion tons of carbon which is more than what is currently emitted globally through the burning of fossil fuels could be sequestered annually by the end of this century through the sequestration of char.

Fungus strain for biodiesel production

Biodiesel, also known fatty acid methyl ester (FAME), has become more attractive as an alternative fuel because of its environmental benefits, including low toxicity and favourable emission profile. There are various methods of biodiesel production. Biocatalytic enzymatic method and chemical transesterification are promising methods among others. Biocatalytic enzymatic method offers mild reaction conditions and reduction in chemical wastes. However, biocatalysis of plant derived oil (PDO) feedstocks has relatively high price of pure lipase enzyme for use in the tranesterification reaction and has short operational period. Jeffrey and Ms. Xiao Man of Faculty of Engineering, National University of Singapore have conducted an investigation to undertake fundamental research on the locally isolated strains of fungus to investigate whole-cell performance as a biocatalyst for the conversion of PDOs to FAME. The investigation has yielded a microbial mold isolate (JN7) from the local environment having a high intrinsic lipase production and suitable for use as a whole cell biocatalyst for the transesterification of PDOs. The transesterification reaction resulted in a 86% yield of FAME in 72 hours when immobilized on biological support particles.

Friday, December 5, 2008

Energy funda

Energy is defined as the capacity of doing work. Energy comes in different forms - heat (thermal), light (radiant), mechanical, electrical, chemical, and nuclear energy. The energy of a body due to its position with respect to another body is called its potential energy. It is stated as, E = mgh, where E is the potential energy, m is the mass of the body, g is the acceleration due to gravity and h is the distance through which it has been raised. The energy of a body due to its motion is called its kinetic energy. It is stated as, E = ½ m v sq(2), where E is the kinetic energy, m is the mass of the body and v is its velocity. We can classify energy into high and low grade for practical purposes. High-grade energy like electricity is better used for high grade applications like melting of metals rather than simply heating of water. The energy lost or dissipated is called as low-grade energy. In our day to day work we use terms like thermal energy, mechanical energy, electrical energy, chemical energy, electromagnetic energy, etc. These are useful forms of energy. The origin of these forms may be in potential energy or kinetic energy or both. For example heat (thermal) energy is a form of kinetic energy due to the random motion of the atoms or molecules of solids, liquids or gases. Chemical energy, stored in atoms or molecules, is a form of potential energy. Energy can be converted from one form to another. According to the first law of thermodynamics, in any process of conversion of energy the total quantity of energy does not change. But practical experiences tell us that the useful energy output of an energy converter is always less than its energy input. This is because of some loss of energy during the conversion. The sum of energy loss and useful energy output is equal to energy input. The ratio of useful energy output to energy input is the conversion efficiency. Because of the losses it is always less than 100%. The conversion efficiency, generally expressed as a percentage, is high if the losses are low..

Hydrogen storage using nano pillared graphene

Hydrogen storage using nano pillared graphene Researchers are exploring new ways of using carbon nanotubes (CNTs) to store hydrogen in fuel cell vehicles. A unique hydrogen-storage structure consisting of parallel graphene sheets layers of carbon just one atom thick and stabilized by vertical columns of CNTs added with lithium ions has been suggested as a storage medium. Chemically modified graphene material has been prepared using several types of common electrolytes and graphene-based ultracapacitor cells have been constructed and electrically tested. The amount of electrical charge stored per weight (specific capacitance) of the graphene material has suggests the possibility of doubling the capacity compared to the existing ultracapacitors. The scientists' calculations has shown that the so-called "pillared graphene" could theoretically store up to 41 grams of hydrogen per liter which almost can approach the DOE's target of 45 grams of hydrogen per liter for transportation applications.