BIOMASS IS CHEMICAL ENERGY

Plants use photosynthesis to convert radiant solar energy to chemical energy. This chemical energy comes in the form of the plant material itself—biomass. We can use the energy of biomass in two ways processing the biomass to produce transportable fuels, or burning the biomass at a properly equipped power plant to produce electricity. Biomass can be grown on demand 

Ethanol from fermentation is relatively expensive because of the great financial and environmental costs of growing food biomass, a process that requires vast amounts of water and fertilizer. Ethanol derived from petroleum is actually less expensive. (But only because crude oil prices are kept artificially low. If taxpayer subsidies, exemptions from paying for the environmental damage from mining and drilling, and the cost of military protection are factored in, the price of crude oil quadruples.) 

Methanol from biomass can also be costly because only relatively small amounts of it are produced through distillation. For this reason, most methanol today is produced from natural gas. The coal industry is even gearing up to produce methanol from its vast coal reserves. However, creating methanol from coal produces more pollution than is saved by burning the cleaner methanol. 

On the bright side, technology is being developed for making fermentable sugars out of low-cost woody feed stocks. Ethanol produced from such inexpensive sources would be greatly cheaper than gasoline. 

Gasohol is gasoline containing an alcohol additive. The alcohol provides an octane boost, allowing an engine to run more effi-ciendy with less pollution. If the alcohol is produced from biomass grown within a nation, there is the added benefit of a reduced dependence on foreign oil. 

Since 1984, the Vermont Biomass Gasification Project has supplied more than 50 MW of electricity to the Burlington, Vermont, area. The electricity is generated by gas turbines powered by the combustion of a gaseous fuel mixture created as wood chips are mixed with very hot sand (1000°C). 

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Biomass Is Chemical Energy solar energy that was captured through photosynthesis. 

Renewable carbon resources is a misnomer the earth s carbon is in a perpetual state of flux. Carbon is not consumed such that it is no longer available in any form. Reversible and irreversible chemical reactions occur in such a manner that the carbon cycle makes all forms of carbon, including fossil resources, renewable. It is simply a matter of time that makes one carbon from more renewable than another. If it is presumed that replacement does in fact occur, natural processes eventually will replenish depleted petroleum or natural gas deposits in several million years. Eixed carbon-containing materials that renew themselves often enough to make them continuously available in large quantities are needed to maintain and supplement energy suppHes biomass is a principal source of such carbon. 

The maximum efficiency with which photosynthesis can occur has been estimated by several methods. The upper limit has been projected to range from about 8 to 15%, depending on the assumptions made ie, the maximum amount of solar energy trapped as chemical energy in the biomass is 8 to 15% of the energy of the incident solar radiation. The rationale in support of this efficiency limitation helps to point out some aspects of biomass production as they relate to energy appHcations. 

Significant differences in net photosynthetic assimilation of carbon dioxide are apparent between C, C, and CAM biomass species. One of the principal reasons for the generally lower yields of C biomass is its higher rate of photorespiration if the photorespiration rate could be reduced, the net yield of biomass would increase. Considerable research is in progress (ca 1992) to achieve this rate reduction by chemical and genetic methods, but as yet, only limited yield improvements have been made. Such an achievement with C biomass would be expected to be very beneficial for foodstuff production and biomass energy appHcations. 

Biomass resources are a major component of strategies to mitigate global climate change. Plant growth recycles C02 from the atmosphere, and the use of biomass resources for energy and chemicals results in low net emissions of carbon dioxide. Since the emissions of NOx and SOx from biomass facilities are also typically low, it is a technology that helps to reduce acid rain. 

Although most ethanol is now produced from corn, research has been done on producing this type of alcohol fuel from cellulosic biomass products including energy crops, forest and agricultural residues, and MSW, which would provide much cheaper feedstocks. The process of chemically converting these cellulosic biomass feedstocks is more involved and until this process can be simplified the price of ethanol will remain high. 

The European Commission wants to have a contribution of 12% energy from renewable sources to the energy budget within the EC in 2010. The relative amount of bio-fuels will increase to a level of 5.75%, this is more than twice the corresponding use of oil. The US Department of energy has set goals to replace 30% of the liquid petroleum transportation fuels with biofuels and to replace 25% of industrial organic chemicals with biomass-derived chemicals by 2025 [7]. 

Beyond the transportation sector, biomass is also a promising feedstock for the chemical industry. This industry accounts for 5-10% of today s oil and gas consumption. It may require an even larger fraction in the future as the demand for chemicals has outpaced that for energy in the last few decades. Recently, the chemical industry has indeed showed a significant interest in converting agricultural feedstock into chemical intermediates such lactic acid or propene-l,3-diol. 

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