Green Energy

The world's energy markets rely heavily on the fossil fuels coal, petroleum crude oil, and natural gas as sources of energy, fuels, and chemicals. Since millions of years are required to form fossil fuels in the earth, their reserves are finite and subject to depletion as they are consumed. The only other naturally-occurring, energy-containing carbon resource known that is large enough to be used as a substitute for fossil fuels is biomass.

Biomass is all non fossil organic materials that have an intrinsic chemical energy content. They include all water and land-based vegetation and trees, or virgin biomass, and all waste biomass such as municipal solid waste (MSW), municipal bio solids (sewage) and animal wastes (manures), forestry and agricultural residues, and certain types of industrial wastes. Unlike fossil fuels, biomass is renewable in the sense that only a short period of time is needed to replace what is used as an energy resource. The capture of solar energy as fixed carbon in biomass via photosynthesis, during which carbon dioxide (CO2) is converted to organic compounds, is the key initial step in the growth of virgin biomass and is depicted by the equation: CO2 + H2O + light + chlorophyll = (CH2O) + O2 Carbohydrate, represented by the building block (CH2O), is the primary organic product. For each gram mole of carbon fixed, about 470 kJ (112 kcal) is absorbed. The upper limit of the capture efficiency of the incident solar radiation in biomass has been estimated to range from about 8% to as high as 15%, but under most conditions in the field, it is generally in the 1% range or less. However, the global energy potential of virgin biomass is very large. It is estimated that the world’s standing biomass carbon; i.e., the renewable, above-ground biomass that could be harvested and used as an energy resource, is about 100 times the world’s total annual energy consumption.

The idea of using renewable biomass as a substitute for fossil fuels is not new. In the mid-1800s, biomass, principally woody biomass, supplied over 90% of U.S. energy and fuel needs, after which biomass energy usage began to decrease as fossil fuels became the preferred energy resources. Some analysts now believe that the end of the Fossil Fuel Era is in sight because depletion of reserves is expected to start before the middle of the 21st century, probably first with natural gas. This eventuality and the adverse impact of fossil fuel usage on the environment are expected to be the driving forces that stimulate the transformation of biomass into one of the dominant energy resources.