Green Energy and the Chemistry Behind
With the dwindling natural fuel resources of coal and natural gas and the ever increasing demand for electricity, generation of power from alternate sources becomes vital for sustaining modern civilizations. The gas produced from biomass is classified as renewable energy source. It is also a sustainable fuel for power generation. There has been a steady increase in global bio-power generation and consumption. Biogas electricity has seen highest growth in bioenergy sector in European Union. One of the significant advantages of green energy is that it can be setup by a small colony or community at very low initial capital unlike other forms of renewable energy sources.
Let us first understand the basic principles involved and what could be the potential bottle necks. Organic matter undergoes degradation under anaerobic (oxygen less) conditions by microorganisms. This process generates biogas. Anaerobic degradation of organic waste from agriculture, industry, municipal sewage has been found to be feasible for sustained production of biogas and aid in environmental recycling as well. These fermenters are connected with gas run engines for power generation. This whole process is very environment friendly because it helps in removal of harmful pathogenic organisms; reduction of water contamination and reduction in use of chemical fertilizers because the digested residual after fermentation can be used as manure in agricultural fields.
However, the crude gas produced from such process cannot be fully utilized as it contains many non-combustible gases that do not aid in production of energy. The crude gas contains about 20% of carbon-di-oxide that reduces its calorific value. Removing the carbon-di-oxide can increase the proportion of combustible hydrogen gas in the biogas. The energy efficiency and energy yield of the biogas can be enhanced by refining the crude biogas mixture into bio-methane by removing gases such as H2S, H2O and CO2. There are several ways of removing g the carbon-di-oxide. In this context, Mahadzir and Ismail from Malaysia have investigated the ability of CaO of 1000 micron particle size to absorb CO2 using thermogravimetric analysis of the absorption and desorption process at different temperatures. The study revealed that CO2 absorption rate was faster at first stage and then slowed down. This research is highly significant in optimizing the CO2 bubbling fluidized bed absorption reactor.