ABSTRACT
Carbon dioxide concentration in the atmosphere has increased significantly during the last century compared to the pre-industrial years where the increase was steady. The concentration of CO2 (carbon dioxide) in the atmosphere during the pre-industrial period was about 280 ppm, while the reported concentration of CO2 in 2013 was 396 ppm which is 40% more than that recorded during the pre-industrial period (IEA, 2014b). This amounts to a mean increase of 2 ppm/year since the year 1800 (IEA, 2014b). The energy sector in the world is the major contributor of CO2 because 82% of the world’s primary energy comes from fossil fuels, which, when combusted, release greenhouse gases. Worldwide, the primary energy sector releases 69% of greenhouse gases (GHG), out of which 90% is CO2, and the rest is made up of CH4 (methane) and N2O (nitrous oxide). CO2 and black carbon (particulate matter) emissions are emitted at their highest levels from the combustion of biomass and incomplete combustion of fossil fuels and that accounts for 14%of total GHG (Figure 3.1). A large amount of CO2 is emitted by coal-fired power plants compared to oil-and gas-fired power plants because they aremore numerous than oil-fired plants, whose contribution to world electricity generation is only about 6%, and is expected to fall by about 4% in 2030 (Chandrasekharam and Bundschuh, 2008). Typically, coal-fired power plants emit 953 kg of CO2/MWh, while oil-fired power plants emit 817 kg of CO2/MWh, and gas-fired power plants emit 193 kg CO2/MWh (UNFCC, 1997, Kasameyer, 1997, Chandrasekharam and Bundschuh, 2008). The CO2 emissions projection indicate that the world is expected to face the worst climate related problems within another decade, when the CO2 increase in the atmosphere will be steep if mitigation strategies are not adopted to control emission trends (Figure 3.2).
