What percentage reduction in carbon emissions do thefollowing natural gas-fired CHP systems provide compared to thespecified separately generated electricity and heat systems? Forcarbon emissions, assume natural gas emits 53 g CO2/MJ, and foraverage grid emissions assume 0.6 kg CO 2 /kWh. The jouleequivalent of 1 kWh of electricity is 3.6 MJ.
a. CHP with 36% electrical efficiency and 40% thermal efficiencyversus an 85%-efficient gas boiler for heat and the above averagegrid for electricity.
b. CHP with 50% electrical efficiency and 20% thermal efficiencyversus a 33%-efficient, 1.0 kg CO 2 /kWh, coal-fired power plantfor electricity and an 80%-efficient gas-fired boiler for heat.
