Analytical model of carbon dioxide emission with energy payback effect

An analytical model is proposed to account for carbon emission behaviour during replacement of power source from fossil fuel to renewable energy in which sustainability of energy supply is stressed. Logistic function of time is assumed for producing renewable power sources. Analyses show that energy payback time (EPT) should be much shorter than the doubling time of manufacturing cycle to secure adequate available energy during, as well as after, the replacement. A nuclear plant, small hydropower plant, wind power plant and photovoltaic cell are taken as representative candidates and investigated as options to replace fossil power until toward the end of this century. Nuclear or small hydropower plants are promising candidates but the photovoltaic cell needs further development efforts to reduce EPT and avoid energy expense after the replacement.