What is the most efficient power generation method in terms of cost and CO2 emission?

Answer

Following two tables are the result of comparison in terms of CO2 emissions and cost to generate electricity. CO2 emissions are calculated based on Life Cycle Assessment which incorporates not only the process of electricity generation, but also mining of raw materials and building of facilities. Nuclear, hydro, geothermal, solar, and wind emit CO2 from consequential processes. The results shows that renewable energies and nuclear are much more efficient than coal, oil and gas power generation. The second table indicates that solar photovoltaic costs much more than other methods. However, the cost of solar photovoltaic is decreasing rapidly partly due to technological development, and partly due to experience curve from high-volume manufacturing. The cost of oil and gas fluctuate in accordance with the price of resources. Ironically, nuclear is efficient with respect to both CO2 emissions and cost.

CO2 emission per 1kWh for each method
Method	CO2 emission(g-CO2/kWh)
Coal	975
Oil	742
Gas	608
Nuclear	22~25
Hydro	11
Geothermal	15
solar energy	53
Wind power	29

Data source: Japansese Environment Agency

Cost per 1kWh for each method
Method	Cost(Yen)
Coal	5.0~6.5
Oil	10.0~17.3
Gas	5.8~7.1
Nuclear	4.8~6.2
Hydro	8.2~13.3
solar energy	46
Wind power	10~14

Data source: Japansese Environment Agency