Happy Earth Day: Cut CO2 emissions by a third!

Electric energy use reported by OurWorldInData for 2021 above was 28,000 TWh(e), or 28 PWh(e), or about 3200 GW average power. World Bank and Statista estimate global GDP for 2022 at $104 trillion, so electric energy intensity is 28/104 = 0.27 kWh(e)/$.

The 28 PWh(e) electric energy use includes 7 PWh(e) generated directly from solar, wind, and hydro sources. The remaining 21 PWh(e) was sourced from 63 PWh of heat energy, converted to electric energy at a ratio about 3 kWh to 1 kWh(e).

Annual world energy use is 176 PWh, so 63/176 or 36% of all heat energy is used for electric energy generation.

Only 3 PWh of that 63 PWh of that annual heat energy comes from nuclear fission, so 60 PWh comes from combustion.

Because new nuclear technology is hot, we can now generate electricity with even less heat energy. New nuclear fission power plants operating at 700°C raise thermal-electric conversion efficiency from typical 33% to over 46%.

Solar panels and wind turbines produce electric energy without heat energy, but there are drawbacks. The large up-front embedded energy and embedded CO2 from manufacturing and installing such dispersed energy sources should be allocated over their lifetimes.

Intermittency is another, difficult problem. Natural gas turbines operate when wind or solar energy is reduced. When the sun rises, clouds clear, and wind pipes up, the turbines use less natural gas and emit less CO2 as they run in standby mode.

Modern combined cycle gas turbine with steam turbine (CCGT) power plants in steady operation achieve over 60% efficiency converting natural gas heat to electric energy. However simpler combustion turbines that power up and down quickly (peakers) to supplement intermittent wind and solar generators operate at lower, 34% efficiency, generating nearly twice the CO2 emissions of CCGTs. This erases much of the CO2 savings compared to using CCGTs steadily without wind and solar interruptions.

New nuclear power costs must and will drop to compete with coal-fired electricity generation, based on cheap uranium fuel and high temperature energy heat source.