Yeah, it’s comparing apples to crabs. It’s only looking at the very final stage and ignoring the efficiencies of the fuel, etc.
If you wanted to make the comparison more fair (and also show how bad it is), a coal power plant maybe has an efficiency of 35%. You can calculate that by dividing the thermal energy in by the electric energy out. You feed in enough coal to generate 8MW of heat, which generates 2.8MW of electricity, so 2.8/8 = 0.35. By contrast, a photovoltaic power plant generates say 2kW of electricity with 0 fuel, so it has an efficiency of ∞%.
Yeah, it’s comparing apples to crabs. It’s only looking at the very final stage and ignoring the efficiencies of the fuel, etc.
If you wanted to make the comparison more fair (and also show how bad it is), a coal power plant maybe has an efficiency of 35%. You can calculate that by dividing the thermal energy in by the electric energy out. You feed in enough coal to generate 8MW of heat, which generates 2.8MW of electricity, so 2.8/8 = 0.35. By contrast, a photovoltaic power plant generates say 2kW of electricity with 0 fuel, so it has an efficiency of ∞%.