CoachThe clean spark spread is the spark spread minus the cost of the allowances for one MWh of electricity from a gas plant, ; the clean dark spread is the same for a coal plant.
Examples
Example 7.8 (Where gas beats coal)
With gas at of fuel, coal at , efficiencies of 55% and 40%, and emission factors of 0.202 and 0.341 tonnes per MWh of fuel (illustrative round numbers), a MWh of electricity emits 0.367 t from gas and 0.853 t from coal, and the switching price is . At and power at the clean spark spread is and the clean dark spread : gas is just ahead.