Marginal Cost

The cost of providing additional electricity; "The competitive price of a MWh of electricity is equal to the additional amount it would cost to generate an additional MWh, once all current demand is met. This additional cost is commonly referred to as the marginal cost. The marginal cost of generating electricity rises as more electricity is produced, because different generators use different types and amounts of fuel_.under competition, the rising marginal cost of electricity leads to high prices when demand is high and low prices during low-demand periods." (GAO-02-828 Restructured Electricity Markets, page 13)