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spark spread

n. (context idiomatic English) The difference between the cost of the fuel required to produce a unit of electricity, and the price of that same unit of electricity.

Wikipedia
Spark spread

The spark spread is the theoretical gross margin of a gas-fired power plant from selling a unit of electricity, having bought the fuel required to produce this unit of electricity. All other costs ( operation and maintenance, capital and other financial costs) must be covered from the spark spread. The term was first coined by Tony West's trading team on the trading floor of National Power Ltd in Swindon, UK during the late 1990s and quickly came into common usage as other traders realised the trading and hedging opportunities.

The term dark spread refers to the similarly defined difference between cash streams (spread) for coal-fired power plants. These indicators of power plant economics are useful for tracing energy markets. For operating or investment decisions published "spread" data are not applicable. Local market conditions, actual plant efficiencies and other plant costs have to be considered. The higher the dark spread the better, for the generator; an IPP with a dark spread of €15/ MWh will be more profitable than a competitor with a dark spread of only €10/MWh.

Further definition of clean spread indicators include the price of carbon dioxide emission allowances (see: Emission trading).