Under a tolling agreement a power marketer or commercial electricity customer provides the fuel, say natural gas, to produce electricity for the marketer or customer at an agreed spark spread which will be dependent on the plant’s efficiency, as measured by its heat rate, and receives the rights to electricity output.

A charge paid to a facility for using it, road tolls being the most common. The term is also applied to use of production facilities, mining operations and other productive plants handling or processing raw materials.