Category: General

The change from one energy structure to another

A general classification of fuels that includes heating oil, diesel fuel and kerosene. Products heavier than motor gasoline/naphtha and lighter than residual fuel oil

The change in cost associated with a unit change in quantity supplied or produced. The cost of providing an additional kilowatt-hour of energy output over and above any energy currently being produced. The energy industry refers to the next kilowatt-hour or next unit as the basis for determining this cost. Marginal costs only include immediate expenses required to produce more energy. Long run marginal cost includes capital costs and embedded costs which are not included in marginal costs. Marginal cost is often used interchangeably with incremental cost, but marginal cost can be applied to the average next-unit cost for a large number of additional units, whereas incremental cost applies strictly to the next unit, not to any average of multiple next-units

Long submarine mountain range that winds along the middle of the ocean floor. The mid-ocean ridge system is essentially a segmented, linear shield volcano. There are a number of major ridges, including the Mid-Atlantic Ridge, which runs down the centre of the Atlantic; the East Pacific Rise in the southeast Pacific; and the Southeast Indian Ridge. These ridges are now known to be spreading centers, or divergent margins, where two plates of oceanic lithosphere are moving away from one another. Ocean ridges can rise thousands of meters above the surrounding seabed, and extend for up to 60,000 km in length. Ocean ridges usually have a rift valley along their crests, indicating where the flanks are being pulled apart by the growth of the plates of the lithosphere beneath. The crests are generally free of sediment; increasing depths of sediment are found with increasing distance down the flanks