Electric power that is guaranteed by the supplier to be available during specified times except when uncontrollable forces produce outages.  Firm power consists of either firm energy, firm capacity, or both.

Substituting one fuel for another based on price and availability.  Large industries often have the capability of using either oil or natural gas to fuel their operations and of making the switch on short notice.

Public Power History

  A fee levied for access to a utility’s transmission or distribution system.  It is a charge for the right to send electricity over another’s wires and is not typically tied to the actual amount of power shipped.

The amount of water it takes to cover one acre to a depth of one foot, equivalent to 1,233 cubic meters, or 325,851 gallons.  This measure is used to describe the quantity of storage in a reservoir or hydro system.  River flows are normally spoken of in terms of millions of acre-feet (MAF).

The title of the chief officer of the Bonneville Power Administration (BPA).

An electric current that reverses direction of flow at regular intervals and has alternately positive and negative values.

A unit of measurement of electric current, equal to one coulomb (6.241 × 1018 electrons) per second.  See “watt.”

Fish (including most salmon) that hatch in freshwater, migrate to the ocean, mature there, and return to freshwater to spawn.  See also “resident fish.”

The power support services provided by a transmission operator to ensure reliability of the transmission system.  They include reactive power, frequency control, balancing reserves, and operating reserves.