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Virtually every facility requires energy conversion for both power and heat. Power may be purchased from an electric utility or private provider, or it may be produced on site. Power is used as electricity for lights and computers and to drive equipment via electric motors. It is also used as mechanical energy in the form of a rotating shaft that directly drives equipment. Heat — or thermal energy — is usually produced on site from purchased fuel through various types of energy conversion devices. Heat is used to raise steam, hot water, or hot air for space heating or process use, or to produce a cooling effect through certain heat-driven cycles.

Power is generally produced by application of prime movers, either on site or at centralized electric generation plants. Prime movers are devices that convert fuel or heat energy into mechanical energy, which in turn can be used to drive virtually any type of shaft-powered equipment, including electric generators and motor vehicles. Due to the laws of thermodynamics, heat is produced as a necessary by-product of power production.

Much of the technology discussed in this book involves three major types of prime movers: reciprocating engines, combustion gas turbine engines, and steam turbine engines. Most of the applications in this book involve strategic deployment of prime mover and certain heat-cycle technologies in commercial, industrial, and institutional facilities. This chapter introduces a number of terms used to describe and compare the application of these technologies.

Facilities rarely have a consistent requirement for power and heat. Generally, these requirements vary based on the time of use or outside ambient conditions. The portion of a facility's power or heat requirements that is constant is referred to as baseload. The portion that varies is referred to as intermittent load. Maximum intermittent requirements are referred to as the peak load.

If thermal requirements are not considered, baseload power requirements are usually met most economically through purchased power from central utility power plants rather than localized on-site production. Advantages associated with centralized power production include: economy of scale, preferential fuel purchase opportunity, lower staffing levels per unit output, diversity, and reserve capacity. These advantages are usually sufficient to overcome inherent disadvantages of centralized power production, such as system efficiency losses associated with power transmission and distribution, as well as an assortment of regulatory obligations.

Intermittent and peak load requirements, on the other hand, are usually served by centralized utility systems with lower economic efficiency. In some cases, these requirements can be served more economically by strategic application of on-site power production technologies. Examples are on-site peak shaving electric generation, which is the on-site production of electricity during peak usage and/or cost periods, and various types of mechanical drive services.

If thermal energy requirements are taken into consideration, on-site power production has a significant thermodynamic efficiency advantage over centralized power production, because heat energy rejected from the power production process can be used. Centralized power plants usually have no use for this heat energy and must liberate it to the environment at an economic loss. When a facility can recover and use this heat energy, the thermodynamic efficiency advantage translates into an economic advantage that may exceed the economic advantages of centralized power production.

Comparison of life-cycle costs determines the degree to which it is economical to produce shaft power on site, rather than purchase power from an electric utility or private power producer. Such decisions involve analysis of an entire facility's energy usage characteristics, including concurrent requirements for both power and heat, since on-site prime movers can provide both.

The life-cycle cost elements of an on-site prime mover are primarily capital, fuel, and operations and maintenance costs, which are also the primary constituents of electric utility and other centralized power producer costs. Electric utility rates assign different portions of these capital and operational costs to different time periods based on the utility's cost to serve. Rate designs, which often include demand charges and seasonal and time-of-use rates, send price signals that influence consumer behavior. The relationship between these price signals and on-site energy load characteristics will largely determine which portion of electricity requirements can be provided more economically by on-site prime movers than by electricity purchased from a utility or other centralized source.

Additionally, the marginal, or incremental, cost of utility power production will largely determine whether it is economical to produce more power than is required on site and export the excess to other sellers or users.

Investment in an on-site prime mover shifts many additional cost factors onto the individual facility. These costs are capital, fuel procurement, and operation and maintenance, as well as costs associated with reserve capacity, emissions control, space considerations, and insurance. The potential payoff for absorbing these added cost factors is lower operating costs and increased economic performance.

Guide to Alternative Fuels

Guide to Alternative Fuels

Your Alternative Fuel Solution for Saving Money, Reducing Oil Dependency, and Helping the Planet. Ethanol is an alternative to gasoline. The use of ethanol has been demonstrated to reduce greenhouse emissions slightly as compared to gasoline. Through this ebook, you are going to learn what you will need to know why choosing an alternative fuel may benefit you and your future.

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