The Wheelabrator Frackville Cogeneration Facility (pictured) is typical of the size and layout of ARIPPA member plants.

The modern era of independent power production began in the 1970s with oil embargoes of that time prompting a search for ways to reduce dependence on foreign oil in the production of electricity.

Long lines at gasoline stations and the rapid rise in prices for home heating oil and electricity forced the recognition that petroleum is a finite commodity.

The U.S. Congress, intent on reducing national dependence on foreign oil, sought to lessen its use in generating electricity through encouraging the use of alternative fuels (waste, wood, biomass, wind, solar, geothermal). The Public Utility Regulatory Policies Act (PURPA) was put into law in 1978.

PURPA essentially did two things:

1. It compelled franchised electrical utility monopolies to allow non-utility generators to connect to the transmission system; and

2. It obliged utilities to buy the power generated by these non-utility operators at a price equal to the cost that the utilities would have incurred in building power plants of their own.

This "avoided cost" mandate proved instrumental in encouraging developers to invest in the new technology needed to find ways to burn the risky "alternative" fuels. Today, a vibrant, independent power production industry exists largely thanks to PURPA.

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At the time that Congress was considering the merits of creating an alternative power production industry to compete with franchised utilities, a new boiler technology known as "Circulating Fluidized Bed Combustion" was under development in the United States and Europe.

The new technology proved capable of burning fuels of substantially lower "heating value" (in terms of carbon convertible to heat energy expressed in British Thermal Units or BTUs) than the types of boilers typically used by the large utilities to burn regular coal.

Simply put, by suspending fuel in air it could be ignited and would swirl around like a fluid — hence the "fluidized bed" part of the name. By circulating the burning fuel in a tall boiler-furnace until all of the available carbon was consumed, coal waste products could be used that had never been considered as useful fuel prior to the development of CFBs.

Today, there are 14 plants burning coal mining refuse in CFBs in Pennsylvania, three in West Virginia and several plants burning coal, agricultural waste and wood in California.