WASHINGTON – If a new plant fueled by chicken waste is approved in Dorchester County, only about half of the power it generates is expected to be used by its owner, poultry processor Allen Family Foods.
The rest will be put on the region’s power grid and sold as environmentally friendly “green power.”
But buying green power — or any other utility’s power — is not as simple as calling up the power company and asking it to flip a switch so the electricity flows to your house.
The region’s power system is interconnected in a way that means that the premium-priced green power sold to some consumers could be coming from the “dirtiest” power plant in the state. And the power sold by a Maryland plant to a Pennsylvania utility may not ever make it over the state line.
Power moves through the region’s electrical grid like sand or water — it flows to fill the void left when electricity is used down the line. In the industry, they talk about “sources” and “sinks,” said Dave Penn, executive vice president of the American Public Power Association.
A large metropolitan area like Baltimore is a sink — it consumes more power than is produced in its power plants, so power flows into the city from the surrounding area.
In a home, “removing” power by using it to power lights or run the television creates a small, localized sink that is filled from a nearby source. That means that power consumed in a home in Aberdeen could be supplied by Maryland’s Conowingo hydroelectric dam or Pennsylvania’s Peach Bottom nuclear plant.
“Ownership and contracting paths have very little to do” with where the power goes, Penn said. Power plants just “push” the power out on to the grid. Customers pull it down from the nearest source, which may or may not be the utility that they sends a check to every month.
The concept that a consumer can buy power from a particular plant is “a fiction that has been built up over the years,” Penn said.
Still, the consumer’s money goes to the generator he selected, even if his power came from somewhere else. Generators essentially settle up at the end of the day for the difference in power generated and power used.
Although the industry predicts plenty of power for Maryland for the next five to 10 years, the interconnected structure of the power grid means “you can’t take comfort in your own locality,” Penn said. Power can be “sucked” to wherever there is a sink.
But Marylanders can take some comfort in the boom in power plant construction in the state.
State officials also said that the structure of the grid does not mean that consumers who believe in supporting green power should avoid paying the extra 10 to 15 percent it costs.
The contract that consumers sign for such power makes it economically feasible for generators to build the leading-edge plants that can burn chicken litter or use other environmentally friendly fuels, said Paul Dunbar of the Maryland Power Plant Research Program.