Could ‘Solar power plants’ spring up at landfill sites?

by Bob Haavind, editor-at-large, Photovoltaics World

May 8, 2009 – The largest commercial solar installation east of Arizona next to a Waste Management landfill in Bucks County, PA, could provide a model for similar projects around the country.

The 3.7 MW “solar power plant,” as it is called by project director Sarah Hetznecker of Conergy of Denver, CO, which built and operates the facility for Exelon, a large national utility headquartered in Chicago, feeds energy through net metering to PJM, a local power company. PJM originally served Pennsylvania, New Jersey, and Maryland, but its range now extends across 15 states as far west as Illinois, according to Hetznecker.

Exelon aims to provide power with a small carbon footprint, and it already has several small methane-fueled facilities, but the company wanted to try out solar power, she explained. Conergy was studying the potential for a rooftop solar installation in the area, but concluded the installation cost would be excessive. Katie McGinty, secretary of Pennsylvania’s Department of Environmental Protection at the time, approached Waste Management Inc., which also is interested in green energy, to find out if the company would be willing to lease land for a PV installation. Already WMI taps methane gas to generate power at its GROWS landfill site outside of Philadelphia — and the buffer land around the landfill in Falls Township could provide the 16.5 acres needed for a fixed-tilt solar panel array. WMI liked the idea.

The result was a 16.5-acre solar panel fixed-axis array using 16,500 of Conergy’s 175W silicon crystalline cells. Conergy’s business model, according to Hetznecker, is to find a suitable location; put a deal together; design, build and operate the facility over the life of the project; and find an investor to provide funding. In this case, 1 Generation LLC purchases the power and renewable energy credits (RECs) through a long-term (25 year) power purchase agreement (PPA), and then sells the power to a grid operator.

(Source: Conergy)

Key to the deal was a model of projected average hourly output curves over a 25-year period provided by the National Energy Lab in Golden, CO, according to Hetznecker. Of course weather is quite variable, but long-term (30-year) observations permitted the development of a long-term projection of expected average hour-by-hour output over a year. Another factor, she said, was quick permitting because of Pennsylvania’s interest in promoting green energy, allowing the project, initiated in August 2007, to be completed by November, 2008.

Until recently, the major market for photovoltaics was residential and multiunit housing and individual business or industrial sites. In the last couple of years electric utility interest, especially in California and other Western states, has been rising as PV costs come down and fossil fuel costs increase. San Diego Gas & Electric, for example, owns and operates a distributed PV system with installations scattered among commercial buildings and multifamily dwellings. Southern California Edison has announced plans for similar utility-owned facilities in its area to reach 250MW within five years. The site where the installation is located gets the benefit of electricity as needed while the excess is metered into the grid.

Some 27-30 states now have renewable energy portfolios, pointed out Conergy’s Hetznecker, and RECs can help repay loans over the life of a project. This is getting the attention of more private investors. But special devices are needed to provide the intelligence needed to use the electricity efficiently and to feed it into the grid, which is designed for large power plants rather than smaller scattered sites. That means that utility participation and some special equipment may be required. Also, state rules vary for how much power can be metered from small-scale generators into the grid. Pennsylvania allows up to 5MW, making the 16.5 acre 3.7MW “solar power plant” feasible, according to Hetznecker. — B.H.

This article was originally published by Photovoltaics World.


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