Homemade Electricity: An Introduction to Cogeneration for Co-ops and Condos

In fact, cogeneration reduces a building's energy usage in three ways. The property generates its own electricity; in the process, it captures and reuses the excess heat; and it burns natural gas, which is cheaper than heating oil and burns cleaner.

On the downside, few residential buildings in New York City have a cogeneration plant, and installing one in costs millions. Of Con Edison's 3.3 million customers, only 125 use a cogeneration plant, and many of them are commercial properties. Co-generation plants are generally found in institutions like hospitals, nursing homes and schools. Among residential buildings, they are almost unheard of, as condo and co-op boards tend to shy away from such a complicated and technical capital project.

"One of the challenges for large residential buildings is educating co-op boards and property managers so they can get over that fear factor," says Margarett Jolly, distributed generation ombudsman for Con Edison. "It is a fairly complex undertaking. You don't just go to Lowe's and buy one and plug it in."

Talkin' 'bout Cogennnneration

What does a cogeneration plant look and sound like? One typical system at a 290-unit co-op in New York is ensconced in a 1,680-square-foot mechanical room where the first thing you notice is the hum. It's a loud, constant noise that tells the story of the electricity being generated here. The noise is so loud that a few nearby apartments have been affected. According to Langer, engineers are working to resolve the problem. The hum is also audible from the back courtyard.

The seven boilers — rectangular units about the size of refrigerators — stand against a sidewall. The cogeneration units sit in the center of the room. They have double doors that open up to show the engines working inside. A network of white, silver, and yellow pipes wind out of the machines.

At any time, day or night, the building's super or the property manager can log into a computer program or check an iPhone app to see what is happening in this room. The program shows the system at work, with every pipe color-coded and the machines spinning and pulsating. If anything goes awry, the staff is alerted instantly. About 90 percent of issues are resolved before anyone notices the water isn't hot or the air conditioning isn't cold.

Next time: How one Queens co-op got financing to install a cogeneration plant … one that's reduced the co-op's Con Ed bills by 85 percent. Eight-five. Not a typo.

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Photo: Centrax Turbine Components