Should Croton Dam Park have hydropower?

This past week Bing.com ran a beautiful photo of the New Croton Dam on its landing page.  Hundreds of thousands of people saw that image of one of our great local sites. 

Could we harvest some of the energy from all that water released from Croton Lake through the dam?

The Mid-Hudson Region already has twenty-eight installed hydropower units. Of these, thirteen were in operation in 2012, delivering delivered 259 gigawatt-hours of energy in 2011.

Keep in mind that the 7 counties of the Mid-Hudson consumed 18,997 gigawatt-hours of electricity per year (Source: Mid-Hudson Regional Sustainability Plan, May 2013). So our regional hydro produces 1.4% of that electricity.

That may seem small compared to our total appetite. But in the world of energy supply, hydropower in New York has the great benefit of being steady across both summer and winter and day and night.

Of the thirteen operating units, the Grahamsville Dam in Sullivan County produces the most electricity (77 gigawatt-hours). Dams in Ashokan, Beacon, Walden and Wappingers have nameplate capacity in the 2 megawatt range and produced an average of over 15 gigawatt-hours per year.

Note: 1 gigawatt-hour/year of electric energy can server 100 homes or 333 people, using the assumptions noted elsewhere. ! gigawatt-hour = 1,000 megawatt-hours = 1 million kilowatt-hours.

The Wappinger Falls unit is owned by Central Hudson Gas & Electric and the units in Beacon and Walden are owned by Consolidated Hydro New York, a private company based near Saratoga Springs, which has $1 to $2 million in revenues and about 4 employees.

In short, we have ample precedent for tapping spill water from our region’s reservoirs to make electricity. 

Is hydropower feasible at the Croton Dam Park? 

Yes!

But, a traditional hydroelectric unit mounted to harvest the water as it falls is not likely. The New York City Department of Environmental Protection has already indicated that it would not permit a hydroelectric facility on its property (the dam itself). That makes sense, given the hand-hewn nature of the structure and the ongoing maintenance the 100-year dam requires.

Instead, it is possible at the site to install a run of the river hydroelectric unit downstream from the Croton Dam. If you know the site, this might be located in the area just up or downstream from the Park’s Bridge over the Croton River below the Dam. Most of the facility could be below ground. Or, it could even be placed in a viewable “visitor’s center” structure to show off the facility.

In fact, from the way the spill water track was cut 100 years ago, you can almost imagine the Dam’s original designer had run of river electric power generation in mind.

Back in our office, we did some rough estimates on the potential electricity that could be produced at Croton Dam Park.  Using some standard formulas, we estimate the entire discharge from the Dam that feeds Croton River could yield between 4.5 and 6.8 megawatts of new renewable generation capacity.

Assuming that one-fifth of that could be captured through diversion to a run of river hydroturbine unit, that potential capacity would be 0.9 to 1.6 megawatts of nameplate capacity. Converted this power to energy yields 8.7 to 14.2 million kilowatt-hours of electricity per year.

How many homes would that light up?  The Croton River Hydropower Plant would provide 100% of electricity for 900 to 1,400 area homes and businesses.

Put another way, assuming the average person uses 3,000 kilowatt-hours per year, the Croton River Hydropower Plant would supply electricity to between 2,900 and 4,700 persons per year.

At today’s residential electric rates, the kilowatt-hours we estimated would have a value from $1.9 to $3.1 million a year! We are assuming an electric rate of $0.22 per kilowatt-hour.

Even if our rough estimates are optimistic, these are still very impressive potential benefits.

Any such project will require a lot of inter-agency cooperation between NYCDEP, Westchester County, Consolidated Edison, potential investors, and the area’s municipalities. 

But, t is not far-fetched to picture a public-private partnership to fund and operate the Croton River Hydropower Plant. And, it can be done while preserving the beauty of the Dam and the Park. 

So, when you watch that water flow by next time you are at Croton Dam Park, try not to think dollars and renewable energy!!

Technical notes:

We assumed an average home consumed 10,000 kilowatt-hours per year. Our estimates are based on taking the annual average discharge flow rate of past 20 years for the Croton River monitoring station (576 cubic feet per second). The USGS has a great WaterWatch site that gives you records on water flow and height at the Croton Dam Park going all the way back to 1934. 

The Mid-Hudson’s hydropower units ranged in nameplate rating from very small (0.2 megawatt at North Salem dam in Westchester County) to modest (25 megawatts at the Neversink Dam in Sullivan County). Together, they represent a total nameplate capacity of 109 megawatts, but the state considers their effective generation capability to be 81 megawatts. (Source: NYISO 2012 Gold Book).