Mill River / Rippowam River, Stamford, CT
Hydro Power Potential



Mill River Park
Owned by the City of Stamford
mill river park


Mill River,North Stamford
Near Interlaken Road
(owned by Aquarion?)
mill river - north stamford


I've read several articles in the Stamford Advocate and elsewhere about conservation efforts by the City of Stamford. Connecticut in general and Stamford specifically are also interested in developing renewable energy (see links on the bottom of this page). I've also read that there are plans for the US Army Corps of Engineers to rebuild / restore Stamford's Mill River and Mill Pond. This got me thinking that we might be able to integrate these two projects and harness the power of the river. The electical power could be used to help power the Government Center building and/or power the lights of the park at night. There is a second dam on the Mill River near Interlaken Road. I believe it is owned by the Aquarion Water Company, but perhaps that too could be harnessed.

Real Time and historical River flow data is available from the U.S. Geological Survey. The unit of measure is cubic feet/second. Taking the mean of monthly steam flows from this page, it looks like the average daily streamflow from 1977 to 2004 is 43.4 cubic feet/sec.
Peak flows are in the spring, and are lowest in the summer. 

I took the following formula from the "How Hydropower Works" website:

Power = (Height of Dam) * (River Flow) * (Efficiency) / 11.8

Power The electric power in kilowatts (one kilowatt equals 1,000 watts).
Height of Dam The distance the water falls measured in feet.
River Flow The amount of water flowing in the river measured in cubic feet per second. 43.3
Efficiency How well the turbine and generator convert the power of falling water into electric power. For older, poorly maintained hydroplants this might be 60% (0.60) while for newer, well operated plants this might be as high as 90% (0.90). 80%
11.8 Converts units of feet and seconds into kilowatts.

For Mill River Park dam, I'll assume a height of 8 feet, which gives: 8 * 43.4 * .8 / 11.8 = approximately 23.5 kilowatts.

23.5 kilowatts * (24 hours per day) * (365 days per year) = 205860 kilowatt hours per year. As of March 2006, CL&P is charging retail customers $0.16 per kilowatt hour, so this works out to about $33,000 per year. I do not know how much the city is paying per kilowatt hour.

Dam Height Kilowatts Kilowatts/Year $/Year
6 17.65 154614 $24,738.24
8 23.53 206123 $32,979.68
10 29.42 257719 $41,235.04

I estimate that the Mill River Pond dam is 8 feet high, and might be increased to 10 feet by the Corps of Engineers. I estimate that the dam near Interlaken Road is 10 feet high.

Links:

Connecticut clean energy fund

Stamford waste to energy project

Solar at Katrina Mygatt Recycling Center, Stamford