Power Plant of the Week - Norwalk Harbor

The Norwalk Harbor Generating Station is located just off Longshore Rd in Norwalk, CT. Its on a peninsula known as Manresa Island that juts out into Long Island Sound giving the plant terrific access to water and deliveries of oil via barge. This plant was built in phases with the first unit coming online in 1960 and the second in 1963. Both units have nameplate capacities of approximately 163 MW and consist of steam turbines fueled with No. 6 oil. 

Norwalk Harbor as seen from Long Island Sound.

Norwalk Harbor as seen from Long Island Sound.

Like almost all New England power plants, Norwalk Harbor was built by the local incumbent utility, Connecticut Light & Power (CL&P). In 1999, it was sold off to NRG during the electric industry restructuring. Things quickly turned sour for NRG and many of the other merchant generators during the early 2000s. The economics of the Norwalk Harbor plant were marginal at the time of the sale and NRG was sliding into bankruptcy by 2002 (they ultimately filed and re-organized in 2003). In the fall of 2001, NRG gave notice to CL&P and ISO-NE that they were considering mothballing this plant due to poor economics.

In the early 2000s, the closure of Norwalk Harbor was not a possibility due to severe reliability problems in the ISO-NE Southwestern Connecticut (SWCT) portion of the grid. The grid in this area was extremely unstable during hot summer days and Norwalk Harbor's capacity was badly needed to prevent blackouts. Despite this, Norwalk Harbor's economics at the time were not good and the hottest days of the summer, when the plant would be needed most, also have the poorest air quality. This issue presented an additional constraint for the plant as air emissions permits for older poorly controlled plants often limit allowable emissions on days when pollutants in the ambient air exceed certain thresholds. Ultimately, ISO-NE awarded Norwalk Harbor a "Reliability Must Run" (RMR) contract to ensure that its capacity would remain online. An RMR agreement is a type of cost of service agreement for plants that are required for reliability despite being uneconomic.

Norwalk Harbor continued to receive extra payments from ISO-NE via an RMR contract until 2010. By then, increased demand response, flat load growth, and the operation of the new Norwalk to Middletown 345 kV transmission line along with other transmission improvements negated the need to keep this plant in service via special RMR payments. Once the RMR contract expired, NRG kept the plant online, but drastically reduced staffing. NRG determined that the plant could eke out a subsistence existence via ISO-NE capacity payments and occasional run hours during days with high power prices. 

Effective June 2013, NRG decided to close the plant. June marks the start of a new ISO-NE capacity period and the capacity prices for the June 2013 through May 2014 period were insufficient to support Norwalk Harbor's fixed costs. Although its always a bit emotional to see a power plant get retired, this plant had been on borrowed time for years. But for the grace of RMR contracts it lived this long and with a heat rate of ~ 12,000+Btu/kWh fueled by No. 6, it was completely incapable of adapting to the new ISO-NE price environment.  In both 2011 and 2012 it had a capacity factor of less than 1% and last generated power during the cold snap in February 2013.