Power Plant of the Week - Exelon's L Street Jet

The Exelon plant on Summer Street in South Boston is a prominent feature in the South Boston skyline. Once upon a time, this plant was able to produce over 700 MW of natural gas power, but today all that remains is a distillate fired jet engine that puts out 12 MW. The story of this plant is a common one in New England. It was built in stages by Boston Edison and the two natural gas fired steam turbine units came online in 1965 and 1967. During deregulation in the 90s, it was sold off to a merchant generator called Sithe Energies which was subsequently acquired by Exelon. 

The 2000s were not kind to this plant. In October of 2002, Unit 2 suffered a catastrophic fire which resulted in the unit being retired. In 2007, unfavorable economics led to the closure of Unit 1. The only active power generation equipment remaining at the site is a 12 MW distillate fired jet engine that fires during periods of extremely high demand in the ISO-NE grid. If you see emissions from the jet unit on a cold winter or a hot summer day, you know that power prices are off the charts since the economics of distillate require prices north of ~ $270/MWh. If you look at the aerial photograph of the site, you'll notice the large tanks used to hold the distillate fuel.

Although this plant is mostly dormant, I wouldn't write it off completely. Its in the NEMA zone which is capacity constrained, it has grid interconnection, a water source, and excellent proximity to load. I'd be willing to bet that Exelon is thinking about re-powering this unit as a modest combined cycle.


Power Plant of the Week - NRG's Kendall Cogen

Those who know me, know that I love physical infrastructure. One of the most delightful things about having office space at the Cambridge Innovation Center is my proximity to and view of the Kendall Cogeneration Plant. This plant has an output capacity of about 225 MW in the summer and 265 MW in the winter. It primarily burns natural gas, but it does have the capability to burn No. 6 oil when gas supplies are tight, although its permits limit oil burn to approximately 720 hours a year. 

This plant really captures many of the environmental and market issues facing power plant operators in the Northeast. The plant was built by CELCo, the regulated utility that ultimately became a part of NStar. It was sold off during deregulation and underwent a massive renovation in the early 2000s that involved a switch to natural gas as its primary fuel. Red Line commuters may have noticed for years that the river never seemed to freeze in winter along the northern bank between the Longfellow Bridge and the Museum of Science. The waste heat discharged as hot water from the plant into the Charles (up to 70M gpd) probably had something to do with this. The Conservation Law Foundation appealed the Kendall Cogen's water quality permit arguing that too much waste heat was entering the Charles. The result was an agreement whereby the Kendall Cogen's owner agreed to construct a pipeline under the Charles to sell steam to Trigen's Boston system as a way to reduce waste heat discharges.

This agreement is a win for the environment, but now it puts the Kendall Cogen in a bind with ISO-NE because the new equipment required to sell steam to Trigen will result in a de-rate of the facility of 27 MW. Since the Kendall Cogen bid its full capacity into the 2016 Forward Capacity Market, ISO-NE is not allowing it to lower its capacity commitment for 2016 even though it must due so to comply with the settlement for its water quality permit. One of the reasons for this is because the plant is located in the NEMA zone of the ISO-NE grid which is seriously capacity constrained. 

Due to the controversy over the Footprint power proposal in Salem, future PPotW featured plants will be in the NEMA zone.