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Clean Up the State Owned Power Plant
Part 3

Carly Densem

December 2022

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Hi Readers, 


This is Carly, the intern with Sierra Club Connecticut. Sierra Club, alongside individuals and organizations in Hartford and allies across the state, is advocating for the state of Connecticut to replace the aging Capitol Area System with 100% clean and renewable energy. I wanted to share some more facts regarding the Capitol Area System (previously referred to as CDECCA) that I have learned through my internship. Below are some details of the history of this facility and current information regarding how it’s powered, works, and what it provides to different buildings. 


The Capitol Area System was built in 1988 and was planned to power, heat, and cool Aetna’s (the original owner of the plant) buildings along with the Legislative Office Building that was being built at the time. The plant is located at 490 Capitol Avenue in Hartford. The fuel source was oil and fossil gas. 


The diagram in figure 1 is of the structure of the system when it was originally built in the 80s. It has not been structurally updated since 1988, so it’s safe to say that the system still looks like this. While this was the start of this system, it is no longer producing electricity, it no longer is used or owned by Aetna, and the buildings it serves have changed over time. 

Today it uses fossil gas to produce hot and chilled water, and steam. It is not considered a cogeneration plant because it does not provide electricity anymore. It heats and cools fifteen buildings, including multiple state buildings, the Bushnell Performing Arts Center, and an apartment complex. Figure 2 is an image of the system and the buildings it connects to from the Connecticut Department of Administrative Services (DAS).

The Department of Administrative Services webpage about the Capitol Area System notes that the system could expand this loop to buildings on Washington Street. It also says that the state is considering the installation of gas-fired hot water boilers as a first step. 


Our advocacy for a clean and renewable replacement seems to have the Department of Administrative Services reconsidering more gas. They instead will first be “issuing an RFP to solicit the assistance of consultants who have experience with the decarbonization of district heating and cooling systems.”  


This is good news. They are paying attention. We need to ensure that paying attention evolves into a full commitment to a 100% transition to clean energy for the Capitol Area System. A 100% transition would satisfy Governor Lamont’s Executive Order 21-3.


One of the ideas mentioned on the Department of Administrative Service’s website is ground source heat pumps. Geothermal energy is renewable, has been becoming increasingly popular for years, and should be considered in what the state decides to do. I have been researching this resource for the Sierra Club and believe that in addition to using it for the Capitol Area System, the state should investigate how to share this system with adjacent neighborhoods that have been harmed by the pollution from the Capitol Area System. 


On a cautionary note, the website also mentions hydrogen burning boilers². The website makes it a point to mention that by using hydrogen boilers CO2 emissions will be eliminated. The problem with this idea is that hydrogen can be considered worse than carbon because there is a higher probability of leaks because of the length it takes for hydrogen to get to its source. 


I hope that in reading this letter you have a better understanding of the Capitol Area System – its history and current status – and that it encourages you to stay on top of this issue. It affects all of those in Hartford, residents or not. I hope that you take to reading the Sierra Club newsletters often to inform yourself of going on in the state and the community. This will be the last newsletter I will be writing. Thanks to everyone who has sent a message to the Governor already. If you haven't, please head over to our Capitol Area System action page where you can write a message to the Governor and sign the petition. All support is appreciated.


Stay Warm!



Carly Densem

Carly Densem is an intern at Sierra Club Connecticut.


Read the first articles in this series:

Clean Up the State Owned Power Plant Part I

Clean Up the State Owned Power Plant Part II

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