District Heating: Utilizing Waste Heat from the McNeil Power Plant

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Trip to St. Paul, Minnesota and Vancouver, British Columbia

Submitted by: Curt McCormack

Our hosts in both cities were the heads of their organizations and they devoted virtually all of their time to us and our work. We had extremely informative meetings with them and with other engineers, operators and consultants. They were very interested in what we are doing in Burlington as well making for valuable give and take for all of us. Speaking for myself, I find touring the facilities with the engineers who run them essential to understanding what they are all about and why they cost what they do. It is inside the facilities that we learn what they think could have been done better and what is working as good or better than planned. We benefit from their success as well as their shortcomings.

In St. Paul, they had to develop the biomass heating plant and in Vancouver, a larger biomass plant is in development. They are already district heating a portion of the city by using sewage waste water sourced heat pumps. Both cities were absolutely envious of our task: get the hot water to places that can use it, the plant and its waste heat, already being in place. The biomass plant is the most expensive, difficult to site, controversial element of the entire district energy systems and we already have that element.

Some notable things that I learned include:

St. Paul

  • Affirmation of the tremendous amount of energy savings and CO2 emissions reductions can be had by utilizing the waste heat from the McNeil generating station. There is enough waste heat presently going up the stack and out of the cooling towers to heat the entire city of Burlington, UVM, the hospital, all government offices, businesses and homes, the entire heating load of Burlington.
  • The St. Paul biomass electric power plant at only 32 megawatts (McNeil is 50) is using waste heat to heat 80% of their downtown. Theirs is actually a more complicated district energy system than what is envisioned for Burlington. They accept other surplus heated water INTO their system from a large hospital for back-up (not much larger than the UVM Medical Cte,. – St. Paul, 1.8 million square feet, UVM, 1.5 million square feet) and their own 1 megawatt solar thermal system (largest solar thermal system in the U.S.). A larger city and a smaller biomass plant compared to Burlington, their system still uses some fossil fuels. The system, at this point, is supplied by 15% coal and oil; 20% natural gas; 65% biomass.
  • The private not-for-profit St. Paul ownership and operations structure is the same as what is envisioned for Burlington. Elements of theirs might be appropriate for ours i.e. the means for membership on the board of directors and 100% debt financing.

Vancouver

  • Many of the political as well as technical challenges in Vancouver are not unlike ours i.e. a private natural gas company supplied the energy to most of the district heating customers such as the University of B.C. (UBC). Natural gas was supplanted in St. Paul as well. UBC has constructed their own biomass plant to generate electricity and use the waste heat for heating a portion of the campus. Regarding the supplanting of natural gas with biomass, they, as well as the City developing the larger district energy plan, were able to make the case before their equivalent of our Public Service Board, that the CO2 emissions reductions were substantial and that these reductions could be accomplished at a monetary savings to the school.
  • Another reason for their success is timing. The City is developing many brown fields in prime locations. New construction is an opportunity to connect to district heating as opposed to replacing existing individual heating plants. At UBC, the most recent boiler was installed in 1969. In Burlington, the timing is right as well and for the same reasons: a development boom of brown fields and other in-fill. However, in Vermont, the zeal for electric, air-sourced heat pumps is giving us new construction with heating systems that are not hydronic. This will make it more expensive to connect to district heating. Heat pumps can obtain their heat from water as well as air. This question needs consideration if we have a future that will take full advantage of a district heating system fueled by McNeil.