Geothermal & Thermal Energy Networks
Conducted by boreholes 5-10 kilometers underground, geothermal energy is energy that is exchanged with the ground or a body of water.
“You have a ground array or loop at the bottom where we’re circulating heat exchange fluid, which is generally water and an antifreeze agent,” explained Mark Metzner at a recent webinar on Selecting and Applying Geothermal & Thermal Energy Networks.
Metzner has worked on major geothermal utility programs across the United States and Canada, including district energy systems. “We’re picking up low grade energy from the earth, moving it up into a building where the heat pump resides, and it goes through a refrigeration cycle that basically compresses a refrigerant," he said. "And we’re exchanging the low-grade energy from the earth across a heat exchanger into the refrigerant. It gets compressed, and the temperature gets boosted. And we can then take that heat and condition space for occupancy comfort.”
There are two primary design philosophies that inform geothermal networks. The centralized design philosophy places critical equipment within a localized area so that finished energy fluids can be sourced to buildings within a specific area. This approach is especially attractive to urban planners, for whom space is at a premium. The other design philosophy—the decentralized approach—is where low- or ambient-temperature energy would be distributed for use by heating pumps. This philosophy makes the most sense in new buildings and is a more efficient system as it can distribute diverse energy loads across building types.
Centralized vs. Decentralized
The objective is to identify areas where you can have initial success and or wins, and you can communicate that success to the public.
Greg Koumoullos is a Clean Energy Project Manager at Con Edison. He has nearly two decades of experience in various fields including gas, engineering and construction. Koumoullos and his team at Con Edison identified 10 potential geothermal pilot projects from Manhattan to Westchester County, N.Y., eventually narrowing the list to three pilots: Chelsea, Rockefeller Center and Mount Vernon. The Mount Vernon network will consist of one to four family housing, low-income residences, the city Fire Department and a recreation center as well as six churches throughout Mount Vernon. This project includes three separate bore fields to be installed on private property and on the land of some churches owned by the city of Mount Vernon. A 16-inch HDPE piping system will then be built to connect all these anchor points by a utility thermal balancing station. This would require Con Edison to acquire a home in the local area to convert into a thermal balancing station for the Mount Vernon project.
Con Edison’s next stop is in the neighborhood of Chelsea, located on the lower west side of Manhattan. The building currently requires lots of cooling conducted by towers on the roof of the structure. Con Edison’s plan would be to use geothermal energy to provide waste heat to multi family buildings in the Chelsea neighborhood. This project would also provide heating and cooling to the Fulton Housing buildings in Chelsea.
Con Edison’s third pilot project is the world-famous Rockefeller Center. This project will use a central plant to power three high rise buildings. This project will allow the buildings to repurpose equipment like ice chillers and condensate recovery systems. All three of these geothermal energy projects, led by Koumoullos and his team at Con Edison, are revolutionizing the future of geothermal energy in New York State.
As an owner there are many opportunities and challenges when it comes to using geothermal. Bob Button, an environmental engineer and client service leader at CDM Smith, has worked with multiple high-profile clients on geothermal energy projects in New York City and Massachusetts.
“Everyone is working to do something different than has been done before, implement new strategies and implement them in areas where there are many challenges that they're facing,” said Button. As owners go about implementing geothermal for their clients and themselves it is important for them to focus on their long-term goals. “The objective is to identify areas where you can have initial success and or wins, and you can communicate that success to the public as a way to continue to build support for the projects and the programs that you're trying to do.”