Vicinity Energy, a Boston, Massachusetts-based district energy provider, plans to install a 35MW (9,952TR) ammonia (R717)-based steam heat pump at its district energy plant in Cambridge, Massachusetts, by 2028 as part of a major decarbonization project.
The heat pump will be provided by MAN Energy Solutions, a German manufacturer of compressors that are at the center of industrial heat pump systems. MAN and Vicinity announced a preliminary agreement in April 2023 to partner on this project for Vicinity’s Kendall Station facility in Cambridge, and launched an official partnership last December.
Replacing a fossil fuel-based system, the heat pump system will harness thermal energy from water in the nearby Charles River to evaporate the ammonia and then return the water to the river. This will generate high-pressure, decarbonized steam − branded as eSteam – and deliver it via an underground network to customers in Cambridge and Boston, including Emerson College and life-sciences developer IQHQ.
“District energy electrification is an efficient, economical pathway to decarbonize cities, and this project represents a pivotal step toward that goal,” said Kevin Hagerty, President and CEO of Vicinity Energy.
In the US, this will be the largest industrial-scale steam-generating heat pump installation, said Alex Gorosito, Sales Director – Region Americas Heat Pump Solutions for MAN Energy Solutions USA, based in Brookshire, Texas. It will be MAN’s first district energy project in the U.S., following several in Europe, which is ahead of the U.S. in the electrification of heat generation, he added.
Multi-phase project
Vicinity launched its electrification strategy for the Cambridge facility in 2022 by deconstructing a steam turbine. In its place, the company installed a steam-producing 42MW electric boiler powered by renewable energy sources; the boiler began operating in 2024. The heat pump project is the next piece of the puzzle.
“We are transforming our historic Kendall facility to meet our communities’ and customers’ needs by leveraging existing infrastructure and installing innovative technologies such as an industrial-scale electric boiler, a river-based heat pump complex, and thermal storage,” said Vicinity in a blog on its website.
Vicinity’s other 11 locations in major U.S. cities will undergo similar electrification processes in the coming years to achieve its goal of net zero by 2050.
The Vicinity system uses steam rather than hot water because in the U.S. and Canada most legacy fossil-fuel systems use steam for heating, explained Gorosito. “Steam can be a better fit for dense urban cities. For instance, it is energy-intensive to pump hot water to the top of high-rise buildings, whereas steam can easily rise to higher elevations due to its lower density and higher pressure.”
Steam also has a faster response, allowing for buildings to quickly heat during sudden increases in demand for heating, noted Gorosito. “This makes steam systems more efficient for heating tall buildings. Many large buildings also use direct steam for humidification and sterilization.”
Moreover, it would be too disruptive to excavate thousands of feet of crowded city streets for hot water piping installations in large urban centers like New York, Boston, Philadelphia and Baltimore, which already have the core infrastructure of existing steam distribution systems in place, Gorosito explained.
In Europe, new district energy plants are designed to heat hot water, making them more suitable to CO2 (R744) heat pumps, Gorosito said. More energy is needed to vaporize water so it is “a little bit more advantageous from an efficiency standpoint, to use hot water,” he added.
Last December, MAN said that a 70MW (19,904TR) CO2 industrial-scale heat pump installed in a district heating plant in Esbjerg, Denmark, had been successfully commissioned and was delivering heat to 25,000 homes.
Also last December, MAN announced that its new district heating plant along the Rhine in Cologne, Germany, will be Europe’s largest river-based heat pump system. It includes three ammonia-based heat pumps providing a total heating capacity of 150MW (42,651TR).
“District energy electrification is an efficient, economical pathway to decarbonize cities, and this project represents a pivotal step toward that goal.”
Kevin Hagerty, President and CEO of Vicinity Energy
