Vicinity Energy, a Boston-based district energy provider, has started demolition of a natural gas boiler at its Kendall Square facility in neighboring Cambridge, Massachusetts, in preparation for the installation of a 35MW (9,952TR) ammonia (R717)-based steam heat pump.

German engineering and manufacturing company Everllence, formerly MAN Energy Solutions, will provide the industrial-scale heat pump. Development company DCO Energy will install the system and perform plant modifications to integrate it with the facility’s existing infrastructure, with completion expected in 2028. Vicinity brands its carbon-free thermal energy as “eSteam.”

“[This project] enables immediate, scalable carbon reductions without the need for costly and time–intensive new electrical infrastructure in Greater Boston,” said Kevin Hagerty, Vicinity Energy’s CEO.

This climate-neutral project will deploy the “world’s largest steam heat pump,” according to Everllence. Most legacy systems in the U.S. and Canada use steam for heating. The new unit will supply heating to Vicinity’s partners in Boston through its existing 29 miles (46.7km) of underground steam piping.

Vicinity reports that it has already secured a “significant portion” of the heat pump through long–term contracts with medical and educational institutions, including Emerson College and life-sciences developer IQHQ. “By adopting eSteam, these institutions are not only advancing their sustainability goals but also positioning themselves to comply with local requirements and aligning with Massachusetts’ Stretch Energy Code,” the provider said.

The details: The new system, capable of producing roughly 50 metric tons of steam per hour, will provide heating for a building space of more than 70,000,00ft² (6,500,000m²) with the Charles River as a heat source, according to Everllence.

• “[Our] solution integrates a vapor compression cycle with steam compression, enabling the generation of high-pressure steam at up to 50bar [725psi] and over 300°C [572°],” the manufacturer said, adding that it uses two multi–shaft integrally geared compressors: type RG40–8 for refrigerant compression and type RG63–6 for steam compression.
• Although he did not indicate the energy type, Hagerty said that the heat pump will operate primarily on renewable electricity.
• To support system operation from startup, Everllence developed an “extensive” digital twin, which allows compressor stress testing during the engineering phase.

Moving forward: Installing the steam heat pump is the second phase of Vicinity’s decarbonization strategy for the Cambridge facility. In the first phase, which started in 2024, the energy provider installed a steam-producing 42MW (11,940TR) electric boiler powered by renewable energy sources.

• The final phase of the Boston project includes installing thermal storage to support on-demand steam from renewable electricity, according to Vicinity.
• “We are establishing the blueprint of how to decarbonize a U.S. city and will be installing similar innovative electrification technologies at our district energy systems across 12 U.S. cities,” Hagerty said.
• The company reports already starting an electrification project in Grand Rapids, Minnesota, with the installation of a 9MW (2,560TR) electric boiler underway.

European projects: Everllence has large-scale ammonia, CO₂ (R744) and hydrocarbon heat pumps in district heating projects throughout Europe.

• Three of Everllence’s ammonia units will supply a district heating capacity of 150MW (42,651TR) to heat approximately 50,000 households in Cologne, Germany, with an expected 2027 startup.
• In December 2024, the company commissioned a 30MW (8,530TR) CO₂ heat pump to deliver heat to 25,000 homes in Esbjerg, Denmark.

Quotable: “District heating remains one of the most efficient and sustainable ways to deliver thermal energy to commercial and industrial users,” said Uwe Lauber, CEO and Chief Sales Officer of Everllence. “With this latest agreement, we are taking a major step forward with Vicinity to bring our proven mega heat pump technology to the U.S. market.”

“With this latest agreement, we are taking a major step forward with Vicinity to bring our proven mega heat pump technology to the U.S. market.”

Uwe Lauber, CEO and Chief Sales Officer of Everllence