Ameresco Inc. and Terrestrial Energy are advancing an advanced-nuclear power project at the U.S. Army’s Aberdeen Proving Ground in Maryland, putting a specific reactor technology behind one of the Army’s newly selected commercial energy-resilience developments. Terrestrial Energy said on September 21 that it will support Ameresco as the supplier of advanced nuclear technology for the project, using its Integral Molten Salt Reactor, or IMSR, plant design. The announcement follows the Army’s competitive selection of Ameresco under its Strategic Capital Initiatives program and gives greater definition to a proposed energy campus expected to combine conventional firm generation with next-generation nuclear power.

The project is planned as a phased commercial power development that would provide generating capacity to the regional electricity market while improving the ability of Aberdeen Proving Ground to maintain critical operations during disruptions to the surrounding grid. According to Ameresco and Terrestrial Energy, the proposed campus would incorporate natural-gas generation and advanced nuclear generation. Terrestrial Energy’s IMSR technology has been identified as the proposed nuclear solution for the later nuclear phase of the Aberdeen development. That combination reflects a strategy in which generation that can be deployed on different schedules is integrated into a single long-term resilience project rather than waiting for every component to become operational simultaneously.

Ameresco’s position stems from the U.S. Army’s September conditional selection of private-sector companies to develop commercial generating assets on underutilized land at several Army installations. For Aberdeen Proving Ground, the Army selected Ameresco to enter negotiations for a long-term Enhanced Use Lease. Ameresco was also selected for a separate project at Picatinny Arsenal in New Jersey, although the technology mix there is different. The Aberdeen selection does not constitute final authorization to construct the proposed facilities. Ameresco and the Army must negotiate the lease, while the project must pass environmental, regulatory, permitting, siting and other required reviews before physical construction can proceed.

The distinction is important for investors and the broader advanced-nuclear industry. The September announcement establishes a development pathway and preferred commercial partners, but significant milestones remain between site selection and an operating nuclear plant. Ameresco said development work is beginning immediately even as lease negotiations proceed. The Army, meanwhile, has said formal lease agreements for its Strategic Capital Initiatives power projects remain in their initial stages. Across the wider program, development could begin as early as 2027, with initial operating capability targeted by or ahead of 2030, although individual technologies and sites may follow different schedules. Terrestrial Energy has separately been working toward initial IMSR commercial deployments in the early 2030s.

The Army is using its Enhanced Use Lease authority under 10 U.S.C. § 2667 to structure the projects. Under that model, the federal government retains title to the underlying property and leases qualifying non-excess, underutilized land to private developers. The Army describes itself as the landlord rather than the owner or operator of the generating business. Private-sector lessees are expected to bear the costs and responsibilities associated with financing, designing, building, operating, securing and eventually decommissioning the facilities. The framework is intended to attract private capital to military-site infrastructure while creating energy capabilities that can also support installation missions.

That commercial structure makes the Aberdeen project different from a conventional government procurement in which the Army directly purchases and owns a power plant. The generating assets are intended to participate in the broader electricity market, adding market-based capacity while maintaining an ability to support the host installation under defined outage conditions. The approach potentially gives developers a wider revenue base than an installation-only project while providing the Army with resilience benefits connected to large-scale generating infrastructure located directly on federal property.

For Aberdeen Proving Ground, the advanced-nuclear component centers on Terrestrial Energy’s IMSR design. The company describes the technology as a Generation IV molten-salt reactor designed to produce both electricity and high-temperature heat. The proposed commercial plant has a nominal electrical output of 390 megawatts and uses a modular architecture intended to support factory-oriented component production and comparatively streamlined on-site construction. Terrestrial Energy says the design operates at high temperature and low pressure and incorporates inherent safety characteristics associated with its molten-salt reactor configuration.

A notable element of the IMSR fuel strategy is its planned use of standard-assay low-enriched uranium, or SALEU, enriched to less than 5% uranium-235. That differs from several other advanced-reactor concepts that anticipate using high-assay low-enriched uranium, commonly known as HALEU. Terrestrial Energy argues that relying on standard enrichment allows the IMSR to draw on established commercial nuclear-fuel supply chains and reduces exposure to the still-developing HALEU supply market. Fuel availability has become an important commercial consideration across the U.S. advanced-reactor sector because deployment schedules can be affected not only by licensing and construction but also by the availability of qualified enrichment and fabrication capacity.

The Aberdeen project also builds on a relationship that Ameresco and Terrestrial Energy established before the Army selection. In June 2025, the companies announced a collaboration covering the identification of potential U.S. sites and development of IMSR power projects, including project design, licensing, construction and operations. That agreement contemplated integrating the nuclear technology with other energy systems and specifically discussed using natural-gas generation as an energy bridge capable of delivering electricity before completion of the nuclear facility. The Aberdeen plan now provides a concrete federal installation where elements of that development strategy could be applied.

Ameresco brings experience in designing, financing and operating energy infrastructure for government and commercial customers, including projects where reliability and lifecycle management are central requirements. The company said it has delivered more than $15 billion of energy and infrastructure solutions and contracted more than 5 gigawatts of energy resources since its founding in 2000. In the Army project, its role extends beyond supplying equipment: the Enhanced Use Lease framework places responsibility for the commercial development, financing and long-term operation of the facilities on the private-sector partner.

Terrestrial Energy, meanwhile, gains another potential deployment site as it works through the technical and regulatory steps required to commercialize the IMSR. The company has been engaged with the U.S. Nuclear Regulatory Commission in pre-application activities concerning the reactor design. Those interactions are intended to resolve important technical and safety topics before a project-specific license application is submitted. A federal-site development agreement does not replace NRC licensing requirements, and the Aberdeen nuclear facility would still have to satisfy the applicable nuclear regulatory framework before construction and operation of the reactor could be authorized.

Environmental review is another major development gate. The Army has said no construction will begin on the Strategic Capital Initiatives projects until required reviews and permits are complete. These include processes under the National Environmental Policy Act as well as applicable Clean Air Act, Clean Water Act and federal, state and local requirements. For a project combining natural-gas generation and nuclear technology, the development process could involve multiple environmental, transmission, utility, security, emergency-planning and land-use considerations. Ameresco has described the Aberdeen proposal as subject to final agreements and all required approvals.

The Army’s broader rationale is energy resilience. Military installations depend on surrounding commercial grids for much of their electricity, exposing them to outages caused by extreme weather, equipment failures, cyber incidents and other disruptions. On-site generation can reduce that exposure when it is designed to continue serving priority loads during external interruptions. The Strategic Capital Initiatives program seeks to combine that resilience objective with private investment and commercially operated assets rather than funding every component through traditional military construction channels.

The Army announced conditional commercial-power lease awards covering several installations and three private-sector groups. Ameresco was selected for Aberdeen Proving Ground and Picatinny Arsenal; other developers were selected for projects at Fort Detrick, Letterkenny Army Depot, West Point and Tobyhanna Army Depot. The proposed technologies across the program include natural gas, nuclear generation and battery storage. The variety of technologies indicates that the Army is not pursuing a single standardized generation model but is matching different commercial solutions with the technical, geographic and mission requirements of individual installations.

Aberdeen stands out within that portfolio because the project connects the Army’s near-term interest in dependable firm generation with a potential commercial deployment of a Generation IV reactor. Unlike intermittent generation, both natural gas and nuclear technologies can be designed to provide continuous output, which can be important for installations with research, testing, communications and other mission-critical loads. For the regional power market, a large commercial nuclear facility could also represent substantial firm generating capacity if the project reaches operation, although final project capacity, configuration, interconnection arrangements and operating schedules remain subject to development.

The commercial implications for Ameresco also remain preliminary. The company explicitly cautioned that the Army selection is a development-stage opportunity and is not necessarily indicative of when or how much revenue might ultimately be recognized. The Aberdeen and Picatinny projects were not included in Ameresco’s reported project backlog as of June 30, 2026. That disclosure underscores the distance between securing exclusive lease negotiations and booking a fully contracted construction project. Final economics will depend on lease terms, capital requirements, power-market arrangements, regulatory outcomes, project financing and the ultimate configuration of the generating assets.

For Terrestrial Energy, Aberdeen potentially expands a growing portfolio of prospective U.S. applications for its reactor beyond purely industrial and data-center markets. The company has positioned the IMSR as a source of both firm electricity and high-temperature industrial heat, arguing that the reactor’s configuration can serve customers whose energy requirements extend beyond conventional grid power. A military installation introduces a different demand profile, with resilience and mission assurance placed alongside commercial power-market economics. Successful progression at Aberdeen could therefore provide an important demonstration of how advanced reactors may fit into large-scale defense infrastructure.

The announcement also illustrates a wider shift in the business model surrounding advanced nuclear projects. Instead of relying solely on regulated utilities constructing large baseload stations, reactor developers are increasingly pursuing partnerships with industrial users, technology companies, government sites and energy-infrastructure developers. These arrangements can combine site access, private capital, power-purchase structures and specialized demand in ways intended to make first-of-a-kind projects commercially viable. Ameresco’s role as an infrastructure developer and integrator gives Terrestrial Energy a partner capable of coordinating the nuclear system with non-nuclear generation and other site infrastructure.

Still, the main investment question is execution. Advanced nuclear projects face long development timelines, significant capital requirements and intensive regulatory review, while first commercial units also carry engineering, manufacturing and construction risks. Terrestrial Energy itself identifies potential licensing delays, cost overruns, specialized-component supply constraints and financing requirements among the risks associated with bringing IMSR plants to market. The Aberdeen site provides a significant potential customer and development setting, but it does not eliminate those underlying project risks.

The next milestones are therefore likely to center on converting the Army’s conditional selection into enforceable project arrangements. Ameresco must complete lease negotiations, define the commercial structure and continue technical and environmental development. The nuclear portion will require progress through the NRC process, while the overall campus will need the permits, interconnection arrangements, financing and construction plans required for a large commercial generating project. The Army has also emphasized community and state engagement, environmental mitigation and compatibility with ongoing installation missions as prerequisites for development.

For now, the September 21 announcement moves the Aberdeen proposal from a broad Army commercial-power selection toward a more defined technology plan: Ameresco as the infrastructure developer and Terrestrial Energy’s IMSR as the proposed advanced-nuclear component. If the partners can complete leasing, regulatory, financing and construction milestones, Aberdeen Proving Ground could become both a commercial power-generation site and an early federal deployment venue for Generation IV nuclear technology. The immediate significance, however, is the establishment of a development pathway rather than an imminent reactor build, with substantial regulatory and commercial work still ahead.