The Department of Defense is moving forward with a plan to use mobile nuclear microreactors as a power source for operating bases in “remote and austere” environments.

The plan comes after Indiana legislators passed laws enabling small nuclear reactors to be built in the state as sources of clean energy.

The DoD’s Strategic Capabilities Office released the agency’s plan to build a prototype mobile microreactor capable of producing up to 5 megawatts of electrical power at the U.S. Department of Energy’s Idaho National Laboratory.

The microreactor will be small enough to be hauled by a semi tractor-trailer and will produce enough energy to power about 650 homes for a year.

The DoD said the project, known as Project Pele, would address the agency’s growing demand for resilient, carbon-free energy that would support mission-critical operations in remote and harsh environments and in areas recovering from natural disasters.

“Advanced nuclear power has the potential to be a strategic game-changer for the United States, both for the DoD and for the commercial sector. For it to be adopted, it must first be successfully demonstrated under real world operating conditions,” said Project Pele program manager Jeff Waksman.

The final design of the microreactor has not been finalized, but so far, the DoD has invested about $170 million in the project. The final price tag will most likely be much higher.

The DoD’s interest in the microreactors could help reduce the climate change impact of the U.S. military in the future. At least one branch, the U.S. Army, is seeking to halve its greenhouse gas emissions within the next 10 years, and microreactors could eventually help it reach that goal.

But critics have warned the microreactors would be unsafe and unsound for their intended purpose — forward operating bases, meaning those near combat zones, and other expeditionary facilities.

A committee report from the National Academies of Sciences, Engineering and Medicine found that the relatively small power output, along with the three-day setup time and two-day cooldown period for microreactors, would be impractical for use in forward areas due to the projected high speed of future military operations.

Another report, from the University of Texas’ Nuclear Proliferation Prevention Project, found that mobile nuclear power plants could be especially vulnerable near forward areas, as attacks from U.S. adversaries targeting reactors could cause a radioactive release, potentially exposing thousands of troops.

The studies found that microreactors could be better suited for permanent domestic and overseas bases.

Waksman said building the microreactor is necessary to finding out its strengths and weaknesses.

“It’s very complicated. There’s a reason why nobody other than the Navy has actually built a reactor from scratch in the United States since the mid-1970s. But should this be a success, should we build this reactor, it’s a huge strategic game changer for the Army and for the country as a whole,” Waksman told the U.S. Navy Postgraduate School in 2021.

The Biden administration and some environmental groups have argued that adopting nuclear energy is “absolutely essential” to improve air quality and meet ambitious climate goals set by the administration.

The U.S. nuclear industry, hoping to take part in the global civil nuclear market estimated to be worth $500-$740 billion over the next decade, has pushed the federal government and state governments to adopt policies to ease the industry’s entrance into the market.

In Indiana and other states, legislators passed laws allowing the construction of small modular nuclear reactors, which are larger and more powerful than microreactors but a fraction of the size of traditional reactors.

Indiana’s law adds small modular reactors to the list of clean energy projects eligible for financial incentives, including the recovery of costs through rate increases for utility customers.

Consumer groups and environmental groups have warned that incentivizing unproven nuclear projects would result in costly failures that provide no clean energy while leaving ratepayers to pay for the effort for decades and while stifling the progress of wind and solar energy projects in the state.

Within the last decade, efforts in Georgia and South Carolina to build traditional reactors have resulted in billion-dollar cost overruns and delays. Ratepayers in Georgia paid an extra $3.5 billion in their electric bills for a nuclear power plant that may not be completed until 2024. Ratepayers in South Carolina paid $2.3 billion in extra charges for a nuclear plant that was started but later scrapped.

Indiana had its own failed nuclear project in the early 1980s, when the Public Service Company of Indiana, now Duke Energy Corp., abandoned the Marble Hill Nuclear Generating Station project in Jefferson County midway through construction.

The company spent $2.5 billion, or $6.7 billion in today’s dollars, during its failed attempt. The company recouped its investment by increasing utility rates for its customers for more than 20 years.

Groups like the Citizens Action Coalition and Hoosier Environmental Council unsuccessfully petitioned lawmakers to delay adding the clean energy incentives to the bill until the technology was more established and companies are able to resolve issues like the fate of spent nuclear fuel, the overall price and whether nuclear projects can actually be completed.

According to the DoD, the only way to answer those questions is to build a reactor.

“We know that this is hard, but the only way to know whether this might work is to build one. You can sit around and do policy papers until you’re blue in the face, but until someone actually builds a reactor that powers a lightbulb somewhere, you really just don’t know if you’re going to be able to do this or not. You really don’t know what the cost is going to be. So, it’s our belief that it’s crucial to the country to do this prototype and see how it goes,” Waksman said.

If the construction of the microreactor goes as planned, it will be the first one built in the U.S. The U.S. Air Force has also said it would install a microreactor at Eielson Air Force Base in Alaska as early as 2027.

The Idaho National Laboratory is also the planned home for the country’s first small modular reactor power plant, the Carbon Free Power Project. Just months after construction began, the utility group in charge of the project said it would be delayed by at least three years and cost $2 billion more than initially thought.