Clean Energy Is Critical to U.S. Military Readiness

The U.S. Department of Defense (DOD) is under increasing pressure, facing both rising challenges from adversaries while contending with diminished domestic manufacturing capacity and recruitment issues. The U.S. fiscal position imposes clear limits on future defense budget increases. It therefore appears sensible to eliminate distractions and focus on the agency’s core mission: defending the country from outside threats.

As a result, climate change research and adaptation initiatives might be on the chopping block. That the DOD should be involved in such research might be surprising to some. However, all branches of the military have long recognized that changes in the natural environment impact their capacity to fulfill their mission. As a result, they have invested extensively in studying the environmental and political impacts of climate change.

As far back as 1990, the U.S. Naval War College assessed that future temperature increases warranted “serious examination by the Navy.” Although this assessment was released more than three decades ago, it set a course that has guided the Navy’s thinking on climate change since then. It argued that the increased occurrence of natural disasters and droughts could have calamitous security impacts, fueling increased migration flows and conflicts. Further, it found that the effects of climate change could directly threaten the Navy itself—sea level rise could imperil bases, increased storm intensity and frequency could impact operations, and changes to the natural environment could render fleet technology obsolete or less functional. The report also warned that climate change could threaten future Navy capacity indirectly by imposing growing climate mitigation demands on federal budgets and forcing the Navy to engage in domestic disaster relief, detracting from its ability to focus on defense.

The report recommended that the Navy take action early to prepare and place itself at the head of DOD research efforts on climate change. To that end, it called for increased investment in climate monitoring and for the Navy to raise its capacity to adapt. Since then, the DOD has funded climate science research, and has invested considerably in new technologies to “climate proof” its bases. The 2024 Climate Adaptation Plan outlined that “DOD has been forced to absorb billions of dollars in recovery costs from extreme weather events typical of those fueled by climate change.” To manage these threats and reduce disruptions from extreme weather, DOD has invested in more resilient infrastructure, such as the building of sea walls to protect against flooding. Importantly, DOD’s climate research has also created resources like the Regional Sea Level Database and the Climate Assessment Tool, which provide invaluable insight into the environmental vulnerability of U.S. bases and enable DOD to safeguard service members while saving taxpayer money.

DOD has also become interested in clean technologies due to the budgetary and strategic downsides of fossil fuels. In the face of rising oil prices, the Defense Science Board presented a report in 2001 to the Office of the Undersecretary of Defense for Acquisition and Technology that directly linked U.S. military capacity with fuel efficiency and identified outsized fuel use as a major strategic liability. The report noted that the price that individual branches paid for fuel did not account for the costs of delivery. Delivering a single gallon of fuel to a battlefield tank could, in some circumstances, cost as much as $600, while procurement managers typically charged a flat fee of no more than $3 per gallon internally. Moreover, budgetary politics often actively discouraged fuel economy, as reduced use would result in lower budget allocations in the future.

Not only did these practices raise the costs of operations, but they also put service members’ lives at risk. During the wars in Afghanistan and Iraq, for example, U.S. forces had to deliver enormous quantities of petroleum to supply bases and forward operations. These fuel supply missions created stinging vulnerabilities that were ruthlessly exploited by enemy combatants. In Afghanistan in 2007 alone, one soldier or civilian was killed for every 24 fuel resupply convoys—nearly 900 fuel resupply convoys were needed per year.

The strategic liability of fossil fuel use has motivated a flurry of research and technological experimentation. Units began powering bases and electronics with solar photovoltaics and conducted research into new propulsion systems, more efficient energy storage, and base insulation to improve efficiency and reduce reliance on costly refueling operations. These scattershot efforts became official DOD energy policy after the 2010 Quadrennial Defense Review, which identified energy security as a national security priority for the United States. The review laid out how DOD expected climate change would affect the international strategic environment and stressed that the current energy demands of the agency were too high. It warned that business as usual could imperil strategic capacity in the future, while laying out how investments in energy resilience would amplify it.

Since then, all U.S. military branches have continued to pursue both climate mitigation and adaptation projects. DOD has invested in energy efficiency measures at bases, ranging from the installation of LED lights to the electrification of noncombat vehicles and the building of large onsite solar farms and energy storage capacity. Between 2010 and 2023, DOD increased its renewable electricity consumption by 80 percent. In 2023, the DOD finalized what was, at the time, the world’s largest combined solar power and integrated energy storage project at Edwards Air Force Base. Onsite energy generation and storage insulate military installations from reliance on the commercial grid, thereby improving resilience against both foreign actors and natural disasters.

DOD is also involved in more cutting-edge energy research and has found applications that increase military capacity. Such efforts include relatively mundane technologies, like more energy-efficient doors or soybean-based tires, that create considerable cost savings. But there are also more spectacular projects. For example, the Air Force’s Research Laboratory, the Naval Research Laboratory, and several commercial partners are collaborating on the Space Solar Power Incremental Demonstrations and Research Project, an initiative to develop technology to harvest solar energy in space and wirelessly transmit it back to Earth. Further, DOD is working with the Idaho National Laboratory to develop a transportable nuclear microreactor.

Ongoing research and development coordinated by DOD is creating and deploying a wealth of innovative technologies that promise to reduce energy costs, while boosting capabilities. To this end, “energy resilience” was included in fourteen critical technology areas integral to US national security as outlined in the 2023 National Defense Science and Technology Strategy. The Secretary of Defense established the Office of Strategic Capital in 2022, which seeks to “crowd in” private capital into areas of core national security interest, which include technologies like advanced energy storage, novel energy generation, and energy efficiency tech.

Further building upon the readiness benefits of fuel efficiency, the military continues to advance energy innovations in partnership with the private sector. Together with private partners, the Army has developed more capable battery technology to be used in communication devices, drones, electric vehicles, and ground robots. Similarly, the Navy develops and tests solar-propelled “eternal drones” with integrated battery storage, creating unmanned aerial vehicles that never need to refuel. The Air Force collaborates with industry on the development and integration of jet fuel derived from captured carbon dioxide. Through such collaborations, DOD accelerates the development and deployment of technologies that the department considers crucial to its future warfighting capabilities, while also incubating innovative new businesses that drive economic growth and create good jobs.

Climate change does indeed imperil DOD’s operational capacity, according to its assessments over the past several decades: environmental threats and changed circumstances impact readiness and create life-or-death risks for troops. Moreover, through the DOD’s efforts to become more energy efficient and reduce fossil fuel use, it has created more capable tools that amplify American military power. Ignoring these realities and blocking the DOD’s capacity to monitor, prepare, and mitigate climate threats, while fielding a more capable force equipped with new technology, is a self-defeating strategy.

Nicolas Wittstock is an assistant professor of political science at Boston University, formerly a 2024-25 IGCC postdoctoral fellow in technology and international security.

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