Article published by the NATO Energy Security Centre of Excellence, May 2025.
This analysis was conducted in 2024, prior to the inauguration of Donald Trump as the 47th President of the United States. It therefore reflects the climate policy positions of preceding administrations.
Over the past fifty years, the U.S. military has redefined its estates energy strategy, gradually replacing its dependency on fossil fuels with a more diversified and resilient energy portfolio. As both a massive energy consumer and a key global security actor, the military’s evolving energy landscape offers critical insight into the intersections of climate resilience, geopolitical strategy, and operational capability.
From Oil Dependency to Diversified Supply:
In 1975, fuel oil accounted for 65% of the Department of Defense’s (DoD) facility energy use, with coal at 25% and natural gas a mere 10%. Triggered by the oil shocks of the 1970s, the U.S. military began a gradual pivot away from imported fuels. By the 1980s, natural gas usage had doubled to 20–25%, thanks to its cleaner profile and cost advantages. By the early 2000s, it had overtaken oil, representing 45% of total consumption by 2005 and reaching 70% by 2020.
The Rise of Renewables and Microgrids:
This trajectory culminated in the 2020s with a significant push toward renewable energy. As of 2022, approximately 45% of electricity on U.S. military installations was generated from renewable sources, primarily solar and wind. Complementing this shift is the rapid development of localized microgrids designed to operate independently from national power systems. The U.S. Army has committed to deploying microgrids across all installations by 2035, reinforcing efforts to enhance energy resilience and autonomy.
Natural Gas: Bridge or Barrier?
While natural gas has been central to reducing emissions and enabling renewable integration, its use reflects a transitional strategy rather than a permanent solution. The expansion of domestic gas production, largely enabled by hydraulic fracturing, allowed the U.S. to avoid rising import dependencies post-1970s. However, projected trends suggest a continued reduction in both fuel oil and coal, with near-complete coal phase-out by 2030.
Navigating Risks: Technology, Cybersecurity, and Climate Extremes
The shift to digitalized, decentralized energy systems introduces new vulnerabilities. Increasing reliance on software-managed microgrids and renewables exposes critical infrastructure to cyber threats. The DoD now faces both a shortage of specialized technical personnel and the need for ongoing upskilling to maintain complex systems.
Climate change further complicates this transition. Extreme weather events, like hurricanes can reduce photovoltaic output by up to 60% and cut solar radiation by 80% over several days. Such impacts underline the need for dependable backup systems, including fossil fuel reserves, to ensure operational continuity during crises.
Geopolitical Constraints and Resource Dependence:
The renewable transition hinges on scarce materials such as lithium, cobalt, and rare earths — many controlled by non-allied nations. This raises concerns over supply chain disruptions during periods of geopolitical instability. The inability to store renewable energy in bulk further adds to the challenge of maintaining readiness in emergencies.
Looking Ahead: Balancing Sustainability and Security
To future-proof its installations, the U.S. military is modernizing its estates with climate-adaptive infrastructure, weather-informed planning, and on-site energy generation systems. Long-term success will depend on advances in storage technology, cybersecurity, and resilient design. The military’s experience illustrates that energy transition, when embedded in strategic foresight, can enhance both national and planetary security.
This text is based on extracts from an article written by Maëly Bardin, May 2025. To read the full paper, follow the link here.
See below for our coverage on similar topics:
- Impact of Critical Energy Infrastructure Security on Military Resilience and Energy Security within NATO
- Defence in a Climate-Changed World: Futureproofing its Licence to Operate
- Defence and Climate: Seven Points for a Common Agenda