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The Hidden Dangers of a Carbon-Neutral Military

If the U.S. military goes electric, it could be good for the planet—and bad for national security.

By , a faculty member at the U.S. Naval Postgraduate School, and , a faculty member at the U.S. Naval Postgraduate School.
A worker washes one of two M1A1 Abrams tanks.
A worker washes one of two M1A1 Abrams tanks that are loaded on rail cars at a rail yard in Washington on July 2, 2019. Mark Wilson/Getty Images

Washington has encouraged the electrification of wide swathes of the U.S. economy as a way to encourage greater use of renewable energy and reduce carbon emissions. The U.S. Defense Department, the largest consumer of energy in the U.S. federal government, is now considering pursuing its own wide-scale electrification. Such a step would have profound strategic effects that should cause policymakers to proceed far more cautiously.

In recent months, the Pentagon has launched studies to examine increased use of electricity by the military, including in battle for vehicles, tanks, ships, and planes. The Pentagon has even studied the deployment of small nuclear reactors in the battle space to provide power. NATO is also promoting increased electrification of its allied militaries. According to NATO Secretary-General Jens Stoltenberg, “it makes little sense to have more and more electric vehicles on our streets while our armed forces still rely only on fossil fuels.”

What Stoltenberg said sounds intuitive but may not be true. Each time a military makes a major change to its energy system, it inevitably has immense geopolitical implications. When former British Prime Minister Winston Churchill made the decision to transfer the main source of fuel for the British Royal Navy from coal to oil, he understood the decision had significant strategic implications. Fueled by oil, the British Royal Navy could cover larger distances without refueling and at quicker speed. Yet, through this decision, London would be dependent largely on foreign-produced oil versus homegrown coal.

Washington has encouraged the electrification of wide swathes of the U.S. economy as a way to encourage greater use of renewable energy and reduce carbon emissions. The U.S. Defense Department, the largest consumer of energy in the U.S. federal government, is now considering pursuing its own wide-scale electrification. Such a step would have profound strategic effects that should cause policymakers to proceed far more cautiously.

In recent months, the Pentagon has launched studies to examine increased use of electricity by the military, including in battle for vehicles, tanks, ships, and planes. The Pentagon has even studied the deployment of small nuclear reactors in the battle space to provide power. NATO is also promoting increased electrification of its allied militaries. According to NATO Secretary-General Jens Stoltenberg, “it makes little sense to have more and more electric vehicles on our streets while our armed forces still rely only on fossil fuels.”

What Stoltenberg said sounds intuitive but may not be true. Each time a military makes a major change to its energy system, it inevitably has immense geopolitical implications. When former British Prime Minister Winston Churchill made the decision to transfer the main source of fuel for the British Royal Navy from coal to oil, he understood the decision had significant strategic implications. Fueled by oil, the British Royal Navy could cover larger distances without refueling and at quicker speed. Yet, through this decision, London would be dependent largely on foreign-produced oil versus homegrown coal.

Today, the United States’ energy mix is well diversified: oil, natural gas, coal, nuclear, hydropower, biofuels, wind energy, and solar energy. Diversification is a key element of any energy security policy and a cornerstone of a system’s resilience. By relying more heavily on electricity and by regulating electricity generation in ways that phase out fossil fuels, the number of major energy sources widely consumed in the United States will inevitably shrink to a less diversified mix.

It will also make the United States more reliant on foreign actors. The bulk of energy supplies currently consumed in the United States are homegrown. The United States can supply all its oil, natural gas, and coal needs as well as uranium for nuclear power. The policy to rely more on electricity means the United States will need to import minerals necessary for electricity systems. The bulk of these minerals are found in China and countries where China is the dominant player in their economies and infrastructure. Fossil fuels, by contrast, are ample and found in diverse places around the globe. There no longer is a geopolitical race to put flags on oil or gas fields since there is enough for all.

The broader renewable energy economy’s dependence on limited rare earths and other minerals is likely to unleash a great game for minerals that is already requiring the U.S. government’s attention. To reduce dependency on imported minerals, Washington is considering granting incentives for domestic mining of these needed materials. Thus, the United States may soon go from mining coal to mining lithium, substituting one environmental threat with another.

The U.S. energy system’s increasing concentration on electricity production also drastically raises the likelihood of cyberattacks. The more interconnected an energy system is, the more vulnerable it is to severe cyberthreats. Moreover, hydroelectric and nuclear power plants—though emitting little to no carbon—have potentially catastrophic cyber vulnerabilities that entail not only the loss of power production but also plant exploitation, which could lead to massive flooding or radioactive exposure.

The United States should be strategizing about ways to combat these vulnerabilities. For it to jump headlong into contributing to those vulnerabilities by de-diversifying its own energy mix would be a disastrous folly.

And this is before even considering the specific vulnerabilities posed by an electrified military battlefield. The more the U.S. military’s equipment, infrastructure, and personnel depend on electricity, the more vulnerable it will be to cyberattacks from foreign militaries. The United States’ adversaries have substantial proven capabilities in cyberspace, some superior to the United States’ abilities. Greater use of electricity in the battlefield will also increase U.S. troops’ exposure to foreign surveillance.

The issue of supply lines will also be complicated by electrification. Almost all of the energy used by the U.S. military today is procured from commercial entities and delivered along civilian pipelines and transportation. This already complicates missions in regions far away from the United States and NATO countries, where access to fuel from friendly countries can be limited. However, access to electricity in battle will be even more challenging as power lines are only efficient over short distances. The risks are high for finding oneself too far from a friendly state. Moreover, those electricity lines, if they exist, will become easy targets of U.S. adversaries.

The time needed to charge batteries versus fueling with liquid fuels will also create an additional constraint on the military. Although planes and land vehicles can be refueled within minutes, charging their batteries could take hours.

Finally, the electrification of the United States may bring many positive effects—but it’s also worth scrutinizing its ultimate environmental impact before extending the transition to all sectors of the economy. Electricity systems require significant amounts of materials and minerals that are mined, and the main sources of these minerals are found in countries where mining practices cause significant environmental damage and are powered by electricity produced by coal or heavy oil. The mining process is likely to wipe out many of the potential environmental benefits of the energy transition to electricity.

Transferring from a diversified U.S. energy mix to one concentrated on electricity will create many new threats to the United States, including its military. This is especially important to consider in the context of competition with China, which will have an immense advantage in this new energy era. These new threats warrant a wider public discussion before the Pentagon flips the switch.

Alan Howard is a faculty member at the U.S. Naval Postgraduate School and is writing a textbook on Operational Energy for the U.S. Department of Defense.

Brenda Shaffer is a faculty member at the U.S. Naval Postgraduate School and is writing a textbook on Operational Energy for the U.S. Department of Defense.

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