On the campaign trail, President Joe Biden made climate policy a key part of his agenda. Within a week of taking office he began to follow through on his pledge to prioritize climate action, signing an executive order on “Tackling Climate Change at Home and Abroad” that placed the climate threat on par with the threat of a rising China. Climate was also a key focus of the administration’s “Interim National Security Strategic Guidance” and in September the Department of Defense released its own “Climate Adaptation Plan.” Secretary of Defense Lloyd Austin has also affirmed the Pentagon sees climate change as a key “national security issue.” The link between national security and climate change is increasingly undeniable and it may manifest itself in everything from increased human migration to widespread food insecurity. It is, in the words of one researcher, “not the wolf at the door, threatening to blow the house down,” but rather “thousands of termites . . . whose collective impact is potentially just as catastrophic.” The unique threat of climate change has perhaps best been described, by the United Nations, as a “threat multiplier.”
As the world’s single largest institutional user of petroleum the Department of Defense can both further the president’s climate agenda and increase lethality by replacing petroleum-based fuels with hydrogen. Brown University researchers have calculated that the military produced nearly sixty million metric tons of carbon dioxide emissions in 2017—more than the entire nations of Sweden or Denmark. Some have argued that the military will have to make sacrifices for the climate change agenda; we don’t believe this. New technologies are making it possible to shift the military away from a near-total dependence on petroleum-based fuels toward greener alternatives without sacrificing lethality. Existing and growing hydrogen production capacity by our allies means that a switch to hydrogen could dramatically change how the military does operational energy. Hydrogen can be generated and used at the tactical edge of the battlefield, whereas petroleum fuels have to be extracted, refined, stored, and transported long distances.
Hydrogen vehicles and platforms also offer significant advantages in performance, which translates to increased lethality on the battlefield. Hydrogen fuel cells already power electric vehicles that are nearly silent, in contrast to the low roar of conventionally powered tactical vehicles or the high-pitched whine of the M1 Abrams’ gas-turbine engine. Hydrogen powered vehicles also have a much smaller thermal signature—making them stealthier on the battlefield. Hydrogen can make vehicles more efficient as well—significantly extending the range and reliability of unmanned aerial systems or, in the case of ground vehicles, giving them large amounts of instantaneous torque through the electric engine.
The True Cost of Addiction
The military has an almost insatiable demand for fuel. In 2019 the Defense Logistics Agency, the military’s authority for purchasing fuels, spent over $12 billion to purchase nearly 4.2 billion gallons of fuel for the military, a decrease from the previous year, but still over ten million gallons per day. In Afghanistan the military used as much as twenty-two gallons of fuel per day, per deployed soldier. This is a massive increase over the roughly one gallon of fuel needed per soldier during World War II. Despite well-intentioned initiatives by the services to reduce military energy consumption, it continues to rise at roughly 1.5 percent per year. Cumulatively, this adds up to a total increase of 175 percent since the Vietnam War. The Pentagon expects this trend to continue. Its 2016 Operational Energy Strategy asserted that:
Next generation weapons platforms and concepts of operation often use more energy than their predecessors. As a result, risks to the logistical underpinnings of U.S. power projection, particularly the availability of operational energy, are an enduring challenge.
In other words, the military is going to need more and more fuel, and it’s going to be more and more difficult to get it.
But the true cost of the Pentagon’s reliance on fossil fuels far exceeds those numbers. The 2009 National Defense Authorization Act or NDAA introduced the concept of a “Fully Burdened Cost of Fuel”—in other words, the cost of fuel after factoring in the price of transporting it from the pump to soldiers and Marines on the battlefield. Taking into account the costs of transportation from where the fuel is bought to where it is used can increase the price hundreds of times over the $2–3 dollars per gallon the Defense Logistics Agency pays for the fuel. Pentagon analysis showed that, on average, the cost of operating and protecting ground fuel convoys tripled the fuel’s cost and transporting it by air increased the cost to $43 per gallon. On the most perilous routes in Afghanistan, officials estimated that getting a single gallon of fuel into a vehicle or aircraft cost an average of $400, and in some areas the figure could be as high as $1,000 per gallon.
Dollars are not the only currency that the Pentagon uses to pay for fuel. Servicemembers often pay in blood to transport fuel in combat zones. Fuel convoys have been one of the most frequent targets of ambushes and improvised explosive device attacks in Iraq and Afghanistan. An Army report found that one in every twenty-four fuel convoys in Afghanistan suffered a casualty from insurgent attacks. According to a RAND study, in the first decade of the wars in Iraq and Afghanistan over half of all US casualties were a result of attacks on US convoys during “land transport missions”—many of them carrying fuel.
The Promise of Hydrogen
Hydrogen is not new to the Department of Defense—its military use dates as far back as the Civil War and it is still in use today. During World War I, the Army Air Service flew 5,800 artillery adjustment and surveillance missions in two-man, hydrogen-filled aerostat balloons. The balloons were so difficult to shoot down and so valuable to operations that the Luftwaffe awarded its pilots one and a half “kills” for every balloon downed. During World War II, hydrogen barrage balloons were used for defense against air attack over the Normandy beaches, above London, and across the United Kingdom, and for attacks against the German power grid. The Department of Defense even produced hydrogen in the field using caustic materials and a wheeled chemical plant, the M1 hydrogen generator. Today, it’s easier. Federal agencies can order a tank of hydrogen from the Defense Logistics Agency’s Aerospace Energy division via a national stock number. The agency supplies multiple grades of hydrogen to federal customers, with compressed hydrogen comprising 4 percent of its Aerospace Energy division’s bulk hazmat shipments.
Today every one of the military services has plans to use hydrogen-filled stratospheric balloons for unique communications and surveillance capabilities. The Army has tested a hydrogen-powered vehicle from Chevrolet and also funded liquid hydrogen–powered testing of unmanned aerial vehicles (UAVs). The Navy has shattered endurance records with its forty-eight-hour flight of a hydrogen-powered UAV. A hydrogen-fueled UAV is under development that will dramatically increase the range of a battery-powered platform US Special Operations Command currently uses. The Army’s Ground Vehicle Systems Center has worked with Pratt & Miller, General Motors, and Nikola Motors to develop several hydrogen-fueled prototype ground vehicles. When the acoustic and thermal signatures were measured on one of those vehicles, they discovered that it was 90 percent quieter than the equivalent DoD combustion engine vehicle, with potentially half the infrared signature.
The private sector is also charging ahead with hydrogen-powered vehicles. The first was a General Motors project that converted a 1966 Handivan to run on hydrogen. There are already hydrogen-powered vehicles on the market from Hyundai, Toyota, and Honda—which get significantly better mileage than battery-powered electric cars and comparable mileage to the most efficient gas-powered cars. Other companies like Nikola Motors and General Motors are preparing to enter the commercial market. Toyota recently teamed up with Yanmar to design a hydrogen-powered boat and Airbus recently announced its intention to have a hydrogen-powered commercial airliner in service by 2035. Multiple companies sell hydrogen–powered generators that emit no exhaust other than water.
The Logistics of Hydrogen
Hydrogen production and logistics also provide an opportunity to engage with our regional allies and partners. Investments in clean hydrogen can support defense but also regional and national climate policies. All of the Five Eyes nations besides the United States—the United Kingdom, New Zealand, Canada, and Australia—have a national hydrogen strategy. Japan and South Korea are already global leaders in hydrogen production, with Japan using political, diplomatic, economic, and industrial policies to become a “hydrogen society.” The French Covid economic recovery package included €7 billion for water electrolyzers. They, along with the Germans, Dutch, and European Commission are exploring the feasibility of converting natural gas pipelines to carry 100 percent hydrogen—which, if done at scale, would replace Russian natural gas. The United States can leverage common interest in hydrogen and defense as a type of energy diplomacy in the Pacific and in Europe.
The gap in hydrogen deployment for DoD has always been at the tactical level. Transporting hydrogen cylinders is less than ideal because of their bulk and weight. But in 2013 researchers at MIT discovered a new process for creating hydrogen from water—using aluminum activated with small amounts of gallium and indium. This would allow units to generate hydrogen to meet their energy needs at the tactical edge of the battlefield without having to transport hydrogen liquid or gas. The aluminum and activation metals are baked in an oven, which prevents the aluminum from oxidizing. When the activated aluminum is combined with water, it creates heat, hydrogen, and aluminum hydroxide—a benign substance that is often taken to relieve heartburn and indigestion. The activation process can be done in a garage with a home oven (or on a conference table in the Pentagon with a $20 hot plate). One of the authors has repeatedly performed the hydrogen production reaction in his home over Zoom calls in demonstrations to Department of Defense stakeholders.
Regionally sourced aluminum and tactical hydrogen production together can revolutionize operational energy. The processes are simple and safe enough that they can be done at the tactical edge of the battlefield for both power production and water purification. Hydrogen fuel cells can generate the electricity to fulfill all the needs of Army and Marine tactical units. Students at MIT have already created small aluminum reactors that could be used at the company or even squad level. The widespread availability of aluminum around the world would allow military forces to scavenge or recycle it to fuel themselves—and reduce their reliance on vulnerable supply chains. Aluminum fuel is a field seeing much innovation; several other organizations are developing their own versions of the aluminum-to-hydrogen process.
Instead of a supply chain that runs from oilfield to pipeline to refinery to tanker to port to battlefield, an aluminum-hydrogen supply chain could run from scrap recycler to battlefield. Aluminum is the most common metal in the earth’s crust and available almost everywhere on Earth in the form of post-consumer waste. Petroleum, by contrast, poses significant risks during transport and storage, even if the maritime segment of the Pentagon’s logistics chain weren’t already hobbled by lack of ships, lack of escorts, and poor readiness. This all adds up to a clear conclusion: using aluminum and hydrogen to fuel the military would begin to release it from the tether of petroleum-based fuels.
What’s Standing in the Way?
The “single fuel concept” is the idea that the military runs on a single fuel to simplify logistics. It is codified in US policy as well as in NATO policy. In practice the military runs on four types of petroleum fuel, with a few exceptions: F-24, a kerosene-based jet fuel that is also used in ground vehicles; JP-8, an almost identical fuel to F-24 with a slightly lower freezing point for use in cold weather; JP-5, a jet fuel with a higher flash point for shipboard use; and F-76, a marine diesel fuel for ships. The single fuel concept was intended to reduce the logistical burden of having to supply dozens of different types of petroleum-based liquid fuels to armies where each vehicle used a slightly different fuel. In this regard, it was successful—though not without its critics. Tanks and Humvees run on the same fuel as jets and helicopters, which eliminated the need to supply multiple types of fuel to the battlefield.
But today this single-fuel dogma, while easing the burden on logisticians, has effectively prevented serious experimentation with, let alone the adoption of, alternative fuels. Despite calls for alternative fuels, even from within the military, there are no major planned or projected platforms that will use them. But while the military stands still, the private sector is already shifting away from conventionally powered vehicles. Five of the largest big oil companies are pursuing renewable sources of energy. Major automaker General Motors announced that it will phase out all gas and diesel engines by 2035. Consumers are catching on too—electric cars continue to expand their market share against conventionally powered vehicles. Yet the military has not electrified any of its tactical vehicle fleet. If the single-fuel concept continues to thwart innovation toward nonliquid alternative fuels, it should either be rewritten in a way that encourages adoption of such fuels, or simply abandoned.
Widespread adoption of hydrogen for military use is also held back by longstanding myths about hydrogen’s safety. “What about the Hindenburg?” is a common refrain. But this perception is misinformed. Hydrogen gas is safe to transport and in many respects is a safer vehicle fuel than gasoline. When modern hydrogen tanks are punctured by a bullet they do not explode, but simply vent hydrogen gas vertically. If ignited, the hydrogen escapes upward into the atmosphere, unlike petroleum fuel, which pools aflame on the ground and on the water’s surface. The nearly perfect combat safety record—only one hydrogen-related fatality—among balloon units in World War I, despite their primitive technology and imperfect processes, is a testament to the inherent safety of hydrogen fuel.
The military operates a global purchasing and distribution network for petroleum-based fuel. Such a massive enterprise cannot be replaced in the short term, nor would it make sense to replace all of the military’s equipment with alternative fuels. However, the military’s decisions about the fuels it will use in the future will necessarily be made in the context of the clearly growing policy emphasis on tacking climate threats. At the same time, it will naturally be mindful of the pressing need to increase lethality. A shift toward alternative fuels is in accordance with both of these factors.
Because hydrogen lies at the intersection of responsible climate policy and lethality, shifting to it can improve the capabilities of current and future platforms and weapon systems while reducing the military’s reliance on petroleum-based fuels and greenhouse gas emissions. Building the necessary hydrogen infrastructure to support such a shift offers opportunities to work closely with allies and partners and overlaps with their domestic policy goals. The military has long realized the potential danger of climate change to national security, noting in the 2014 Quadrennial Defense Review the need to “employ creative ways to address the impact of climate change.” The shift to using hydrogen as a fuel for unmanned systems and tactical vehicles will improve lethality by reducing signatures and improving performance over legacy engines. Emerging technologies and processes make shifting away from petroleum to alternative fuels a win-win for the Pentagon.
Capt. Walker D. Mills is a Marine infantry officer. He is currently serving as an exchange officer at the Colombian Naval Academy. He is a nonresident master of arts student at the Naval Postgraduate School’s Center for Homeland Security and Defense, a nonresident fellow at the Krulak Center for Innovation and Future War at Marine Corps University, and a nonresident WSD-Handa Fellow at Pacific Forum. He holds an MA in international relations and modern war from King’s College London and received a BA from Brown University in history and archaeology.
Erik Limpaecher leads the Energy Systems Group at MIT Lincoln Laboratory, a Department of Defense federally funded research and development center in Massachusetts. He is a member of the Defense Science Board task force on DoD dependence on critical infrastructure and a nonresident fellow at the Krulak Center for Innovation and Future War at Marine Corps University. He holds a BSE in electrical engineering from Princeton University.
The views expressed are those of the authors and do not reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.