The Combustion Engine Strikes Back: Volvo Reimagines Hydrogen

We go for better electric solutions, we go for fuel cell electric solutions, and we also continue to invest in combustion engines. As a data point, it’s rather interesting to say that last year, 2024, was a record year for us in investing in combustion engines. Some people believe that this is already technology of yesterday, sunset technology, but we believe that combustion engines running on renewable fuels, including hydrogen, will be part of the equation for our industry going forward.

Hydrogen and Electric Spirit at Volvo

The Volvo Group recognizes that decarbonizing heavy transport will require a diverse mix of technologies. Committed to achieving fossil-free operations by 2040, the company is pursuing a multi-path approach to decarbonization. This strategy centers on three complementary propulsion technologies: battery-electric vehicles, fuel cell electric vehicles—particularly suited for long-haul transport—and hydrogen-powered internal combustion engines tailored for high-load, demanding applications.

On July 2, 2025, Volvo Group President and CEO Martin Lundstedt, along with 30 senior executives from leading energy, automotive, and hydrogen companies, signed a joint letter addressed to EU and Member State leaders. Together, they issued a clear and urgent message: hydrogen mobility must be strategically placed at the center of Europe’s clean transport and industrial policies. The letter emphasizes that hydrogen is essential to achieving the continent’s climate goals and securing its economic resilience. The CEOs warn that without a more coordinated and pragmatic policy framework—particularly to support the rollout of infrastructure—hydrogen mobility in Europe risks stagnation.

A similar call to action is urgently needed in the United States. The U.S. heavy-duty hydrogen market has recently lost two of its early movers, Nikola Trucks and Hyzon Motors—companies that, in many ways, entered the market ahead of its readiness. With sales and investor confidence lagging, their exits highlight the fragile state of the industry and pose a threat to the slow development of the country’s seven hydrogen hubs. For example, California’s ARCHES H2 hub aims to deploy 5,000 hydrogen-powered heavy-duty trucks to serve the Ports of Long Beach and Los Angeles. However, as supplier options dwindle, market development becomes more difficult. While the root challenges may differ between the EU and the U.S., both regions share a critical opportunity: to leverage abundant renewable energy resources and accelerate the transition to a hydrogen-based economy.

Volvo Group maintains a comprehensive and locally focused truck manufacturing operation in the United States, producing all Volvo trucks for the U.S. market domestically, about 30,000 per year. The company’s primary facility is the New River Valley Plant in Virginia, where trucks are built from the ground up—including cab welding, painting, trimming, and full assembly. This plant also produces autonomy-enabled trucks, equipped with redundant safety systems essential for future autonomous operations. Engines and transmissions are manufactured at Volvo’s Hagerstown, Maryland facility and then shipped to Virginia for final integration. This tightly integrated U.S. manufacturing footprint allows Volvo to efficiently serve the North American market, meet regional regulatory requirements, and swiftly implement new technologies such as autonomous driving systems.

Electric Trucks on the U.S. Market

Volvo Trucks began offering a comprehensive portfolio of electric trucks in 2019. As of April 2025, the company has delivered 5,000 battery-electric trucks to customers across 50 countries. With eight electric truck models currently available, the U.S. market is served by the Volvo VNR Electric with approximately 700 units deployed domestically. The electric model range is designed to meet the needs of urban and regional distribution, as well as the construction and refuse sectors. Volvo’s top five markets for electric truck deployments are Germany, the Netherlands, the United States, Norway, and Sweden. In parallel, the company has been actively developing fuel cell trucks through its joint venture with Daimler Trucks, with cellcentric— their joint venture fuel cell company—supplying power units. The latest generation fuel cell system delivers up to 375 kW (>500 Hp) of power. Volvo’s fuel cell developments were previously discussed in greater detail in Volvo’s Hydrogen Trucks: A 3-Year Journey. Currently, there are five fuel cell trucks in testing, the number is planned to double by 2026, then by 2027 Volvo plans to introduce around 50 trucks in a small-scale customer fleet on European roads.

Hydrogen Fueled Engines

In recent years, significant competition has emerged among OEMs and engine manufacturers to develop the most effective hydrogen combustion engines as a cost-efficient alternative to more expensive fuel cell powertrains. Being a global industrial giant, Volvo has entered this race not with one but with two innovative solutions based on a diesel engine platform, rather than the more common spark-ignition systems adopted by other manufacturers. In both cases, Volvo technology is based on hydrogen as the main fuel where a small amount of biodiesel ignites hydrogen—an unconventional and bold solution.

CMB.TECH solution

Volvo’s hydrogen combustion engines operate similarly to traditional diesel engines but are specially adapted to handle hydrogen as the main fuel, displacing diesel and reducing particulate and CO₂ emissions from combustion. This technology has been adopted in Volvo engines in cooperation with CMB.TECH, a marine and stationary technology company that has developed and refined hydrogen–diesel dual-fuel technology. The author came across this company in 2019 while learning about the pioneering hydrogen tugboat plans during a visit to the Port of Antwerp. The CMB.TECH approach is to have ultimate flexibility in their engines where amount of added hydrogen can vary up to 85% power coming from it. But their engines can still run 100% on diesel when hydrogen is not available. The Volvo strategy is that the use of hydrogen is maximized, and diesel is just the flame initiating agent—a key aspiration toward sustainability and transition to clean transport.

In the traditional diesel engine, turbocharged air is brought into the cylinder and compressed by a piston moving to the top of the cylinder. At this point, diesel—all of the fuel—is introduced as an atomized spray from the injector directly into the hot air, initiating combustion. This is followed by a power stroke, deriving net power from the engine.

In the Volvo-adopted technology, hydrogen is supplied from 350-bar storage tanks and reduced to a lower pressure to enable port injection into the engine’s air supply at the moment of air induction and in the appropriate quantity. Hydrogen displaces diesel as fuel. The air–hydrogen mixture is compressed and then ignited by a small injection of diesel that burns completely and produces the required power. This technique allows for controlled ignition and efficient power delivery while minimizing emissions, with no power reduction. Hydrogen can replace up to 85% of diesel. The system is designed to work on top of the engine’s existing architecture and electronics, simplifying the overall conversion. When CO₂-neutral biodiesel is used, the engine emits limited CO₂, with water vapor as the main byproduct. While some NOₓ emissions are still present due to high combustion temperatures, they remain within the proposed Euro 7 limits. This approach provides a practical path to decarbonization, particularly for long-haul applications where electric charging or hydrogen fuel cells may not be feasible due to infrastructure or operational constraints.

The first deployments of this technology are already underway. Volvo is focusing on developing FH Aero heavy-duty trucks with a 13L engine. In late 2024, the Port of Gothenburg celebrated the opening of Hydri’s hydrogen refueling station, enabling Volvo Penta’s field testing of a dual-fuel hydrogen–diesel terminal tractor at the RoRo (roll-on/roll-off vehicles) terminal. CMB.TECH’s hydrogen genset features a Volvo Penta Stage V D8 340 hp industrial engine, applying hydrogen dual-fuel technology that could be used in decarbonizing port operations and off-grid power generation. In 2023, the partnership launched Hydrobingo, an 80-passenger ferry operating in Japan, powered by Volvo’s dual-fuel engines while achieving CO₂ emissions reductions of up to 54%.

Cespira Joint Venture

The second approach, looking into the future, is based on injection technology being further refined by Cespira, a joint venture established in 2024 between Volvo Group and Westport Fuel Systems to accelerate the development and commercialization of high-pressure direct injection (HPDI™) fuel systems for hydrogen and natural gas combustion engines. Westport contributed intellectual property, assets, and business opportunities to the venture, while Volvo acquired a 45% stake for an initial $28 million, with an additional $45 million tied to performance-based milestones. Cespira focuses on adapting internal combustion engine technology to run on cleaner fuels while meeting increasingly stringent emission standards like Euro 7 and U.S. EPA regulations. HPDI-enabled engines offer a viable alternative to fuel cells by allowing continued use of familiar diesel-based engine architecture—making the transition more cost-effective for OEMs and fleet operators.

In this setup, hydrogen is injected into the combustion chamber as air is being compressed, along with a small quantity of pilot fuel such as biodiesel, which is used to initiate ignition and the consequent combustion of hydrogen with air. Volvo’s fuel injection system uses a dual concentric needle injector—a patented technology that precisely delivers both pilot fuel and hydrogen into the cylinder. It first injects a small amount of pilot fuel to start combustion, followed by high-pressure hydrogen gas.

By advancing both dual-fuel and high-pressure direct injection hydrogen technologies—through in-house innovation and strategic partnerships like CMB.TECH and Cespira—Volvo is creating practical, scalable alternatives to fossil fuel transport. Together with battery-electric vehicles and hydrogen-powered fuel cell and diesel engines, Volvo’s three-pronged strategy is driving targeted competition toward meeting global sustainability standards.