Locomotives, typically classified as 50-year assets, are primarily electrically driven. Despite the common label as ‘diesels,’ they are better described as ‘hybrid-electric’ vehicles. This is because their diesel engine powers an alternator which generates the electricity required to operate the electric traction motors mounted on the locomotive’s axles. As reported by the American Association of Railroads, transporting freight by rail is three to four times more fuel-efficient than highway transportation. Trains are capable of moving a ton of freight, approximately 492 miles on just a single gallon of fuel1. Yet, investing in a current Tier 4 locomotive today implies that you may still be burning carbon-based diesel well past 2050.
As both the Aero and Rail industries strive to incorporate cost-effective zero-emission technologies, there is active investigation into next-generation equipment and fuel alternatives. Among these is the application of hydrogen, a ’clean’2 fuel, either through a hydrogen internal combustion engine or via a reaction with oxygen inside a hydrogen fuel cell. These fuel cells use hydrogen to generate electricity. The world’s first passenger trains powered by hydrogen fuel cells, which produce the electric power to drive the traction motors, are already in commercial service in Germany, specifically for short-haul suburban rail services. In the U.S., companies like Caterpillar, Wabtec, Progress Rail, Cummins, and others are undertaking efforts to verify the feasibility of hydrogen as a viable substitute for traditional fossil-based fuels in line-haul services.
There exist alternatives to batteries for achieving net-zero transportation. Fuels made from non-petroleum sources, often labeled as ‘sustainable’ fuels, are derived from alternative sources in contrast to fossil-based fuels. These include oils from plants, algae, greases, fats, waste streams, alcohols, sugars, or captured CO2. Hydrogen, the simplest known chemical element, offers the highest energy density of any fuel. The byproducts of using hydrogen as an energy source are environmentally friendly heat and water.
Aviation fuels are distinctive due to their ‘specific energy’3, or energy per unit of mass. The current Jet-A fuel is a carbon-based kerosene fuel. While hydrogen offers three times the energy of kerosene per unit of mass, it demands four times the volume of the current Jet-A kerosene-based fuel to achieve the same outcome. The possibilities for hydrogen-based aircraft propulsion include electric motors powered by fuel cells, hydrogen-powered gas turbines, or hybrid systems that incorporate both fuel cells and hydrogen-based gas turbines. For short to medium-range aircraft, conventional gas turbine engines could be modified to use liquid hydrogen combustion. Hybrid aircraft, powered by hydrogen fuel cells, are currently being explored as zero-carbon alternatives. However, integrating hydrogen as a fuel source will likely necessitate the redesign of aircraft configurations4.
New technologies frequently come with high costs and are not instantly practical. The economics and investment timelines needed to transition to reduced carbon alternatives remain subjects of exploration. This transition will entail long-term efforts in designing new equipment, developing necessary material supply chains, devising cost-effective energy production alternatives, and establishing Aero and Rail fuel distribution and logistics networks. Despite the remaining challenges, investment in current midlife Aero and Rail equipment appears more attractive. Opportunities with lower risk and existing cash yielding attributes are available. Call RESIDCO.
Glenn Davis, 312-635-3161
1. Aii – Do Longer Trains Pose Problems or Solutions?
2. Office of Energy Efficiency & Renewable Energy – Hydrogen Fuel Basics
3. Wikipedia: Aviation fuel – Energy Content of Aviation Fuel
4. Siemens – Hydrogen Aircraft Technology
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