Considerable interest and early developments in electrification and hydrogen drive a lot of the daily conversation around what kinds of fuels and technologies will power heavy-duty trucks for the future. And these may offer some promising possibilities further down the road, but let’s not lose sight of what’s possible with innovations for diesel in the future.
The U.S. Department of Energy (DOE) SuperTruck Program (now in its second iteration, SuperTruck II) is a partnership between government and industry where teams of engineers from engine and truck makers and suppliers come together for research to achieve greater energy efficiency and lower emissions.
SuperTruck II has three targets: a greater than 100 percent improvement in vehicle freight efficiency (on a ton-mile-per-gallon basis) relative to a 2009 baseline for a long-haul freight application, demonstration of a minimum 55 percent engine BTE at 65 mph (104 km/h) on a dynamometer, and the development of cost-effective efficiency technologies.
A recent announcement from the U.S. DOE that the Cummins SuperTruck II team had attained a never before achieved 55 percent brake thermal efficiency in a heavy-duty diesel engine gives an indication of the level of progress possible for future diesel technology. Consider that when the technologies developed under the SuperTruck I initiative hit the market, they are projected to save 7.9 million gallons of diesel fuel per day and reduce CO2 emissions by 33 percent from the 2009 baseline. SuperTruck II demonstrates a further 50 percent reduction in CO2 emissions, doubling efficiency.
Let’s take a look at seven examples of innovation that will keep diesel engines at the forefront of long-haul trucks in the years ahead:
Combustion Efficiency: Through advances in metal components – engine hardware like cylinder and piston designs, bearings, rings, valves, camshafts – there are many advances and innovations anticipated through advanced materials/metallurgy and specialized coatings that can impact the rate/configuration of combustion and/or formation of combustion byproducts. For example, like work at Tenneco.
Engine Management: Controlling combustion events and optimizing engine performance for the conditions at hand. Dynamic skip fire, cylinder deactivation, is a whole new area of opportunity, with some recent announcements affirming this showing a five percent reduction in CO2 emissions, also verified in low-load cycle. Could we also see engine combustion tailored and optimized on a real time basis to accommodate growing use of e-fuels and renewable diesel fuels?
Future Engine Configurations: Today most engines are inline V configurations. Achates Power is testing its acclaimed opposed-piston (OP) engine that could be a game changer; Walmart is testing the new diesel engine now. Not only do the OP engines offer substantial efficiency improvements, they have important advantages in reducing NOx – so much so that the California Air Resources Board is funding a Class 8 Heavy-Duty Diesel Demonstration Program to demonstrate the ability to reduce NOx by 90 percent while also reducing CO2.
Electrifying Engine Components: Reducing parasitic losses on the engine through electrifying components means more efficiency and is made possible by new technologies based on a 48V electrical system that will help reduce emissions and improve fuel economy and performance. A 48V system can also enable integrated starter alternators and can enable hybridization of some medium and heavy-duty trucking segments.
Optimized and Integrated Powertrain: Engines and automated transmissions designed and working together are proving to be a great match that delivers maximum efficiency and performance that translates directly into fuel savings and reduced CO2 (Volvo Trucks, Cummins).
Emissions Control System Optimization: Selective Catalytic Reduction (SCR) systems and particulate filters are getting more compact and more efficient at reducing emissions and during all driving cycles. The next generation systems will be key in meeting the next round of engine emissions standards (Johnson Matthey, Umicore).
Fuel Revolution: Biobased diesel fuels are a proven and growing attribute for diesel engine technology of all types, bringing immediate reductions in emissions compared to pure ultra-low sulfur diesel fuel. Used in blends or in 100 percent configurations like renewable diesel fuel, the near and long-term decarbonizing benefits from the portfolio of low-carbon renewable fuels cannot be ignored (Neste, Renewable Energy Group, Phillips 66, National Biodiesel Board).
Synthetic E-fuels: The vast numbers of internal combustion engines in use today will be around for many decades, so attention to improving their performance has turned to the types of fuel used. Produced using clean electricity, synthetic or e-fuels have the potential to bring a climate-neutral solution to the large existing population of internal combustion engines Tenneco, Bosch and Umicore are contributing to this global effort.
These are just seven examples of innovation around and inside the diesel engine that are happening today. If past accomplishments are any measure of future success, the diesel engine is poised to continue to deliver the goods and the benefits in the decades ahead.