Cummins ETHOS 2.8L optimized E-85 engine demonstrates 50-80% reduction in CO2 emissions in medium-duty truck
|The ETHOS 2.8L demo truck. Click to enlarge.|
Cummins has developed an E-85-specific engine and powertrain that reduce carbon dioxide emissions by as much as 80% compared with a baseline gasoline-powered medium-duty truck. The work was jointly funded by Cummins and partners ($3,790,027) in partnership with the California Energy Commission (CEC) ($2,712,140).
The Cummins ETHOS 2.8L is designed specifically to use E-85 (85% ethanol and 15% gasoline). To take full advantage of the favorable combustion attributes and potential of E-85, the engine operates at diesel-like cylinder pressures and incorporates advanced spark-ignition technology. It delivers the power (up to 250 hp / 186 kW) and peak torque (up to 450 lb-ft / 610 N·m) of gasoline and diesel engines nearly twice its 2.8-liter displacement.
For the CEC project, approved in 2011, Cummins originally envisioned adapting a medium-duty engine specifically to use E85 fuel, reducing the engine size from 6.7L to 4.5L as a means to increase fuel efficiency, and developing the integrated start/stop system.
In 2012, Cummins came back to the CEC with a request for a 6-month extension (although with no change in funding), to accommodate a reduction in the size of the downsized engine to the current 2.8L version, matching the size of the ultra-efficient ATLAS diesel engine under development with US Department of Energy (DOE) funding. (Earlier post.) The two engines share a good number of components and a common design approach, and were developed simultaneously, according to Cummins.
More than 1,000 miles and 1,500 hours have been accumulated on the ETHOS 2.8L engine over the past two-and-a-half years, demonstrating that this technology is capable of far exceeding the 50% CO2 emissions reductions outlined in the project’s goals, Cummins said. A final on-road validation testing phase has been underway in the Sacramento, California, area since June and continuing into this month, and is being managed by Cummins Pacific, the exclusive California and Hawaii distributor for Cummins Inc.
The Cummins ETHOS 2.8L engine also incorporates an integrated stop-start system, which further reduces fuel consumption and emissions. In stop-start mode, the engine shuts down after the vehicle comes to a complete stop and the brake pedal remains depressed. As the driver’s foot is lifted from the brake, the system automatically starts the engine to seamlessly allow acceleration from the stop.
Cummins-integrated specific system controls, along with a robust starter, smart alternator and sensors, are all designed to handle the additional stop-start duty cycle and maintain reliable operation over the life of the engine.
Cummins also worked closely with Allison Transmission to integrate the 2000 Series transmission for smooth and efficient stop-start operation. The transmission is equipped with hydraulic circulation features to ensure smooth operation and quick vehicle launch during stop-start driving.
Additional partners in the project included Valvoline, which provided NextGen engine oils specifically designed for lower CO2 emissions, and Freightliner Custom Chassis, which provided a prototype MT45 Class 5 step-van vehicle.
Using corn-derived E-85, the high thermal efficiency and power-to-weight ratio of this engine results in 50 to 58% lower well-to-wheels CO2 emissions compared with the gasoline engine baseline.
Using second-generation lignocellulosic-derived E-85, the powertrain’s efficiency features deliver an impressive 75 to 80% lower well-to-wheels CO2 emissions, depending on the drive cycle. Cellulosic E-85 is less intensive in terms of land use, tilling, fertilizing and harvesting than corn-derived E-85.
Although not in high-volume production today, cellulosic ethanol represents a promising production pathway for future fuels. This demonstrates that significant reductions in GHG emissions can be achieved with current commercially available E-85 fuels, with even greater potential in the future when cellulosic ethanol technology matures and becomes mainstream, Cummins said.