Near-zero heavy duty diesel engine enters fleet service

31 March 2022

Climate Investment

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Achates Power’s opposed-piston engine on the road with Walmart Challenge

The Californian Air Resources Board (CARB) has introduced regulations that require a 90% reduction in tailpipe NOx from commercial vehicles, starting in 2027. With many governments moving in similar directions there is an urgency for commercial vehicle fleets to move toward net zero, and for the traditional fleet required during transition, to be as low emission as possible.

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In a project funded by CARB and partners including South Coast Air Quality Management District, San Joaquin Valley Air Pollution Control District, and the Sacramento Metro Air Quality Management District, Achates Power has developed an ultra low-NOx diesel engine that meets the stringent standards without requirement for any additional emissions control devices.

It is engineered to improve fuel efficiency by managing exhaust gas temperatures, improving combustion and reducing pumping losses. The heavy duty opposed piston engine maintains aftertreatment temperatures at optimum operating conditions in all driving conditions.

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Through California’s Heavy Duty Diesel Demonstration Programme, Achates Power built and tested four 10.6L engines, finding a 96% reduction in tailpipe NOx, a 75% reduction in engine-out particle matter against a diesel engine benchmark, and a 7% reduction in carbon dioxide compared to U.S. regulatory standards.

The Achates Power engine complies with the CARB’s NOx emissions regulations due to come into effect from 2027, and has entered fleet service with WALMART Corporation in a Peterbilt 579 tractor.

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Expanding impact

The opposed-piston engine can be manufactured using existing facilities, processes, materials, components and supply chains, enabling rapid deployment. Without the need for any additional emissions control devices, cost, complexity, and compliance risk are reduced, and the engine is expected to cost less than current engines.

Achates Power is conducting further testing with a fully aged catalyst (the equivalent of 800,000 miles of operation) to demonstrate continued ability to meet CARB’s stringent standards.