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Lightning Hybrids releases initial emissions testing results for medium-duty hydraulic hybrids

The Lightning Hybrid system. Click to enlarge.

Lightning Hybrids, a maker of hydraulic hybrid systems for medium- and heavy-duty trucks and buses (earlier post), released initial results from emissions testing conducted by an independent testing facility in Colorado of two medium-duty trucks upfitted with the Lighting Hybrids system. The results show decreases in NOx of up to 90% and decreases in CO2 emissions of up to 16% over the same baseline vehicle, depending upon the drive cycle tested.

Lightning Hybrids tested two vehicles: a 2013 Ford E450 6.8-liter V10 and a 2010 GMC 3500 Savana Cutaway 6.0-liter V8. Both vehicles were first tested without Lightning’s hydraulic hybrid system to provide a baseline with which to compare the results with the hybrid system installed.

Lightning Hybrids’ system functions like other hybrids that add a secondary power source to an existing engine. Hydraulic pumps/motors and an accumulator (power storage unit) are added to gasoline, diesel, propane or CNG engines to store braking energy and use the captured energy to accelerate the vehicle, significantly saving fuel and brakes and cutting emissions.

Lightning Hybrids met or exceeded all California Air Resources Board (CARB) Heavy-Duty hybrid emissions certification standards using published HD HEV Certification Test Procedures. The testing was completed at the SGS Environmental Testing Corporation dynamometer facility in Aurora, Colorado. SGS provides inspection, verification and testing services around the world, and the Aurora facility is used by large vehicle makers to validate drive cycles and provide high altitude testing for a variety of major vehicle manufacturers.

The vehicles were tested on the SGS dynamometer using SGS drivers and equipment. Three published drive cycles were tested, and one specific to a Lightning Hybrids customer. Published drive cycles tested—and the results—included:

  • Orange County Bus: Developed by West Virginia University to replicate suburban transit bus drive cycles, one of two drive cycles used by CARB for hybrid certification. The cycle extends the Heavy Duty UDDS cycle (representing “city” driving for heavy duty vehicles) to 30 min. With its high average speed(18.9 mph), low 2.1 stops/mile, and 25% idle time, the cycle is not ideal for the Lightning Hybrid system, which is more suited for urban, rather than suburban, operation. CO2 emissions were reduced by 4%, compared to the standard vehicles, and NOx emissions were reduced by 3%.

  • Braunschweig City Driving Cycle: EU legislative cycle for bus approval. The Braunschweig cycle features an average speed of 14.2 mph with 3.8 stops/mile and 17% idle time. On this cycle, the Lightning Hybrids hydraulic hybrid system reduced CO2 emissions by 16% and NOx emissions by 90%.

  • Artemis: Developed by 15 EU nations tasked with emissions study for cars. On this cycle, CO2 emissions are reduced by 16% and NOx emissions are reduced by 67%.

Lightning also outlined a diesel replacement scenario being considered by the rental car shuttle fleet. The essence is to replace a diesel-powered GMC 4500 shuttle with gasoline Ford E450s upfitted with the Lightning Hybrids system. Customer reluctance to switch from diesel to gasoline is primarily due to torque losses, Lightning notes; the hydraulic hybrid systems gives torque back. The Lightning Hybrids gasoline HHV (hydraulic hybrid vehicle) reduces NOx by 457% compared with a diesel conventional vehicle. The Lightning Hybrids gasoline HHV also improves both power and fuel economy when compared with a conventional gasoline vehicle.

Lightning Hybrids currently has vehicles in ten fleets in the US and Canada and has orders for vehicles in fleets in the US, India, Mexico and England that will be delivered over the next three months. These vehicles include medium-duty delivery trucks and shuttle buses and heavy-duty transit and school buses on a variety of platforms including Ford, Freightliner, Ashok Leyland, DAF, and Mercedes-Benz.

There are a variety of federal and state incentives and grants for clean vehicle technologies like Lightning Hybrids’ product. Massachusetts has now released incentive funding for vehicles and specifically included funding for Lightning Hybrids’ hydraulic system, and Colorado just passed a clean truck initiative that also specifically includes hydraulic hybrids in the new tax incentives for clean and alternative fuel vehicles.



This article is rather loose with the numbers and the math. How do you reduce the NOx emissions by 457%? Reducing it by 100% would imply no emissions. Also some of the reduction assumes that a diesel engine is replaced with a gasoline engine plus their hydraulic hybrid system.

It would probably be more efficient to replace the hydraulics with ultracaps and an electric drive but it might not be less expensive.

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