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Emissions testing shows Lighting Hybrids hydraulic hybrid drive delivers significant reduction in NOx, up to 18% improved fuel consumption

The LH gasoline hydraulic hybrid shows an extreme reduction in NOx compared to a diesel baseline. Source: Lightning Hybrids. Click to enlarge.

Lightning Hybrids (LH), a provider of hydraulic hybrid drive systems for fleet vehicles such as shuttle buses, delivery vehicles and work trucks (earlier post), has released some results from its ongoing emissions testing with SGS Environmental Testing Corporation. Broadly, the test results show significant reductions in NOx, particularly against a non-hybrid diesel baseline, and fuel economy improvements of up to 18% for the vehicle and under the drive cycles tested.

By design, LH noted, a hybrid drive system provides benefits during a vehicle’s braking and subsequent acceleration phases, so not all drive cycles will take equal advantage of the system. For example, an urban delivery truck which stops many times per mile will benefit strongly, whereas a truck that spends most of its time on the highway would not be a good candidate for any form of hybridization.

SGS tested the LH systems under the Orange County Bus (CARB certification for heavy duty hybrids) and Braunschweig City (European Union certification for buses) drive cycles. Both drive cycles were based on city bus routes, and define the speeds and times, including idling, that are reproduced during testing on the dynamometer at SGS.

The hybrid vehicle under test was a 2010 GMC 3500/4500 Savana Cutaway with a GM 6.0 liter gasoline V8 engine, loaded with a concrete dummy load to bring the weight up to 10,800 lbs (4,899 kg). Exhaust gases were captured in order to measure the vehicle’s emission of carbon dioxide (CO2) and NOx.

NOx results for the gasoline engine vehicle (started with the engine already hot). Source: Lightning Hybrids. Click to enlarge.

Previous testing at SGS provided two sets of baseline results which LH uses for comparison to allow the improvements provided by the hybrid system to be quantified. These sets of results are the same GMC Savana with the hybrid system removed (gasoline baseline results); and a GM 4500 chassis with GM Duramax 6.6 liter diesel engine, hybrid system disabled (diesel baseline results).

On both drive cycles, the hydraulic hybrid’s most significant improvement is the reduction of NOx emissions. Results for the gasoline vehicle show a 50% (or slightly greater) reduction in NOx with the hybrid system on. The gasoline-powered truck with the Lightning Hybrids hydraulic system emitted just 5% of the NOx emitted by the conventional diesel vehicle.

Fuel savings and corresponding reductions in CO2 emissions. Source: Lightning Hybrids. Click to enlarge.

The benefits of the hydraulic hybrid system extend to fuel savings and corresponding reductions in CO2 emissions with results that show a 14-15% reduction in CO2 emissions for both cycles, and a corresponding fuel economy improvement of about 18%.

As with any quantified benchmarking, LH cautioned, results are not directly transferable to what a hybridized vehicle may exhibit on the road.



editor note: Co name is misspelled in header.


It would be worthwhile to compare the fuel economy of the gasoline hybrid with the diesel on the same cycles.  Gasoline is considerably cheaper than diesel in the USA, and getting toward parity in fuel economy would swing the economics strongly in favor of the hybrid.

Henry Gibson

Even on the highways, Artemis digital displacement hybrids can reduce fuel consumption by 30 percent or more in automobiles; heavy vehicles will also show efficiency and performance improvements. Without much cost, trailers of heavy vehicles can be equipped, even retrofitted, with hydraulic hybrid equipment for more reliable braking and faster acceleration as can individual rail cars. Engines can be operated in peak power mode at all times when desired or peak efficiency if need.

Hydraulic hybrid transmissions have been fitted to one large and two giant wind-turbines for testing where they can be more reliable and use simple standard generators to feed the mains with the turbine energy efficiently without power electronics. Such machines can be greatly overloaded briefly to support the survival of the mains or adapted to aberrant mains frequency without danger of failure during recovery.

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