Emissions Test Results:
Lightning Hybrids Hydraulic Hybrid System
installed on a GM 6.0L V8 Petrol Vehicle
April 2015
Hydraulic Hybrid Delivers Major Emissions Reductions
Introduction
Over several years, Lightning Hybrids has engaged SGS Environmental Testing Corporation, based in Aurora, Colorado, for
regularized, independent emissions testing of vehicles equipped with our hydraulic hybrid drive systems. This provides certified
results which quantify the emissions reductions that Lightning Hybrids’ technology can deliver to lorry and bus fleets, and
which are key to the value proposition of the system, along with fuel and brake savings.
By design, most hybrid drive systems use regenerative braking that provides benefits during a vehicle’s braking and subsequent
acceleration phases, so not all driving cycles will take equal advantage of this type of system. For example, an urban delivery vehicle which stops many times per mile will benefit the most, while a lorry
Orange County Bus
that spends most of its time on the motorway would not show the same
drive cycle
gains. With this in mind, Lightning Hybrids requested that SGS perform
testing according to documented standard drive cycles which are accepted
for regulatory certification in certain regions of the world and which are
representative of city bus routes. These drive cycles are:
• Orange County Bus (CARB1 certification for heavy duty hybrids)2
• Braunschweig City (European Union certification for buses)3
Both drive cycles were designed based on city bus routes, and define the
speeds and times, including idling, that are reproduced during testing on
the dynamometer at SGS.
Methodology
Braunschweig City Bus
drive cycle
The vehicle, a 2010 GMC 3500/4500 Savana Cutaway with a GM 6.0 liter petrol V8 engine, was placed on SGS’s dyno and driven on the Orange
County and Braunschweig City drive cycles. The vehicle was loaded with
a concrete dummy load to bring the weight up to 4,800 kg. Exhaust gases
were captured in order to measure the vehicle’s emission of carbon dioxide
(CO2), a “greenhouse gas”, and nitrous oxides (NOX), which are “criteria
pollutants” which are written into United States EPA regulations4 on air
quality, and into equivalent European Union legislation5.
Baseline comparisons
Previous testing at SGS provided two sets of baseline results
which can be used here 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
(petrol baseline results)
• A GM 4500 chassis with GM Duramax 6.6 liter diesel
engine, hybrid system disabled (diesel baseline results)
GMC Savana vehicle under test
on SGS’s dyno
Petrol without hybrid
Petrol with hybrid
Results
On both drive cycles,
the hydraulicCity
hybrid’s
most dramatic improvement is the reduction in NOX emissions. Chart 1 shows the
Braunschweig
Bus cycle
NOX results for the petrol engine vehicle (started with the engine already hot)6.
0.16
0.14
0.14
0.25
Chart 1
0.12
0.20
0.10
g/km
km
0.08
0.15
0.06
0.04
0.10
0.02
0.00
0.05
0.07
NOX g/km
NOx g/km
0.19
0.14
0.09
Petrol without hybrid
Petrol with hybrid
0.07
Petrol with
hybrid
Orange County
Petrol without
hybrid
Petrol with
hybrid
Braunschweig
are0.25
chosen over petrol for their greater low-end torque. However,
the Lightning Hybrids hydraulic hybrid system delivers additional700
torque to the drive line during acceleration from a stand-still,
0.20
which
600 means that a hybridized petrol-powered vehicle has the dual
advantages
of very low NOX emissions and strong torque.
0.15
500
/km
The benefits of the hydraulic hybrid system extend to fuelNOsavings
x g/km
0.10
400
0.19
and
corresponding
reductions in CO2 emissions: see Chart 3.
0.14
636
g/km
X
Petrol without hybrid
Petrol
with
hybrid
The petrol-powered
vehicle with
the
hydraulic
hybrid
system emitted just 5% of the NOX emitted by the
conventional diesel vehicle. This is especially interesting
to European fleet operators, who are concerned that
the new Euro VI emissions regulations will make diesel
vehicles difficult to justify. In many cases, diesel vehicles
Braunschweig Bus cycle
1.40
1.20
Chart 2
Chart 3
600
500
400
300
200
100
636
546
622
529
CO2 g/km
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
0.25
0.20
1.28
1.00
0.15
0.80
0.60
NOX g/km
0.40
622
300 results show 14-15% reduction
g/km
0.14
These
in CO2 emissions
forCO
both
2
0.05
546
0.20
0.09
529
0.07
0.07
cycles,
200 and a corresponding fuel economy improvement of about
0.00
8
Diesel without
Petrol without
Petrol with hybrid
18%.
0.00 Fuel use and CO2 emissions are closely correlated , so an imhybrid
hybrid
100
Petrolin
without
Petrol with will
Petrol
without
Petrol with
provement
fuel economy
show
a commensurate
reduction
hybrid
hybrid
hybrid
hybrid
in CO
0 2 emissions. Of note here is that these tests are performed in
Orange
County
Braunschweig
Petrol
without
Petrol
with they
Petrol
Petrol with
a laboratory.
Therefore
while
arewithout
appropriate
for testing, we have found that they do not correlate precisely with our cushybrid
hybrid
hybrid
tomers’ real-life drive cycles. Our customers
inhybrid
urban delivery and bus routes report over 30% fuel savings (so we can assume
Orange
County
Braunschweig
the parallel
30% CO
savings as well).
2
700
g/km
NO g/km
0.09 when comparing
The
results become even more dramatic
0.10
these petrol results against the equivalent diesel vehicle.
0.05
Adding
diesel results to the petrol data for the Braunschweig Bus, we obtain Chart 27.
0.00
0.00
Petrol without
hybrid
Bus cycle
Both results showOrange
a 50%County
(or slightly
greater) reduction
0.25NO . NO is a key contributor to air pollution, most
in
X
X
notably smog,0.19
so this level of reduction is significant for
0.20
cities, states and nations that are working to meet air
quality
targets.
0.15
0.10
0.05
0.00
700
Hydraulic advantages
Orange County Bus cycle
600
700 every hybrid technology is capable of these levels of
Not
636
emissions
savings, especially in the delivery and transit bus
600
546
vocational
cycles. Lightning Hybrids’ hydraulic drive sys500
tem provides intense torque (up to 850 ft-lb) acceleration
400
when emissions are at a peak. This allows us to achieve
CO g/km
300
higher
reductions in criteria pollutants than battery or
200
ultra-capacitor
based hybrid designs.
500
2
100
Although most electric and hydraulic hybrid drive systems
0
share
the same basic principle – regeneration of braking
0
Petrol without hybrid
Petrol with hybrid
Petrol without Petrol with Petrol without Petrol with
energy – a hydraulic solution has a number of major
hybrid
hybrid
hybrid
hybrid
advantages. Hydraulics have a much higher power density,
Orange County
Braunschweig
which is a measure of how quickly the braking energy can
be captured and the acceleration energy delivered to the
wheels. Clearly, if a hybrid drive system cannot store energy quickly, there’s an increased likelihood that not all of the braking
energy will be captured, eroding the fuel and emissions benefits. As a result of this, and the fact that there are fewer opportuni-
400
300
200
100
0
ties for energy losses in a hydraulic system, Lightning Hybrids’ system can regenerate in excess of 70% of the energy captured
during a braking event. For a battery hybrid system, that figure is closer to 30%. Clearly, the higher the efficiency, the better
the system’s contribution to fuel economy and emission reductions.
Conclusion
As the first hybrid technology developer to focus primarily on emissions reductions for medium and heavy-duty vehicles, these
results – immediate, material, and consistent emissions reductions – show that Lightning Hybrids’ hydraulic hybrid system is a
clear winner.
1 California Air Resources Board
2 West Virginia University. See arb.ca.gov/regact/bus02/appc.doc
3 Technical University of Braunschweig
4 www.epa.gov/oaqps001/urbanair/
5 ec.europa.eu/environment/air/quality/standards.htm
6 A cold engine generates heavier NOx emissions primarily because the catalytic converter is designed to function when hot.
7 Hot-start diesel data was not captured for the Orange County Buss cycle
8 www.fueleconomy.gov/feg/climate.shtml
© 2015 Lightning Hybrids