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6th December 2007
Page 62
Page 62, 6th December 2007 — PUMPING GREEN
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Which of the following most accurately describes the problem?

We've heard a lot about alternative fuels and electric hybrids, but the US Environmental Protection Agency has come up with a very different type of environmentally friendly vehicle

— a hydraulic hybrid. Tom Cunningham reports.

Back in 2000, parcels giant Fed-Ex approached the US Environmental Protection Agency (EPA) in search of a commercially sustainable fuel-saving delivery vehicle.This was in line with President Bush's policy of reducing the country's dependence on fossil fuels —as one American we met in Shanghai put it:"We're sick of buying oil from countries who hate us."

To pursue this goal the EPA's boffins enlisted help from Eaton Corporation, UPS, International Truck and Engine Corporation. the US Army National Automotive Centre, bodybuilder Morgan-Olson,FEV Engine Technology and the Southwest Research Institute.Between them they developed the hydraulic hybrid vehicle (HHV).

Based on a standard International chassis and sporting the ubiquitous UPS-spec Morgan-Olson aluminium bodywork, the I 3-tonne parcels truck is powered by a mnventional 6.0-litre International VT365 liesel. But the rest of the driveline breaks new vound,such as incorporating two principal Tteans of delivering traction.The diesel engine hives a rear-mounted hydraulic pump which eeds two rear hydrostatic drives located Iround the rear duff. At the same time a second low of pressurised oil is fed into two h ighressure gas tanks (known as accumulators) illed with non-flammable nitrogen.

:ompression and release \s the gas is compressed,energy is stored, It's ihit like a giant spring: when the compression caches maximum, the diesel engine is stopped ,nd the gas is released,foremg hydraulic oil hrough the hydrostatic drive in place of the oil iumped by the engine.

The EPA vehicle also features regenerative 'raking. When the brakes arc applied, energy rom the wheels is used to pump fluid from a 2w-pressure reservoir into the high-pressure accumulator:11ns process recovers more than 70% of the energy otherwise wasted during braking: it is also said to reduce wear on the brake linings by 75%.

This gas/hydraulic system also restarts the engine; battery power is only needed if the gas tanks are empty.

"It's the same basic idea as an electric hybrid.but using compressed gas and hydraulic pressure instead of electric motors," says Kevin Newman,controls engineer at the EPA's National Vehicle & Fuel Emissions Laboratory."It takes roughly 15 seconds for the system to charge the gas tanks to full pressure, which will power the vehicle for half a mile at typical neighbourhood delivery speeds. The system is deadly silent—you can hear the International's sprung suspension system creaking away when the engine's off. rIbe EPA claims 60-70% better fuel economy (in laboratory tests) and a40% (or greater) CO. reduction.'

A second hybrid A second UPS demonstration vehicle is being used to assess the cost-effectiveness of a full hydraulic hybrid system configuration under a variety of load and driving-cycle conditions. EPA also plans to install an EPA Clean Diesel Combustion (CDC) engine in this vehicle.The CDC engine would not require SCR or EGR to achieve the US's 2010 emissions standards.

According to the EPA and UPS, the investment in the hydraulic hybrid system will pay for itself within three years. If produced in high enough numbers, the hybrid components for a parcel delivery vehicle would cost about £3,500, which would be recouped in less than three years by lower fuel and brake maintenance costs.

UPS says that coupled to an almost entirely aluminium construction, and with a predicted service life of 20 years, estimated savings

over a standard diesel vehicle could be in the region of £25.000.A second benefit is that the production of aluminium-bodied vehicles generates less CO, than that of their steel counterparts, and they are readily recyclable.

And if fuel prices continue to increase faster than general infl ation, the lifetime savings would be even greater. UPS is no stranger to this type of technology; it has more than 1,600 CNG,LNG,propane,electric and hybrid electric vehicles in operation.comprising the largest private fleet of alternative-fuel vehicles in the US parcels industry In total they already cover in excess of 126 million miles a year.


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