Part of this year’s Colorado Clean Cities meeting involved attendees driving alt-fuel vehicles and reporting on their experience, including fuel economy and overall vehicle performance during the trip. This entry is from Brian Johnston, systems and testing engineer at Lightning Hybrids. His account explains what the company’s hydraulic hybrid technology was able to achieve in the Ford E-450 passenger shuttle bus he drove to the event.
I am Brian Johnston of Lightning Hybrids in City of Loveland, Colo. I drove a Ford E-450 based, 25 passenger shuttle bus with a 6.8L V-10 engine to the statewide meeting at the National Renewable Energy Laboratory (NREL). This bus employs our company’s hydraulic hybrid drive system which captures regenerative brake energy in a hydraulic accumulator, then uses it to propel the vehicle from a standing start to about 35 mph. This technology is ideal for heavy vehicles which drive on intensive stop and go drive cycles such as city transit buses, delivery vehicles, or refuse haulers.
My route to NREL consisted of 56 miles of almost exclusively highway style driving. This is not the sweet spot for a hydraulic hybrid which has outstanding power and torque, but limited energy storage. The vehicle used its stored hydraulic energy to initially accelerate to highway speed, and then spent most of the trip operating like a conventional vehicle. Had I been forced to take a local route, the benefits of hydraulic hybridization would have been far more significant (up to 20% improvement over the conventional equivalent). This highlights the need for our technology to be paired with specific drive cycles. A fleet of intercity buses or airport shuttles could see major fuel economy improvements, while an Over-The Road trucking company would not see significant gains.
There was negligible planning or adaption required to drive this trip. The vehicle’s engine operates on regular gasoline available anywhere. Our system displaces, but does not replace petroleum fuels. The 56 mile trip is only 10% of the available vehicle range with a 55 gallon tank and 11 mpg average observed on the highway. It was hot, so I ran the air conditioning with the windows up. While 11 mpg may not sound very impressive, customer vehicles in this class usually only achieve 7-8 mpg on some of the worst drive cycles in terms of fuel economy. Also remember that with 25 seats, this vehicle has the potential to displace 5-25 sedans if it is driven with a full load of passengers. With that in mind its performance is far more impressive. To truly demonstrate the performance of this vehicle, I should have given all the stakeholders a ride home!
I would also like to mention a few of the benefits of the hydraulic hybrid technology in addition to improved fuel economy. These include increased brake performance and component life, improved acceleration, and a three year return on investment. The parallel hybrid architecture also allows the user to disable the system in the event of a malfunction and continue with its assigned mission. Our vehicles have never required a tow home in the company’s history. This allows the fleet manager to schedule maintenance during off shift hours and maintain higher reliability ratings.
Thanks for your interest in this green transportation alternative. When applied to the right style of driving, hydraulic hybrids provide an excellent choice to save gas without sacrificing vehicle performance. Feel free to contact me with any additional questions at Lightning Hybrids! BJ