INL demonstrates solar powered air conditioning for their buses


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INL No Idle HVAC System equipped bus. | Mike Price,

IDAHO FALLS — Solar powered buses? We’re not quite there, but solar powered air conditioning on buses is here.

Idaho National Laboratory, in collaboration with Bergstrom Inc, a vehicle climate systems designer and Motor Coach Industries, has designed a solar powered bus cooling-ventilating system.

The system, demonstrated in Idaho Falls on Aug. 30, will reduce emissions and improve fuel efficiency by not requiring the engine to run while the bus idles.

“The main driver was our idle and our fuel costs,” INL bus supervisor Jeff Brown said about the inspiration behind designing this system.

Brown told their entire bus fleet idles around 124 hours per day combined.

“If you take the whole fleet, then you take three-quarters of a gallon per hour — it doesn’t take long even at a hundred gallons,” Brown said. “At a hundred gallons a day and you times that by $4.50 (cost of fuel) and you do that seven days a week 365 days a year, that’s a huge bill.”

Info graphic explaining the No Idle HVAC System | Mike Price,

The systems solar panels on the top of the bus charge the dual batteries that run the HVAC system.

Because of INL’s goal for efficiency, the solar panels needed to conform to the curve of the bus so as to not create extra wind resistance.

“The challenge here was to design a system that was efficient in charging the batteries and helping offset the power consumption of the air conditioning system that Bergstrom had developed,” Senior Technology Director for Merlin Solar, Arthur Rudin said.

Brett Hermann from Bergstrom said this system is ideal for INL’s fleet of buses. The buses, generally, drive for an hour or so then idle for an hour.

“You’re going to save quite a bit of fuel on a cycle like that,” Hermann said.

For the time being, the system only supports air conditioning. Brown explained integrating heating into the system will be simple.

INL is currently running one bus with the new system and hopes to gather sufficient data by this time next year to determine whether or not to install it on the majority of their fleet of buses.

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