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September 4, 2009

Mass Transit to Save More Energy

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Filed under : General Green
New MAX LRVs in Old Town

Mass Transit to Save More Energy

Everyone knows that taking the bus can help reduce your carbon footprint.  But did you know that using mass transit can save more energy?  Well, at least that’s the case in Portland, Oregon!

Recently, TriMet made an exciting announcement that will reduce cooling costs for buses in the Oregon major metropolitan region.  A new technology that was developed for Army tactical vehicles will now be used in TriMet buses, replacing the cooling fan with eight electrically-powered fans that instead will turn on only when needed.

You might wonder why  – and how – reducing cooling costs could save energy in Portland, Oregon?  After all, the area is one of the wettest, cloudiest areas in the nation.  Yet, TriMet has determined that it can save 700 gallons of fuel each year, for each bus with the new technology!  And it partnered with Engineered Machined Products, Inc. (EMP) to do so.

Top of Mt. Hood, Oregon

Near Portland Oregon

Mass transit helps save energy, not so much because each vehicle is energy-efficient, but because you get multiple riders in a single bus or tram.  Yet, diesel buses only get a few miles per gallon.  Why not improve the efficiency and save fuel?

And here’s the coolest (pardon the pun) part – the technology is inspired by NASCAR.

In Portland, its buses have already been retrofitted with new hardware, which will save the following:

  • $138,000 in diesel fuel costs each year
  • save 512 tons of CO2 emissions annually

In addition, the retrofitted systems will pay for themselves in 3-5 years, or less.

Cooling fans for TriMet buses (image from Abby Metty, The Oregonian)

Cooling fans for TriMet buses (image from Abby Metty, The Oregonian)

Portland is not the only city that is using mass transit to save more energy!  Many other agencies in the United States have decided to install similar retrofits for their fleets, or even order buses that already have the NASCAR cooling systems pre-installed.  Federal stimulus funds can help these efforts.  Not surprisingly, the Environmental Protection Agency (EPA) awarded TriMet with a Clean Air Excellence Award for developing the device.

The name for the technology?  Its called a “minihybrid thermal system.”  Sounds cool to me!

As described in a recent Oregonian article, this is how Portland’s mass transit can save more energy:

The conventional buses TriMet runs have large hydraulic fans in the back, cooling the engine under the buses’ rear seats.  That’s where the problems begin.

The fan – about 2 1/2 feet in diameter – sucks hydraulic fluid constantly.  Depending on the size, a bus could carry 300 to 500 pounds of fluid just to keep the fan going.

The fan comes on full blast when any part of the engine or coolant gets too hot or cold.  It runs on an alternator greased with oil and prone to occasional leaks.

Among several reasons why the minihybrid thermal system can help save fuel is the fact that pounds of hydraulic fuel need not be carried with the vehicle.  It is more efficient, as well, using only 16% of the peak output of the buses’ engines.  The agency is applying for federal stimulus funds to retrofit 154 more buses with the new cooling systems.  A grant would help TriMet gather data for a study on fuel efficiency impacts.

Major kudos go to TriMet for wondering about – and then implementing – the experimental technology.  In a few short years, the agency took a pointed question about whether the system might be used for mass transit and completely transformed the future of cooling systems on buses in the Portland, Oregon metropolitan area.

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