NYC Decides Diesel Buses Are Cleaner than Hybrids

The Manhattan hybrid back when. The Manhattan hybrid back when.

Back in 2009, The New York Times proudly reported that New York City was operating "by far, the nation's biggest fleet of hybrid buses, which run on electricity and diesel fuel, with nearly 1,000 in all five boroughs, most in Manhattan."

In the mid-1990s, said Joseph J. Smith, senior vice president for the department of buses for the MTA New York Transit Authority to The Times in 2009, the city was looking for ways to clean up its bus fleet. After rejecting buses that ran on compressed natural gas for being way too pricey, in 1998, the transit authority bought 10 hybrid-electric buses at a cool million bucks each.

Mean Distance to Failure.

Things went swimmingly: "By 2001, the city had ordered another 125 and subsequently bought hundreds more," the Times wrote, adding that "today, New York has the largest fleet of hybrid buses of any city in the country -- 850, out of a fleet of 4,500."

According to the International Business Times, New York's bus fleet comprises "14 different bus models, including the Orion VII, which is manufactured by Orion International at facilities in Mississauga, Ontario, and Oriskany, N.Y."

After extolling the benefits in cleaner air and quieter buses in the city, the Times threw in the observation that "the hybrid buses are easier to fix -- and most important, don't break down as often, which the department measures as 'mean distance to failure,'" or MDF.

That MDF turned out to be approximately four years.

And Things Went Fine, Until...

According to the New York Post, New York City's MTA (Metropolitan Transit Authority) "hasn't purchased an electric-diesel hybrid bus in three years, and as many as 389 -- 23 percent of all its hybrids -- could be retrofitted with new diesel engines soon."

One reason for the switch might be that two hybrids burst into flames in 2009. It could be because pranksters have discovered the switch one can throw on the side of the bus to shut it down in mid-service. But mostly, it's that they simply haven't worked as advertised.

"An insider" told the Post that "maintenance workers constantly have to repair hybrid engines. The electric-traction motors are burning out. They're so expensive to replace that it'll be cheaper to stick a diesel engine in there."

And indeed, the Post reported that a July 2012 contract between the MTA and Indiana-based engine manufacturer Cummins Inc. "confirms that the MTA is evaluating how to convert hybrid buses to a diesel-engine-only application."

More Diesel Engines = Cleaner Air. Really.

Ironically, the switch back to diesel engines could mean cleaner air in New York. Henry Sullivan, the MTA's chief maintenance officer for buses, said that the hybrids the MTA runs conform to 2004 Environmental Protection Agency emission standards. The new diesel engines, he told the Post, conform to stricter 2007 standards: "When we first went with the hybrid in 2004 that was the way to go. The diesel is better than the hybrid now."

MTA spokesman Charles Seaton also observed that "in high-speed operation," diesels "work better." This appears to be the major factor in the decision to switch back to diesels, since five-year warranties on 100 hybrid buses are about to expire, The Post reports, "which means repairs to the buses' engines will no longer be covered by the manufacturer," and the MTA would have to pick up the hefty tab.

As the IBT wrote, hybrid city buses are really made for "intense stop-and-go routes where the average speed is 8 miles per hour." Such as Manhattan. And the city's keeping hybrids there. But "in situations where buses travel longer distances at higher speeds, the hybrid system is less useful because the lithium ion battery harvests power from when the vehicle brakes and when the bus is coasting," the IBT explained, which is why they'll be fine for Manhattan, where buses "travel much slower and brake more often than the buses in the outer boroughs."

Hybrids Losing Their Luster?

New York's experience is similar to that of other cities experimenting with hybrid buses around the world. DieselNet, perhaps a bit too happily, wrote recently that "Fuel consumption in hybrid buses is very sensitive to the test cycle, as it depends heavily on regenerative braking." Unfortunately, most cities aren't built for hybrids.

ottawa"Transit agencies in a number of cities became disillusioned with the real-life fuel efficiency of hybrids -- especially so when the buses were operated on suburban routes with fewer stops," DieselNet wrote, adding that colder cities such as Toronto and Ottawa also discovered they had to replace the lithium-ion batteries more often than they were expecting to, at about $60,000 per battery.

CBC News reported last October that Ottawa is so disappointed in its hybrid bus fleet, what with fuel costs being millions of dollars more than expected, that "the city's draft budget for 2013 includes $550,000 for a pilot project to rip out the hybrid electric/diesel engines and replace them with regular diesel engines."

The city runs 177 hybrid buses, and estimates retrofitting would cost about $75,000 per bus, which comes to a cool $13 million. New York would pay about the same per bus to retrofit their fleet.

Not The End of The Line for Hybrids.

It's not a death knell for hybrid buses in municipal fleets. Used correctly, in the right situation, they can work well. In Adelaide, Australia this March, Minister for Transport Services Chloë Fox launched a new fuel-efficient hybrid electric-diesel bus for the Central Business District.

London's newest electric bus. London's newest electric bus.

Fox noted at the time of the announcement that "The trial on the Free City Loop involves short distances and frequent stops which makes it particularly suitable for this type of vehicle... The more the bus brakes, the less diesel-generated power is required. That is why the Free City Loop is the ideal operating environment for a hybrid bus."

Actually there's no telling what problems could crop up with hybrids. The Voice of Russia, UK Edition, reports that Londoners "have been sweltering as temperatures soar because The New Bus for London, the greenest diesel-electric hybrid bus in the world, which costs £354,000 each, has no opening windows upstairs, leaving passengers in temperatures of over 30 degrees C."

The Mayor of London, Boris Johnson, described the buses as offering "an unparalleled passenger experience."

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