In hilly central Massachusetts, the Worcester Regional Transit Authority's six electric buses average the equivalent of 16 to 18 mpg and have saved the agency an estimated $80,000 on fuel since last fall.
The Southeastern Pennsylvania Transportation Authority, which serves the Philadelphia area and first experimented with hybrid buses about a decade ago, has 400 hybrids in its 1,400-vehicle fleet and will soon receive 60-foot articulated hybrid buses.
Close to booming natural gas exploration, Dallas Area Rapid Transit, or DART, is phasing out diesel and liquefied natural gas (LNG) from its 612-vehicle fleet in favor of compressed natural gas (CNG).
Just as American drivers balance fuel economy, sticker price and overall value when buying cars, transportation departments nationwide are increasingly forced to weigh fiscal constraints with long-term economic and environmental merits and pitfalls before placing their next bus orders.
In 1996, 95 percent of buses in the United States were diesel-powered and just under 3 percent used CNG, LNG or blended fuels, according to the American Public Transportation Association's September report.
As of 2013, the most common bus systems have shifted significantly: 58 percent of U.S. buses ran on diesel; 20 percent used natural gas and blends; 13 percent were electric or hybrid buses; and 7 percent relied on biodiesel.
Faced with a diversity of choices as electric bus makers have multiplied and as diesel and hybrid engines have become more efficient, transit providers are following their own blueprints.
N.J. charges ahead; Ann Arbor has sticker shock
The transit authority for Ann Arbor, Mich., is debating hybrid buses -- the chairman has stated that their fuel savings aren't enough to offset upfront cost -- and the New Jersey Transit voted unanimously in early October to spend at least $35.2 million on 36 new hybrids.
The epicenter of 10 of the 50 biggest public transportation agencies in the country, New York City announced last summer that it would remove a quarter of its 1,677 hybrids from the city's roads and replace them with diesel models.
"The plan is to continue to buy about 100 hybrid buses a year," said Erik Johanson, SEPTA's manager of strategic business planning. "In our stop-and-go environment, hybrid buses thrive."
SEPTA's hybrid buses average 40 percent better fuel economy than diesel, Johanson said. Hybrids come with lower maintenance costs, as well -- technicians spend less time on brake realignments and assessing transmissions -- he added.
But hybrids and electrics are significantly more expensive up front.
An Ann Arbor Area Transportation Authority study found that a new diesel bus would cost about $455,000, while a hybrid would cost about $650,000. The AAATA estimated those buses would cost approximately $760,000 and $950,000, respectively, during their entire life cycles, which would include a $35,000 battery replacement for the hybrid.
Fully electric vehicles are pricier still. Proterra, an American electric bus manufacturer from South Carolina, sells its vehicles for $850,000.
Ralph Wilder, the superintendent of transit maintenance at StarMetro in Tallahassee, Fla., manages five electric Proterra models that cost more than $1 million apiece. Steve O'Neil, the administrator for the Worcester transit authority, said six electric buses cost his agency $970,000 after a grant from the Federal Transit Administration.
Johanson said prices between diesels, hybrids and electrics vary and initial prices omit long-term expenses.
"Hybrid technology typically adds about $200,000 more than a conventional bus," said Chuck Wurzinger, the assistant director of bus maintenance at Metro Transit, which serves Minneapolis and St. Paul.
More expensive initially and with their primary long-term benefit undercut by falling prices at the pump, hybrid and electric buses are too expensive for many buyers.
"There are no plans for us to go hybrid," said Morgan Lyons, a spokesman for DART, which has a 612-bus fleet of natural gas and diesel buses rolling throughout the Dallas-Fort Worth area.
Lysons said DART will replace the fleet in the next few years, with 500 buses in the next order, and has a grant for an electric bus from the U.S. Department of Transportation.
The organization, he said, was able to recently finalize a 20-year natural gas contract that was hard to pass up.
"We were able to lock in CNG over an extended period of time," Lyons said. "Natural gas just made the most economic sense."
Los Angeles tries all-electric
The Los Angeles County Metropolitan Transportation Authority -- the fourth-largest transit agency in the United States based on passenger miles traveled -- will receive five electric buses by January from BYD, a Chinese car and battery manufacturer backed by Warren Buffett's Berkshire Hathaway, and could get 25 more with board approval.
"We have the largest fleet in the United States in terms of alternative buses," said Marc Littman, an LACMTA spokesman, adding that all the agency's roughly 2,200 buses are CNG-fueled.
The LACMTA board made the decision to shift away from gasoline buses about 20 years ago, largely due to air-quality concerns, Littman said.
"Other cities may not be facing the environmental challenges that we are here," he said, citing asthma, choking traffic congestion and the way in which the Los Angeles Basin traps smog.
The break-even point at which hybrid or electric buses would pay for themselves through better fuel economy and lower emissions for their regions and riders -- a positive public health byproduct -- depends on fuel costs, vehicle life span, ridership and a host of other factors.
Mulling the financial and environmental arguments for and against diesel, CNG and hybrid buses, the Regional Transportation District in the Denver metro area conducted a study in February, concluding that hybrid buses are the most costly option even within a long time frame.
Diesel-electric hybrids are 13 percent more expensive than standard diesel buses over their life cycles, while CNG buses are 8 percent less expensive than diesels.
Compressed natural gas buses, however, require specific CNG-equipped garages that meet fire and safety standards. In its analysis, RTD estimated that those upgrades and modifications could cost from $8 million to $57 million per facility.
Wurzinger, at the Twin Cities' Metro Transit in Minnesota, is wary of the danger of investing in natural gas buses and matching facilities with its cold climate.
"We have to store our [buses] indoors, because of the weather," he said, explaining that a gas leak in a CNG-equipped garage and a spark could spell disaster.
Wurzinger said Metro Transit, which uses 132 diesel hybrids in its 920-bus fleet and subsidizes 80 to 85 percent of its bus procurement costs with federal grants, is "seriously looking at electric buses."
For hybrids to become cost-competitive, according to Wurzinger, fuel prices would have to spike, hybrid manufacturers would have to lower their prices and buyers would have to use those vehicles longer.
"We're not right around the corner" from hybrid engines becoming cost-competitive, he said, adding that Metro Transit has scaled back its hybrid deliveries. "It's really, in my opinion, off in the distance."
Traffic-packed cities may be ideal for hybrids.
Scrutinizing the performance of a diesel bus against a hybrid in New York City's Manhattan borough; Orange County, Calif.; and the Seattle area, a 2012 study from Iowa State University noted that the hybrid bus generated better fuel economy in each driving environment. The hybrid was 30 percent, 50 percent and 75 percent more fuel-efficient in Seattle, Orange County and Manhattan, respectively.
Worcester sees payback in energy costs
Beyond their initial price tag, electric buses are paying off in some U.S. communities.
As part of pilot project to test Eaton Corp.'s fast-charging equipment, Tallahassee, Worcester, and Stockton, Calif., received "DC HyperChargers" from the power equipment company in late 2013.
"It's doing an incredible job," said Wilder, the Tallahassee official. Wilder's five electric buses run on an 18-mile loop and stop for a seven-minute fill-up before continuing.
Steve O'Neil, the Worcester manager, said his electric Proterra buses charge in five to six minutes and go out for four to five hours before returning for a charge -- saving tens of thousands on fuel and upkeep.
"I think if you're getting 10 to 12 years out, you're getting to the point of payback," he said, adding that bus fleets nationwide are seven years old on average.
In Stockton, the San Joaquin Regional Transit District typically runs its electric buses on an hourlong loop before charging, but the drivers can make two complete routes without running out of power, said the communications manager, Paul Rapp.
In a seven-month fuel economy comparison, the agency found its electric buses were twice as efficient as hybrids -- the electrics cost 30 cents per mile, while the hybrids cost 62 cents.
According to the report from RTD in Denver, diesel, CNG and hybrid buses average between about 3.5 and 5.6 mpg. CNG buses earn the worst mark and hybrids the best, while diesels average roughly 4.6 mpg. But CNG buses are the cheapest for distance, averaging 46 cents a mile.
In 2012, Americans traveled more than 20 billion miles on public buses -- the country's most popular public transportation mode -- but drove almost 3 trillion vehicle miles in the same year.
Seattle sees health benefits
As more Americans move into cities, the public health and environmental benefits would be significant.
"We're not here simply because we want to save polar bears," said Kevin Desmond, the general manager for King Count Metro Transit in the Seattle region.
After beginning to use hybrids in 2004, Seattle metro officials assessed the long-term cost of investing in hybrids, making assumptions on fuel cost, and concluded that "hybrid buses would pay for themselves."
"At over $4 a gallon [for diesel], the hybrid buses easily paid for themselves," Desmond said.
Desmond said city and county leaders aggressively advance sustainability policies and noted that midlife battery replacements are a big maintenance issue with hybrids.
"I would foresee in 10 years, these buses would be more prevalent," he said. "The quick charge is the critical factor."
In the wake of the 2008 financial crisis, Desmond said, it's understandable that many transit agencies aren't buying hybrid or electric buses.
"It's been a struggle the last couple of years," he said. "We're driven by a very strong public policy."