TriMet considering augmenting its bus fleet with compressed natural gas buses


Initial purchase of cleaner running buses could come in next few years

TriMet may add a new, more environmentally friendly type of bus to its fleet that’s different from a hybrid – it would run off compressed natural gas (CNG). Next week, the TriMet Board will consider a resolution authorizing a multi-year bus purchase contract that includes the option to buy up to 120 40-foot CNG buses. The new contract is part of TriMet General Manager Neil McFarlane’s accelerated bus purchase program and would provide for future-year bus deliveries in 2015 through 2019.

“TriMet has been exploring numerous green transit options and is currently analyzing the costs and benefits of adding CNG buses to the fleet,” said TriMet General Manager Neil McFarlane. “The option to buy CNG buses is part of TriMet’s ongoing effort to increase our sustainability and improve air quality throughout the region.”

The CNG buses would join TriMet’s clean diesel buses that by the end of October will make up more than 20.5 percent of the existing bus fleet. The clean diesel buses have reduced TriMet’s emissions, both smog and smoke. CNG is cleaner than diesel, although modern clean diesel technology puts it close to CNG vehicles.

Despite the higher initial purchase costs – the agency pays close to $420,000 for a diesel bus now, and a CNG bus would cost roughly $55,000 more – CNG buses offer the potential to save money in the long run. Natural gas is currently 30 percent less expensive than diesel. Lower and more stable fuel prices mean that their initial expense could be recovered within the first few years of operation.  However, CNG buses have somewhat lower fuel economy (10-20%) and higher maintenance costs (10-15%) than diesel buses, which would offset some of the fuel cost savings.

There are also other costs associated with the logistics and infrastructure of switching to CNG fuel. This will influence the project’s overall cost effectiveness which is currently being analyzed.

Should TriMet decide to pursue the CNG bus technology it will require converting one of TriMet’s bus maintenance facilities to accommodate the CNG vehicles. TriMet’s Merlo garage is currently under consideration.  CNG is kept under high pressure, so it will require implementing a new fueling system with associated safety and maintenance requirements in the shop.  TriMet is considering a number of different options for how to fund this conversion.

If we move forward with the CNG project, the TriMet Board will be asked to activate the option for purchasing the CNG buses.

Bus purchases under the proposed contract will be funded from a combination of federal and state grants, available operating resources and bond proceeds.  The funding mix for each bus order will vary and be part of the budget process for that year.

Earlier this year, TriMet introduced four hybrid buses to the fleet and will be adding four super-hybrid (all electric-powered) buses in the next year.

Bus innovations – keeping us green

Burning less fuel
Burning less fuel means fewer emissions and a more sustainable transit system. We are one of the most fuel-efficient transit providers in the country, thanks to our creative operators and mechanics who keep finding new ways to conserve fuel.

TriMet is the nation’s first transit agency to test and operate buses cooled by a NASCAR-inspired electrified cooling system. Traditional systems draw up to 50 horsepower off the engine, draining power and consuming fuel. The electrified cooling system uses less engine power, resulting in approximately 5 percent better fuel economy. The system also significantly cuts maintenance time and costs and is safer to maintain. Additionally, a drivetrain computer in the engine compartment of each bus saves fuel and improves driving safety. It monitors the engine, transmission and braking system, and uses the data to adjust acceleration, braking, traction control and fuel injection.

Using improved fuel
Our buses use a cleaner burning biodiesel fuel blend and TriMet is the largest biodiesel user in Oregon. The blend, including the petroleum-based share of the fuel, meets new federal standards for ultra-low-sulfur diesel (ULSD). It reduces emissions, especially carbon dioxide, carbon monoxide, sulfur dioxide and smoke.

Solar powered bus shelter lighting
TriMet has installed Solar-powered lighting systems at bus stops to harness the sun’s energy, providing greater visibility and safety at dark bus stops. They reduce both the initial costs and the ongoing expense of providing power to shelters and are environmentally friendly. We have installed more than 200 such systems at well-used sheltered stops where direct power connections are impractical.

Bus purchase background
The agency delayed new bus purchases for a few years due to the recession. However, in 2012 McFarlane accelerated the bus replacement schedule to address TriMet’s aging bus fleet that had become more expensive to maintain and less reliable. Some buses in the fleet are more than 18 years old.

In 2012 the agency purchased 51 diesel and 4 new hybrid buses. This year the agency purchased 70 40-foot diesel buses, the largest order in the accelerated bus purchase. During the next three years, TriMet will add another 184 buses. By 2016, the average age of our fleet will be the industry-recommended standard of eight years. By 2017, TriMet will have replaced all of the remaining high-floor buses (those with steps at the door) in the fleet.