In the last few years, electrified, zero emissions buses have become, if not common, at least accepted in cities around the world. One bus line in Milton Keynes, UK, runs a fleet of electric buses that recharge on the driver’s break via an inductive charging pad buried in the road.
One limitation of the electric bus, as with all electric vehicles [EV], is range. If a Milton Keynes Route #7 Bus goes off the route, it won’t get more than 20 miles before discharging completely.
One option to increase range is to generate electricity on board, but a gasoline- or diesel-powered generator would cancel out any benefits of running pure electricity. This is where hydrogen fuel cells [HFC] come in.
Over the last ten years, great advancements in HFCs have brought prices down while increasing power density. The main benefit of the HFC, though, is they produce electricity directly from fuel without combustion, releasing nothing more harmful than oxygen and water into the atmosphere.
Another benefit, especially for EV owners, is they refuel just as fast as at a gas station, instead of the hours required by pure EVs. General Electric’s new HFC zero emissions bus uses HFC-generated electricity to drive its electric motors, but with the addition of two battery technologies.
The most prevalent EV battery today is Lithium-ion [Li-ion], which is a balance of battery technology favoring performance, rather than range. Li-ion batteries are great for short-term energy storage and can deliver relatively large bursts of power, which makes for great acceleration and battery longevity, but at the sacrifice of range. Sodium-ion [Na-ion] batteries, on the other hand, aren’t very good for short bursts of power or lifespan, but excel at providing a long range.
Combining the best characteristics of both Li-ion and Na-ion batteries, General Electric’s Durathon combination battery pack should allow the bus to operate at full performance with a much smaller HFC. “For years fuel cells have been talked about as a clean transportation alternative but cost has always been a roadblock to widespread adoption,” said Tim Richter, Systems Engineer in the Electric Propulsion Systems Lab at GE Global Research.
“With GE’s battery technology and dynamic dual battery management system, we’re starting to push that roadblock aside.” Building a zero emissions bus with a reduced-size HFC could reduce costs by as much as 50% and still emit zero greenhouse gases.
