GE has built and demonstrated a new electric bus powered by a dual battery system.
The company’s hybrid systems research team said it thinks the designcould be a breakthrough for the electrification of bus fleets, deliverytrucks and other larger, heavy-duty vehicle fleets.
The design pairs a high-energy density sodium battery with a high-powerlithium battery. GE researchers believe a dual system with high powerand energy storage capacity could achieve the optimal electric drivingrange and acceleration requirements at a more practical size scale andcost for larger vehicles.
The research is being done as part of a $13 million research project GEis engaged in with the Federal Transit Administration (FTA) andNortheast Advanced Vehicle Consortium, funded under the National FuelCell Bus Program.
“We’re entering a decade of unprecedented activity and developments inelectrified transportation,” said Lembit Salasoo, Senior ElectricalEngineer and Principal Investigator on the hybrid bus project at GEGlobal Research. “With heavier vehicle platforms, both energy storageand power are a premium to deliver optimal vehicle performance, but theexact needs can vary based on a vehicle’s size and drive cycle. Thebeauty of our dual battery system is that it can be scaled to deliverjust the right combination of power and storage.”
Many of the 843,000 buses registered in the U.S. (including most of the63,000 transit buses and 480,000 school buses) travel less than 100miles per day. Enabling more of these buses to transition to anall-electric, zero emissions platform would dramatically reduce CO2emissions and petroleum fuel consumption.
Most types of batteries today come with a trade-off between power andenergy storage. For example, lithium batteries, provide a lot of powerfor acceleration, but are not optimized to store energy for drivingrange. Sodium batteries are on the opposite side of the spectrum. Theystore large amounts of energy, but are less optimized for power. Thedual battery approach attempts to combine the best attributes of bothchemistries into a single system. In the hybrid transit busdemonstration, the lithium battery focused on the high poweracceleration and braking, while the sodium battery provided an evenelectric power flow to extend the bus range.
In addition to optimizing performance, a dual system can reduce the cost of a battery by up to 20% compared to a single battery system, GE said. The key cost advantage of a dual system is that it provides flexibility to integrate less expensive battery chemistries without having toincrease the size of the battery to address a vehicle’s power and energy storage needs. A single battery system would require a more costlyscale up in the size of the battery to achieve the same result.
The development of a dual battery system and partnership with the FTA is a key part of GE’s growing hybrid and electric technology portfolio. GE said it is actively exploring partnership opportunities across theelectric vehicle value chain through its Licensing business tocommercialize its dual battery technology.