Around the world, on-board energy storage systems are being implemented to collect unused energy usually lost during braking events for reuse during higher power demands during vehicle propulsion. The U.S. is behind in policy in relation to other parts of the world however, lacking a concrete energy plan to guide the development of future technology.
In the transportation industry, the world’s largest energy consumer, ultracapacitors improve a vehicle’s energy efficiency through regenerative braking systems. In stop-and-go transit applications, the savings for energy and fuel can be significant, as well as the emissions reduction for cleaner air.
“There are a number of applications of that in the world today that use ultracapacitors for energy recuperation, primarily diesel-electric hybrid buses,” said Chuck Cook, sales application engineer, Maxwell Technologies.
Braking energy recuperation systems in electric and hybrid vehicles save fuel and electrical energy by using resistance from the electric motor to stop the vehicle, thereby converting kinetic energy that would be wasted in a conventional friction-based braking system into stored electrical energy. Ultracapacitors' rapid charge/discharge characteristics uniquely enable them to capture and store more energy during each braking event than battery-based systems, which have limited ability to absorb energy in the few seconds required to stop a vehicle.
Maxwell partner—co-exhibiting at APTA 2014 with Maxwell Technologies—Crosspoint Kinetics makes bolt-on systems for trucks and light buses (Class 3-7). The bolt-on system, The Kinetics Hybrid, puts the torque motor in line with the driveshaft to collect the energy during braking events and give the energy back to the vehicle when needed while reducing greenhouse gas emissions. When applied and driven correctly vehicles can see up to 30% greater fuel efficiency, and corresponding emissions reductions.
SEPTA’s light rail system is using Maxwell’s ultracapacitors in a hybrid configuration, which is reducing SEPTA rail vehicles’ grid-supplied energy consumption by 10 to 20 percent on top of the extended battery life. The SEPTA model goes beyond recovering brake energy by also helping the electricity grid to be more stable and efficient with fast regulation support.
“I think what we will find is as more of these applications become well known, the technology will start to make sense,” said Cook.
