Maxwell Technologies, Inc has announced that Win Inertia, an engineering firm specializing in power electronics, energy storage and control and communication systems, is using its ultracapacitors for a stationary wayside braking energy recuperation system at an electric rail system in Cerro Negro, Spain. Win Inertia designed and installed the system under a contract with the Spanish government's Administrator of Railway Infrastructures (ADIF). In this installation, the system also enables ADIF to store excess energy in a battery bank that supplies an electric vehicle (EV) charging station located at the rail station. The facility also seamlessly integrated a photovoltaic (PV) generator to supply additional energy if required.
The recuperation system employs Win Inertia's SHAD® hybrid control technology (international patent pending) to integrate batteries and Maxwell ultracapacitors to increase energy recovery efficiency and reduce stress on the batteries, thereby extending battery life. 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. Win Inertia's high-efficiency hybrid energy storage and power delivery system furthers ADIF's return on investment as it enables dual use of the recuperated energy for rail vehicle propulsion and EV charging. By converting kinetic energy into stored electric energy through regenerative braking, the system recovers 8 to 10 percent of the total energy used by the railway system, which is then used to power the EV charging station.
"By incorporating ultracapacitors, which accept charge from the braking energy recuperation system much more efficiently than batteries, the system recovers significantly more energy," said Eugenio Domínguez Amarillo, Win Inertia's CEO and chief technology officer. "Additionally, by using ultracapacitors to relieve the batteries of the stress of repetitive cycling, we expect to extend battery life by 20 to 25 percent."
Braking energy recuperation systems in electric and hybrid rail vehicles save fuel and electrical energy by using resistance from the electric motor to stop the vehicle, and, through that process, converting kinetic energy that would be wasted in a conventional friction-based braking system into stored electrical energy. Ultracapacitors' high reliability and extremely long operational life also make them a preferred option for heavy cycling electric utility grid applications.
Dr. Franz Fink, Maxwell's president and CEO, said, "Transportation is the world's largest energy consumer, so systems that enhance energy efficiency and reduce fossil fuel consumption and emissions can play a transformational role in energy management and create tremendous long-term growth opportunities for rapidly advancing ultracapacitor technology."
Unlike batteries, which produce and store energy by means of a chemical reaction, ultracapacitors store energy in an electric field. This electrostatic energy storage mechanism enables ultracapacitors to charge and discharge in as little as fractions of a second, perform normally over a broad temperature range (-40°C to +65°C), operate reliably through one million or more charge/discharge cycles and resist shock and vibration. Maxwell offers ultracapacitor cells ranging in capacitance from one to 3,000 farads and multi-cell modules ranging from 16 to 160 volts.