Category: Renewable energy

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.

Harvard researchers have developed a battery that harnesses energy by using the electrochemistry of organic molecules rather than metals. The battery, which they say can be applied on a power-grid scale, uses naturally abundant and small organic compounds called quinones rather than electrocatalysts from costly precious metals such as platinum.

Quinones would be inexpensive to obtain and can be found in green plants or synthesized from crude oil. The battery designed by Harvard scientists and engineers used a quinone molecule that's almost identical to one that's found in rhubarb.

Unlike solid-electrode batteries, flow batteries are recharged by two chemical components dissolved in fluids that are kept in separate tanks. Flow batteries are well suited to storing large amounts of energy, but a major drawback to metal-based flow cells has been cost.

According to MIT Technology review, a conventional metal-reliant flow battery costs an estimated $700 per kilowatt-hour of storage capacity, whereas the Harvard team's metal-free technology would bring those costs down to $27 per kilowatt-hour.

"The whole world of electricity storage has been using metal ions in various charge states, but there is a limited number that you can put into solution and use to store energy, and none of them can economically store massive amounts of renewable energy," said Roy G. Gordon, one of the researchers who helped screen more than 10,000 quinone molecules to find the best candidate for the novel battery.

"With organic molecules, we introduce a vast new set of possibilities. Some of them will be terrible and some will be really good. With these quinones we have the first ones that look really good."

Source: Harvard