While batteries still generate more headlines, the role of ultracapacitors in energy storage and efficiency applications moved toward center stage this summer with high-profile transportation projects for two notable players, Ioxus and Maxwell Technologies.
Although they look a lot like batteries, ultracapacitors can be charged and discharged far more quickly, making them attractive for applications that require rapid bursts or occasional boosts of power. Primarily that's because they rely on electrostatics, and not a chemical reaction, to perform. It's not uncommon to find them in hybrid buses (especially in China), where they help boost fuel efficiency by providing propulsion for acceleration, or paired with batteries (which can store more power) and used to harvest and store energy from wind turbines or solar panels.
But several projects announced in the past three months happen to center on the ultracapacitor's potential for improving rail transit energy efficiency.
In New York state, for example, the Long Island Rail Road is testing Ioxus ultracapacitors as a means of reducing energy consumption and providing voltage support to trains when the electric grid load is high. The technology is installed in a 20-foot shipping container connected to the rail traction feeds and a high-power DC-DC converter. They're too big to install on the trains themselves.
"Right now, LIRR can't launch more trains at one time because of the system draw," said Chad Hall, cofounder and vice president of marketing and product management for Ioxus, which snagged $21 million in new funding in April. "This can really drop down the requirements, as much as 30 percent. In fact, each station where we install this can reduce consumption by 500,000 kilowatt-hours of energy throughout the year."
Interest in Ioxus's technology is growing so quickly that the company just opened its second manufacturing plant in Oneonta, N.Y., near its headquarters. Aside from transportation, its iMOD products are being used in combination with photovoltaic arrays and manufacturing equipment to improve energy efficiency.
Maxwell also is working closely with railway customers: Its latest wins include a braking energy recuperation system that is part of an upgrade to Philadelphia's light rail system and an installation announced this week in Cerro Negro, Spain, where its technology is capturing excess energy from an electric rail system to power an electric vehicle charging system.
"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 Dominguez Amarillo, CEO and chief technology officer for Win Inertia, the engineering company behind the installation.
In Philadelphia, a system called Enviline is being used by contractor ABB to cut power consumption for the Southeast Pennsylvania Transit Authority. ABB uses Maxwell ultracapacitors to capture energy generated during the train braking process and "recycle" it back into the system, where it can be used to help a different train accelerate. Usually, power is lost during the braking process.
What ABB is doing isn't entirely a new concept; what's unique is the installation's role in enabling the Southeast Pennsylvania Transit Authority to provide frequency regular services back to the PJM Interconnection Network. The transit agency actually could earn between $150,000 and $200,000 by coordinating to meet PJM demand signals.
"There is absolutely a local market for this," said Jacques Poulin, ABB product manager for energy storage and rail. "During the balance of the day, this can become a regulation asset. … But you need to have the willingness of the transport authority and the market" to support a project of this nature.
How fast will ultracapacitors catch on? Research from IDTechEx suggests this year will mark a turning point for adoption, kickstarting compound annual growth of 30 percent between now and 2024 when revenue is projected to reach $6 billion. Aside from the applications already discussed, another big contributor will be the automotive sector, which is designing the technology into forthcoming hybrid and electric vehicle models.