The biggest drawback preventing widespread use of renewable energy isn’t cloudy, wind-free days. It’s actually the relative stubbornness of the batteries used to store the energy generated by the solar panels and windmills. They fill up too quickly, but don’t discharge the energy quickly enough. They don’t last very long and are expensive to replace. And once they’ve run their course, it’s rather tricky to dispose of them safely. Drexel engineers have been working on a more accommodating energy storage system for the last few years – and now we have a first look at a prototype of the device called the “electrochemical flow capacitor.”
Its secret, as we learn from the freshmen engineers who undertook construction of the prototype, is in the sludge – or rather, the carbon-electrolyte slurry that captures and stores electrical charges, and bears a striking resemblance to the bottom of a strong pot of coffee that sat on the burner a few hours too long.
According to Yury Gogotsi, PhD, director of the A.J. Drexel Nanotechnology Institute and part of the interdisciplinary team developing the EFC, this makes the main limiting factor the size of the electrolyte reservoirs. So depending on the size of the storage tank, the system could be used for household energy storage or scaled all the way up for use in regional power grids.
“The most unique feature of this device is that we can store energy in tanks, which hopefully will be very large tanks, allowing us to store more energy,” Gogotsi said. “You just cannot have many small batteries like the ones we use in our cell phones, computers taking up space…we want to be able to store energy in an inexpensive way in a flowable system and this is clearly the least expensive solution.”
The freshmen engineering students, from the departments of Materials Science and Engineering and Chemical and Biological Engineering, who made the prototype also demonstrate it using a solar cell to collect energy with the EFC storing it and powering an LED at the touch of a button.
Gogotsi’s team undertook the challenge of creating this scalable energy storage device about two years ago. Their proposal, which was published in the journal Advanced Energy Materials, was a response to the nation’s goals of gradually uncoupling itself from fossil fuel-based energy generation.
While it’s still just a prototype at this point, Gogotsi anticipates that with continued testing and development, the EFC could eventually be a way around one of the largest obstacles blocking more widespread use of renewable energy.
“I believe that localized energy generation from solar batteries, wind power generators and other sources will become very, very common,” Gogotsi said. “Every home, every building will have some energy generation system to produce renewable energy.”