Tree huggers, rejoice: Researchers at the Massachusetts Institute of Technology have created a new battery prototype that may make renewable sources of energy, including wind and solar power, more dependable.
What’s so great about a battery?
Engineering professors Cullen Buie and Martin Bazant worked together with graduate student William Braff to create a new rechargeable flow battery that eliminates the most expensive part of the older device: its membrane, according to an Aug. 16 MIT press release.
The membrane is the part of the battery that keeps two flowing, energy-creating chemicals from mixing inside the battery itself. It is important to keep these chemicals separate for efficient operation, but the membrane is not cheap due to the cost of its raw materials, Buie said. The material costs drive up the cost of the membrane’s production, which itself is pricey as it requires manufacturing a tiny dividing wall thin enough to fit inside of a battery.
“You want to make these membranes very thin,” Buie said. He said it would be expensive to make something that is both thin and that does not have problems that could lead to crossover. “It’s a much tougher engineering feat.”
Therefore, disposing of the membrane in favor of a different design would likely reduce costs — or so this group of scientists hoped.
Of course, other researchers have attempted to create batteries without membranes, but none have been as successful as Buie and Bazant. In fact, this battery can generate three times as much power per square centimeter as previous experimental batteries without membranes. This means that the MIT researchers’ battery is just as efficient as today’s commonplace lithium-ion battery and other commercial batteries while still cheaper to produce. It even meets a goal set by the U.S. Department of Energy to produce energy at an efficiency of $100 per kilowatt-hour.
How did they do it?
To make a successful battery without a membrane, Buie and Bazant harnessed a phenomenon called laminar flow. Two different liquids — a liquid bromine solution and hydrogen fuel — are pumped through a channel where they undergo electrochemical reactions between two electrodes, thus either storing or releasing energy. Because there is nothing separating the two chemicals, there is still a possibility of them mixing, but Buie said this risk is present in both models with and without membranes.
“There’s a chance of [crossover], but you can engineer around it,” Buie said. “Mind you, even with a system with a membrane, there’s a chance of this mixing, because no membrane is perfect — they can have defects, holes or abnormalities that can lead to crossover as well.”
Buie said finding a way to avoid this crossover completely is a goal of future research.
“Mixing would be problematic, but it wouldn’t be catastrophic,” he said. “The problem would be it would lower your efficiency.”
The team at MIT chose to use bromine because of its relative inexpensiveness and massive quantity – more than 243,000 tons are produced in the U.S. each year.
Furthermore, bromine and hydrogen react to create enormous energy storage potential. The two are not used together often, because hydrobromic acid is corrosive and tends to eat away at the battery’s membrane. However, since Buie and Bazant’s new model does not have such a membrane, this corrosiveness is not a problem.
Why does it matter?
Bazant said this research is a “quantum leap” in energy storage technology. With increasingly ubiquitous research on deteriorating environmental conditions, it seems we need as much energy efficiency as possible. Researchers believe this new battery may be a step in the right direction toward saving Earth’s atmosphere.
Professor Robert Kaufmann, co-director of Boston University’s Clean Energy and Environment Sustainability Initiative, said current energy-producing methods, including coal burning, are emitting too much carbon dioxide into the atmosphere.
“[It’s] changing the Earth’s climate to which human beings and all the world’s ecosystems have adapted over the last 20,000 years,” Kaufmann said. “So any rapid change in climate is going to disrupt everything on the planet.”
Renewable sources of energy production have been evaluated more lately — especially by organizations such as the National Renewable Energy Laboratory — for their potentials to produce enormous amounts of energy without emitting hazardous carbon dioxide. However, Kaufmann noted a problem with these: There is not always a constant supply of energy. Clouds often roll in front of the sun, and it is not always windy. Therefore, researchers must find a way to store the energy generated by these environment-friendly methods even when weather conditions are not ideal.
“If you could generate a reliable battery that’s relatively inexpensive and that can store large amounts of energy, it’d be a huge breakthrough,” Kaufmann said.
The MIT researchers explained that this is exactly what they have done.
Because Buie and Bazant’s membrane-less prototype can hold such significant amounts of energy, allowing renewable sources to store energy for peak hours of demand is a real possibility.
“Think about the electric grid,” Kaufmann said. “You have to have the electricity production equal the electricity consumption on a second-by-second basis. The problem is, for renewables like wind and solar, they’re intermittent … This intermittency makes it very difficult for the grid operators to keep supply and demand balanced. If you could store this renewable energy, you could smooth out the peaks and valleys from these renewable sources.”
Several BU students said they support the prospect of more renewable energy sources.
“I think it’s better for the environment and it’s more resourceful,” said Amy Misencik, a College of Arts and Sciences junior.
Not just yet
Of course, there is still much work to be done. The prototype created was only palm-sized, much smaller than those that would be needed for commercial or industrial use. Therefore, more research is needed before widespread use of the battery. Scientists will need to work out certain flaws, such as maintaining an appropriate temperature. While hot temperatures in solar panels, for example, actually improve the efficiency of the battery, colder temperatures reduce their efficiency.
Buie was cautious to project what kind of an effect this new technology may have on our environment.
“The environmental impact … that’s hard to judge,” he said. “With any new technology, I would be hesitant to judge that simply because there could be unforeseen circumstances.”
However, he agreed with Kaufmann that this research is a big step forward.
“It would certainly enable renewables such as wind and solar to be far more cost-effective,” he said. “So if we got a greater percentage of our energy from renewables like solar or wind, that would greatly offset our carbon emissions.”
School of Education junior Caroline Koncent said she is hopeful that this will bring benefits to college students by cutting down school expenses on energy.
“Especially as a college student or young adult living on one’s own, affordable housing is important,” she said. “Even if universities used this battery for housing or other facilities, maybe it would cut down the price of room and board, or even tuition.”
Koncent said she thinks a product like this fits into national goals of “going green.”
“I hope to see this battery lead our country towards a more green and affordable lifestyle,” Koncent said. “Oftentimes, it’s expensive to be green, making it challenging to take part in this beneficial trend.”
Buie also mentioned a possible money-saving idea for the home with this new technology.
Electricity is priced differently at different times of the day. It is most expensive during peak hours when demand is higher, and cheaper at ‘off’ times, such as 2 a.m., when demand is lower.
“What you could do if you had one of these systems is buy electricity from the grid,” Buie said. “Basically, plug your system into the grid and store electricity when the electricity’s cheap — and then when electricity is expensive, instead of getting it from the grid, you’d get it from your storage device.”
Good idea, Professor Buie. Good idea.