Harvard University researchers are working on a new type of battery based on organic molecules to store renewable energy in an effort to make it more viable for wide-scale use.
The Department of Energy's Advanced Research Projects Agency (ARPA) has awarded a team of researchers at the university's School of Engineering and Applied Sciences (SEAS) a $600,000 innovation grant to develop what is called a flow battery for the storage of energy from sources such as wind turbines and solar panels, according to ARPA and the university.
Researchers are collaborating with Sustainable Innovations LLC, a commercial electrochemical system developer, on the project to develop the battery with practicality in mind, hoping to displace fossil-fuel energy through its development, they said.
While automation, robotics, and other types of technology are making the use of renewable energy sources generated by solar and wind power a more competitive option to traditional power, the energy is still largely dependent on the forces of nature because there currently is no good, practical way to store large quantities of it, said Michael Aziz, a professor of materials and energy technologies at SEAS.
"Storage of very large amounts of energy is required if we are to generate a major portion of our electricity from intermittent renewable sources such as wind turbines and photovoltaics," he said in a press release. "Currently no cost-effective solution exists to this large-scale storage problem."
Aziz and his team think flow batteries, a type of highly rechargeable fuel cell that stores electrical energy in the form of liquid chemicals, could be the answer to this problem. The batteries are so-named because the chemicals are flowed past electrochemical conversion hardware and then stored externally in low-cost tanks that can vary in size, according to researchers. The tanks can be very large, permitting the designers to decide on the size of the electrochemical conversion hardware for setting peak power capacity and the storage tanks that set the energy capacity.
As a point of contrast, in solid-electrode batteries, such as those in cars and mobile devices, power-conversion hardware and energy capacity are packaged together, which means they can only maintain peak discharge power for less than an hour. However, studies show that renewable energy needs one or two days of peak discharge power to move through the electrical grid, researchers said. This makes the use of these types of batteries cost prohibitive, according to Aziz.
Flow batteries alone aren't the answer either, since those currently under development also have limitations in terms of price. "The chemicals used for storage in flow batteries can be expensive or difficult to maintain," Aziz said.
The key to researchers' work is to replace those chemicals in a flow battery with organic molecules found in plants that can be synthesized artificially without a high price tag. Other benefits of the molecules are that they are non-toxic, can be stored at room temperature, and cycle very efficiently between the chemical states needed for energy storage, Aziz said.
Harvard researchers won the grant as part of ARPA's OPEN 2012 program, which distributed $130 million in funding to support innovation in energy technology.