Apparao (Raja) Rao explains how his team uses nanomaterials to build capacitors.Photo courtesy of Clemson UniversityCarbon nanotubes play a central role in a four-year research project at the Clemson Nanomaterials Center.

Scientists at the center are using the tube-shaped molecules and graphene sheets as thin as a single atom to build capacitors that are now capable of lighting up small electronics, such as alarm clocks, but could one day help capture solar and wind power.

The scientists are working their magic by combining a range of materials, including  store-bought aluminum foil, a byproduct of papermaking and a high-tech material called “buckypaper.”

The ironic part is that many of the nanomaterials involved in the research come from coal, the same material that has been blamed for creating greenhouse gases when burned for energy could be an important part of making an alternative more affordable.

Apparao (Raja) Rao, who leads the team of scientists, said they proved in the first year that their concepts can work and are now trying to figure out how to do it on a larger scale while looking for industrial partners.

“We’re at the very tip of the iceberg,” said Rao, who is the R.A. Bowen professor of physics.

It could be years until the team’s research makes its way into commercially available capacitors, but it has begun to chip away at some of the barriers that have limited the use of renewable energy.

Their research comes as interest in solar power grows in South Carolina. The state’s first solar farm recently opened in Colleton County.

While wind and sun power are free, they are intermittent. Turbines don’t make electricity without wind, and solar panels don’t work at night.

A key step in making renewable energy more cost-effective will be to find a better way of storing unused energy until it’s needed to light homes and power businesses. The trouble with current technology is that while capacitors can release energy quickly, they can’t store much at once.

The Rao team is trying to solve the storage problem, using materials as affordable as possible.

The researchers start with either a thin sheet of nanotubes called buckypaper or by growing their own nanotubes on a sheet of aluminum foil in a roll-to-roll process similar to newspaper printing. Then the scientists coat the sheet with lignin, a byproduct of the papermaking process.

The buckypaper and foil and act as a highway to carry electrons, while the lignin provides a cheap material for energy storage, said Mark Roberts, an assistant professor of chemical engineering.

The sheets are then rolled up with other necessary components to make the capacitor.

“We’re taking coal and we’re taking trees, and we’re making batteries,” Roberts said. “I would argue they have comparable performance to lead-acid batteries.

“Our capacitors have their value, and they have their limitations. But they’re non-toxic, environmentally friendly materials that can fill a role in our energy landscape,” he said. “The lignin is bio-renewable, and buckypaper can be recycled.”

One of the big challenges now is figuring out how to make the capacitors on an industrial scale, the goal of a $1.2 million grant from the National Science Foundation.

Rao said the team’s focus now is on powering industrial tools, but the goal is to make the technology adaptable to automotive technology that could be of interest to fellow researchers at the Clemson University International Center for Automotive Research.

Eventually, the technology could also apply to storing wind and solar energy.

“At some point, we want industrial partners to come in and take over,” Rao said. “One team cannot do everything.”