Heating accounts for nearly half of the global energy demand, and two-thirds of that is met by burning fossil fuels like natural gas, oil, and coal. Solar energy is a possible alternative, but while we have become reasonably good at storing solar electricity in lithium-ion batteries, we’re not nearly as good at storing heat.

To store heat for days, weeks, or months, you need to trap the energy in the bonds of a molecule that can later release heat on demand. The approach to this particular chemistry problem is called molecular solar thermal (MOST) energy storage. While it has been the next big thing for decades, it never really took off.

In a recent Science paper, a team of researchers from the University of California, Santa Barbara, and UCLA demonstrate a breakthrough that might finally make MOST energy storage effective.

The DNA connection

In the past, MOST energy storage solutions have been plagued by lackluster performance. The molecules either didn’t store enough energy, degraded too quickly, or required toxic solvents that made them impractical. To find a way around these issues, the team led by Han P. Nguyen, a chemist at the University of California, Santa Barbara, drew inspiration from the genetic damage caused by sunburn. The idea was to store energy using a reaction similar to the one that allows UV light to damage DNA.

When you stay out on the beach too long, high-energy ultraviolet light can cause adjacent bases in the DNA (thymine, the T in the genetic code) to link together. This forms a structure known as a (6-4) lesion. When that lesion is exposed to even more UV light, it twists into an even stranger shape called a “Dewar” isomer. In biology, this is rather bad news, as Dewar isomers cause kinks in the DNA’s double-helix spiral that disrupt copying the DNA and can lead to mutations or cancer.

To counter this effect, evolution shaped a specific enzyme called photolyase to hunt (6-4) lesions down and snap them back into their safe, stable forms.