We can speed the transition to a clean electric grid by storing excess energy in batteries, but lithium-ion ones are expensive.

Solar and wind power have become dramatically cheaper over the past couple of decades. However, these sources still depend on environmental conditions -- without wind, turbines can't spin, and if the sun isn't shining, solar panels (usually) can't harvest energy.

That makes these sources less consistent than fossil fuels, which can be dispatched on demand, and so even while solar and wind continue to grow, utilities continue to rely on gas to fill gaps and keep the electric grid stable.

Energy storage: We can speed the transition to renewable power by storing excess energy in batteries and then deploying it when the sun and wind aren't cooperating with demand. Many newer renewable energy plants are being paired with big banks of lithium-ion batteries, but lithium is expensive, and mining it is bad for the environment in other ways.

"Storage solutions that are manufactured using plentiful resources like sodium ... have the potential to guarantee greater energy security."

Room-temperature sodium-sulfur (RT Na-S) batteries are a promising alternative for renewable energy storage. They rely on chemical reactions between a sulfur cathode and a sodium anode to store and deploy electrical energy, and they use low-cost materials, which can even be easily extracted from saltwater.

"Storage solutions that are manufactured using plentiful resources like sodium ... have the potential to guarantee greater energy security more broadly and allow more countries to join the shift towards decarbonisation," said Shenlong Zhao, an energy storage researcher at the University of Sydney.

What's new? Existing RT Na-S batteries have had limited storage capacity and a short life cycle, which has held back their commercialization, but there's now a new kind of RT Na-S battery, developed by Zhao's team.

According to their paper, the device has four times the storage capacity of a lithium-ion battery and an ultra-long life -- after 1,000 cycles, it still retained about half of its capacity, which the researchers claim is "unprecedented."