A Fluid Can Store Solar Energy and Then Release It as Heat Months Later

Freeman writes:

https://arstechnica.com/science/2026/02/dna-inspired-molecule-breaks-records-for-storing-solar-heat/

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.
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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.
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Previous attempts at MOST systems have struggled to compete with Li-ion batteries. Norbornadiene, one of the best-studied candidates, tops out at around 0.97 MJ/kg. Another contender, azaborinine, manages only 0.65 MJ/kg. They may be scientifically interesting, but they are not going to heat your house.

Nguyen's pyrimidone-based system blew those numbers out of the water. The researchers achieved an energy storage density of 1.65 MJ/kg-nearly double the capacity of Li-ion batteries and substantially higher than any previous MOST material.
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Achieving high energy density on paper is one thing. Making it work in the real world is another. A major failing of previous MOST systems is that they are solids that need to be dissolved in solvents like toluene or acetonitrile to work.
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Nguyen's team tackled this by designing a version of their molecule that is a liquid at room temperature, so it doesn't need a solvent.
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The MOST-based heating system, the team says in their paper, would circulate this rechargeable fuel through panels on the roof to capture the sun's light and then store it in the basement tank.

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