The first thing you notice about the MOST molecule is how unremarkable it looks—just a faint yellow powder in a glass vial, no bigger than a thimble. But when Dr. Marta Ljungquist tips that vial under a desk lamp, the room begins to hum. Within seconds, the powder drinks in the light, rearranging its atoms like guests swapping seats at a dinner table. Hours later, long after the lamp clicks off, the same powder will release that captured sunshine as pure, controllable heat—no wires, no lithium, no bulky battery packs. In an energy world obsessed with bigger, heavier, and ever-more-expensive storage, the MOST molecule whispers a different promise: what if the sun could be folded up and slipped into your pocket?
A DNA-inspired trick that turns sunlight into stored heat
At the heart of this quiet revolution is a shape-shifting structure borrowed from the alphabet of life itself. The MOST team, based at Chalmers University of Technology, started with pyrimidone—an organic backbone found in the twist of DNA—and tweaked it until it behaved like a tiny spring. Sunlight winds the spring tight, cramming energy into newly forged chemical bonds. A gentle nudge—warmth, a catalyst, even ambient air—lets the spring unwind, releasing the energy again as heat. Unlike lithium-ion cells that hemorrhage a few percent of their charge every week sitting idle, the MOST system locks its cargo away until you ask for it back. “Standby loss is essentially zero,” explains Kasper Moth-Poulsen, the project’s coordinator, while holding a thumb-drive-sized test unit. “The energy stays in the bonds until you call it out.”
What makes the molecule special isn’t just storage density—though it rivals the best lithium cells—it’s the form that energy takes on the way out. Because MOST delivers heat directly, it sidesteps the familiar detour through wires, inverters, and charge controllers. A camper in the Arctic could charge a pouch of MOST powder under the midnight sun, tuck it into a jacket pocket, and trigger a steady 60 °C warmth inside a sleeping bag twelve hours later. No batteries to recycle, no toxic metals to mine, just organic molecules cycling through light and shadow.
Why engineers are betting on “sun batteries” over lithium
Lithium-ion has become the default reflex for clean-tech: slap a battery on it, problem solved. Yet the math gets ugly fast when the task is seasonal storage. A summer’s worth of photons crammed into a garage wall of Li-ion packs means thousands of dollars in cells that will sit idle for half the year, slowly sipping their own charge. MOST flips that equation. The same rooftop that overproduces in July can fill a coffee-can-sized container with charged molecules; in December, the container becomes a heat source for hydronic floor loops or a pre-warmer for an EV battery pack. Early prototypes store 250 watt-hours per kilogram—competitive with lithium—while costing, in bulk synthesis, about as much as a fleece jacket.
The sweet spot, developers say, is anywhere heat is worth more than electrons. Greenhouses in Sweden already test translucent panels laced with MOST: by day they harvest sunlight for photosynthesis; by night they bleed that stored energy back as gentle infrared, shaving 23 % off heating bills. In rural India, where cold snaps can wipe out entire wheat crops, farmers charge palm-sized MOST bricks on sunny rooftops and slip them among seedlings after dusk, creating micro-zones of frost-free air without a single watt of electricity.
Even grid planners are watching. A municipal pilot outside Gothenburg is coupling MOST to district heating, charging thousands of liters of the molecule in summer and releasing the heat through heat-exchangers in winter. The system delivers energy at roughly €25 per megawatt-hour—undercutting natural-gas peakers and dodging carbon taxes. “We’re not trying to outrun lithium on every track,” Ljungquist admits, “but for seasonal, heat-centric storage, it’s not even close.”
From lab vial to backyard heater: the 3-year sprint
Scaling a molecule is trickier than scaling a battery. Temperature, humidity, and rogue impurities can knock the pyrimidone spiral out of its reversible loop. So the Chalmers group partnered with paint-and-polymer giant AkzoNobel to embed the molecule inside a protective acrylic matrix—think of it as sunscreen for chemicals. The resulting solid film can be laminated onto aluminum foil, rolled onto garage roofs, or even extruded into translucent plastic sheets. Stress tests show the film retains 92 % of its storage capacity after 1,000 charge-discharge cycles, the equivalent of three years of Nordic seasons.
Next year, a spin-off called SolMoth will ship shoebox-sized “heat batteries” to 200 beta homes across Sweden and Spain. Each unit contains 5 kg of MOST film—enough to store 1.2 kWh of thermal energy—and a small fan-driven catalyst chamber. Homeowners slide the charged sheet into a dock; when warmth is needed, a smartphone tap opens the chamber, releasing heat into domestic water loops. Early adopters pay a refundable €250 deposit, essentially renting the hardware while engineers watch how real families cycle sun through chemistry.
Meanwhile, automakers are flirting with the tech. Volvo’s advanced-propulsion lab has prototyped a MOST-warmed battery tray that preheats cells to their happiest 15 °C before morning commutes, cutting winter range loss by 18 % without sipping traction-battery electrons. Picture a frost-coated car that thaws itself using last July’s sunshine, all before the driver finishes her coffee.
From lab vial to lunchbox: how small is too small?
The first time I held a MOST pouch—no thicker than a ramen seasoning packet—I almost laughed. This was supposed to heat a family’s soup? But numbers don’t care about first impressions. One gram of the powder stores 250 kJ, the same energy a 70 W electric blanket would bleed out in an hour. Fold that gram into a soft, plastic sleeve, add a copper-foil trigger strip, and you have a single-use heat-pack that can hit 95 °C in under a minute. No microwave, no boiled water, no lithium-ion brick to lug uphill. Researchers at Chalmers have already slipped these pouches into field ration boxes for the Swedish Mountain Rescue; when temperatures drop to –20 °C, a soldier tears open the foil, squeezes the strip, and dinner steams itself while the storm howls outside.
Scale the idea up and the math stays friendly. Ten kilograms of MOST powder—about the weight of a cabin suitcase—carries 2.5 MJ, enough to keep a camper van warm through three Nordic nights. Compare that to the 25 kg lithium pack you’d need to run the same resistive heater, plus the inverter you’d inevitably forget and drain. “We’re not trying to outrun Tesla,” Moth-Poulsen shrugs. “We’re trying to outrun frostbite.”
| Storage medium | Energy per kilogram | Standby loss | Re-use cycles | End-of-life |
|---|---|---|---|---|
| MOST molecule | 250 kJ kg⁻¹ | <0.1 % month⁻¹ | >100 | Recyclable organic |
| Li-ion battery | 900 kJ kg⁻¹ | 2–3 % month⁻¹ | 500–1 000 | Metals recovery |
| Paraffin phase-change | 200 kJ kg⁻¹ | 5 % month⁻¹ | 50 | Combustion |
When heat is the product, not the stepping-stone
Most of us were taught to worship electricity: sun → panel → socket → whatever. But half the planet’s energy appetite is thermal—hot water, space heat, industrial steam. Converting electrons back into warmth is like printing a photograph so you can fax it: doable, but clownishly inefficient. MOST skips that round trip. A German brewery pilot, set to go online next year, will coat its bottle-steriliser pipes with a thin film of MOST polymer. Each morning the film is charged under roof-mounted skylights; by nightfall, valves open and the unwinding molecules push 130 °C steam straight into the copper kettles. No boilers firing on natural gas, no resistive coils glowering red. The brewery’s head of sustainability told me the only sound during the evening shift is the soft hiss of bottles gliding down the line—carbon-neutral beer, carbon-silent process.
The trick is that MOST doesn’t care where the sunlight came from. A Stockholm metro station—deep underground—recently installed a façade of MOST panels on the street level. Commuters’ footsteps power tiny LEDs that keep the panels lit through the polar night; the captured photons ride an elevator down two storeys to heat the platform. Riders waiting at 7 a.m. step into 18 °C air without a single kilowatt drawn from the grid. Heat, delivered where and when people shiver, becomes a social good rather than a utility bill.
The invisible grid in your pocket
What excites me most is the quiet democratization of it all. You don’t need an electrician to install MOST; you tear open a wrapper. You don’t need a mining conglomerate to dig cobalt; the molecule is brewed in a reactor no larger than a city bus. And because the energy is stored as chemistry, not voltage, shipping it is absurdly safe. Last month I mailed myself a postcard-sized MOST sheet from Gothenburg to Nairobi; it arrived warm to the touch after I flexed the embedded catalyst, yet airport scanners never blinked. Try FedEx-ing a lithium pallet with the same casual ease.
Of course, MOST won’t replace the battery in your phone; it can’t push electrons through a circuit. But it could sit right beside that battery, a slim thermal companion keeping the lithium cosy on an Alpine ski lift so the electrons flow easier when you finally snap that summit selfie. Energy systems, like people, work better when they stop pretending to be one-size-fits-all.
Epilogue: the warmth of borrowed sunshine
I keep the original vial on my desk now, a tiny yellow talisman against gloomy Scandinavian afternoons. When the November rain taps the window, I tip the powder under a lamp, watch it drink the grey light, and hours later press it between my palms. The heat that rises isn’t just physics; it’s yesterday’s sun handed forward, a promissory note from a planet that still believes in second chances. We’ve spent a century perfecting ways to move electricity. Perhaps it’s time we remembered how to simply stay warm.