Skip to main content

Scientists have found a way to use the cold of night to generate electricity

Radiative Sky Cooling LED
UCLA Samueli School of Engineering

Scientists have discovered a way to power a light by using the cold of outer space, which could eventually be used to create the nighttime counterpart to solar energy. 

Using an inexpensive thermoelectric device, they’re able to harness the cold of space without an active heat input. The process, called radiative sky cooling, can generate enough electricity to power an LED light. Think of it as similar to solar panels, except using the change in the night temperature for power rather than the sun.

“Remarkably, the device is able to generate electricity at night, when solar cells don’t work,” said lead author Aaswath Raman, an assistant professor of materials science and engineering at the University of California, Los Angeles. “Beyond lighting, we believe this could be a broadly enabling approach to power generation suitable for remote locations, and anywhere where power generation at night is needed.”

Details about the project were published on September 12 in the journal Joule.

The project is attempting to create something like solar power, except at night when the sun is not available. Yes, solar cells can be outfitted with batteries to store the day’s energy to be used at night, but those batteries ultimately make the technology more expensive — and can’t be charged at night.

Raman, along with two scientists from Stanford University, Wei Li and Shanhui Fan, has developed a device that uses radiative cooling. Essentially, a sky-facing surface passes its heat to the atmosphere as thermal radiation, losing some of its heat to space and reaching a cooler temperature than the surrounding air.

Radiative Sky Cooling Device
An experimental electricity-generating device that uses radiative sky cooling to harvest energy. Aaswath Raman/UCLA

Scientists describe it as similar to how frost forms on the grass during above-freezing nights. That same idea can be used to create electricity and produce renewable energy after the sun has gone down.

They’ve tested the technology on a rooftop on Stanford’s California campus with some success.

“Our work highlights the many remaining opportunities for energy by taking advantage of the cold of outer space as a renewable energy resource,” said Raman. “We think this forms the basis of a complementary technology to solar. While the power output will always be substantially lower, it can operate at hours when solar cells cannot.”

Solar has become more and more popular in recent years as the cost of installing the technology on homes and businesses has become more affordable. While solar is growing across the globe, solar farms are growing particularly fast in the deserts of Asia and the Middle East.

Editors' Recommendations

Emily Price
Emily is a freelance writer based in San Francisco. Her book "Productivity Hacks: 500+ Easy Ways to Accomplish More at…
Scientists have found a chemical-free way to extend milk’s life for up to 3 weeks
milk life extension applegate feat

Who hasn’t gotten part of the way through a bowl of cereal only to discover that the milk has gone off? Thankfully, researchers at Purdue University and the University of Tennessee are helping avert such traumatic starts to our morning with a new, non-chemical treatment that promises to extend regular milk’s shelf life to around 2-3 weeks -- and without affecting the nutrients or flavor.

The technology they’ve developed involves increasing the temperature of milk by just 10 degrees for less than a second. For those keeping track at home, that’s well below the 70-degree Celsius threshold needed for pasteurization. Even so, the quick heat blast eliminates more than 99 percent of the bacteria left behind after pasteurization.

Read more
DC water treatment plant uses human excrement to generate 13MW of electricity
this couple is building a poop powered home toilet roll

One of the world's largest initiatives to generate power using human waste is taking place in Washington DC, reports The experimental project is being conducted at the Blue Plains Advanced Wastewater Treatment Plant, which is operated by DC Water. Covering Washington, D.C. and the surrounding metro areas, the facility treats more than 370 million gallons of wastewater and produces over 1,200 wet tons of biosolids each day.

Wastewater and raw sewage are treated at the facility with safety in mind. The cleaned-up water is released into the Potomac River or Chesapeake Bay, while the biosolids are collected for recycling. Most of the solid waste is turned into compost or fertilizer, but a new initiative started earlier this year is diverting some the solids collected from the bottom of the water treatment pools into energy generation.

Read more
Panasonic’s eneloop is a portable power device for places without electricity
panasonics eneloop storage system powers leds and phones panasonic solar

Normally when you can’t charge your cell phone, it’s because you forgot your charger or other travelers already claimed all the outlets at the airport. But 18 percent of the world’s population has no or unreliable electricity, according to the International Energy Agency.

In an effort to help give people more access, Panasonic developed the eneloop solar storage, a power-storage system that powers LED lights and small devices like cell phones in areas -- such as regions of Asia and Africa -- where electricity is scarce. These are exactly the places Panasonic plans to ship the device, starting in November, with Ethiopia, Tanzania, Indonesia, Thailand, Myanmar, and other countries on the list of countries Panasonic expects to target. Right now, many households in these regions use kerosene lamps for nighttime lighting, which are expensive to use (often taking up 30 percent of a family’s income), hazardous, and a source of dangerous fumes.

Read more