Solar energy is considered one of the most promising alternatives to fossil fuels. However, to fully embrace this sustainable energy, there are still challenges we must overcome, one of which is the long-term storage of solar energy. Storage is vital to ensure that we have access to energy even when the sun is not shining.
However, a number of research articles offer hope, as they describe a novel approach to storing the sun’s energy.
The liquid acts as an efficient battery
In 2018, scientists in Sweden developed a “solar thermal fuel,” a specialized fluid that can reportedly store energy captured from the sun for up to 18 years.
“A solar thermal fuel is like a rechargeable battery, but instead of electricity, sunlight is introduced and heat is extracted, which is activated on demand,” explained Jeffrey Grossman, an engineer who works with these materials at MIT. . NBC News.
The fluid has been in development for more than a year by scientists at Chalmers University of Technology in Sweden.
Liquid changes form under sunlight.
The solar thermal collector called MOST (Molecular Solar Thermal Energy Storage System) works in a circular fashion. A pump circulates the solar thermal fuel through transparent tubes. When sunlight comes into contact with fuel, the bonds between its atoms rearrange and it transforms into an energy-rich isomer. Then the energy from the sun is captured between the strong chemical bonds of the isomers.
Incredibly, the energy remains trapped there even when the molecule is cooled to room temperature. To utilize the trapped energy, the liquid flows through a catalyst (also developed by the research team) creating a reaction that heats the liquid to 113 ° F (63 ° C). This returns the molecule to its original shape, releasing energy in the form of heat.
“When we come to extract the energy and use it, we get an increase in heat that is greater than we dared to expect,” said research team leader Kasper Moth-Poulsen, a professor in the Department of Chemistry and Chemical Engineering at the Press release.
When there is a demand for energy, the energy-rich fluid can be used to power a building’s water heater, dishwasher, clothes dryer, and much more. There could also be industrial applications, including low-temperature heat used for cooking, sterilizing, bleaching, and distilling.
The liquid is then pumped back to the solar thermal collector to be reused. So far, researchers have cycled the fluid more than 125 times without causing significant damage to its molecular structure.
Moth-Poulsen has calculated that, at its peak, fuel can store up to 250 watt-hours of energy per 2.2 lb (1 kg). Pound for pound, that’s about twice the energy capacity of the Tesla Powerwall Batteries.
In late 2020, an EU project led by a Chalmers team will work to develop prototypes of the technology for large-scale applications. The project has received 4.3 million euros from the EU and will last 3.5 years.
“With this funding, the development we can now do in the MOST project can lead to new emission-free solutions powered by solar energy for heating in residential and industrial applications. This project is heading into a very important and exciting stage, ”says Kasper Moth-Poulsen.
Along with this grant comes news of progress in the development of MOST. Researchers have used the technology in a window film to even out the temperature inside on hot days. Application of the molecule in blinds and windows has already begun through a spin-off company called Solartes AB.
The researchers believe the technology could be in commercial use within 10 years.