New liquid stores solar energy for almost two decades

Solar energy is considered one of the most promising alternatives to fossil fuels. However, in order to fully embrace this sustainable energy, there are still challenges that we must overcome – one of which is the long-term storage of solar energy. Storage is vital to make sure we have access to energy even when the sun is not shining.

However, a number of research papers offer hope, as they outline a new approach to solar energy storage.

The liquid acts as an efficient battery

In 2018, Swedish scientists have developed “solar thermal fuel”, a specialized fluid that can store energy captured from the sun for up to 18 years.

“A solar thermal fuel is like a rechargeable battery, but instead of electricity, you put in sunlight and take out the heat, which is triggered on demand,” said Jeffrey Grossman, an engineer who works with these materials at MIT. NBC News.

The fluid has been under development for more than a year by scientists at Chalmers University of Technology in Sweden.

Liquid changes are formed in sunlight

The solar thermal collector called MOST (Molecular Solar Thermal Energy Storage System) works in a circular manner. A pump cycles the solar thermal fuel through transparent tubes. When sunlight comes in contact with the fuel, the bonds between its atoms are rearranged and turn into an energy-rich isomer. The sun’s energy is then captured between the strong chemical bonds of the isomers.

Incredibly, the energy remains stuck there even when the molecule cools to room temperature. To use the captured energy, the liquid flows through a catalyst (also developed by the research team) creating a reaction that heats the liquid by 113 ° F (63 ° C). This restores the molecule to its original form, releasing energy in the form of heat.

“When we come to extract energy and use it, we get an increase in heat that is greater than we dared to hope,” said Kasper Moth-Poulsen, a professor in the Department of Chemistry and Chemical Engineering. press release.

When an energy demand occurs, the energy-rich fluid can be used to power the building’s water heater, dishwasher, clothes dryer and more. There may also be industrial applications, including low temperature heat used for cooking, sterilization, bleaching and distillation.

The liquid is then pumped back into the solar thermal collector for reuse. To date, researchers have introduced fluid into this cycle more than 125 times, without significantly affecting its molecular structure.

Moth-Poulsen calculated that, at the peak, the fuel can store up to 250 watts-hours of energy per 2 kg (1 kg). Pound for pound, this is about twice the energy capacity of Tesla Powerwall batteries.

Large-scale application

By the end of 2020, an EU project led by a team from Chalmers will work to develop technology prototypes for large-scale applications. The project received 4.3 million euros from the EU and will last 3.5 years.

“With this funding, the development we can now do within the MOST project can lead to new solar and emission-free solutions for heating in residential and industrial applications. This project is heading towards a very important and interesting stage “, says Kasper Moth-Poulsen.

Along with this funding comes the news about the progress in the development of MOST. The researchers used the technology in a window film to even out the temperature inside on hot days. The application of the molecule in blinds and windows has already started through a derivative company called Solartes AB.

Researchers believe the technology could be used commercially within 10 years.

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