Your browser is not supported. Please update it.

13 April 2022

Localized solar power looks to chip away at grid demand

A new way of converting solar power directly into stored energy has been pioneered by researchers in Sweden. Rather than targeting the disparity between supply and demand in a renewables-heavy grid, however, the devices that could stem from this technology are likely to focus on supplying clean power directly. Reaching the required scale, however, even for this, still looks distant.

The new technology stems from the Molecular Solar Thermal Energy Storage (MOST) being developed by Chalmers University of Technology, Sweden. The closed-loop system is based around a molecule – a combination of carbon, hydrogen and nitrogen – which changes shape when hit by sunlight to become an “energy-rich isomer.”

This isomer can then be stored in liquid form, holding the energy for up to 18 years, before a specially designed catalyst allows it to be released as heat, while the isomer returns to its original shape, creating a repeatable, closed loop system with zero emissions.

The study published last month in Cell Reports physical Science, outlines the next step that the researchers have taken to commercializing this technology. By adding an incredibly thin thermoelectric generator, with a thickness in the order of micrometers, the system can now provide undisrupted clean energy on a local level.

“This is a radically new way of generating electricity from solar energy. It means that we can use solar energy to produce electricity regardless of weather, time of day, season, or geographical location. It is a closed system that can operate without causing carbon dioxide emissions,” says Professor Kasper Moth-Poulsen at the Department of Chemistry and Chemical Engineering at Chalmers.

The combination of this technology with this ultra-thin chip – developed at Shanghai Jaio Tong University – has created an early buzz in the consumer electronics space. While the utility-scale power sector has a clear route to renewables-plus-battery technologies, supplemented by other large-scale storage types, the small-scale nature of the device could lead to self-charging electronics using stored solar energy on demand, according to the research.

Headphones, smart watches and telephones have been outlined as early examples of potential applications. In total, portable electronics account for between 1% and 2% of global electricity consumption, so removing their charging from the grid would represent an easy win. Once commercially feasible, the uptake of the technology would also be largely consumer driven, with users increasingly looking for ways to make their lives more ‘eco-friendly.’

Looking at the technical performance of what has been created as Chalmers, though, it is obvious that the technology is far from reaching the scale needed. The proof-of-concept produced a power output of just 0.1 millionth of a Watt, with its power output per unit volume reaching just 1.3 Watts per cubic meter. To put that into context, the average cell phone draws nearly 4 Watts of power when charging through conventional means.

While powering up through sunlight would likely provide more of a ‘trickle-charge,’ a device of below 1 Watt would probably suffice. However, at current energy densities, a cubic-meter sized battery replacement won’t tick any consumer boxes.

“Together with the various research groups included in the project, we are now working to streamline the system. The amount of electricity or heat it can extract needs to be increased. Even if the energy system is based on simple basic materials, it needs to be adapted to be sufficiently cost-effective to produce, and thus possible to launch more broadly,” says Kasper Moth-Poulsen.

This is the same story as we’ve seen in many other endeavors trying to create a renewable fuel directly from sunlight. Academics from Cambridge, Tokyo and Edinburgh have developed an artificial photosynthesis device which can mimic a plant’s ability to convert sunlight, carbon dioxide and water into a carbon neutral fuel, without the need for any input electricity. But at solar energy to formulate efficiency of around 0.01% the technology is still far below the 6% seen within the natural photosynthesis it was trying to create, making it almost impossible to produce fuel at scale.

The most likely breakthrough we expect to see in this field is within the direct production of hydrogen from solar power. Last year, research from a collaboration of Israeli and Italian scientists resulted in an ‘artificial photosynthesis’ nanorod technology, using platinum spheres to prevent hydrogen and oxygen recombining, which claimed to convert solar energy into hydrogen at an efficiency of 3.6%. While this may appear small, the US Department of Energy has previously stated that a 5% to 10% efficiency is all that is needed to reach the “practical feasibility threshold” for solar hydrogen generation.

Researchers from Japan have also developed a two-step process that can improve the hydrogen yield from the technique by 100-times – marking a significant step towards commercial viability.