In their constant search to find a renewable energy source, scientists may have found a solution to harness solar energy more efficiently. Up until this point, it was difficult to consider solar energy as a renewable source; while the Sun is a constant source of energy, there was no cheap and efficient way to store all that energy. Now, a team from Chalmers University of Technology, based in Sweden, has developed a fluid, solar thermal fuel that could store energy from the Sun. Often compared to a rechargeable battery, the fluid takes the sunlight and is able to convert it to heat.
The fluid itself is a liquid consisting of norbornadiene which has photophysical properties, meaning it does not involve any chemical change. Instead, the fluid stores energy by isomerization, a chemical process that transforms the compound’s structure while maintaining its chemical makeup. This process means byproducts are not produced, something that could happen during a chemical reaction.
The isomerization process starts when the liquid norbornadiene is hit by sunlight. The fluid’s atoms become denser, which causes the liquid norbornadiene to become quadricyclaneand trap the sun’s energy. In a sense, it is similar to how insects get trapped in amber or sap. Energy from the sun stays in the fluid, even after the liquid is removed from sunlight.
Members of the team claim that the system can store energy for up to 18 years and energy can be extracted whenever need be. Best of all, no emissions are produced, reducing pollution in the atmosphere.
The system itself, called The Molecular Solar Thermal Energy Storage (MOST), is made from a concave reflector with a pipe down the middle that tracks the sun’s movement in the sky. The fluid is pumped through the pipes in order for it to be warmed by sunlight and absorb the sun’s energy. The norbornadiene is moved through pipes and stored at room temperature to reduce energy loss. When needed, the fluid filters through a catalyst that heats it, allowing the molecules of energy to revert back to their original state. The energy is released as heat, which can be used by heating systems to power appliances. The now cold-liquid is returned to the MOST to collect solar energy once again, repeating the cycle.
The system could be the reason why solar energy can be considered a replacement for fossil fuels the world has been trying to replace. While other sources, such as solar panels, power buildings during the daytime, the MOST can transfer energy stored throughout the day during nighttime and the winter. This is crucial for countries that do not experience strong or consistent sunlight. For example, during the month of January, the sun rises at 8:47 a.m. in Sweden, but sets at 2:55 p.m. For solar energy to be a fossil fuel replacement, it must be available when needed.
The researchers who developed this system have conducted this cycle over 125 times without significant damage to the fluid itself. They have also claimed that their system has about the same amount of power as two Tesla Powerwall batteries, which can power a house for more than seven days during an outage. While the MOST can continue tobe improved upon, its potential is exciting. A world powered by the sun could help mitigate the effects of climate change.