- Renewable energy is predicted to become cheaper than fossil fuels by 2020
- Storage remains the biggest obstacle to the wider adoption of solar power
- Swedish researchers have found a way to bottle solar energy and store it for later use
- The MOST system is capable of storing energy for up to 18 years
As the world became more and more aware of the consequences of climate change, renewable energy sources have emerged in recent years as an increasingly attractive alternative to fossil fuels. While fossil fuels still account for the majority of the world’s energy generation, that’s likely to change over the next couple of decades if current trends continue. In 2015, renewable sources accounted for approximately 23 per cent of global electricity generation, according to the U.S. Energy Information Administration (EIA). By 2040, that figure is predicted to grow to 31 per cent.
By 2020, renewable energy will probably be cheaper than fossil fuels
Another factor contributing to the growing popularity of renewable sources are the decreasing prices. In fact, the International Renewable Energy Agency (IREA) estimates that by 2020, renewable energy will become cheaper than fossil fuels, which will only accelerate its adoption in the future. “This new dynamic signals a significant shift in the energy paradigm,” says Adnan Amin, director-general of the IREA. “Turning to renewables for new power generation is not simply an environmentally conscious decision, it is now – overwhelmingly – a smart economic one.”
Storage remains the biggest obstacle to the wider adoption of solar power
When it comes to solar power in particular, storage has always been the biggest obstacle to its wider adoption. While it’s possible to convert solar energy into electricity and store it in batteries, these are prohibitively expensive and harmful to the environment, as our existing battery technology still relies heavily on the use of toxic materials. But what if there was a better way? What if we could essentially bottle solar energy and store it for later use without the need for batteries? It may sound like the stuff of science fiction, but that’s precisely what researchers from the Chalmers University of Technology in Sweden have managed to do.
Swedish researchers have found a way to bottle solar energy and store it for later use
The researchers have discovered a specialised molecule capable of capturing solar energy, storing it for prolonged periods of time, and then releasing it on demand in the form of heat. Known as norbornadiene, the molecule consists of carbon, hydrogen, and nitrogen atoms. When exposed to sunlight, the chemical bonds between these atoms are rearranged, transforming norbornadiene into an energy-rich isomer called quadricyclane. The process also traps the solar energy within the newly formed compound, which retains it even after it’s been cooled down. To make use of the captured energy at a later date, all you need to do is pass it through a catalyst, which converts the quadricyclane back into norbornadiene and releases the energy contained within as heat.
As a proof of concept, the researchers have created a prototype system called Molecular Solar Thermal Energy Storage, or MOST, which consists of a network of transparent tubes linked to a solar thermal collector on the roof of a building. The collector acts as a satellite dish, focusing the rays of the sun onto the tubes that transport the liquid norbornadiene. This causes the norbornadiene to transform into quadricyclane and capture the solar energy, after which it is conveyed through the tubes to storage tanks and kept at room temperature. To use the stored energy, the quadricyclane first needs to be pumped through a cobalt-based catalyst, which creates a chemical reaction that warms the liquid by 63 degrees Celsius and causes the quadricyclane to transform back into norbornadiene. The heated liquid can then be used for a wide variety of purposes, including heating residential and commercial buildings.
The MOST system is capable of storing energy for up to 18 years
The concept of solar thermal fuels isn’t new. Other researchers have experimented with norbornadiene in the past, albeit without much success. The liquid fuels they developed could only last for a few cycles before breaking down, they couldn’t hold the energy for long, and had to be mixed with toxic solvents that diluted the fuel. But the Chalmers researchers managed to solve all of these issues. “The energy in this isomer can now be stored for up to 18 years. And when we come to extract the energy and use it, we get a warmth increase which is greater than we dared hope for,” says Kasper Moth-Poulsen, a professor at the Department of Chemistry and Chemical Engineering at Chalmers University of Technology and the leader of the research team. Furthermore, they were able to run the fuel through 125 cycles with almost no degradation and found a way to use the isomer without the flammable chemical toluene, which was present in the initial versions of the system. According to Moth-Poulsen, their fuel is capable of storing up to 250 watt-hours of energy per kilogram, which is twice the energy capacity of Tesla’s Powerwall batteries.
However, there’s still a lot of room for improvement and it will be at least a decade before MOST is ready for commercial use. The fuel currently has very low efficiency and responds only to ultraviolet and blue wavelengths of sunlight, which accounts for just 5 per cent of the total solar energy available. In the future, the team hopes to be able to expand the fuel’s sensitivity to include more of the spectrum and to boost the temperature increase to at least 80 degrees Celsius, which would enable the system to generate electricity as well.
Solar energy has become increasingly popular in recent years, but it hasn’t yet achieved widespread adoption. One of the main reasons is that we still don’t have a cheap, clean, and efficient way to store that energy for later use, which severely limits its usefulness. However, that may be about to change, thanks to researchers from the Chalmers University of Technology, who’ve found a way to essentially bottle solar energy and store it for later use without the need for batteries. While still not ready for commercial use, this is a revolutionary innovation that could significantly accelerate the transition to renewable energy sources and maybe even help us solve the issue of global warming.
