A Swedish research team believes it found the breakthrough renewables was looking for, a solar thermal fuel that can store the sun’s energy for up to 18 years.
Hydrocarbons, in part, became the world’s dominant energy source because they are relatively cheap to extract, can be stored for long periods of time, and can be utilized immediately. These factors make it a great source for energy to power on-demand. As batteries continue to develop in their capacity to store energy and for long periods of time, they have begun to supplant hydrocarbons, i.e. electric vehicles.
As an alternative to batteries, the specialized solar thermal fluid can hold the sun’s energy for long periods of time and expel that energy on demand. Unlike batteries, which discharge electricity, the solar thermal fuel emits heat when activated through a catalyst. This means the fluid would be ideal for heating residential and commercial homes.
The fuel is composed of carbon, hydrogen and nitrogen molecules. The molecules can be seen in the figure below, with the original fuel source being norbornadiene molecules. When these molecules are hit by sunlight, some of the bonds between atoms are rearranged to form quadricyclane.
Conversion of the solar fuel from norbornadiene to quadricyclane.
This chemical conversion into a different molecular structure called an isomer traps energy within the molecule. The energized version of the molecule is stable, with strong chemical bonds. This is key in that the stable molecule can sit for nearly two decades without losing the stored energy.
To release the energy, the molecule can be passed through a catalyst, which rearranges the chemical bonds back to norbornadiene and with it releases quite a lot of heat.
The team found that the catalyst process heats up the fuel by 63 degrees Celsius (113 degrees Fahrenheit). This means if the ambient temperature in the room is around 70 degrees Fahrenheit, the fluid would heat up to 183 degrees F. The heated fluid could then be used to heat homes, commercial buildings, etc.
A schematic of how the thermal fuel process works
With additional testing and optimization, the team believes they can produce a molecule that can heat up the fuel by over 176 degrees F. The fuel could then be considered for electricity generation.
While there’s quite a lot of additional work to be done, the research team believes the technology could be commercially available in a decade. This is partially due to the increased interest from investors in the technology.
The development and commercialization of this thermal fuel could be another key component in the migration to renewable energy sources. The thermal fuel requires no outside input beyond the sun and operates in a closed loop system. As we continue to develop novel technologies and advance existing technologies, the transition to renewable resources not only becomes easier but becomes economically favorable.