All-Day Solar Fuel Reactors

One of the biggest problems that solar energy faces in terms of viability on a large scale is its intermittency. The production process is lacking in stability and is thus unreliable, and to function smoothly for longer periods of time solar energy requires considerable effort from energy storage innovation. Similarly, this also applies to other renewable energies that aren’t a constant – such as wind energy.

One of the recently proposed solutions to the problem is to create solar fuel reactors. This technology allows for the conversion of excess solar power produced during peak supply hours into a portable fuel such as hydrogen. This can be produced from water using electrolysis with the photovoltaic electricity supply and compared to the most common way of usually doing so by processing methane, solar fuel reactors offer a much cleaner option.

Such an approach of storing the energy in fuel means solar energy can be transferred not only be stored for later use, but it also enables solar power to be transported to areas where sunlight is weak or insufficient to generate its own solar power. However, unfortunately the energy can only be converted into fuel under extremely hot temperatures: 800 – 900 degrees Celsius. While the most cost-effective and easiest way to achieve this is concentrated solar power (CSP) where lenses and mirrors focus rays to heat up the desired area, this doesn’t solve the problem of fuel production being intermittent and completely dysfunctional during the night.

Now a new type of solar reactor has been created by the German Aerospace Centre in collaboration with other scientists around the world – CONTISOL. It uses energy storage to continuously provide solar power regardless of the time of day or solar presence, meaning as soon as the solar power is stored in the reactor, it can be converted to fuel even after the sun has set.

One of the research’s lead authors, Justin Lapp, explains how CONTISOL has two reactors in its core: “One where sunlight is directly doing chemical processing, the other side for storing energy. In the chemical channels the high temperatures of the material drive the chemical reaction and you get a change from reactants to products within those channels, and in the air channels cooler air goes in the front and hotter air comes out the back.” As it currently stands, the current device is in its prototype stage and during testing achieved an output power of 5kW.

While the power output is likely required to be considerably higher for further deployment to be considered, the opportunity this technology provides is particularly exciting with many possible applications, and we look forward to hearing more in the future.