Reducing the emission of greenhouse gasses and stop global warming is widely regarded the challenge of our time and as one of the most severe environmental issues. “Therefore there is a clear demand to find ways to drastically decrease the net CO2 emissions”, says Richard Engeln from the Eindhoven University of Technology. “We need to build a CO2-neutral energy infrastructure”.
Currently our entire energy infrastructure is based on liquid fuels. If this infrastructure could be used for CO2-neural fuel, the transition to sustainable energy would go both easier and faster. There is not a lack of energy on Earth, every day 10.000 times more solar energy enters the Earth than needed. Linking this abundance of sustainable energy with the existing infrastructure, completely build around gasoline, could revolutionize the energy market.
The storage problem of solar energy
At this time a lot of sustainable energy is produced by wind turbines, tidal systems or solar cells. The problem with these methods is that the best places to produce energy are literally on the other side of the world than where the demand is. “Most energy can be produced in the Sahara and the Australian Outback while most demand exists in Western-Europe the American East-Coast and Japan”, says Engeln.
To make this work, the energy has to be transported efficiently. “At this time this would imply transport on such a scale that it is not yet possible”. Another challenge at this time is the storage of energy. Most energy is produced during the day, when the sun shines and winds are stronger. Alas, a lot of energy is used after sundown.
Storing energy can level this off, and it can be done in a variety of ways. “Batteries or super capacitors are options”, explains Engeln, just like heat storage or latent energy storage in aquifers. However there is a more familiar option, the storage of energy in a fuel.
“The best fuels are those that contain the most energy kilogram. Gasoline for example has an extreme high amount of energy per both weight and volume”, says Engeln. Engeln’s solution is in this direction, a new type of fuel, the so-called solar-fuel.
A fuel that is produced by activating gas mixtures by sunlight, direct or indirect, is called a solar fuel. In its basics it does not really differ from photosynthesis in plants, using the energy from the sun and CO2 to create energy that is needed to grow. Many new methods are being developed to create energy without the production of biomass, and thereby making the production of energy more efficient.
The only problem is that not CO2 is needed but CO, and it costs a lot of energy to split the CO2-molecules. “In the solar-fuel production from water and CO2 the reduction of CO2 to CO is energy wise the most demanding step. Non-thermal plasmas are suggested to enhance the CO production yield.”
CO2-neutral energy cycle
To put it simple, at an energy plant solar fuel is produced using the energy from the sun. By putting all this energy in, normal CO2 can be transformed in a fuel, methanol for example. Subsequently this solar fuel is transported to factories that need energy. At these places the solar fuel is burned, creating CO2. This CO2 is transported back to the energy plant to turn it into a solar fuel once more.
Research on this topic only started two years ago. “Solar fuel research is still in its infancy”, says Engeln. However, the first plasma experiments already show promising results. In maybe ten years, ‘plasma-assisted CO2 neutral fuel’, as this solar fuel is called, could be produced on a large scale.