Solar Fuels: All-in-One?

Rıza Kızılel

PhD. Koç University Tüpraş Energy Center

The need for alternative fuels is one of the grand challenges to science and engineering. It has all the important ingredients: a very hard problem with the possibility of leading to game-changing technology, if successful. On one hand, the conversion of solar energy to hydrogen by means of water splitting process provides clean and sustainable fuel without depleting earth’s natural sources, and on the other hand, unreactive carbon dioxide (CO2) contains the possibility of alternative fuels within itself. Whichever it is, it will integrate the energy conversion, energy storage and energy distribution, all-in-one.

Solar based water splitting is a hydrogen-based production which yields hydrogen and oxygen from water through chemical and electrochemical reactions using sunlight as a fuel. It grants zero greenhouse gas emission, however, it is not as easy as it sounds. Efficient reactor designs; enhanced sunlight absorption; durable, long-life and inexpensive materials should all be improved for promising, alternative hydrogen-based fuels in energy market.

Similarly, conversion of CO2 into something valuable is more challenging than ever before with the release of billions of tons of unreactive gas into environment. However, if you walk after the footsteps of photosynthesis, you will observe that nature has been hosting one of its beauty in plants. Now it is the time to mimic the process of photosynthesis to overcome the decades’ long energy related problem which has been a growing and serious issue for human kind.

Plants use sunlight to make carbohydrates from carbon dioxide and water. While achieving this, they use only 1% of the energy from sunlight. Likewise, microalgae may utilize as much as 3% of the same energy to produce biofuels if they are kept under controlled environment, however, it is costly. On the other hand breathtaking progresses on solar fuel technology shows that conversion of solar energy into solar fuels with 10% efficiency or more is around the corner.

On-going technologies captures and stores solar energy and make use of the energy to convert CO2 into valuable solar fuels, in other words energy dense liquid fuels. The process starts with the capture and absorption of sunlight which splits charges. The charges are then transferred to the active sites where the reactions occur. Electrons derived from these reactions move from one specie to another with the reduction of chemically inert CO2 into first CO and then into methane, synthetic petroleum or other liquid fuels with lesser wasted energy and a shorter time compared to mother nature.

The main problem for the production of solar fuels is the complete lack of suitable electro-catalysts. Besides, existing technologies are either extremely inefficient or highly expensive to commercialize. It is why there is urgent need to develop novel technologies for economical production of solar fuels. Fortunately little sparks has arouse with the development of new materials and waiting for a little but devoted push to grow bigger.  Our main goal now is to conduct research that will make major contributions to sustainable energy, particularly to solar fuels.

Rıza Kızılel holds a Ph.D. in chemical engineering from the Illinois Institute of Technology and an M.Sc. and B.Sc. in chemical engineering from Boğaziçi University. He currently work as an Executive Director at Koç University Tüpraş Energy Center.
Contrary to the topic of the article, Dr. Kızılel is specialized in Advanced Batteries Systems for Hybrid/Electric Vehicles. Batteries gives off significant amount of heat when they are discharged. This huge heat should be removed to keep the battery operating safe. Dr. Kızılel's research activities focus on alternative cooling systems for safety of Li-Ion battery packs, modeling and design of Li-ion batteries. His team also investigates the design limitations and efficiency of microchannel heat exchangers in order to remove all the heat generated from the batteries during its operation period.