Will artificial photosynthesis be an alternative to solar panels?

In 1912 an article was published in Science in which Professor Giacomo Chamichan wrote the following: “Coal offers solar energy to humanity in its most concentrated form, but the coal is exhausted. Is fossilized solar energy the only thing that modern life and civilization can use? ” And later, in this article, he adds:

“Glass buildings will be everywhere; photochemical processes that until now have been a protected secret of plants, but which will be mastered by human industry, will learn how to make them give more abundant fruits than nature, because nature is in no hurry, and humanity is on the contrary. Life and civilization will continue as long as the sun shines. “

After a hundred years, Chamichan first introduced artificial photosynthesis as a means of excommunication from fossil fuels, since then the search for solutions has continued and even flared up with renewed vigor.

While solar panels are limited by the theoretical limits of their effectiveness, somewhere there is room for artificial photosynthesis, a long-forgotten brother of solar panels. It is very likely that people will continue to burn liquid and solid fuels that burn, while solar panels can only provide us with electricity.

Climate change is giving new impetus to research into artificial photosynthesis. Plants do something else that is useful: they capture carbon dioxide. Most climate models that allow us to meet the Paris agreement (2 degrees Celsius) require a lot of bioenergy with carbon capture and storage. This is a technology of negative emissions, when plants capture carbon dioxide, turn into biofuel and then burn. Carbon is trapped and sequestered underground.

Artificial photosynthesis can be a carbon-negative source of liquid fuel such as ethanol. Environmental advocates often turn to the “hydrogen economy” as a solution to the problem of reducing carbon emissions. Instead of replacing all our infrastructure – relying on solid and liquid fuels – we simply replace fuel. Fuel like hydrogen or ethanol can be produced with the help of solar energy, as in artificial photosynthesis, so we will continue to use liquid fuels with less damage to the environment. Universal electrification can be a more complex process than simply switching from gasoline to ethanol.

Artificial photosynthesis is definitely worth exploring. And in recent years, great steps have been taken. Powerful investments from government and charitable foundations are poured into solar fuel. Several different photochemical processes are explored, some of which already have the potential to be more efficient than even plants.

In September 2017, the Lawrence National Laboratory in Berkeley described a new process that can convert CO 2 to ethanol, which can then be used as fuel, and ethylene, which is needed for the production of polyethylene plastic. This was the first demonstration of the successful transformation of carbon dioxide into fuel and plastic precursors.

In a recently published work in Nature Catalysis, a technique was discussed in which photovoltaic panels are connected to a carbon dioxide electrolyzing device. Then the anaerobic microbe converts carbon dioxide and water, using electrical energy, to butanol.

They noted that their ability to convert electricity to the desired products was nearly 100% effective, and the system as a whole was able to achieve 8% efficiency in converting sunlight to fuel. It may seem that this is a small figure, but 20% is perfect for solar panels that directly convert sunlight into electricity; even the most productive plants, such as sugarcane and millet, gain no more than 6% of the effectiveness. That is, it is comparable to biofuel, which is currently used, such as corn bioethanol, as corn is less effective in converting sunlight into stored energy.

Other forms of artificial photosynthesis are concentrated on hydrogen as a possible fuel. Researchers from Harvard recently presented an impressive version of the “bionic leaf”, which can convert solar energy into hydrogen. One of its main advantages is that its efficiency grows rapidly if it is allowed to breathe pure carbon dioxide. If we are going to live in the future, in which huge volumes of carbon dioxide are extracted from the atmosphere, now we will have a very good application for them. Although recently people dislike this idea (the thermodynamics of using electricity to split water into hydrogen and oxygen is not always ideal), research is still being conducted on fuel cells for cars and hydrogen for heating houses, especially in Japan.

One of the problems associated with any efforts to create artificial photosynthesis is that the more steps you have in the process of conversion, the more energy will be lost along the way. The use of electrified devices with energy generated directly from the sun will be much more effective than any scheme for converting electricity and carbon dioxide into fuel, which you will then burn to restore the proportion of electrical input.

In addition, from an environmental and practical point of view, the construction of billions of artificial plants can be far less feasible than sowing seeds for several well-chosen biofuels. On the other hand, these plants often require good soil, which deteriorates rapidly due to agricultural pressure. Biofuels have already been suspected of using land that could feed a growing population. Plus artificial photosynthesis is that you can see how these “plants” thrive in the desert or even in the ocean.

As it often happens, we draw inspiration from nature – but to understand it, to subordinate it and even to improve it is a problem for us.

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