FreeWord – Artificial Photosynthesis

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In this article, we’ll study artificial photosynthesis, its vast potential, and how far it has come.

At a time when people are searching for ways to limit society’s contribution to climate change and reduce dependence on fossil fuels and geopolitical and supply problems associated with it, it is natural to turn to photosynthesis to find solutions. Photosynthesis is an inevitable natural process that keeps not just plants, but just about everything else on Earth alive, including us. For billions of years, they have developed perhaps to be the world’s most efficient energy source. When plants convert carbon dioxide and water into carbohydrates, they feed themselves and release oxygen for us to breathe.

Nature knows how to do chemistry and humans know how to make electricity. It makes a lot of sense to put the two things together.

Thomas Moore, Solar energy student

As of today, we can already harness sunlight to generate electricity through solar PV cells. However, the current electricity distribution system has a fundamental problem – we do not have enough capacity to store the power we produce. Therefore we have to use most of the electricity as it is produced; otherwise, we basically lose it. The beauty of photosynthesis is that it locks the sun’s energy inside the chemical bonds within the glucose molecule. Therefore, plants not only obtain the ability to produce energy, but also the ability to store it.

What is Artificial Photosynthesis (AP)

While humans are unable to perform photosynthesis naturally, scientists have created an Artificial Photosynthesis system to produce liquid fuels and reduce CO2 levels in the air. Artificial photosynthesis is a chemical process that biomimics the natural process by using the same green light portion of the visible light spectrum to convert CO2 and water H2O into liquid fuel. Plants use sunlight, CO2, and water to produce and store solar energy in the form of energy-dense glucose, which becomes fuel for the plant. Humans, on the other hand, are looking for liquid fuel to power cars and electricity to run the grid. So for an artificial system to work for our needs, the output must be changed. Instead of releasing only oxygen at the end of the reaction, it should also release liquid hydrogen (Methanol is another possible output).

Liquid fuels are ideal because they are easier, safer, and more economical to transport than gas and because they are made from long-chain molecules, containing more bonds—meaning they pack energy more densely.

Prashant Jain, a chemistry professor and co-author of the study

Current Status

The synthetic biology industry has been progressing rapidly over the last few years. Recent advances in spectroscopycrystallography, and molecular genetics have clarified much of the image. Researchers are actively trying to transform functional, efficient, synthetic systems known from the process that uses endless energy supply from the sun. At the moment, the essential steps in artificial photosynthesis work, but it’s not nearly as efficient as in plants.

How Does it Work? 

For an AP system to work, it has to be able to perform two vital things. Firstly, it has to be able to efficiently absorb sunlight. Secondly, it should be able to split water molecules into oxygen and hydrogen. As for the end result, oxygen is released in the atmosphere, and the hydrogen can be used as a source of clean energy. Obtaining the hydrogen production process is not a problem as it already exists in water molecules, and capturing sunlight is no problem with the current solar systems.

The challenging part is to divide the water molecules to obtain the electrons needed to facilitate the hydrogen-producing chemical process, which also requires about 2.5 volts of energy supply. So the process requires a catalyst – something to get the whole thing moving. The catalyst reacts with photons in the sun to initiate a chemical reaction.

Over the last decade, there have been significant advances in the catalyst area. One of the most promising new ways of achieving AP is by producing high-energy hydrocarbons by leveraging electron-rich gold nanoparticles as a catalyst. Some of the most successful catalysts include manganese, dye-sensitized titanium dioxide (TiO2), and cobalt oxide (CoO).

AP opportunities are countless. As for an example, the Research Group of Daniel G. Nocera engineered a particular bionic leaf bacterium that takes in nitrogen from the atmosphere and produces fertilizer.

Enhancing Plants and Organisms

What if we could improve on this fundamental, ancient process? Some researchers have chosen another path to improve living plants by implementing a high-resolution mass spectrometer in vitro in living organisms. Studies have shown that the new pathway is capable of capturing carbon dioxide faster than the natural Calvin cycle in plants. This route could be up to five times more efficient than the in vivo rate of the most common natural carbon capture pathway. They are eventually leading to a faster and less energy-intensive carbon capture. AP has the potential to produce more than one fuel type as the photosynthetic process is adjustable.

The bionic leaf is the bacterium working in concert with the artificial leaf, taking the hydrogen plus carbon dioxide and making liquid fuel.

Daniel G. Nocera, Professor of Chemistry and Chemical Biology

Conclusion

AP might be the solution for large-scale hydrogen production. It answers to the current problems of how to efficiently and cleanly generate liquid hydrogen. It can potentially create an endless, relatively inexpensive supply of energy that comes in a storable form of fuel without producing any harmful by-products.

Like for many other renewable energy technologies, the breakthrough hasn’t happened yet, and the cost of production has simply remained too high. In addition, finding the right materials and creating a stable system have also been one of the significant challenges. However, these systems could change the way we power our world. We’re just not quite there yet.

Nevertheless, we shouldn’t forget that currently one of the best ways to fight climate change is to plant trees and plants as much as possible, since branches and leaves help to trap carbon dioxide, effectively reducing overall pollution in the atmosphere.

Photo Credit: https://futurism.com/synthetic-photosynthesis-new-tech-recycles-carbon-dioxide-faster-than-plants


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