Artificial Photosynthesis 101: What It Is and How Does It Work?

Artificial photosynthesis is a scheme that helps specialists capture and stores the energy coming from the sun in the chemical bonds of a fuel. One of the most useful and challenging projects when wanting to generate large amounts of power with little greenhouse gas emissions is developing a leaf. Numerous scientist around the world are doing their best to be the first to come up with an economical method to generate energy from artificial photosynthesis.

The main idea that lies on the ground of this process is splitting water molecules to produce fuel. This process is similar to natural photosynthesis that occurs in plants. Artificial photosynthesis uses carbon dioxide, water, and sunlight. However, instead of generating oxygen and sugar, the product is hydrogen. Therefore, artificial photosynthesis may reach to develop a new industrial revolution. This process could help us deliver energy with low-emissions. The energy could be stored and even transported in the same way we use natural gas today.

Statistics show that plants use water and sunlight to develop outstanding energy conversions. They can transform 1,000 billion metric tons of CO2 into organic matter on an annual basis. In case scientists manage to use artificial photosynthesis to large-scale commercial production, then we could use hydrogen to produce electricity. In this way, we would be able to replace fossil fuels in transportation.

Furthermore, we can also use it as feedstock in the production of plastic, pharmaceuticals, and fertilizers. In the same way, we transport natural gas, we could also transport hydrogen in gaseous form. Another possibility would be in a cooled, liquid form. These methods could help us make transport by sea, rail or road more economical.

Natural photosynthesis vs. artificial photosynthesis

In the case of natural photosynthesis, the plant’s leaves absorb carbon dioxide and sunlight while the roots absorb water. Then, light energy stimulates chloroplasts. These are light-sensitive organelles located in plant cells. They trigger numerous chemical reactions that involve chlorophyll, enzymes and other proteins to split water molecules into oxygen, electrons, and hydrogen.

The oxygen is eliminated. Hence, the electrons and hydrogen react with the molecules of carbon dioxide to generate glucose, and the glucose turns into fuel for plants. About 2.5 volts of electrical energy is needed to split a water molecule. In order for this process to occur in an artificial environment, a catalyst combines with light energy. As a catalyst, scientists use light-sensitive substances like cobalt oxide, manganese, and dye-sensitized titanium dioxide.

When it comes to artificial photosynthesis, the structural lead contains thin membranes, microscopic and conductive artificial structures, and nanowires. Scientists use numerous structures and materials to develop artificial photosynthesis. The nanowires in the surface membrane of the leaf structure absorb carbon dioxide, water, and sunlight.

The light energy stimulates the electrons in the catalyst, determining a chemical reaction which splits the H2O into protons and oxygen. Hence, the artificial leaf releases the oxygen into the atmosphere while the carbon dioxide and protons move through the nanowires and the next membrane which features another catalyst. Then, a chemical reaction appears between carbon dioxide, protons, and the catalyst, yielding hydrogen fuel.

Green leaves in the light

Artificial photosynthesis could help us diminish greenhouse gas emissions and air pollution.

Protecting the environment

For billions of years, plants have developed one of the most efficient power supply in the world. For plants, usable fuel is constituted by fats, carbohydrates, and proteins. On the other hand, humans try to find liquid fuel to power cars and electricity to run refrigerators. Photosynthesis could be the solution to our problems. This process could help us diminish the amount of fossil fuels. Hence, this could provide an environmentally-friendly source of energy.

We would no longer use natural gas to generate energy, being able to replace it with the hydrogen fuel obtained through artificial photosynthesis. This could be an efficient way to produce green energy since this process will not contribute to the emissions of greenhouse gases. If we diminish these dangerous emissions from the atmosphere, we will be able to accomplish the goal set through the Paris agreement.

How the process works

The energy provided by sunlight is an endless resource. The photovoltaic-cell technology makes great use of sunlight. However, this is very expensive, and it is not so efficient. The semiconductor-based system does instant conversions from sunlight to electricity. Furthermore, the energy output is not stored for a rainy day.

However, an artificial photosynthesis system could bring a lot of benefits, creating an endless and cost-efficient supply of clean “gas”. This could help us power our lives, coming in a storable form. In order for an artificial photosynthesis system to work and cater human needs, the output needs to change. At the end of the reaction, instead of releasing only oxygen, the process should also release liquid hydrogen.

In this way, we could use that hydrogen directly as liquid fuel. The system does not have a problem when producing hydrogen since it retrieves it from water and it works perfectly when capturing sunlight. Nevertheless, it is pretty hard to split the water molecules in order to obtain the electrons necessary to enhance the chemical process which produces the hydrogen.

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The chemical process

We could use liquid hydrogen in the same way we use gasoline in hydrogen-powered engines. Furthermore, this could also be channeled into a fuel-cell setup. This can effectively reverse the photosynthesis process. Hence, it could generate electricity by combining oxygen and hydrogen into water. Then, hydrogen fuel cells can produce electricity.

Artificial photosynthesis is a clean way to produce liquid hydrogen to generate large-scale hydrogen energy. However, another possible output is methanol. Therefore, instead of emitting pure hydrogen through the photosynthesis process, the photoelectrochemical cell can produce methanol fuel. This is derived from the methane in natural gas. Often, methanol is added to commercial gasoline to make it burn more cleanly.

Summing up

The process of artificial photosynthesis could help us give up on fossil fuels, replacing them with a greener source of energy. In this way, we would be able to diminish air pollution by cutting down on greenhouse gas emissions. If this process will have great availability, then we would get energy at lower costs.

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William E. Eubanks
 

I'm one of the main writers on the site; mostly dealing with environmental news and ways to live green. My goal is to educate others about this great planet, and the ways we can help to protect it.

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