Artificial Photosynthesis: Creating Energy Like Plants

Over billions of years, plants, most algae, and some types of bacteria have perfected turning carbon dioxide, water, and sunlight into usable forms of energy. Now scientists can replicate this with artificial photosynthesis. In fact, they believe it can usher in a paradigm shift in clean, sustainable energy production.

Researchers from the University of Illinois developed a method involving gold nanoparticles to mimic photosynthesis. In the end they created liquid fuels such as propane, methane, ethylene, among others. They published their paper recently in the journal Nature.

They believe it could provide the world with an entirely carbon-neutral method of energy production. It also provides many benefits that typical methods of solar collection can’t.

In particular, photovoltaic cells, the kind commonly found in solar panels, create electricity that must be used immediately. This results in grid-level problems like what is seen in the duck curve.

Also, energy produced like this must be converted to a chemical form before it can be stored, resulting in a loss of energy.

With artificial photosynthesis, on the other hand, researchers can produce liquid fuels that can be easily stored and transferred. This is a major problem for solar and wind. It also offers the added benefit of directly removing and storing carbon from the atmosphere.

What is Photosynthesis?

The basic idea of natural photosynthesis is that sunlight is absorbed by chlorophyll, where it is used to break water into its hydrogen and oxygen components. These are then combined with atmospheric carbon to produce glucose, a common energy source for life.

6CO₂ + 6H₂O + sunlight → C₆H₁₂O₆ (glucose) + 6O₂

An essential element of this process is the creation of free electrons when the water is split. Free electrons create a charge imbalance that allows for particles like protons to move along what is known as an electrochemical gradient. This facilitates the creation of more complex molecules like glucose.

Artificial Photosynthesis

To replicate this, scientists have tried using various transition metals because they easily give up electrons when bombarded by photons from the sun. Researchers use these free electrons to catalyze specialized reactions between atmospheric carbon and water, allowing scientists to create specific hydrocarbons like propane and methane, which store large amounts of energy.

The problem has been this process was only possible with expensive, rare metals that tend to corrode easily.

However, Yu and Jain from the University of Illinois have created a new method involving near-spherical particles of gold 12 nanometers in diameter. Gold is more readily available and is the least reactive of all metals, meaning it can resist corrosion.

Possible Problems

While researchers are excited about the potential that this process offers, they acknowledge several problems that still need to solved before this is adopted on a wide scale. For example, the most common method of releasing energy from the hydrocarbons is through combustion, which releases the carbon back into the air, making the process counterproductive. However, researchers from around the world are actively researching better, cleaner methods of converting hydrocarbons into fuel.

Another problem is that this method of artificial photosynthesis is nowhere near as efficient as natural photosynthesis. Though, Yu and Jiang are confident their technique can be refined substantially, thus increasing the catalytic potential of gold nanoparticles.

Working Together

Though, real progress is likely to come from combining other innovative techniques. For example, Daniel Nocera from Harvard pioneered a technique to feed hydrogen created by splitting water to specialize bacteria. These are specialized bacteria that have been bioengineered to produce hydrocarbons. Other researchers have employed hydrogenase. This is a specialized enzyme that can efficiently convert protons to hydrogen, providing the raw materials for building hydrocarbons.

Likewise, researchers from universities and corporations are actively pushing the field forward. This will bring the world within reach of satisfying all of its power needs from the sun. Italian professor Giacomo Ciamician first proposed this idea in his seminal 1912 lecture.

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