Thursday Dec 08, 2022

Who Needs Plants When You Can Harness Solar Energy With An Artificial Leaf? – CleanTechnica


The idea of a human-made device that can process solar energy to make usable fuels has been tantalizing researchers since the 1970s. There being no such thing as a free lunch, it is not so easy to engineer a device that mimics photosynthesis, which Mother Nature perfected a long time ago. Nevertheless, researchers at the Department of Energy’s Lawrence Berkeley Lab in California appear to have solved an important piece of the “artificial leaf” challenge.

Solar Energy & The Artificial Leaf Of The Future

The concept of the artificial leaf first crossed the CleanTechnica radar in the form of a card-sized photoelectrochemical cell, back in 2011. Instead of converting sunlight into electricity, the cell acts as a catalyst that deploys solar energy to break water into oxygen and hydrogen.

Initial versions of the device required purified water. By 2013, researchers figured out how to prevent a film of impurities from coating the solar catalyst, enabling it to be used in contaminated water.

Around the same time, additional improvements on the artificial leaf concept popped up, one main area of research being to lower the cost of the solar catalyst. New iterations also included an artificial leaf that uses sunlight to convert carbon dioxide into carbon monoxide, a ubiquitous chemical building block.

By 2014 researchers at Berkeley Lab were working on a “bionic” version of the artificial leaf concept. They zeroed in on hydrogen production through solar energy, based on the premise that the energy storage value of hydrogen would help create a cost-effective pathway for a commercial version of the artificial leaf.

Just one year later, researchers at Lund University announced  a “supersonic” artificial leaf, based on engineered molecules that can collect solar energy and act as a catalyst. This version, too, was aimed at hydrogen production, with the potential for adding methane to the list.

Why Bother With Synthetic Photosynthesis When We Have Wind & Solar Energy?

Now that wind and solar energy are so inexpensive, it’s fair to ask why researchers are still so hot to make synthetic photosynthesis happen. If the aim is to produce hydrogen from water, that can be done by deploying solar energy to run an electrolysis system, which uses an electrical current to push hydrogen gas out of water.

For the answer, let’s turn to Purdue University, which ran an article last June on the advantages of mimicking photosynthesis over generating electricity from wind turbines and solar panels.

“The closest process to artificial photosynthesis humans have today is photovoltaic technology, where a solar cell converts the sun’s energy into electricity. That process is famously inefficient, able to capture only about 20% of the sun’s energy,” Purdue noted. “Photosynthesis, on the other hand, is radically more efficient; it is capable of storing 60% of the sun’s energy as chemical energy in associated biomolecules.”

Sad, but true. Researchers keep coming up with new solar cells that keep breaking solar energy conversion records. The most efficient ones have topped the 20% mark by a wide margin, but they don’t come anywhere close to 60%.

Purdue cited biophysicist and solar energy researcher Yulia Pushkar, who emphasized the artificial leaf advantage.

“With artificial photosynthesis, there are not fundamental physical limitations,” she said. “You can very easily imagine a system that is 60% efficient because we already have a precedent in natural photosynthesis. And if we get very ambitious, we could even envision a system of up to 80% efficiency.”

You Can’…….


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