Scientists create liquid fuel from carbon dioxide and water after taking inspiration from plants and inventing a form of ‘artificial photosynthesis’
- It copies how plants use light, water and carbon dioxide to make glucose
- Gold nanoparticles replace a plant’s natural chlorophyll as the catalyst
- The technology could replicate the reaction on a large scale to make liquid fuel
- Would turn excess carbon dioxide and sunlight into solar energy for later use
A way to mimic the natural process of photosynthesis could one day be used to reduce the level carbon dioxide in our atmosphere and power engines, experts say.
The process is crucial to plants as it converts carbon dioxide and water into energy, with a little help from sunlight.
It has now been replicated and adapted to produce liquid fuel for the first time.
The reaction produces propane which is high in energy and is useful for powering engines.
If it can be reproduced on a large scale, it could hoover up excess carbon dioxide and use sunlight to produce high-energy chemicals that powers cars and planes.
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A way to mimic the natural process of photosynthesis artificially could be used to reduce the level carbon dioxide in our atmosphere
Liquid fuels are better than gas as they are easier to transport, safer and pack in more energy, said scientists.
Natural photosynthesis is the process by which green plants uses energy from the sun as well as water in the soil and carbon dioxide in the air to make food in the form of energy-dense glucose – a form of sugar.
Chlorophyll is the catalyst behind the reaction, as well as being the pigment that makes plants green and also absorbs sunlight.
Instead of chlorophyll, however, scientists are replicating the reaction in the lab using a metal to absorb light energy.
This energy drives the transfer of electrons and protons in the chemical reactions between CO2 and water.
It is the process through which plants absorb light using chlorophyll to produce chemical energy in the form of oxygen and glucose.
During the process, glucose is used by the plants or is converted into starch, while oxygen is released as a waste product – giving us the air we need to breathe.
The rate of photosynthesis is altered by differing carbon dioxide levels and light intensity.
If either is increased then the process will also increase, up to a limit.
Temperature also plays a part, with a higher temperature increasing the rate.
However if the temperature is too high, beyond (104°F) 40°C, the rate slows down.
Photosynthesis provides most of the energy necessary for life on Earth to exist.
The researchers from Illinois at Urbana-Champaign, found that gold nanoparticles work particularly well as a catalyst in artificial photosynthesis.
Their surfaces interact well with carbon dioxide and are efficient at absorbing light.
Furthermore, due to gold’s lack of reactivity, it does not break down or degrade after multiple rounds of use like other metals.
Dr Prashant Jain, co-author of the study said: ‘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, contain more bonds – meaning they pack energy more densely.’
There are several ways in which the energy stored in hydrocarbons can be captured and turned into fuel.
However, the conventional method of combustion – burning carbon dioxide – ends up producing more carbon dioxide, Dr Jain said.
Instead of chlorophyll, however, scientists are replicating the reaction in the lab using a metal to absorb light energy. This energy drives the transfer of electrons and protons (shown in the diagram) in the chemical reactions between CO2 and water
WHAT IS ARTIFICIAL PHOTOSYNTHESIS?
A lab reaction that replicates the natural process of photosynthesis found in plants that produce glucose from water and carbon dioxide.
The reaction in which plants use sunlight to convert carbon dioxide to glucose has been artificially replicated in a lab to produce liquid fuel for the first time.
The artificial process uses the same green light portion of the visible light spectrum used by plants during natural photosynthesis to convert carbon dioxide and water into fuel.
Scientists use electron-rich gold nanoparticles as a catalyst to speed up the reaction so that it happens much faster than in nature.
‘They could be used to power fuel cells for producing electrical current and voltage. There are labs across the world trying to figure out how the hydrocarbon-to-electricity conversion can be conducted efficiently,’ Jain said.
Currently, the artificial photosynthesis process is nowhere near as efficient as it is in plants and the scientists admit they still need to fine tune the catalyst to increase the efficiency of the chemical reactions.
After this, they will think about making the process commercially viable.
Dr Jain added: ‘Then we can start the hard work of determining how to go about scaling up the process.
‘And, like any unconventional energy technology, there will be many economic feasibility questions to be answered, as well.’
Previously, researchers at the University of Illinois at Urbana-Champaign and the University of California, Berkeley collaborated to make plants soak up the sun more quickly, which could lead to better crop yields.
The report is published in the journal Nature Communications.
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