Scientists have studied photosynthesis in plants for centuries, but an international team believes they have unlocked new secrets in nature’s great machine that could revolutionize sustainable fuels and fight climate change.
The team says it has found that it is possible to extract an electrical charge at the best possible point of photosynthesis. This means harvesting the maximum amount of electrons from the process for potential use in electrical grids and some types of batteries. It can also improve the development of biofuels. Although it is still early days, the findings, reported in the journal Nature, could reduce greenhouse gases in the atmosphere and provide insights into improving photovoltaic solar panels.
The key breakthrough came when researchers observed the process of photosynthesis on ultrafast time scales.
“We can take pictures at different times, which allows us to watch the changes in the sample really, really fast — millions of billions of times faster than your iPhone,” Dr. Tommy Bycki of the University of Cambridge’s Cavendish Laboratory told CNET.
The team used a technique called ultrafast transient absorption spectroscopy, which can be understood simply as illuminating a sample with laser pulses and recording what happens at extremely short intervals. This makes it possible to observe the electrons as they move through the entire process of photosynthesis.
Previous demonstrations have connected cyanobacteria, algae and other plants to electrodes to create so-called bio-photoelectrochemical cells, which engage in the process of photosynthesis to generate electricity.
Baikie said they were surprised to find a previously unknown energy flow path early in the process that could allow the charge to be extracted in a more efficient way.
“We rely on plants for everything we eat and all the air we breathe, and maybe we can use their electrons, too.”
Scientists have found that the place in the cell where photosynthesis begins is a “leakage” of electrons. In nature, this can protect plants from the harmful parts of sunlight.
The discovery of the new, permeable pathway could also have major implications for the production of renewable biofuels, typically derived from plants or algae. Biofuels can be carbon neutral because they both take in carbon dioxide when plants are grown and release it back into the atmosphere when they are burned, compared to fossil fuels that release carbon that has been stored deep in the Earth for centuries. How much carbon a biofuel adds to or removes from the atmosphere depends on how the plants are grown and how the fuel is produced.
This research can be used to develop more efficient processes for creating biofuels.
“This is a completely new approach to biofuel production. We collect electrons from the earliest and most powerful points of photosynthesis and redirect them there,” research coordinator Dr. Jenny Zhang, also of Cambridge, said by email.
Zhang says others have tried to harvest electrons from an earlier point in the photosynthetic process, but concluded it was impossible. She says at first the team was convinced they had made a mistake.
“It took us a while to convince ourselves that we did,” Zhang said in a statement.
The breakthrough essentially promises to harness more of the incredible efficiency of photosynthesis when it comes to converting sunlight into energy.
“What makes photosynthesis really special is its almost 100% efficiency in converting light into electrons,” Baiki explained. “By understanding the mechanisms of photosynthesis, we can use this knowledge to inspire us to improve existing solar cell technology.”
In addition to more efficient energy production, fine-tuning photosynthesis may also allow plants to better absorb and store carbon dioxide, helping to combat climate change in the process.
Zhang envisions a future where the use of photosynthesis allows us to “grow our energy the way we grow our food,” but to do so through organisms like cyanobacteria that won’t require competition with food production.
In fact, she says the new insights gleaned from this research could actually boost crops by making them more tolerant of intense sunlight.
“In the long term, if we can generate renewable energy and fuels from self-generating, self-recycling living materials, that would be one of the greenest opportunities one can imagine to move forward for sustainability.”