Photosynthesis is, arguably, the most important  biological process there has ever been.  Aside from simply creating the climatic  conditions that made multicellular life   possible, photosynthesizing organisms continue  to graciously provide our planet with the oxygen   that basically everything needs to live.

And, yet, scientists are looking for ways  to make photosynthesis even better. And if they crack it, we could use  photosynthesis to power stuff like cars! [♪ INTRO]  You might remember the equation for photosynthesis  from your freshman biology class.

The process is   relatively simple: basically, plants take  in sunlight, water, and carbon dioxide and   turn that into oxygen and stored energy in the form of glucose.  And while it’s the foundation for virtually all  life on earth, photosynthesis is surprisingly   inefficient. Plants are only able to  store about one percent of all the  energy they receive from the sun. But researchers know they can do better   than that.

So for decades they’ve been trying  to create artificial forms of photosynthesis   in order to power our whole world. Now you might be thinking, “but isn’t   that just a solar panel?” Well, yes and also no.  Solar panels soak up the sun’s rays to generate  electricity, which is an immediate energy   source resulting from the flow of charged  particles, photosynthesis makes something  that stores energy. So, think the difference between electricity  and something like gasoline.

Gasoline stores energy within   its chemical bonds, and then releases  that energy when it gets ignited,  and takes up very little space to do so. And while generating solar electricity is   able to power our homes and cars, it can’t  always substitute for combustible fuels,   which provide an unbeatable combination of power and compactness.  Roughly 40% of global transportation is incapable of being electrified.  I mean, you’d need a pretty big battery to get a Boeing 747 off the ground.  So while solar panels generate electricity,  the goal of artificial photosynthesis is to   use solar energy to produce usable fuel, which  is done by splitting apart water molecules,  just like plants do. This basic design for   artificial photosynthesis has existed  since 1998.

And even back then,   it was way more efficient than nature’s version. However, in basically all the designs we’ve ever   had for the process, it can either be durable,  efficient, or cheap, but never all three at once.   Which is a big part of why we haven’t been  using artificial photosynthesis much so far.  But if we do manage to make the process cheap  and efficient, what could it be used for?  Well, one type of fuel that researchers want  to make is hydrogen, which burns cleanly,   is zero-carbon, and could be used to power  future combustion engines or fuel cells.  However, hydrogen gas is pretty scarce, and is still mostly derived from fossil fuels.  But, we can make hydrogen fuel using a  system called an artificial leaf. These   pseudo-leaves utilize a design that  features two electrodes immersed in   a water-based solution, called an electrolyte.

The electrodes each gather energy from sunlight,   and use that energy to split the  water into hydrogen and oxygen.  This is a tricky process, not only generating  the gasses, but keeping them separate from   each other. Hydrogen gas is very flammable, and  can full-on explode in the presence of oxygen.  But the biggest problem often involves that liquid  electrolyte we discussed earlier. That’s because   water has a tendency to corrode the electrodes.

And as you might imagine, that’s not great for   the performance of electrodes. Most devices that  used these liquid electrolytes could only function   for less than a day before their electrodes  would completely corrode and need replacement.  But in 2018, researchers at the Joint  Center for Artificial Photosynthesis in   California made a major breakthrough for  keeping their equipment in tip-top shape.  Very basically, they used a solid electrolyte  instead of the usual liquid kind, and only   fed water vapor into the system. Without liquid  electrolyte, the risk of corrosion went way down.  Doing so minimized moisture exposure while  still allowing sunlight to be harvested,   making the resulting system capable of 100  continuous hours of hydrogen production.  But hydrogen and oxygen aren’t the only things  we can make with artificial photosynthesis.  Researchers can also make methane.

Methane is the primary component   in natural gas, and the same greenhouse  vapor that gives cows a bad reputation.  Methane is a pretty potent greenhouse  gas, but it also has major potential as an  energy-dense fuel source. And instead of harvesting this methane   from bovine burps, we could be making it from carbon dioxide, water, and sunlight.  While natural photosynthesis results in molecules  called carbohydrates, methane is a hydrocarbon,   which is a whole different kind of molecule. And making it involves a major, difficult  re-engineering of nature’s formula.

But in late 2022, researchers at the   University of Chicago announced they had created  a novel system that signals a big step towards   realizing this technology on a larger scale. Their design utilized what’s called a   metal-organic framework, or MOF.  Which is basically a bunch of  metal ions held together by organic molecules. After adding amino acids to the MOFs, the team   found these compounds were really efficient at  both splitting water and augmenting CO2 molecules,   rearranging them into methane.

Like ten  times more efficient than any previous model.  These are only a couple examples  of the work currently being done   to take a leaf out of Mother Nature’s book . And while it may be a while before we’re cooking   with green methane or filling our tanks with  solar fuel, artificial photosynthesis could be   a key part of getting the world to become carbon  neutral and slowing down the climate crisis.  So thank you to all the plants out  there for giving us the blue print,   or maybe the green print? I don’t know.  And thank you for watching  this episode of SciShow.  If you liked this video, consider becoming a patron of ours at patreon.com/scishow  and getting more science in your media diet.

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