banana leaf

Reverse photosynthesis turns plants into biofuels

Photosynthesis is maybe the most important chemical process on Earth, turning sunlight and CO2 into the oxygen we breath and the food we eat. This process can be reversed, however. Danish researchers were the first to demonstrate how biomass can be broken down by sunlight in the presence of an enzyme and turned into useful chemicals like biofuels or renewable plastic.

banana leaf

Image: Pixabay

“This is a game changer, one that could transform the industrial production of fuels and chemicals, thus serving to reduce pollution significantly,” says University of Copenhagen Professor Claus Felby, who heads the research published in Nature Communications.

“It has always been right beneath our noses, and yet no one has ever taken note: photosynthesis by way of the sun doesn’t just allow things to grow, the same principles can be applied to break plant matter down, allowing the release of chemical substances. In other words, direct sunlight drives chemical processes. The immense energy in solar light can be used so that processes can take place without additional energy inputs,” says Professor Claus Felby.

Breaking down plant material is mainly done using industrial processes with high energy inputs, and can take a long time. The process developed in Denmark relies on lytic polysaccharide monooxygenases, a natural enzymes also used in industrial biofuel production, which aided by the sun’s energy can break down plant material in less than 10 minutes.

Tests were made on biomass — straw or wood — sprinkled with chlorophyll and the enzyme. The sun’s rays then break the sugar molecules inside the biomass into smaller constituents.

“We use the term “reverse photosynthesis” because the enzymes use atmospheric oxygen and the Sun’s rays to break down and transform carbon bonds, in plants among other things, instead of building plants and producing oxygen as is typically understood with photosynthesis”, says Postdoc Klaus Benedikt Møllers

Using this process biofuels could be made much faster. Methanol, an important fuel, could be sourced directly and at ambient conditions without additional energy inputs, for instance.

There’s reason to believe this reaction occurs naturally on the planet, though no one has reported it yet.


10 thoughts on “Reverse photosynthesis turns plants into biofuels

  1. Tibi Puiu

    agreed, or those straw crops that can grow very well in conditions where food crops can’t. see camelina sativa or mischantus.

  2. Brian

    When I looked into using marginal land, even that does not make sense. Every “energy crop” has other uses that are far more appropriate. “Energy crops” also tend to be invasive weeds. Its seems to virtually always be better to grow what you can for uses besides energy, then use the wastes for energy. Solar panels are 100 times more efficient at producing electricity from sunlight as crops are.

  3. Tibi Puiu

    Right, but most of the time this isn’t a this or that solution. It’s a mix that varies by location, according to the needs and resources of the community. Any source on that 100 times more efficient? Thanks for the comments.

  4. Brian

    Certainly it’s theoretically possible that there would be some situation where using 30 to 200 acres for crop fuels instead of one acre for solar pv would make sense, and the rest for food, fiber and lumber. I just can’t imagine one. Most of the organic chemical energy is still available when we are done with our food, fiber and lumber, so we get to eat our cake and have the energy too.

  5. Tibi Puiu

    Don’t get me wrong, I think biofuels are crap in the long run but they do have a use in the mix as a transitional fuel. Energy comes in many forms , and since electricity and liquid biofuels aren’t equivalent there will be demand for one or the other, despite massive land use. In most of the world, transportation is dominated by gasoline and diesel engines. The diesel can be made to run on biofuels, but not on electricity. We also don’t have electric airplanes either yet, so biofuels are great here cutting tailpipe emissions by up to 50%. Most of the world is also poor. It’s a lot more technologically accessible to make biofuels (a very straightforward chemical process) than building a small solar farm. Like I said, it depends on who needs it and demand is pretty high for biofuels, largely because demand is high for conventional petroleum liquid fuels. Until we transition to EVs massively, i think biofuels will still have a role. Some are terrible life cycle wise, but instances where it’s WORSE than petroleum are rare or due to mismanagement.

  6. Brian

    Biofuels from wastes, yes, but not from crops. There are plenty of technologies to turn wastes into drop in gasoline diesel and jet fuel. Gassification followed by Fischer–Tropsch works great.

    We pay to collect and dump wastes, so there is a double savings. The fuels from waste makers get paid to take the wastes. It’s very energy efficient compared to the alternative of dumping, it save land and water, and pollution.

    Many studies have shown corn ethanol actually getting negative energy gain: it takes more energy to make the ethanol that it returns, and it wastes massive amounts of land and water.

  7. Brian

    And we can also convert out plastics, tires, wood, all organics carbon materials to fuel. We can use excess solar and wind to make it even more energy efficient. It’s the tech we need, it’s better now, and necessary for any sustainable system. We can’t dump things.

  8. tibipuiu

    Yeah ethanol is pretty bad, that’s why production is capped. It should be capped at a lower threshold, if you ask me, somewhere more reasonable. As long as farm land isn’t displaced and forests cleared, biofuels can be cool. Not all arable land on this planet is actually used. Some fuel crops can be harvested in rotation or on marginal land, too. When the two interfere — energy and food demand — we have a problem. I think at more than 5 percent biofuels we start running into this sort of problem.

  9. Brian

    You seem to get it, but why do you think we need any crop fuels? I don’t like the term biomass or bio fuels, because it includes both crops fuels which are bad, and waste fuels which can be good. Every crop I have looked has has other food, fiber, chemical uses that are worth far more than the fuel use. Rotational crops make great compost or livestock feed. Corn ethanol caused corn prices to increase vastly causing hunger for poor people. We may already be hitting peak arable land. we are losing arable land every year globally. what land is not used for crops is often used for grazing. I just don’t see any surplus for energy and fuels we can get after we use the land for other uses.

    If you have an exception, I would love to hear it.

    I can imagine one possible exception and this is making specialty fuels that can’t be made from wastes, but I don’t know of any.

    Give them an inch and they will take millions of acres as corn ethanol has. Even cane ethanol which has worked well in Brazil, would probably be better sold as sugar, but the USA blocks that with tariffs.

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