To stop the self-made apocalypse that is climate change, we humans need to change our ways by banishing fossil fuels, embracing renewables, and becoming far more harmonious with nature. As we start adopting these planet-saving measures, something becomes apparent: we not only need to become carbon-neutral, we also need to be far more efficient. Otherwise, our revolutionary technology will just cause a different ecological disaster. But, plants, including the crops that feed humanity, only convert 1% of the light energy that hits their leaves into sugars and usable energy, making the food we rely on incredibly inefficient. Amazingly, scientists have recently figured out a way to solve this problem by turbocharging plants’ efficiency. It could also unlock an astonishing array of world-saving technologies, from carbon-neutral farming to scaleable carbon-neutral biofuels. It may even help feed the first human base on Mars. Welcome to the brilliant world of artificial photosynthesis!
So yes, plants only convert around 1% of light into usable energy, which has served them well for the billions of years they have existed on Earth. But our solar panels can already trounce this figure. A cheap panel can achieve 15%-20% efficiency, and some of the upcoming top-of-the-range ones can get up to 50% efficiency. So if we could make plants solar-panel powered, then we could make our farms or plant-based technologies far more compact, efficient, and maybe even ecologically harmonious.
This is exactly what Elizabeth Hann and her team set out to do. In a process dubbed artificial photosynthesis, Hann’s team discovered a way to grow plants far more efficiently using solar power, a super-efficient two-step acetate electrolyzer, and a heterotrophic cultivator. Now, these tools all sound very complex, but they really aren’t. Allow me to explain.
Firstly, the team used commercially available solar panels, which have an efficiency somewhere in the region of 20%. This power was fed to an electrolyzer, which is a fancy name for a device that uses electricity and catalysts to convert chemicals into useful substances. In this instance, it took in carbon dioxide and water, passed it through a super-efficient two-stage process, and spat out acetate. This could then be used as food for all sorts of organisms, from microbes to fungi and even multicellular plants, in a process known as heterotrophic cultivation.
Picture vast numbers of plants growing in the dark with their roots bathed in acetate. It might sound very sci-fi, but the results are anything but fantasy.
After extensive testing, Elizabeth and her team found that they could grow algae four times more efficiently than those in sunlight! This algae can be used as a foodstuff, but unsurprisingly, most people don’t want to eat algae. Luckily, the team also reckoned that crops such as cowpea, tomato, tobacco, rice, canola, and green pea could all grow well with artificial photosynthesis. A little selective breeding or genetic modification may be needed to ensure they can grow on it as efficiently as the algae did, but that should be easy enough to accomplish.
Okay, so we now have the technology to grow plants in the dark using solar power more efficiently than the plants can on their own with photosynthesis. Great! But why is this a planet-saving technology?
To start off, it could eradicate the need for pesticides and significantly reduce fertiliser use. Both of these substances damage ecosystems, and the process of manufacturing them produces copious amounts of carbon emissions. But by growing crops inside in a controlled environment, we don’t need pesticides, given that no pests can get to them. The acetate bath will likely require additional nutrients in comparison to fertiliser, but the end result will be far more efficient, as no fertiliser is lost to the surrounding environment. Overall, this means there will be less environmental chemical damage and a massive reduction in farming’s greenhouse gas emissions.
Moreover, given these plants don’t need sunlight, we can stack them in vertical farms. This would mean that an entire farm’s worth of land could fit inside a reasonably large building across several floors and will make farms far more compact, which means we can preserve more natural habitats. This is crucial as ecosystem fragmentation caused by human deforestation and farm sprawl puts many keystone ecosystems at risk of collapse.
But it can do far more than stop farms from encroaching on nature. If this technology became widely available, countless fields would go unused as farms shrank fourfold. But we could put this spare land to good use.
We could use the land for carbon capture technology, such as GM plants, soil biomes, direct air capture, or even biochar. These technologies could reverse climate change by absorbing all the extra carbon in the air, but in normal circumstances would take up far too much additional land and, in the process, cause a massive drop in biodiversity. So, strategically placing them in this “spare” farmland could make a significant dent in our carbon emissions without encroaching on nature any more than we already have.
Alternatively, we could just grow more crops and use them for other means. If humanity could grow four times as many crops as it currently does using the same land area, then carbon-neutral bio-fuels would become a viable climate solution. You see, the sugars within plants can be turned into fuels such as petrol, diesel, and even kerosene. But because the plants use photosynthesis to build these sugars out of carbon dioxide, these “biofuels” are carbon-neutral (as long as they are refined with carbon-neutral energy). In theory, if everyone switched to these fuels, the world could become carbon neutral overnight. But the land area needed to supply that volume of fuel is enormous and would, again, have a catastrophic impact on the global ecosystem. But with our super-efficient artificial photosynthesis, we could make this fuel and feed ourselves using the land we already have as farmland.
Finally, artificial photosynthesis could be used to feed humans on Mars. Due to the orbits of Earth and Mars, crewed Mars missions can’t just be a quick trip there and back. There is only a tiny window to get from one planet to the other every two years, given that is when the planets align and exist the closest together. This means that if we are the first venture there, we need to live and thrive on the surface for extended periods of time. Well, artificial photosynthesis could allow them to produce enough crops to feed the crew using the weak sunlight on Mars and protect the plants from the harsh Martian environment. These astronauts could even switch to nuclear power rather than solar power, giving them access to more energy and, therefore, more essential food.
I could carry on about the benefits of artificial photosynthesis, including how we could have location-independent farms and grow a wide variety of crops anywhere in the world, which could solve global hunger and reduce the carbon footprint of food logistics. But if I did, this article could quickly become a book. Yet it is vital to bear in mind that this is a technology in its infancy. There may be unforeseeable snags in the future, or the ever present risk of development funding drying up. But the potential upsides of this technology are literally world-changing, and so, for the sake of humanity’s future, I hope this astonishing technology comes to fruition.