They will not, on their own, solve the climate crisis… but they do give hope!
THE FACTORY THAT PURIFIES THE AIR
How it works ?
The largest CO² capture plant (one of the main greenhouse gases) in the world opened in September 2021, in Iceland. Thanks to fans, the air is sucked inside eight collectors. The CO² is filtered there using a special material and then collected. The air expelled on the other side of the fans is therefore almost pure! The captured CO² is mixed with water and injected through pipes more than 800 meters into the ground to be stored there, before quickly turning into stone. With this promising project, the Swiss start-up Climeworks and the Icelandic company Carbfix want to reduce the amount of CO² present in the air, and thus partially limit global warming.
What can change
Each year, 4000 tonnes of CO² can be eliminated thanks to this plant. This is little compared to the 34 billion tonnes emitted in the world in 2020, it is imperative at the same time to reduce our emissions (industry, transport, etc.) But it’s going in the right direction, especially if this kind of factory multiplies!
ALMOST GREEN STEEL
How it works ?
Steel is made from iron, obtained by smelting ore. To do this, you have to burn coal. But there are alternative methods. Hydrogen (chemical element present in water, usable in the form of gas as an energy carrier) does not melt the ore, but allows it to be purified and to obtain iron, which can be transformed into steel. Electrolysis (an electric current passes through materials to trigger a chemical reaction) could make it possible to transform iron ore into metal, without releasing CO².
What can change
The steel industry was responsible for 7% to 9% of global CO² emissions in 2020 and this material is present everywhere. Hence the importance of manufacturing “greener” steel! But these innovations have to face two challenges: hydrogen is itself still mainly from fossil fuels (natural gas, oil, etc.) rejecting CO². And the investments needed to transform such a huge industry (nearly 2 billion tonnes of steel produced each year!) are colossal. Nevertheless, the Swedish Hybrit project based on “green” hydrogen will continue its tests until 2024, and the American start-up Boston Metal is planning its smelter for 2024.
SOLAR PANEL WINDOWS
How it works ?
Solar panels convert the sun’s energy into electricity using special materials: semiconductors. By absorbing the sun’s rays, they release electrons which form an electric current. Silicon is the material most used to manufacture them. But there are other, more innovative ones, such as perovskite panels.
What can change
Silicon solar panels, opaque and heavy, must be placed in places capable of supporting their weight, and which do not require light to pass through, such as the roofs of buildings; or directly on the ground. Perovskite panels, which are lighter, potentially just as efficient and semi-transparent, can be used as window panes, then capable of producing electricity! Their two main defects are a short lifespan – a few months or years, while silicon lasts 25 years – and the toxicity of certain components, such as lead. Challenges that manufacturers are trying to meet, who have already launched production plants, such as Saule Technologies, in Poland.
HYDROGEN TRANSPORT
How it works ?
A hydrogen vehicle is electric, it powers its battery with hydrogen and releases… water vapour! A technology allows this feat: the fuel cell. Inside the latter, the chemical reaction between the hydrogen in the tank and the oxygen in the air releases heat, water and electrons which form an electric current. The hydrogen tank ensures rapid recharging and better range than an “only” electric vehicle. Many cities (Auxerre, Pau, etc.) welcome hydrogen buses and, in 2020, the French State announced massive investments in this sector.
What can it change?
Vehicles that drive without emitting CO²: the dream! Hydrogen trains and even planes are being developed. However, in addition to ensuring that the machines are secure, it is necessary to deploy all the infrastructure that goes with it, such as service stations and a hydrogen production sector from green energy sources – wind, solar, etc.
WOOD WITH SUPERPOWERS
How it works ?
What if it was possible to improve the wood, to make it stronger and limit its degradation? This is what laboratory projects (the University of Maryland, United States) and start-ups (the French company Woodoo) promise. The researchers treat the wood by heating it and compressing it, or removing its lignin (a kind of glue it contains) to replace it with a resin – a chemical compound, which can be of natural origin. They thus obtain a more solid material, which does not rot.and can even have new properties: transparent, or sharp to be transformed into knives!
What can change
Working with wood generally consumes less energy than other materials (concrete, metals, etc.), and generates fewer CO² emissions. These processes would also make it possible to use certain woods not exploited by the industrialists. It remains to be seen whether these “new woods” will be technically and financially competitive enough to compete with other materials.
PALM OIL WITHOUT PALM
How it works ?
What if we replaced the famous palm oil with a more sustainable alternative? Instead of extracting oil from plants, such as that of palm trees, laboratories and start-ups (the University of Bath, in England, the Americans of C16 Biosciences, etc.) have taken a somewhat crazy bet to produce it using yeasts. These micro-organisms are indeed capable of producing oil -similar to palm oil- by consuming and transforming food and agricultural waste!
What can change
Palm oil is widely used today, from food to cosmetics to biofuels. But the palms needed to produce it are often grown by destroying wild forests, especially in Southeast Asia. This massive deforestation, in addition to destroying the ecosystems, is responsible for many CO² emissions due to the cut trees, the machines used, the destruction of the swamps, etc. However, replacing such a gigantic production – tens of millions of tons of oil per year! – requires a large number of production plants and considerable amounts of waste to use. If demand increased, then plants would have to be grown to feed the yeasts. And the problem would be transferred to other cultures!
METAL GATHERING PLANTS
How it works ?
Metal growing in fields is not a science fiction scenario! This is possible thanks to plants called “hyperaccumulators”: plants which, while growing, absorb metals present in the soil and store them in their stems, leaves or sap. Phyllanthus rufuschaneyi for nickel, Brassica juncea for gold… Depending on the plant, it is possible to “harvest” different types of metals. They are then recovered by burning the plants, or by using them directly in the chemical, metallurgical, glass industry… Fields in Greece or Albania already collect 150 kilos of nickel per hectare!
What can change
Harvesting metals this way is less polluting than extracting them via mines, even if the amount of metal obtained is much lower. This technology would also make it possible to effectively clean the floors, and to make available for other crops places that have become unsuitable for agriculture. This process takes time -10 to 30 years- and still needs to be improved, but it is already raising great hopes, because there are undoubtedly many “metal-gathering” plants to be discovered!
ALGAE THAT CAPTURE CO²
How it works ?
When they are cultivated, these tiny algae are able to capture CO², present in the atmosphere through photosynthesis, and therefore purify the air. Hence the idea of installing micro-algae “factories” next to industrial sites rejecting CO². Once the latter has been captured by the plants, it can be reinjected into the crops, to avoid diffusing it directly into the atmosphere. In Montalieu-Vercieu, in Isère, industrialists and the University of Nantes have joined forces to use the CO² emissions and heat from the manufacture of cement to grow micro-algae. Another field of application: water treatment. Microalgae have the ability to “clean” wastewater by absorbing pollutants such as nitrates. A method already used in Australia and Spain.
What can change
Micro-algae and their properties raise great hopes. In addition to being able to absorb CO², some of them are edible and can be sources of protein and nutrients; or usable in cosmetics to impart color or texture to a product. But it is on the side of green chemistry that the applications are the most promising: biofuels, bioplastics… These algae could even replace oil in certain cases!
Texts: Corentin Paillassard and Laure Blancard – Illustrations: Kevin Deneufchâtel