The author is an astronomer, science communicator and professor of science education at UQAM
Humanity is clearly not heading in the right direction when it comes to our greenhouse gas (GHG) emissions. Already we are unable to meet the less ambitious reduction targets resulting from the 2015 Paris agreements, now the invasion of Ukraine and the sanctions imposed on Russian oil and natural gas by European countries are pushing the latter towards the coal as an alternative energy source.
After Germany and Austria, it is now the Netherlands’ turn to push its coal-fired power stations to their full capacity, when they were only supposed to operate at about a third, precisely to reduce their emissions of CO2. If we collectively fail to emit less carbon dioxide into the atmosphere, could we not at least try to remove some of it by capturing atmospheric carbon to store it where it will no longer harm?
The idea of capturing carbon, not at all far-fetched, has already received the endorsement of the Intergovernmental Panel on Climate Change (IPCC) of the United Nations. Released last April, the latest IPCC report unequivocally calls for the rapid development and deployment of carbon capture technologies to avoid the worst. These technologies would make it possible to offset the most difficult emissions to reduce (transport and agriculture, in particular) while removing from the atmosphere part of the emissions that have accumulated there since the beginning of the industrial era.
In the United States, the Department of Energy now has a budget of several billion dollars to promote the most promising technologies. And there will be work to do, since the IPCC estimates that between 5 and 10 billion tonnes of CO2 will have to be extracted from the atmosphere per year by the year 2050 if we want to prevent the planet from overheating. too. How will we go about it, exactly?
A first approach consists in injecting the carbon dioxide extracted from the atmosphere into alkaline rocks or mining residues, where it will be fixed in the long term. Asbestos mine tailings are particularly reactive in the presence of CO2 and are therefore good candidates. One could also store gigatons of carbon dioxide permanently by using it to make synthetic materials, such as carbonate rocks, which could then replace sand and gravel in the manufacture of cement.
One can also simply inject the carbon dioxide into appropriate geological formations, such as are found in abundance in Canada and the United States. But this approach must be considered with caution and subject to thorough geological studies to prevent the gas from escaping or the injection process from causing unwanted seismic tremors.
On the biological side, it is also possible to use carbon dioxide to stimulate the growth of beneficial algae. A carbon-rich product, biochar, is also showing increasing promise. Carbonized biomass in the absence of oxygen, biochar is composed of 45% to 85% carbon. It can be applied to agricultural land as a fertilizer and can store carbon for hundreds or even thousands of years under favorable conditions. Obviously, planting trees on a very large scale is also one of the relatively simple and inexpensive solutions for storing part of the atmospheric carbon in the form of ligneous matter.
The US company Ebb Carbon has developed an unusual electrochemical approach that uses carbon dioxide to raise the alkalinity level of seawater being desalinated before returning it to the ocean. This has the effect of reducing its acidity level, which is of significant interest when considering the devastating effects of ocean acidification. The carbon thus extracted is found in the form of neutral carbonate and is deposited at the bottom of the water, where it will remain for tens of thousands of years. An interesting by-product of this reaction is hydrochloric acid, which is used in the manufacture of many products and can therefore be sold.
Most of these capture technologies require more energy to operate than they produce, and they must therefore be coupled with renewable energy sources, such as solar or wind energy, otherwise the game is not worth it. not the candle. In regions of the globe where these energy sources are less abundant or unpredictable, new-generation mini nuclear power plants, more reliable than current power plants, easily moved as needed and producing no GHGs, would be the ideal solution, despite their current lack of social acceptability.
Between two evils, you have to choose the lesser. If humanity does not manage to get rid of its dependence on fossil fuels quickly, perhaps it will at least manage to reduce the damage by cleaning up the atmosphere a little!