War on CO2: the five “tech” ways to capture it | VIDEO

CO2. A carbon atom bonded by two double bonds to two oxygen tomes forms a carbon dioxide molecule, which we mere mortals call carbon dioxide.. CO2 is not a toxic or dangerous gas: on the contrary, a natural and fundamental component of the atmosphere, which contributes to the natural greenhouse effect, the temperature regulation system of the Earth.

Like everything, even healthy CO2 in “small doses”: the progressive increase in the concentration of carbon dioxide in the atmosphere since the industrial revolution is causing much of the environmental and climatic damage that we are witnessing today, which has been destroying the planet for some time. in a lethal grip.

For some time there has been talk of the possibility of resorting to negative emission technologies to keep the current level of global warming (the highest in the last 24,000 years) below 2 degrees centigrade and thus get closer to the aims of the Paris Agreement. But what are they? And what types are currently used?Let’s clarify this article, with the necessary premise that, not being exponents of the scientific world, we will limit ourselves to observing the question from another angle, relying on the opinion of the scientific world.

The urgency to channel collective efforts towards combating climate change goes hand in hand with the worsening of their effects. The current picture is indeed all out of favor: the Mauna Loa Observatory has recently revealed the gravity of the situation, harassed by a level of CO2 in the atmosphere equal to 420.99 ppm (parts per million), a record that didn’t show up for millions of years.

Even the latest IPCC report (Intergovernamental Panel on Climate Change), the United Nations climate change research group, stressed the inadmissibility of the even minimal delay in global action aimed at reducing emissions. , the increase in the planet’s temperature compared to the pre-industrial era amounts to just under 1.3C, a figure that risks undermining the achievement of targets set by the 2015 Paris Agreementswhich instead point tokeep it well below the 2 degrees Celsius threshold (with a “allowed” maximum of 1.5 degrees Celsius).

To reduce the impacts of Climate Change, the scientific world immediately supported two different approaches, complementary to each other, which translate into as many policies to protect the population from the effects of the anomalous situations we are already witnessing, prevent future impacts and reduce emissions. : the dispute and adaptation.

Under the broad umbrella of “mitigation” approaches are grouped all the attempts to reduce the emission of greenhouse gases in the atmosphere – among the main causes of global warming – to keep those already existing at sustainable levels, thus building the irrigation around the incessant increase in the Earth’s temperature. . An example is the limitation to the circulation of internal combustion transport, pursued by the latest European directive onstop on endothermic cars from 2035Adaptation, on the other hand, means knowing how to manage the impacts that have now become unavoidable and prevent potential damage, but also seize any opportunities.

for the mitigation measures we want to focus on in this article: within this category one of the most courageous technological challenges of recent decades is underway.

For a net-zero future, a circumstance in which the same amount is subtracted for each ton of CO2 or another greenhouse gas released into the atmosphere, experts speak of unavoidable need to remove CO2 from the air. How? They exist in an approach natural, which exploit the physiological capacity of plants and trees to absorb carbon dioxide with chlorophyll photosynthesis, such as the practices of reforestation and regenerative agriculture, which allows soils to absorb tons of carbon every year; or, we appeal to technology, and here the aforementioned negative emission technologies come into play, that is systems capable of permanently removing carbon dioxide from the earth’s atmosphere.

Negative emission technologies are numerous and different from each other, contested by many and held to be fundamental for the fight against climate change by others. Let’s make a brief overview of the most significant ones.

One of the best known processes is called CCS (Carbon Capture and Storage) and is based on the carbon dioxide capture and storage where it is produced, that is, in large combustion plants, such as factories, coal plants and incinerators. How does it work? The CO2 produced is intercepted, captured through different modes, transported – almost always in a liquid state – and placed in a geological trap that scientists believe can contain the gas for hundreds of years. It is an expensive and energy-consuming technique, hampered by still large engineering gaps and high risks, such as the unexpected release of large quantities of CO2 following natural events or a gradual release over time.

There is a variant of this technique, according to but which also has its criticalities, called BECCS (Bio-energy with carbon capture and storage). Unlike CCS, BECCS aims to absorb the carbon dioxide produced by the combustion of biomass – plant residues and agricultural waste – instead of fossil fuels, and then store it under the ground.

Among the other methods of capture and storage, which therefore fall within the macro-scope of the CCS, figural ‘direct intake of CO2 from the air, known as Direct Air Capture. In Iceland, the Swiss startup Climeworks has started work on the construction of Mammoth, a plant powered by geothermal energy (therefore carbon-free), which it sucks in the air, filters it by retaining carbon dioxide and transforms the latter into minerals.

Its massive fans absorb the air and push it towards their filters, which separate the CO2 and accumulate it. The carbon dioxide is then mixed with a large amount of water and the resulting compound is transported and injected underground, where it reacts to the basaltic rock creating carbonate minerals. In this way, the CO2 remains “captive” for life without the risk of leakage accidents. This Icelandic plant is the twin of Orca, capable of capturing up to 4 thousand tons of CO2 per year, the equivalent of the emissions of about 800 cars. In the case of Mammoth, the results are even more promising: the power plant, whose works could be finished in the next 18-24 months, would be able to “suck up” and transform into minerals about36 thousand tons of carbon dioxideevery year. And the company does not intend to stop there: in the future plans of Climeworks there is the design of an even larger plant, closely followed by other similar models, which would instead be able to retain half a million tons of CO2. All this, to reach the ambitious target of 1 billion tons of CO2 per year by 2050.

To ensure that there are points ahead in the war on global warming, thousands of similar systems would be needed: according to the IEA, the International Energy Agency, to witness a massive intervention of direct capture systems on the climate situation , these should be able to trap 85 million tons of CO2 over the next few years. Considering that today these technologies account for 0.01 million tons, it is quite unlikely that they will reach the target within the established time frame.

There are also alternative and experimental methods of CO2 removal that are equally interesting, such as the “Desarc-Maresanus” project carried out by the Politecnico di Milano, which provides for the shedding in the seas of calcium hydroxidethe famous lime used in construction, capable of performing a double function: not only to remove CO2 from the atmosphere, but also tocounteract the acidification of the watersone of the most serious consequences of the increase in carbon dioxide.

Calcium hydroxide combines in a spontaneous process with water and allows the sea to buffer its acidity and avoid the decrease of PH, a mechanism that consequently favors the removal of CO2 from the atmosphere. In short, acting on the sea to heal the atmosphere.

A group of researchers from North Carolina State University recently devised a textile-based filter that combines a cotton fabric with an enzyme, carbonic anhydrase, capable of breaking down carbon dioxide from air and gas mixtures. In this case, action would be taken directly at the source, capturing the particles in question before they can even reach the atmosphere and without costly technological upgrades aimed at materially reducing emissions.

The idea of ​​using these filters to reduce CO2 emissions from coal, gas or biomass power plants. Its advantage is that it can be easily used on a large scale through traditional textile factories. The first tests have shown the goodness of the project, collecting 52.3% of the CO2 passed through a filter and 81.7% in a double version of the filter. Something, therefore, manages to pass but these values ​​would already be more than exciting if applied to the world of industry.

According to experts, however, the theories on negative emissions technologies lose their relevance if the underlying problem is not considered.use of fossil fuelswhich continues to be among the main sources of carbon dioxide emissions.

Without stopping emissions at source, scientists say, achieving climate goals will be really difficult.

And what do you think of it?