Climeworks’ “Mammoth” vacuum cleaner is not a solution to the climate crisis

Human-caused climate change is an existential threat to life on earth, as the excess greenhouse gases in our atmosphere trap energy from the sun and heat the planet. Direct air capture (DAC) is designed to operate like a vacuum cleaner pulling carbon dioxide (or CO2) out of the air. Proponents claim that, at scale, DAC could make a meaningful contribution to reducing the global (and growing) stock of greenhouse gas emissions. But it’s important to look past the fanfare of today’s launch, at what is really being offered, and the broader implications for our planet and its oceans. Despite the fact that many countries are incorporating technofixes like direct air capture into their net zero plans, it is far from certain that they could ever scale to meet such demands, or more importantly, whether they even should.

Firstly, DAC technology is very expensive; Climeworks current plant, “Orca”, captures CO2 at costs upwards of $1,000. This amount, ironically, begins to point to the real costs of emitting a tonne of CO2, but for now we keep venting greenhouse gases into the atmosphere like it is an open sewer. Given the DAC costs to suck this pollution out of the atmosphere later on, it would theoretically be considerably more economical to just buy-out companies like Shell and keep the fossil fuel in the ground in the first place. Not to mention that by keeping our future emissions in check we could avoid breeching critical climate tipping points that have not yet been reached.

Climeworks’ newest DAC plant, Mammoth, is purported to capture ten times the amount of CO2 as Orca; some 36,000 tonnes of CO2 per year. It is, however, unclear how much emissions generated during its operation and the initial construction of this vast plant actually put a dent in that number, and Climeworks has not been forthcoming with this information. If 36,000 tonnes sounds like a big number, it’s not: It equates to one one-millionth of our annual global emissions. Even if Climeworks and other DAC companies do build hundreds of these DAC plants, it would not equate to even one per cent of current annual global emissions.

The footprint of DAC plants is not just in its emissions, but in the energy and materials required for it to work. Climeworks uses chemical pellets to absorb CO2, which will create waste and require expansion of extractive industries, as DAC grows. Energetically, DAC is highly inefficient, requiring vast amounts to capture a much smaller quantity of CO2. Of course, to avoid putting even more CO2 into the atmosphere, fossil fuels must not be used. Like Orca, mammoth, takes advantage of the abundant geothermal energy in Iceland, which happily enables the country to run on virtually 100% “renewable” energy. But globally, this is far from the case, and until we have achieved an excess of renewable energy, it is deployed far more efficiently in displacing further fossil fuel use, rather than powering DAC.

Why is OceanCare taking a stance on DAC?

Although they do it poorly, DAC plants do capture some CO2, there is still the problem of what to do with it. For this, Climeworks partners with Icelandic company, Carbfix, which stores the carbon by mixing it at pressure with water and then pumping it underground where it carbonates or mineralises as rock.

This process uses a lot of water, at least 25 tonnes per tonne of CO2. Climeworks claims that between 10,000 to 1,000,000 gigatonnes of carbon could be stored worldwide, although how quickly tunnels in the rock would clog up remains unknown. Nevertheless, at any scale that would approach anything climatologically meaningful would require inordinately large quantities of freshwater, while the fixing process may itself further contaminate natural water sources, such as aquifers.

OceanCare is engaging then because, as in so many cases, the problem is redirected towards the oceans. Carbfix has begun to trial using seawater to sequester carbon, which would be pumped and stored in sub-ocean basalts. The oceans are our best ally in the fight against climate change, but ingesting large quantities of seawater will have significant ocean impacts. For example, by killing enormous numbers of fish larvae that would have knock on effects throughout the food chain, likely negatively impact fisheries and threatening marine life.

The construction of pipelines and subsequent pumping operations will have significant marine impacts such as underwater noise pollution, while the inevitable leaks of CO2 will alter local ocean chemistry, damaging ecosystems. Injecting water at high pressure into the earth also induces seismic activity, especially in basalt rock which is prone to fracture under pressure. Unsurprisingly, storing CO2 beneath the seafloor would also induce seismic activity, which may release some of the commonly occurring sub-sea pockets of methane; a potent greenhouse gas.

Even if seismic activity large enough to induce tsunamis is improbable, smaller earthquakes will nonetheless generate significant impacts on the marine environment including noise, habitat loss and the displacement of sediment that can disorient, displace, and kill marine life. If DAC were to grow and expand, so too would these unnecessary risks to the marine environment.

Direct air capture and storage is therefore an expensive, insufficient, and an environmentally incompatible technofix that distracts, or worse deters, essential efforts and resources needed to phase out fossil fuels immediately. The promotion of such technologies might be compared some misguided science experiment to resurrect a long extinct species. Indeed, in the case of Climeworks’ Mammoth, the evidence suggests that its time already up.