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Could olivine rocks help our carbon capture efforts?

As climate scientists search for feasible ways to remove carbon dioxide from our atmosphere, a plentiful type of rock called olivine – and the process of chemical mineralisation – is providing an exciting lead.

It’s looking increasingly likely that achieving our net zero goals will depend not only on green industry transitions, but also mobilising carbon capture methods to address our current mess.

To date, the most effective means of locking away atmospheric carbon involve utilising natural banks like kelp fields and wetlands, as well as underground and deep sea reserves.

There are companies currently injecting carbon into concrete and creating biodegradable polyester competitors from it, but this makes up a meagre percentage of the gas we’ve sequestered overall.

While the natural methods are most effective right now, the majority do, however, share a common (and significant) drawback. That is, if such ecosystems are to perish for any reason, sizable dumps of carbon will be released in a single instance and potentially cause marked shifts to our climate. That wouldn’t be good, obviously.

One natural solution that doesn’t come with this risk is chemical mineralisation, which involves locking carbon inside robust rock formations. Scientists have long searched for possibilities to utilise this on a widescale.

How does carbon mineralisation work?

Able to lock harmful carbon away safely for literally thousands of years, this chemical reaction is constantly occurring as rocks are weathered.

When porous rock types are exposed to carbon in the air, the gas will actually fill the pours and spark a molecular process which causes them to become a solid mineral (usually carbonate) at one with the rock. The only issue is once cavities are filled, the process stops happening effectively.

Because of this, up until recently, carbon mineralisation was never considered a particularly promising avenue to make a sizable dent in existing emissions. The quantity of rock that would need to be utilised in pollutant heavy regions would frankly be ridiculous.

So, why are climate scientists suddenly optimistic about carbon mineralisation again?

What makes olivine so promising?

Recent experiments in the last six months have identified several types of rock that may not have such a limited capacity for carbon, after all. Chief among them, is a green crystalised rock called ‘olivine.’

If you want to get technical, olivine is a magnesium-iron silicate, but the most important thing to note is that it’s one of the most plentiful minerals on Earth – making up between 60% and 80% of the planet’s mantle.

This is considered a significant stroke of luck for climate scientists, because, unlike the vast majority of rocks, olivine is able to form new crystals and pours during carbon mineralisation. Effectively, it absorbs way beyond what most other rocks are capable of.

In fact, a single ton of the rock is reportedly able to absorb the equivalent weight of carbon emissions. Results from a study carried out by the American Geophysical Union in December showed that some of these rocks continuously absorbed carbon for over a month.

European climate initiative Climate-KIC estimates that olivine could capture as much as 850,000 tons in emissions, if it was used in small-scale projects throughout Rotterdam alone. Beyond carbon capture, it also has supposed applications in developing circular fertiliser, building gravel, and sustainable paper.

Where its primary talent is concerned, the proof of principal phase is largely out the way. We’re now trying to ‘optimise the process so we can help implement pilot projects around the world,’ says Catalina Sanchez-Roa of Colombia University’s Climate School in NYC.

Let’s hope this mineral is a nifty in the wild as it has proved under laboratory conditions, eh.