Moving mountains to lead in global carbon capture race

Unsplash/Niklas Weiss

Earth’s atmosphere, ocean, biosphere and crust are perpetually engaged in an intricate dance. Rocks are exposed at the surface by mountain-building upheavals and volcanoes, their silicate minerals are weathered by water and carbon dioxide, then form the carbonate shells of tiny creatures, and are buried again.

Over aeons, this natural thermostat regulates the climate, avoiding runaway greenhouse or icehouse conditions.

But we really cannot wait that long to tackle global warming. Is there any way we can speed it up? The mountains of Oman and the northern UAE may hold a key.

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Between unliveable climatic extremes, there is plenty of room for variation.

In the Paleocene-Eocene thermal maximum, 55 million years ago, temperatures rose between 5 and 8C in less than 50,000 years, sea-levels were 200 metres higher than today, and crocodiles basked in the Arctic.

In the last ice age, which ended about 10,000 years ago, global temperatures were 5C lower than today’s, which may not sound like much, but the sea was 130 metres lower and Chicago sat under a kilometre of ice.

Neither of these scenarios sounds good for global civilisation.

A few hundred parts per million of carbon dioxide more or less in the atmosphere made the difference. We have increased the pre-industrial level by 50 percent already. The natural weathering of rocks will soak up that excess, but only over hundreds of thousands of years.

The Cop28 climate deal reached on Wednesday morning mentions carbon dioxide removal as one critical technology. 

There are numerous ways to do this. Burning biomass – wood or plant wastes, which use carbon dioxide from the air to grow – and capturing the result underground is one method.

Wood can be partly burnt to yield charcoal-like “biochar”, which enhances soil fertility as well as locking away carbon. Or arrays of machines can use chemicals and heat to strip out the 420 parts per million of atmospheric carbon dioxide, with the UAE oil giant Adnoc and the US oil company Occidental planning a demonstration of this technology.

Another method gaining attention is to speed up the Earth’s geological thermostat. Certain minerals react particularly readily with carbon dioxide, notably olivine, a major constituent of igneous rocks that form the oceanic crust and blanket significant parts of the land, such as India’s Deccan Traps, and Iceland.

The formations, known as ophiolites, are parts of the ocean floor that have been forced up over the continents. They are particularly rich in olivine, and the world’s best example is in the Oman Mountains which stretch into the northern UAE.

Natural solution

These rocks in Oman naturally capture about 100,000 tonnes of carbon dioxide per year. Now several groups are investigating their potential to do more. A startup called 44.01, named after the molecular weight of the greenhouse culprit, was founded by the Omani entrepreneur Talal Hasan.

The company is working with Adnoc, the clean energy company Masdar and Fujairah Natural Resources Corporation to inject carbon dioxide, captured from the atmosphere and mixed with water, into the ophiolite in the emirate of Fujairah. Here it should react with olivine within 12 months to form harmless solid minerals, locking it away forever.

The first pilot has started with 10 tonnes, but 44.01 wants to scale up to billions. The company has partnered with Aircapture, a US direct air capture company, to run a larger project starting in Oman in late 2024.

RAK Gas from the neighbouring emirate of Ras Al Khaimah is planning something similar, and revealed more of its concept at Cop28. Saudi Aramco has investigated the storage potential of basalt rocks in the west of the country.

An alternative approach, instead of bringing the carbon dioxide to the rock, is to bring the rock to carbon dioxide. The San Francisco-based company Vesta spreads ground-down olivine on beaches. Here, it breaks down in seawater, helping to neutralise dissolved carbon dioxide. 

Or, crushed olivine or basalt can be spread on farmland, lowering soil acidity, adding nutrients, and sequestering carbon as the rock breaks down. 

However, these methods are not substitutes for reducing emissions rapidly. 

They are complements: to mop up the unavoidable residual emissions even in a net-zero carbon world, and to draw down our legacy of excess carbon dioxide in the air. The scale required is huge, but not absurd, beside the similarly vast amounts of material moved by global industries of coal, sand and gravel, or water treatment.

There is no shortage of the required rocks: basalt is extremely common, ophiolites rarer but still more than sufficient for the job.

The next couple of years should see results from 44.01, Vesta and other such pilots. If they can demonstrate reliable, safe storage at speed, and reasonable costs, these technologies could expand quickly for those ready to pay. And the rugged, dark brown rocks of the Oman Mountains would move from geological curiosity to essential environmental resource.

Robin M Mills is CEO of Qamar Energy and author of The Myth of the Oil Crisis