The Hajar Mountain range in northeastern Oman is a geologist’s dream.
Universally acknowledged as the world’s best-preserved ophiolite, a rock that once formed the volcanic floor of a pre-historic ocean, it has long been a magnet for scientists seeking insights into the earth’s many mutations.
But in recent years, this jagged testament to the geological shifts that have shaped the globe has attracted a different type of pilgrim altogether, visitors who are more preoccupied with the planet’s future than its past.
The reason is that this igneous rock – more commonly known as Samail Ophiolite – has been found to possess properties that could one day help reverse climate change.
To understand how researchers came to that conclusion, it’s necessary to look 10,000 kilometres further north to Iceland. There, in a large power plant just outside Reykjavik, environmental scientists made a major discovery in 2016.
Conducting experiments into carbon capture and storage (CCS), they found that the volcanic island’s basalt rocks could serve as excellent repositories for planetwarming carbon dioxide (CO2).
Mixing CO2 with water and pumping it directly into the rocks, the researchers were able to turn the substance into a storable solid. Impressively, the mineralisation process they used took just two years – at least five times faster than their most optimistic predictions.
Buoyed by this success, Juerg Matter, an assistant professor at the University of Southampton who worked on the project at Iceland’s Hellisheidi geothermal plant, is now turning his focus to Oman. The rocks there, he says, could produce even better results.
By his estimates, the coarse-grained rocks that once formed the earth’s mantle in the Samail Ophiolite may react even more rapidly with CO2 than Icelandic basalt. “In the area where Oman is, mantle peridotite rock has huge potential in CCS,” he says.
So much potential, in fact, that the Oman Drilling Project, for which Matter is now one of the lead managers, has been able to secure funding from major institutions including NASA and the European Research Council. The researchers’ task is to determine how Omani rocks naturally mineralise the atmosphere’s CO2 and find ways to enhance and scale up this CO2 storage process.
Rock Steady
Their new technology improves on a traditional technique which has been around for decades but has proved costly and unreliable.
Conventionally, CCS technology takes CO2 from coal, gas and industrial plants and buries it in underground reservoirs in a liquid-like form. But there are problems with this method – stored gas could leak out back into the atmosphere, especially in earthquake-prone countries like Iceland. Studies show most capture schemes lose up to 75 per cent of carbon to leakage. In Iceland, Matter’s team studied how basalt rocks naturally mineralise CO2 in a so-called weathering process that often takes millions of years. The researchers managed to speed up that process by adding a CO2-heavy liquid similar to sparkling water.
“We convert CO2 emissions back to stone through a reaction with rocks. (This method has) a huge advantage in terms of storage and security because it’s permanent. Stones do not leak out of the ground,” he says.
It’s permanent. Stones do not leak out of the ground.
The team captured 220 tonnes of CO2, and is looking to scale that up to 10,000 tonnes in the near future.
In the scheme of things, that won’t change the world. Globally, the planet belches out more than 36 billion tonnes of CO2 every year.
But it is a start.
“The problem is so big CCS cannot solve the CO2 problem alone. We need a lot of other solutions too,” Matter says. “CCS has to be included because we have the infrastructure which is based on fossil fuels. CCS is a bridge technology into a more sustainable future.”
While it is not a permanent storage solution, traditional CCS is still a promising method which the International Energy Agency (IEA) estimates could reduce global CO2 emissions by 19 per cent. The IEA also says that fighting climate change could cost 70 per cent more without CCS.
Matter estimates that each cubic kilometre of mantle peridotite naturally absorbs on average a tonne of atmospheric carbon each year – adding up to 100,000 tonnes annually in the Hajar Mountains region.
With effort and some luck, that amount could be much greater. Theoretically, Matter says that there is enough peridotite in Oman and the neighbouring United Arab Emirates to absorb 33 trillion tonnes of CO2, equivalent to 1,000 years of human output, if present-day emission rates remain unchanged.
Similar pilot projects are under way in the US, where researchers at the Department of Energy’s Pacific Northwest National Laboratory have injected 1,000 tonnes of pure CO2 – instead of CO2 sparking water – into basalt below ground near Wallula, Washington. This way, greenhouse gas can be captured without the need for water, allowing even land-locked countries to adopt the method.
“CCS is currently the only large-scale mitigation option available to make deep reductions in the emissions from industrial sectors. Failure to utilise CCS technology in industrial applications poses a significant threat to the world’s capacity to tackle climate change,” the IEA said in a report.
Showstopper: politics
The Icelandic project had an added bonus of trapping emissions more cheaply than conventional methods. In Iceland it cost USD30 to capture a tonne of CO2. That compares with USD50-150 at traditional coal power plants. Matter expects the cost of CCS in Oman will be in the same range as Iceland.
Cost is, however, still a hurdle to this emerging field of scientific research. Just last year, the UK cancelled a GBP1 billion CCS development competition at the last minute, citing high costs.
“The first, second generation technology is there, we have over a decade of experience. What is now stopping the show? It’s the politics; there’s no legislative framework. Regulations are still missing and there’s no economic model. Who will pay for it?” Matter says.
He has personally come across opposition from some politicians who say they don’t want their land to be used as a “dumping ground of CO2”.
At least the UK is having a rethink. The government’s new advisory group says CCS is a priority if the country is to achieve its 2050 climate goals of reducing emissions by up to 80 per cent at least expense. The UK could capture 40 per cent of its emissions by 2050 using CCS, preliminary research shows, saving up to GBP5 billion a year compared with alternative strategies.
CCS is a bridge technology into a more sustainable future...Doing nothing is very costly.
“It is basically disposal of waste. It’s always tricky to find an economic model for that. At the beginning to get these technologies off the ground on an industrial scale, you need incentives, companies need incentives. That’s where the government comes in,” Matter says.
“Doing nothing is very costly.”
