Coal, carbon, and global warming

One simple fact that many in the coal industry know is that the world will continue to burn coal for decades. Why? Because the planet needs the cheap power offered by coal to keep the lights on and – arguably – reduce fuel poverty in developing nations. Yet another fact grounded in years of scientific research published in a recent report is that the planet faces the potentially catastrophic effects of global warming and the risk of unstoppable sea level rise, unless 80% of the world's coal reserves remain in the ground. One of the ideas for mitigating climate change, then, is removing carbon pollution from the air and burying it deep underground.

However, carbon capture and storage (CCS) technology still has a long way to go before it becomes feasible. Yet in Iceland, a new CCS project is hoping that new technology could help reduce carbon emissions from coal. CarbFix, a US$10 million project is working on a solution to one of the major challenges of the CCS approach: How to make sure the carbon stays in the ground. 

According to a New York Times article, CarbFix injects the gas into water (25 t of liquid per tonne of gas) and pumps it into basalt, a reactive rock that makes up 90% of Iceland's underground. Using basalt speeds up a natural chemical reaction, which turns the carbon into a harmless solid—a rock. But under natural circumstances, the process can take centuries. Before that can happen, carbon would bubble up to the surface, and leak into the atmosphere. CarbFix, though, is studying how to speed up this process so it occurs in a matter of years. What is unique about CarbFix's process is how it combines the gas with water, an extra step that makes storage both more effective and more expensive. Other forms of carbon storage condense carbon into a liquid-type substance without water, leaving it more likely to escape to the surface.

Iceland is an ideal country to trial this technology – the porous basalt needed to store the carbon is in abundance thanks to ancient lava flows from the Hengill volcano.

Sandra Snaebjornsdottir, a doctoral student at the University of Iceland, is one of the CarbFix team hoping to turn gas into stone. She and her colleagues are certain that their process works, but are currently waiting on the results of detailed analysis at a laboratory in Reykjavik before they can truly celebrate their accomplishments.

Proponents of the technology say that just like scrubbers "clean" coal to lower sulfur and nitrogen emissions from power plants, carbon capture can cut down on carbon emissions. 

There are currently only a dozen large-scale CCS projects operating around the world, storing less than 30 million tpy, according to the Global CCS Institute, which promotes CCS technology. Only one of these projects is at a power plant – the Boundary Dam project in Saskatchewan, Canada, which began capturing and storing emissions from one of its coal-fired boilers last autumn.

CarbFix differs from conventional CCS approaches by using water along with carbon dioxide, and by injecting them into volcanic rocks. The technique is designed to exploit the ability of CO₂ to react with the rocks and turn into solid minerals.

“Basically we’re using a natural process and engineering it for climate-change mitigation,” said Juerg Matter, a geochemist at the University of Southampton, UK, and one of the lead researchers on the CarbFix project.

Because the gas, in affect, disappears, the CarbFix team avoid using the term carbon storage. Instead, the preferred term is mineral carbonation.

Although the costs of CarbFix process are high – an estimated US$17/t of CO2 – the team hope that the approach might have the cost advantage over traditional CCS methods in the long run. Because of the risk of leakage, a conventional storage site would have to be monitored, potentially for hundreds of years, at a cost that is difficult to estimate. A CarbFix site, with its stable minerals, could be left alone.

But even if CCS science develops, it likely will not reach the kind of scale—billions of tonnes of stored carbon—that is necessary to fight climate change. The technology faces two major obstacles: Economic cost and political indifference. The costs outlined by CarbFix highlight just how extraordinarily expensive it is to capture and store carbon. It not only requires power plants to install equipment for capturing and transporting the carbon, but also necessitates huge water reserves. Coal companies have no incentive to invest in the technology on their own, when it is inexpensive to let carbon escape into the air. This may be why companies, such as Peabody Energy, are happy to promote the idea of “clean coal” and leave it at that: as an idea, with no actual investment. Peabody is notorious in the UK for its run in with the country's advertising authority, which ruled Peabody's "Advanced Energy For Life" advertising campaign was "misleading" in the way it used the term 'clean coal'. The term is misleading, the argument goes, because there is nothing clean about coal – the most polluting of the fossil fuels – and that CCS is undeveloped and at any rate can never truly negate the emissions released by the burning of the "black stuff". Coal companies know this, and so they, like Peabody, are happy to tout lines about CCS and pay lip service to the idea of reducing emissions without taking any real course of action to curb global warming and climate change. This attitude explains why there are only a handful of large projects around the world. And why would the coal industry want to spend its money on expensive technology? The US$17/t cost of CarbFix's method is, after all, about twice the cost of transporting and injecting the gas alone.

Of course, regulation and the right policies can compel companies to invest in CCS. For example, an aggressive tax on carbon—essentially fining companies for polluting—would help to make CCS more appealing. The Obama administration’s proposed regulations on power plants also require future plants to invest in CCS technology to capture between 30 – 50% of their carbon emissions. 

Arguably, however, investing in renewables and energy efficiency makes more sense than mandating an unproven technology that does not solve long-term warming. As the Times noted: “given the economics of carbon storage are already poor, it is difficult to see many companies taking on the added expense of injecting water, too.”

According to a report from the National Research Council and National Academy of Sciences, "most carbon dioxide removal strategies have limited technical capacity, and absent some unforeseen technological innovation, large-scale deployment would cost as much or more than replacing fossil fuels with low carbon-emission energy sources." When it comes to mitigating climate change, the report said, "There is no substitute for dramatic reductions in greenhouse gas emissions."

In short therefore, it seems as though the time may have come when we begin to leave coal and other fossil fuels where they come from: in the ground. 

Edited from various sources by Sam Dodson

Read the article online at: https://www.worldcoal.com/power/11022015/coal-carbon-and-global-warming-1872/