Carbon capture and storage (CCS), which coal-miners worldwide hope will guarantee a future for coal as an energy source, may not be viable, technically, economically, and in terms of liability.
This is the view of Canadian scientist, environmentalist, and a former director of Greenpeace International, Dr Patrick Moore.
“It’s a huge technical problem. It’s massive volumes we’re talking about here – millions of tons of gas. All the feasible approaches that I have seen would end up using a very large portion of the energy from the power plant just to do the sequestration,” he says.
CCS is, in principle, quite simple – carbon dioxide produced by industrial facilities is captured, and then stored somewhere secure (Mining Weekly February 22, 2008).
Carbon dioxide is, of course, a key contributor to climate change. It is generated in significant quantities by a variety of industrial operations, but the single biggest industrial source of carbon dioxide emissions is the burning of fossil fuels to produce energy. This accounts for some 33% of all carbon dioxide emissions caused by human activities. And, among fossil fuels, the biggest producer of such emissions is coal. A single large power plant can generate eight-million tons of carbon dioxide every year. It has become imperative to reduce these emissions drastically in as short a period as possible.
That is the intended role of CCS. (Note that CCS could, in principle, be applied to all fossil fuels, not just coal.) A coal-fuelled power station with CCS could have 80% to 85% fewer emissions than one without CCS, reports the World Energy Council. One drawback, however, is that retrofitting carbon capture technology to existing coal-fired power plants could reduce their efficiency by up to 12%.
Once the carbon dioxide has been captured, it must be sequestrated. This involves transporting it, whether in gaseous, liquid, or supercritical form, by pipeline and/or road tanker and/or ship, through storage sites, to the sequestration location. The catch is that this sequestration has to endure for a very long time indeed – at least centuries, if not millennia. In theory – and, currently, in limited practice – the carbon dioxide can be injected into permeable geological formations, surrounded by impermeable rocks, such as deep saline formations, exhausted oil and gas reservoirs, unminable coal seams, and even abandoned coal mines.
“I do not believe that it is economically or technically feasible, compared to other technologies,” affirms Moore. “In other words, if the coal-fired power industry was required to sequester its carbon, I think they would stop building coal plants and build nuclear plants instead, where you don’t have this problem.” Moore is a strong supporter of nuclear power and hydroelectric power as the most environment-friendly options for baseline power generation.
Even with CCS in place, there is still the problem of other forms of air pollution created by coal-fired power stations. Apart from carbon dioxide, coal power plants also emit nitrous oxides, sulphur dioxide (both of which, for example, react with water vapour in the atmosphere to create what is popularly called acid rain), and particulate matter, the last being in the form of both solids – including dust, soot ash, lead, and nitrate and sulphate salts – and liquids (sulphuric acid, polychlorinated biphenyls, better known as PCBs, and dioxins). Although the levels of these emissions have been very significantly reduced over the past 25 years, they are still not zero. “If we really cleaned up the air from coal-fired power plants, it would cost a tremendous amount of money,” he highlights.
Then there is the question of liability concerning CCS. “The insurance industry is not very excited about it,” he points out, “because they’re afraid the carbon dioxide might come back to the surface and asphyxiate people.” The carbon dioxide has to be sequestered for centuries, at least. If it is pumped into old coal-, oil-, or gasfields, will all the old shafts and wells be securely sealed? Will they be adequately inspected over a sustained period? How long will these seals hold? “Sure,” says Moore, “we’ll have a demonstration plant here and a pilot plant there. But on a mass level, with all the coal-fired plants there are in the world, I don’t think it is going to happen.”
Where does that leave countries, like South Africa, that are heavily dependent on coal-fired power stations? “From a practical point of view, they will continue to operate until they are no longer workable, until they’ve lived their lifespan,” he says. “Perhaps, in the interim, better pollution control will be put on them.” Thereafter, they should be replaced by other forms of power generation, particularly hydroelectric and nuclear.