Carbon capture and storage: the black sheep of green energy?

Solar panels gleaming in the midday sun while turbine blades turn peacefully in the breeze – the appealing idea of harnessing nature’s power has had no trouble in winning fans. The idea of sucking up our CO2 emissions and piping them underground has, unsurprisingly, struggled to drum up as much enthusiasm as a means of lessening our impact on the environment, with its reminiscence of sweeping the problem under the carpet and hoping it will go away. Despite being a regular feature in proposals for reducing global CO2 emissions to safe levels, carbon capture and storage, or CCS, is opposed by environmental groups such as Greenpeace, who tend to see the technology as a ploy for the fossil fuel sector to continue its dirty work. While scientists have been busy trying to bring CCS to practical reality over the last decade, this kind of ideological resistance to the idea of CCS has probably done more to limit its use than any of the technological issues encountered. Although frequently criticised as an unproven technology which may not work, some examples of CCS have actually been around for decades, and 15 installations worldwide are currently storing around 40 million tonnes per year of CO2 which would otherwise be released into the atmosphere.

Much of the confusion comes from the fact that nearly all these facilities take CO2 from industrial processes rather than the primary carbon culprits – the coal-fired power stations which account for a quarter of the world’s emissions and are usually considered the real goal for CCS. This CO2 is much less concentrated, and therefore much harder to capture than oil and gas industry processes which have so far been targeted. Following a decade of cancelled plans, only one coal power plant has so far been fitted with CCS, the Boundary Dam plant in Canada whose opening in late 2014 was seen as a landmark moment for the technology. However, early technical problems at this facility which limited the amount of CO2 it could actually capture have been seized upon by CCS critics as further evidence of its shortcomings, despite protests from the owners that such teething problems are standard for a new technology. What was to be a pioneering year for CCS power generation then ended on a sour note following the recent announcement by the UK government that, as part of widespread budget cuts, it was cancelling £1 bn in funding previously earmarked for building a CCS power plant. Perhaps more significantly, the USA is still betting big on CCS, with two large coal plants set to open this year, although the massive delays and cost-overruns suffered by the Kemper County plant have also helped cast a shadow over the future of carbon capture. Like many carbon-free energy sources, power from CCS is expensive.

At the moment, government grants of the kind once proposed in the UK are usually required to help companies build a plant and set up an infrastructure for transporting and storing the CO2, but this should quickly become unnecessary as other investors begin to see the technology can actually work. More importantly, there is obviously no business case for undertaking the costly task of storing CO2 without any financial reward. Regulations which put some price on CO2 emissions are one means of valorising the carbon capture business, but existing schemes like the EU emissions trading system currently set this price far too small to be profitable. Of course, renewable energies like solar panels and wind turbines usually need both these kinds of financial help as well, and have taken off largely thanks to subsidies which effectively charge the customer more for their clean energy. The cost of carbon-free power from CCS is generally estimated to be cheaper than many renewables such as photovoltaics and offshore wind turbines. Otherwise, it would not even be on the table as a viable option.

So why does CCS struggle to find the same level of support? Part of the answer may lie in the nature of the cost of CCS, which is mainly associated with the large amount of energy needed to separate and purify CO2 from other gases. To drive the current processes available for this task, a power plant needs to consume almost half again as much fuel as normal – also having to capture and store the extra CO2 produced. Burning that much coal just to clean up the original coal is an idea which sits uneasily with many. Critics point to the fact that more coal mining will be needed, and even if the CO2 is disposed of, does it really make sense to produce so much more of it? This ties into a second source of concern dogging CCS, which is a lack of faith that CO2 will actually stay underground reliably. Some of this disbelief may stem from a popular misconception that the gas sits in vast subterranean caverns when in reality it is soaked into porous rocks as a pressurised liquid – much like the oil and gas we have removed to produce it. In fact, even if leaks were to occur from these CO2 stores over time, it would probably do little to diminish the value of such large repositories for carbon which would serve a similar role as the oceans and forests.

However, while CCS proponents have fought to convince politicians and the public over the scientific and economic sense of the idea, it is clear that the technology will inevitably be held to a higher standard than its more popular, renewable energy cousins. There is a strong feeling that if we are to resort to this inelegant solution to our climate problems, it should cost much less than the alternatives, and not require so much help to get going. The main trump card of CCS over most renewables is its ability to produce power on demand, not just when the wind blows or the sun shines – a service which energy markets are still struggling to put a suitable value on. Without CCS, new energy storage technologies will be needed to even out the supply of renewable energy, rendering these already costly energy sources even more expensive. The alarming extent to which the batteries that power our phones and laptops have lagged behind the devices themselves is some indication of how challenging these technologies are to develop. Nevertheless, the aesthetic superiority of this brave new world of energy is such that people and governments may well be prepared to pay more to avoid any reliance on the comparatively antiquated practice of burning fossil fuels.

The major international climate change talks held in Paris at the end of last year brought little attention to CCS, with only Norway and Canada specifically mentioning the technology in the official action plans submitted by each country. However, a closer look at the hugely ambitious targets laid down by the meeting can only emphasise the inevitable role of CCS if these goals are to be achieved. The real challenge with the famous ‘two-degree scenario’ or 2DS agreed to in Paris, is that it effectively allocates humanity a fixed amount of CO2 which can safely be emitted. At our current rate (around 40 billion tonnes per year), this budget of roughly 400 billion tonnes will not last very long, and most predictions show we are almost certain to overshoot it. The new ‘1.5-degree scenario’ proposed as an aspirational target in Paris presents an even greater challenge. Even if the energy industry is completely decarbonised without recourse to CCS, we will still need to start storing CO2 just to get the atmosphere back to a healthy state. What’s more, carbon-intensive industries such as steel and cement production which are much more difficult to clean up will have no choice but to turn to CCS under this strict new regime. It may seem strange, therefore, that there is so much focus on CCS for power generation, where it needs to compete with far more appealing alternatives.

In reality, we are so perilously close to exceeding our carbon budget that CCS needs to be developed now, and applying it to clean up some of the vast number of coal plants worldwide makes more sense than trying to suck CO2 out of the atmosphere in the future. All the more so when many of these plants are brand new and predicted to run for decades, regardless of the impressive growth in renewable generation. The belief is that CCS is primarily in need of a dramatic image makeover if it is to fulfil its potential role in decarbonising our society. Much of the necessary change in perception can be driven by new technologies which are promising to capture CO2 at far less cost and energy. As the use of CCS slowly increases, people are also likely to become more used to the idea of storing CO2 underground. However, the industry could do worse than look to another black sheep of clean energy for proof that attitudes can change – nuclear power, which in many countries has gone from environmental pariah to climate change hero in less than two decades.

Toby Lockwood

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    By: Toby Lockwood

    Technical author and analyst at the IEA Clean Coal Centre

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