Carbon sequestration means we can meet our Kyoto commintments without relying on unpopular nuclear power or unrealistic projections for renewablesby Richard Barry / March 20, 2003 / Leave a comment
The forthcoming energy white paper, expected in March, will need to be read with our Kyoto greenhouse gas commitments in mind. Last May, without great fanfare, Britain, along with the other 14 EU countries, ratified the Kyoto protocol. The protocol will not come into force until it has been ratified by countries which account for at least 55 per cent of the carbon dioxide (CO2) emissions of the developed world. But that will happen later this year when Russia ratifies the protocol. Ninety days after that happens, our Kyoto promises become binding commitments.
But what exactly are those? By ratifying, we have promised that during the target period 2008-2012 we will reduce our emissions of a basket of greenhouse gases by 12.5 per cent, measured in most cases from a 1990 baseline. In fact, we have essentially done it already and can almost certainly maintain our virtue throughout the target period. The latest forecast from the European Environment Agency identifies Britain as one of four EU countries most likely to keep its promise (along with Luxembourg, Germany and Sweden)-a performance of which we can be proud.
The secret of our Kyoto success lies in the basket. It is made up of the six greenhouse gases that contribute most to global warming: the largest volume is CO2; the others are methane and four obscure gases that, while emitted in small quantities, are tonne for tonne quite disproportionately damaging. We have been pretty successful in reducing emissions of methane and the obscure four, but less so in reducing our CO2 emissions. But for Kyoto it is the total basket that counts.
That said, our failure to get to grips with CO2 emissions is going to become an increasingly serious problem. There are two reasons for this gloomy view. First, the existing Kyoto commitment is just a start; demand for deeper cuts after 2012 must be expected. With methane and the obscure four already cut to the bone, meeting second (“Kyoto II”) and subsequent demands will leave us no alternative but to reduce our CO2 emissions substantially. Yet last year our CO2 emissions actually increased, and forecasts show that after 2010 our CO2 emissions are likely to have returned to a steadily increasing trend.
Second, the government has made another promise, this time nothing to do with Kyoto. This so-called “domestic goal” requires us to reduce CO2 emissions by 20 per cent from the 1990 baseline by 2010. With no basket to help us here, this is going to be very difficult.
In the baseline year 1990, we emitted roughly 600m tonnes of CO2. By 2010, we will have reduced this to about 550m. To be confident of satisfying the domestic goal and any likely Kyoto II, we will need to have clipped a further 70m tonnes a year off this figure-ideally by 2010, more realistically by 2020.
HOW CAN WE REDUCE CO2 EMISSIONS?
At present, hopes of achieving that reduction depend on two strategies. First, the use of renewable energy sources-notably wind power. Unfortunately this strategy is looking fragile: a recent study by the Royal Academy of Engineering casts serious doubt on the practicability of large-scale wind-power generation and in any event, falling power prices make new investment in generation capacity hard to justify today. Yet even in the unlikely event of renewables providing a fifth of our power by 2025, we would have done nothing more than replace our non-greenhouse gas emitting nuclear power stations-all but one of which will have retired by then-by non-greenhouse gas emitting windmills. This contributes nothing to that 70m tonnes of extra emission reductions we need each year-it merely prevents nuclear retirement from making matters worse.
The second strategy is to persuade the 60m inhabitants of Britain to change their behaviour-fly less, drive less, use public transport, improve home insulation and so forth. But getting people to change behaviour is difficult and often unpopular-as Ken Livingstone is discovering with his congestion charge.
The limits of these two strategies explain the growing interest in an alternative: sequestration-the capturing and locking away of CO2 to exclude it permanently from the atmosphere. There are many ways of doing this; for example, trees and soils sequester large amounts of CO2, and their careful management can increase the amount sequestered. Unfortunately, this form of sequestration is neither permanent (a tree dies and rots, releasing its CO2) nor easy to monitor, quantify and verify. Efforts to persuade the US to adopt the Kyoto protocol foundered for a number of reasons, one of which was the US’s insistence that it receive credit for CO2 sequestered in its farmland-a position rejected, ridiculed even-by other countries. The fallout from this fight left the whole concept of sequestration unjustly discredited.
The natural sequestration of CO2 remains an attractive concept. But neither reforestation nor soil management is likely to provide verifiably permanent sequestration on anything like the scale needed. Yet if nature will not do this for us, why not do it ourselves? That is the focus of today’s interest in sequestration: do it ourselves by permanently storing CO2 deep underground in depleted oil or gas fields or in deep saline aquifers.
This is a huge task, although Britain is better placed to succeed than many other countries-for reasons of geography and geology.
HOW SEQUESTRATION COULD WORK IN BRITAIN
Not counting humans and animals, there are at least 50m sites in England and Wales that emit CO2 (homes, vehicles, workplaces and so forth). Yet the top 20 sites alone (see table on next page) account for 24 per cent of the total, and the top 100 account for more than 40 per cent.
Not only are the CO2 emissions intensely concentrated by site, the sites themselves are clustered geographically, with many big emitters in the Humber-Mersey corridor and another cluster around the Thames estuary. Indeed, for connoisseurs of greenhouse gas emissions, there is a hillock near Pontefract from where one can see in a single vista the chimneys of Ferrybridge, Eggborough and Drax power stations which, together, pour forth a tonnage of CO2 almost equal to the total emitted by Norway. This unusual degree of concentration may provide the key to our long-term CO2 salvation.
Britain is also geologically blessed for sequestration. Sam Holloway at the British Geological Survey is leading a team investigating the feasibility of sequestering CO2 in our depleting North sea oil and gas reservoirs. The results look encouraging. By 2020, the three big gas fields close to the Norfolk coast will have been depleted and, in principle, then be available for the permanent storage of almost 2 billion tonnes of CO2. When this space is filled, the saline aquifers overlying these gas fields can provide a vast quantity of additional storage space. Holloway points out that the Norwegians, led by Statoil, are sequestering 1m tonnes a year of CO2 in this way, and have been doing so since 1996.
Capturing CO2 from the flue stacks of top emission sites is not going to be easy-although probably easier than getting us all to change our lifestyles. The technology for separating CO2 from other gases has been used by the oil industry for more than 40 years-although seldom on the scale required here.
The atmosphere contains about 0.04 per cent of CO2 by volume. By contrast, the flue gas from a coal-fired power station, such as Drax, contains about 13 per cent CO2, the rest being nitrogen and unburned oxygen. The process for removing this CO2 from the flue gas stream is simple: a solvent liquid is cascaded down a large tower up which the flue gas is flowing. As the solvent and the gas pass, they mix, and almost all of the CO2 is absorbed in the solvent. The nitrogen and oxygen are not absorbed and pass out of the top of the tower and into the atmosphere. Meanwhile, the CO2-saturated solvent flows from the bottom of the tower into a boiler. The solvent is heated to drive off the CO2 and refresh the solvent so that it can recirculate to the absorption tower. The CO2 is then compressed until it becomes a liquid, ready for pumping to its underground storage site.
All this is easily said but, in fact, requires a considerable amount of engineering sophistication to achieve. Although the basic design of these systems has not changed since the 1950s, continuous improvement and the discovery of better solvents have greatly improved efficiency over the last 50 years.
What makes the problem daunting is the sheer scale. Drax emits 50,000 tonnes of CO2 daily. The Fluor company (a leader in this field of engineering) believes that a CO2 removal capacity of about 6,000 tonnes per day represents a maximum practicable size of flue gas cleaning plant. Drax would require seven of these. Given that our national experience with super-big projects is not a happy one, the idea of having a number of smaller plants rather than a single whopper is probably a good one.
Such a 6,000 tonnes per day plant would today cost about ?150m. To capture 100m tonnes of CO2 for sequestration, as many as 50 such plants would be needed adjacent to the top emitters across the nation. Very roughly, these plants would cost upwards of ?7 billion in total. In addition, significant investment in pipelines would be needed to transport captured CO2 from large sites to the Norfolk coast and from there out to sea for injection into the depleted gas reservoirs.
PAYING FOR SEQUESTRATION
How much would all this cost, and who would pay? The DTI has collated estimates from many sources; these point towards a figure in the range of ?25-?50 per tonne of CO2 sequestered. The capturing and sequestering of CO2 is itself an energy-intensive activity; to clip a net additional 70m tonnes off our annual CO2 emissions will require the gross sequestration of about 100m tonnes. This is likely to cost us about ?5 billion a year-not a great sum in the overall scheme of things. The temptation to raise this sum by imposing a fee on all electricity-not just electricity generated by burning fossil fuels-of 1.3p per kilowatt-hour should be resisted to avoid harming our industrial competitiveness. It might be wiser for the government to enter long-term contracts to buy sequestered CO2. Nationally, our personal taxable income totals ?555 billion, so funding the government’s purchase of sequestered CO2 would require the equivalent of 1p of additional income tax.
There are three extra bonuses. First, sequestration of CO2 would reduce-perhaps even eliminate-the need for more nuclear power stations. Rightly or wrongly, these seem to terrify many of us, and plans to build more would surely face formidable resistance.
Second, the quirkiness of our national accounting system means that CO2 capture and sequestration would actually add to GDP-demolishing the fear that Kyoto and its successors will damage economic growth.
Third, to the extent that in meeting our domestic goal we sequester more CO2 than required for our Kyoto commitment, we will generate “carbon credits” called ERUs (Emission Reduction Units) which can be sold to nations that are failing to keep their Kyoto promises. There will doubtless be many of these, and the proposed EU penalty for failure (at least <40 per tonne) is pretty stiff, so this trade may be quite lucrative. We spent the first decades of the 20th century digging carbon out of the ground and selling it around the world: there would be a pleasing symmetry if we spent the first decades of the 21st century putting carbon into the ground and selling its credits around the world.
There are two problems with the underground sequestration of CO2. First, it contravenes the London convention against dumping at sea, as presently drafted. This is an unintended consequence of the convention, and it would need to be amended accordingly. Second, and much more important, is the issue of public acceptance. The fact that the underground reservoirs in which the CO2 would be stored have held natural gas securely for tens of millions of years may not be as reassuring to the public as it is to the geologist. A recent letter in Time illustrates the point: “I am no Luddite, but isn’t it technology that’s got us into our environmental mess? Are we wise to expect technology to get us out of it?” It will need great care and patience to convince the letter writer that, although the answer to his first question is partly “yes,” the answer to his second question is unequivocally “yes.”
It is less easy to feel sympathy for another class of objections-the idea that we need to be punished for our profligacy. Any solution to greenhouse gas emission that would permit us to continue on our merry way with just a penny on our income tax is going to be deeply offensive to some environmentalists.
In summary, the sequestration of CO2 from our biggest emission sources seems to offer energy policymakers a way of squaring the circle-a way of avoiding new nuclear power stations without having to rely on unrealistic projections of renewable energy, or on a Damascene conversion of 60m people from profligate sinners to environmental saints.