Future prospects for carbon capture and storage (CCS) deployment could be wrecked if a negative answer is given to that most basic question, "is CO2 storage safe?"  Given that use of the technology is the only means we possess for curbing emissions from a number of hard-to-abate industrial sectors such an answer would be unfortunate. 

The European Commission president, Ursula von Der Leyen, has said that the EU must be placing 300 million tonnes of CO2 in permanent storage annually by 2050 if net-zero emission ambitions are to be met.  The Commission's proposed Net-Zero Industry Act calls for a start to be made by having storage capacity of 50Mt annually available by 2030.  Doubts as to whether CO2 storage is safe do not feature, although, to be fair, there is not a great deal of direct experience upon which to base the judgement.

Fortunately, Europe can always point to Norway's experience of storing CO2 from the Sleipner and Snohvit gas production fields.  

Injection of CO2 into the offshore sites started in 1996 and 2008 respectively, and something in excess of 20Mt in total has now taken place with no incidences of leakage recorded in any of the 150 academic papers that have paid them attention.  On this basis, safe and apparently permanent CO2 storage has been successfully achieved.  

So a new report that suggests that risks continue, and that casts doubt on whether long-term CO2 storage can be safely accomplished, is far from welcome.  

'Norway's Sleipner and Snohvit CCS: Industry models or cautionary tales?', commissioned by the Institute for Energy Economics and Financial Analysis, claims to call into question the world's offshore CO2 storage ambitions.

The findings of the report, suggests author Grant Hauber, an Energy Finance Analyst, "call into question the long-term technical and financial viability of the concept of reliable underground carbon storage."

This should be worrying, except that it is not.  For there is nothing in this report that wasn't known already and is taken into account whenever CO2 storage is discussed by geologists.

"Every project site has unique geology," writes Mr Hauber, as though it is a revelation. "I think we know that," the geologists might reasonably respond.

He records that CO2 at Sleipner rose until it met cap rock, and had it "...not been fortunate enough to be geologically bounded, stored CO2 might have escaped."  It's a bit like saying that if pigs had wings they might fly.  But pigs do not have wings, and the CO2 didn't escape because there was a cap rock, the existence of which was the reason why the storage site had been considered suitable in the first place.

The site for Snohvit storage proved more difficult, and problems were encountered. This is well known, and CCS supporters have to admit that not every CO2 storage site is going to meet expectations.  Mr Hauber has the grace to admit that "...remedial actions and permanent long-term alternatives needed to be, and were, identified on short notice..." (and at quite a cost).

"Monitoring must run for decades after closure", he declares, accurately but with unwarranted hyperbole.   Back in 2008 I was the European Parliament's rapporteur for the Directive on the Geological Storage of Carbon Dioxide, and I can testify that we knew all about the need for long term monitoring; the principal question at the time was about payment for it.

Missing from Mr Hauber's conclusions is any mention of the characteristics of injected CO2, of the mineralisation that can occur as years pass (and in some circumstances after very few years), or of other factors that may promote the stability of its storage.

No doubt critics of CCS, amongst them some environmentalists who should know better, will seize upon the report as evidence that it is folly to capture and store CO2 even though it would otherwise be released into the atmosphere. But if the Institute for Energy Economics wanted a report that demolishes the case for CCS it will have to do better than this.  

Next time the Institute might ask its authors to answer a question or two from me.

European governments have over the past year built up their gas reserves and seen off a major threat from Russia.  A good deal of that gas is held in depleted natural gas or oil fields, with more in aquifers overlaid by an impermeable cap rock.  Does this sound very different from the conditions of a CO2 storage site?

The strengthening of our gas reserves has been a very welcome development, and all the more so because reports of any leakages of the gas have been few and far between.  (I haven't personally heard of any at all, but I leave room for qualification).

Why is permanent CO2 storage offshore any greater a concern than the temporary storage of natural gas, which is quite often onshore?  I mean, what's the difference between the two gases?

Oh, I remember now.  One is inflammable, and potentially explosive.  And the other, well I'm just going to open a bottle and drink some to see. 

Chris Davies

Director, CCS Europe