Injecting CO2 underground to reduce emissions by 15%

To fight against glob­al warm­ing, it is pos­sible to cap­ture and store part of our CO₂ emis­sions under­ground. This tech­no­logy, in addi­tion to efforts to reduce green­house gas emis­sions at the source, is ready to be deployed. Is it pos­sible to safely cap­ture and store CO₂?

Isa­belle Czer­nichow­ski-Lauri­ol. Yes, it is pos­sible, and it is already being done. To launch pro­jects of this type, involves extens­ive char­ac­ter­isa­tion of poten­tial stor­age sites the polit­ic­al will to do so and fin­an­cial policies to sup­port it. Coun­tries which suc­ceeded in doing so have developed effect­ive sup­port sys­tems. In the USA for example, tax cred­its helped increase the num­ber of pro­jects in the pipeline. The European car­bon mar­ket, how­ever, is not enough. Pro­jects exist in Nor­way because the coun­try has intro­duced a CO₂ tax. Moreover, a sub­sidy mech­an­ism was just estab­lished in the Neth­er­lands, and the Brit­ish gov­ern­ment has decided to massively invest in CO₂ cap­ture technology.

Where do we stand today?

There are more than twenty indus­tri­al-scale pro­jects in the world, includ­ing two in Europe – Sleipn­er and Snøhvit in Nor­way. But oth­ers are also under devel­op­ment in the North Sea, near Nor­way, the Neth­er­lands, and the United King­dom. Like­wise, there are plans to store car­bon emis­sions from indus­tri­al areas in Dunkirk and Le Havre under the North Sea. The Bur­eau of Geo­lo­gic­al and Min­ing Research (BRGM, Bur­eau de recherches géo­lo­giques et min­ières) is coordin­at­ing a European research pro­ject to devel­op and study vari­ous CO₂ stor­age scen­ari­os in oth­er indus­tri­al regions in south­ern and east­ern Europe, includ­ing the French Rhône val­ley and Par­is basin.

An indus­tri­al pro­ject takes approx­im­ately 7 years to become oper­a­tion­al. We must there­fore start plan­ning now if we want to get star­ted before 2030. Many act­ors in research and industry are mobil­ised to do so in France. It is pos­sible to cre­ate a French sec­tor and thus save and gen­er­ate employ­ment in France, espe­cially by ensur­ing that indus­tri­al activ­it­ies are not relo­cated near the cur­rent stor­age facil­it­ies in the North Sea.

What is the cost of this technology?

The most expens­ive aspect is the cap­ture of CO₂ in indus­tri­al fumes, which rep­res­ents up to 80% of the cost. Trans­port and stor­age require less expense with the whole pro­cess cost­ing between 30–130€/ton of CO₂ – some­times more depend­ing on the con­fig­ur­a­tion. It is there­fore more expens­ive than the price of CO₂ on the European mar­ket, which is cur­rently around 25€/ton, but it has been much lower in the past (as little as 3€). This price tag is not highly encour­aging for indus­tri­als if they are to make the leap, espe­cially because of the big com­mit­ments required: 40 years of operations!

What are the steps in CO₂ capture?

CO₂ is cap­tured where it is most con­cen­trated from indus­tri­al fumes. There are tech­niques for cap­ture from the atmo­sphere, but they are cur­rently less effect­ive as CO₂ is con­sid­er­ably more diluted mak­ing extrac­tion very dif­fi­cult – even though this does remain one of the options for neg­at­ive emis­sions put for­ward by the Inter­gov­ern­ment­al Pan­el on Cli­mate Change (IPCC). The CO₂ is cap­tured by using dif­fer­ent types of amine solvents, but there are also tech­no­lo­gies using mem­branes, or cryo­gen­ics. The BRGM is work­ing in part­ner­ship with an Amer­ic­an com­pany to devel­op a tech­no­logy to cap­ture CO₂ by dis­solv­ing it in water – it’s a very green and low-cost solu­tion. On the Tech­no­logy Read­i­ness Level (TRL), our object­ive is to reach TRL6 soon¹.

Once cap­tured, the CO₂ can be injec­ted in geo­lo­gic­al form­a­tions over a kilo­metre deep. To do so, we must first determ­ine the quant­ity of CO₂ in a giv­en time that can be injec­ted by drilling into the reser­voir rock (“reser­voir injectiv­ity”). You must also assess the cap rock prop­er­ties to guar­an­tee its res­ist­ance and stor­age integ­rity and secur­ity. Finally, you must assess the stor­age capa­cit­ies of a site. All this makes it pos­sible to determ­ine the num­ber of drill­ings required and the trans­port­a­tion infrastructure.

Are there any risks involved?

The stor­age site must be well char­ac­ter­ised and injec­tion oper­a­tions sized accord­ingly. We make sure that there are no leaks by using sur­veil­lance tools to meas­ure what is hap­pen­ing in the reser­voir rock, cap rock, overly­ing rock and at the sur­face. We com­pare these sur­veil­lance meas­ure­ments with com­puter sim­u­la­tions of the reser­voir in time. If these do not match, sim­u­la­tions are refined and remedi­al meas­ures are planned: lower­ing the injec­tion pres­sure, seal­ing off the leak­ing well, or even stop­ping and stor­ing else­where. The risks are more import­ant dur­ing the injec­tion peri­od but these can eas­ily be con­trolled. In time, they decrease because the pres­sure drops and stor­age becomes more stable. By choos­ing appro­pri­ate geo­lo­gic­al loc­a­tions, CO₂ stor­age can be car­ried out safely. How­ever, advanced stud­ies in the com­ing years are required before an indus­tri­al pro­ject can emerge.

What quant­it­ies of CO₂ could be stored in this way?

The low car­bon strategy of France, for example, con­siders that 15 mil­lion tons of CO₂/year in 2050 must be cap­tured and stored to com­pensate the incom­press­ible CO₂ emis­sions of this coun­try and achieve car­bon neut­ral­ity. But we can even do more. On an inter­na­tion­al level, the Inter­na­tion­al Energy Agency (IEA) estim­ates that CO₂ stor­age could rep­res­ent 15% of the efforts to reduce CO₂ emis­sions. A few months ago, the IEA pro­duced a report² call­ing for mobil­isa­tion to rap­idly deploy this tech­no­logy. France is behind on its com­mit­ments to reduce green­house gas emis­sions: we must not wait 20 years! We must launch a ser­i­ous pro­ject now that can be expan­ded later if necessary. 

But these tech­no­lo­gies also have flaws. For example, CO₂ stor­age also con­sumes energy?

Yes, but oth­er solu­tions to decar­bon­ise industry like elec­tri­fic­a­tion or the use of hydro­gen also con­sume power. Thus, the ques­tion is: what is the cheapest, clean­est solu­tion, which demands the least amount of energy? As such, dif­fer­ent tech­niques must be stud­ied on a case-by-case basis. And, in any case, we must com­bine all pos­sible means to fight against glob­al warm­ing as quickly and effi­ciently as possible.

To find out more: CO2 cap­ture and stor­age: the geo­lo­gic­al car­bon sink.