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.