Tankers are interested not usually recalls

It is a new loop human being impose on the carbon cycle. In a few days, Total will begin testing of injection of carbon dioxide in the Pyrenean basement, a first in France. The gas has adapted the Lacq facilities, where he operates the last reserves of methane, to experiment with this method very expected strong emitters of CO2. Since 2006, its engineers have studied a complete system to capture a share of CO2 emissions from boilers of the complex of Lacq, to 30 km away, and then send it under pressure in the depleted pool of Rousse. An investment on 60 million euros.

The device will capture the carbonic gas on one of 5 complex boilers in methane, producing steam for industrial processes. 30 MW boiler will issue two years up to 150,000 tonnes of CO2 storage. Total chose an original technology to extract CO2 from combustion of boiler smoke: the oxy-fuel combustion. The classic track tested by most of the current experiments is to separate carbon dioxide with solvent based of amines to the contact of the fumes. It has the advantage of being able to be embedded easily end in a thermal plant. The disadvantage is that the CO2 in such conditions is strongly diluted in other nitrogen gas, it must regenerate constantly solvents, serious in terms of energy.

Total technology, provided by Air Liquide and Alstom, simplifies the CO2 capture operating different combustion. The boiler burn the gases with air, but will be almost perfect combustion of the gas with a 95-99 pure oxygen. Smoke reduce then to CO2, water vapor, an excess of oxygen over a few traces of argon and nitrogen. To a drying and a simple filtering are sufficient to retrieve a very pure CO2. This imposes on the other hand to integrate upstream module for the production of oxygen, energy source, and modify the boiler burner so that it supports the high temperatures of pure combustion.

Maturity of the technology

"A single boiler has an efficiency of 80-85, a performance which falls below 65 when we transplant a first generation amine capture system." "We hope to reach 70-75 of performance with oxy-fuel," explains Nicolas Aimard, project leader master of waste gases in Total. Its objective is to prove the maturity of the technology, to 300 MW units for 2015. "Our aim is the CO2 capture for future operations of hydrocarbons outside standards that require strong steam treatments or much energy." "It is the case of the oil to the Canada or acid gas in the Middle East", he said. Four projects of the national agency of research were also used to brush the project in recent years.

Unlike the capture phase, Total did not wished experiment of innovative technology for the transport and storage of CO2. The transport of CO2 on 30 km will be in the gas phase in a pipeline used to send the deposit of Rousse to Lacq methane. The injection phase will use standard equipment, the aim being especially to follow the behaviour of the geological reservoir during the operation. The gas will resume a part of the place liberated by operated methane. The deposit is housed in the microporosity of dolomite, comparable to a very dense pumice rock. Thirty years ago, at the beginning of its production, the pressure of the tank was 480 bars. Today, it is more than 30 bars, but the will to 70 bars CO2 injection in two years. Geologists will monitor the effect of these movements and do not exclude that the initial pressure may trigger of small local earthquakes without gravity. For Christian Fouillac, Scientific Director at the BRGM, the critical period of a landfill is located at the beginning more than at the end. Specialists are reassuring, particularly regarding the vicinity of the Pyrenees, a seismic field: "We have lots of data on the microseismicity." The reservoir is a small structure in clay with a cover of 2,000 m depth that sleeps no fault. A single well provides access and its State is described as very good. "CO2 is not an unknown intruder, the original pocket of gas contained 4," assured Nicolas Aimard. "We are more specific than usual studies." We deepen the mineralogy of the site, the cover of the reservoir is better studied. Failures analyses are more stringent. "Its geologists were thus fully modeled the basement of the site, to the aquifers. "Tankers are interested not usually", recalls.

Precautionary measures

Aware of the sensitivity of the subject, Total not a homework on precautionary measures, in particular in the monitoring of the site. Injection well was equipped with 3 stations of seismic listening to more than 4,000 metres deep, which communicate with the surface by optical fibre. Another drilling for seismic listening conducted more than 100 metres deep and six others will be run to detect regional earthquakes. To reassure the population, a battery of 35 sensors sniffing any possible gas leak on the surface. Researchers will also monitor the global environment in a circumference of 6 kilometres, for which they perform this year an inventory of the State of reference. CO2 injection will also last only two years, followed by three years of observation. And the industrial promised to make the reversible operation: in case of problems, the CO2 will be recoverable.

A public inquiry before the site and is work of pedagogy. It is with some technical glitches, which caused the small year of delay of the injection.

The public has reasons to be wary of CO2. This gas that is permanently is lethal at high dose, as the tragedy of Lake Nyos in Cameroon. A natural CO2 outgassing due to ground movement had killed more than a thousand and a half people in the vicinity of the Lake. By contrast, is whether the geological storage of the gas is commonplace. SFM uses geological reservoirs to bury part of its stocks. Tankers regularly inject CO2 in their fields in decline to retrieve more crude. And the nature incubates for millions of years of the pockets of methane and CO2 from the decomposition of organic matter. Beyond more or less rational fears, the public inquiry has especially shown skepticism of the people on the relevance of this approach to solve the greenhouse effect. A query that also share many of scientists, environmentalists and policy.