accompanied with a small temperature peak. The maximum of this exothermic peak corresponds to the pressure curve inflexion point (point D). This period of second hydrate crystallisation, characterized by this strong decrease in pressure, is hereafter called the high-rate CO2capture phase. Then, the pressure curve reaches a pseudo-plateau (just before point E), and the reactor temperature return to the target value, indicating the enclathration reaction reaches its end. In this example, the pseudo-plateau pressure is equal 16.6 ± 0.5 bar, which is very close to the equilibrium pressure for pure CO2 hydrate formation . Therefore, the CO2capture stops when the reactor pressure reaches the CO2 hydrate equilibrium pressure. Our pressure trends are consistent with those obtained by Liu et al. (2008)  on the same system, and their final pressure was as well very close to the equilibrium pressure of pure CO2 hydrate. However, these authors did mention neither visual observation nor any exothermicity temperature peak during the reactor cooling step.
 M. K. Mondal, H. K. Balsora, P. Varshney, “Progress and trends in CO2capture/separation technologies: A review”, Energy 2012, 46, 431-441.
 Y.-J. Lee, K.W. Han, J.S. Jang, T.-I. Jeon, J.Park, T. Kawamura, Y. Yamamoto, T. Sugahara, T. Vogt, J.- W. Lee, Y. Lee, J.-H. Yoon, “Selective CO2 trapping in guest-free hydroquinone clathrate prepared by gas phase synthesis”, ChemPhysChem 2011, 12, 1056 – 1059.
Table 1: Kinetic data on the CO2capture by HQ clathrate formation.
This study brings some information on the potentiality of HQ clathrates for CO2capture and storage process. The measured equilibrium conditions suggest the possibility to overcome specific process limitation, as CO2-HQ clathrates can be formed in a wide range of temperature (reaching at least 354 K) and at moderate pressure (few MPa). Furthermore, on a kinetic point of view, it is shown that the enclathration kinetic can be improved by a specific conditioning of HQ allowing to increase the gas/solid contact area. The induction period can be avoided with a non- negligible increase of enclathration rate using HQ-silica composite materials. Now, some works are necessary to evaluate the viability and feasibility of such reactive media in clathrate-based processes.
depleted emission stream and the energy consumed for post-capture CO 2 liquefaction are
considered in this simulation study. A numerical modeling of the membrane process and a brief description on assessing both the capital and operating costs of the process are provided. It is found that the membrane area requirement is dominated by recovery of the lower concentrations of CO 2 in the tail portion of the flue gas stream. Process optimizations allowing the minimal CO 2
2. Historical context
Total's integrated CCS pilot project takes place in a valley along the Gave de Pau river, in the
Béarn cultural area, in the Pyrénées Atlantiques (64) department of France.
The Lacq natural gas field was discovered accidentally at -3 550 m while digging for oil in 1951. It has been an important national asset for France, providing up to one third of the domestic natural gas consumption. Production peaked in 1982 at 33 million m³/day. But the flow has declined to under 10 million m³/day by 2009, and the end of the field's economic life is announced for 2013. As Illustration 1 shows, there are now many empty lots in Lacq's processing plant. After 50 years of natural gas bonanza, economic development plans for the valley are being reinvented. Several specialty chemicals production facilities, a bioethanol plant, a carbon fiber plant and a combined cycle power plant have been attracted. In this context where the economic future of the area is at stake, Total's announcement of the carbon capture and storage project had a clear value to the community. The project fits with the firm's broader strategy to manage responsibly the plant shutdown, not only by supporting local small and medium enterprises through its subsidiary 'Total DDR' but also by directly investing in training and R&D activities on the platform.
the EU. The CO 2 -Energicapt project aims to demonstrate the feasibility of CO 2 capture by
coupling CO 2 capture technologies and oxygen enrichment systems. A pilot plant on a
small scale is built to demonstrate the efficiency of a membrane based CO 2 capture
technology integrated to an existing District Heating Plant in the Paris region.
the atmosphere. Currently, the most common commercial technology to capture CO 2 is
amine-based absorption, but its application is limited to small scale, low temperature (40- 150°C) and very high energy cost 1 . Alternatively, these drawbacks can be overcome by using metal-oxide-based inorganic sorbents to capture CO 2 selectively from flue gas streams.
 Abu Zahra M., 2009. Carbon dioxide capture from flue gas. PhD Thesis, TU Delft, The Netherlands.
 Léonard G., Toye D., Heyen G., 2014. International Journal of Greenhouse Gas Control (in press). DOI: 10.1016/j.ijggc.2014.09.014.
(among others the (acid) water washing of the flue gas at the column outlet), the problem of volatile products emissions is still significant in large-scale operating plants . As underlined by , there is no advantage at capturing CO 2 if this implies the emission of other products like ammonia.
So far, the process energy penalty and the degradation of amine solvents have been studied separately and previously published models of the CO 2 capture process did not consider solvent degradation at all. The only one
Reducing the valuable energy consumption of solvent regeneration remains the biggest technical challenge to full-scale deployment of post-combustion carbon capture. Aspen Plus modeling is applied to validate the new application of ejectors to upgrade external waste heat in the conventional absorption and desorption process for carbon capture. In this application, ejectors upgrade external waste heat with the goal of reducing the quantity of valuable turbine steam required to regenerate the solvent. The energy consumption of the base case capture process in this study is within the range of published data. The reference solvent is 20% wt. MEA (monoethanolamine). Three strategies for producing the ejector secondary steam are evaluated. Producing the ejector secondary steam from either the stripping column condensate or from the lean solvent are viable options, showing respectively valuable energy savings of 10 and 14%. In both cases the potential valuable energy reductions are limited by the finite amount of condensate available to create the ejector primary steam. Using the rich solvent stream to produce the ejector secondary stream does not reduce the valuable energy consumption. The choice of preheating the ejector primary fluid by means of waste heat or by heat integration is also discussed.
led to little attention to CCS from the industrial sector. Developing a market for CCS, through the creation of commercial conditions, could result in reducing commercial risks. In such conditions, more investors would be interested in CCS. Currently, two of the biggest challenges for the commercial development of CCS are the costs and the risks. Thus, according to the interviews, opening the carbon trading scheme, at national level, can enhance the confidence for CCS investment and guarantee stable profits of enterprises involved in CCS activities. Vietnam could take lessons learnt from the emission trading systems which have been implemented Kazakhstan and South Korea along with the pilot experiences launched in China and Japan (Isl et al. 2015; infrastructurene.ws 2013) to develop its own scheme in the future. Apart from the technology and cost, the main factor influencing CCS market development is Vietnam’s scant attention to CO 2 commercial values, such as EOR, which causes the devaluation of all CCS projects. In addition, the insufficiency of data for qualified storage sites decrease CCS’s commercial potential, and CO 2 capture enterprises may suspect that the CCS business cannot be guaranteed over a long period of time. Meanwhile, because there is no clear division of responsibilities and duties, it is difficult to determine who is responsible for by- products, such as CO 2 . Accordingly, no enterprises are willing to accept the risks of managing a CCS business.
CO 2 reuse is another alternative for reducing CO 2 emissions. CO 2 reuse is defined as any practical application of captured CO 2 that adds value (such as revenue generation,
or environmental benefit), and which can partially offset the cost of CO 2 capture
[GCCSI, 2011b] . Enhanced Oil Recovery (EOR), production of chemicals such as urea, beverage carbonation, food processing, preservation and packaging, pharmaceutical processes, horticulture, pulp and paper processing, refrigeration systems, welding systems, fire extinguishers, and water treatment processes are some examples of the existing CO 2 uses. Enhanced Coal Bed Methane recovery (ECBM), polymer processing,
The global demand for fossil fuels continues to increase and concerns over emission of green- house gases and their associated problems has never been greater. Search for solutions to global warming has received the needed attention and several technologies are under devel- oped. Use of amine based liquid adsorbents are commercially available but cost and environ- mental consequences limit their frequent deployment. Calcium looping (CaL) is also under development but an expensive air separation unit is required. We need a technology that overcomes deficiencies in the use of amine based and CaL carbon capture and sequestration techniques.
 C. Makhlouﬁ, E. Lasseuguette, J.C. Remigy, B. Belaissaoui, D. Roizard, E. Favre, Ammonia based CO 2 capture process using hollow ﬁber membrane contactors,
J. Membr. Sci. 455 (2014) 236–246 .
 T.G. Skog, S. Johansen, M.B. Hägg, Method to prepare lab-sized hollow ﬁber modules for gas separation testing, Ind. Eng. Chem. Res. 53 (2014) 9841–9848 .  A. Ortiz, D. Gorri, T. Irabien, I. Ortiz, Separation of propylene/propane mixtures using Ag þ -RTIL solutions. Evaluation and comparison of the performance of gas-liquid contactors, J. Membr. Sci. 360 (2010) 130–141 .
Figure 3: Reduction of the capture rate from 90% (10% of the CO 2 is not captured) to 20% (80% is not captured) when the duration of the set-point change ramp is modified
However, when decreasing the capture rate down to 10%, the stripper liquid level could not be stabilized by varying the washing temperature. In this case, the amine solvent is barely regenerated and absorbs very little CO 2 in the absorber. Since the absorption is an exothermic reaction, the flue gas temperature in the absorber doesn’t increase enough, and less water exits the process with the cleaned flue gas, even if the flue gas is not cooled anymore in the washing section. Consequently, water accumulates in the stripper. Since the stripper liquid level rises very slowly (about 1cm/hr), it will only be problematic if the 10%-capture rate regime lasts for several hours.
which is higher than the values reported in the literature for PVDF. Moreover, the overall mass transfer coefﬁcient for CO 2 capture using the Dþ[emim][Ac] ﬁbers also presented highly competitive values.
Carbon dioxide capture and sequestration (CCS) is currently a major concern globally to reduce the impact on the atmosphere and protect humans against the associated risks. However, CO 2 capture is the bottleneck step where efforts have to be applied to develop more sustainable processes from technical and econom- ical perspectives  .
When using powdered HQ, it was demonstrated that high temperature, and more particularly high pressure, enhanced kinetics. Comparison of the results obtained in the CO 2 capture
experiments using pure HQ in three forms (native, powdered, and compacted) as the reactive medium revealed that the enclathration kinetics can be improved by conditioning the HQ which increases the gas−solid contact area. Indeed, HQ pellets are more eﬃcient than HQ powder, with a particle size of 25 μm, and native HQ. Our experimental results therefore demonstrated the important eﬀect of textural parameters on kinetics. In addition, the preforming eﬀect of HQ was conﬁrmed after a ﬁrst gas capture run, as signiﬁcant improvements could be observed for native, powdered, and compacted HQ in the second gas capture run. This observation proved that HQ could be recycled to perform successive gas Table 4. Equilibrium Storage Capacities, Equilibrium
the results, the capture efficiency increases with decreasing inner membrane diameter because the gas–liquid two-phase contact area increases with increasing number of hollow fiber membranes. This results in an increase in the packing density and shell-side mass transfer coefficient. Eslami et al. ( 2011 ) investigated the effects on the CO 2 capture efficiency for a liquid flow rate of 0.1 m/s, an absorbent concentra- tion of 0.5 mol/L, and increasing number of hollow fiber membranes from 3000 to 10,000. As a result, the capture efficiency increases from 36 to 100%. Furthermore, Faiz and Almarzouqi ( 2010 ) used a membrane contactor to remove CO 2 from natural gas under high pressure. The results show
As shown in Fig. 7 a and b, the removal efﬁciency logically decreases with the gas velocity for both contactors, due to the decreasing contact time. For carbon capture application, a carbon capture ratio larger than 85% is classically recommended. Experi- mental results are ﬁtted, thanks to Eq. (7) , with the overall mass transfer coefﬁcient K being taken as the only ﬁtting variable. It can be seen that for all operating conditions, a good agreement between experiments and model is obtained, similar to previously reported studies [15,29] . An example of results reproducibility for two different Oxyplus membrane contactors is shown in Fig. 7 b.
We suggest that the two most important factors in estimating the long-run perfor- mance of energy technologies are, first, the basic physical and thermodynamic con- straints and, second, the technology’s near-term performance. Section 2 addresses the first factor, the ultimate physical and economic constraints that may determine the long- run performance of air capture technologies. The second factor is addressed in Section 3, which presents two examples of how air capture might be achieved using current technology. Our view is that air capture could plausibly be achieved at roughly 500 $/tC (dollars per ton carbon) using currently available technologies, and that the com- bination of biomass with CCS could remove carbon from the air at about half that cost. While these technologies are not competitive with near-term mitigation options such as the use of CCS in electric power generation, they may be competitive with other prominent mitigation technologies such as the use of hydrogen fuel-cell cars [Keith and Farrell, 2003].