The world’s carbon dependence has overwhelmed the planet’s ability to process the resulting carbon dioxide emissions. What solutions exist to restore balance to the carbon cycle?

The first immediate major solution is to decrease the future emission rate, that is - reduce plethoric energetic consumption, since fossil fuel consumption for energy production is the main source of anthropogenic CO₂ emissions. Therefore increasing the efficiency of current fuel consuming processes, and also refraining from frivolous or excessive usages, is of pivotal importance.

The second and intermediary solution is to remove CO₂ from the current emission balance. This could be done by geological storage, which is being explored as an option, and still raises several questions. Removal of CO₂ from the current emission balance can also be achieved by chemically embedding CO₂ in a value-added and long-lasting product. Inorganic carbonates or polymeric polycarbonates are good examples. As a chemist, I immediately recognise the potential and feasibility of transforming CO₂, a molecule usually considered as a waste and a nuisance, into a new molecule: chemistry is the key technology for turning problematic molecules into useful ones.

A third family of solutions consists in replacing fossil fuel with renewable energies as our primary source of energy. One of the hurdles is storing these intermittent sources of energy. Storage in the form of chemical energy is one of the possible solutions. Here too, CO₂ can be the molecule that helps close the loop. It is no coincidence that this molecule, considered to be waste, will be the key to the turnaround just like CO₂ is in nature: being the end-molecule of biomass transformation in the cycle of life, the same molecule has to be the entry molecule in photosynthesis when bridging solar energy to biomass. No long term solution is possible without circularity, and no circularity in global anthropogenic activities is possible without a key role played by CO₂.

What are the main obstacles to the implementation of a viable CCUS system in Europe?

I will focus my attention on CDU (carbon dioxide utilisation). Some CDU solutions are already technically feasible and deployed on very large pilots. The low price of oil coupled with dull incentives or policy blockages (e.g. if CO₂ is labelled as a waste can we sell products made from it?) sometimes make the new solution difficult to deploy. Very well established incumbent technologies, with all the necessary infrastructures already in place, also make replacement more difficult.

Some new solutions are ready to be tested at the pilot level, but which organisations are capable of taking on the risk of the investment needed to perform these very large-scale tests?

As in many instances, a lack of financing at the research level can slow down our capacity to identify and remove lingering obstacles.

What benefits, if any, does CO₂ recycling offer over storage as a method of greenhouse gas (GHG) emission control?

Producing value added and marketable products out of CO₂ is an obvious plus compared to remediation-like technology, where there is an “all cost - no sales” model.

The public perception will also potentially be less negative when the technology yields products that are practically indistinguishable from analogues already marketed, as opposed to technologies that currently raise substantial public concern.

Finally, being able to “discover” a new feedstock, CO₂, which can be “mined” directly in Europe, and build industrial plants here around its chemical transformation, can form a substantial economic asset. When these processes feed into the energy sector and thereby contribute to European energy self-reliance and security, the benefits become even more compelling.

CDU could also be compatible with delocalised smaller-scale models of production and distribution, which are promoted by some as an interesting model to consider for future highly-connected and renewable energy based societies.

What are the most promising conversion routes from CO₂ to marketable carbon derivatives?

It is worth remembering that urea, a chemical produced at the rate of almost two hundred million tonnes a year, is synthetized from CO₂. Other established chemicals can be cited too, one example is acetylsalicylic acid, a precursor of aspirin, whose industrial synthesis from CO₂ is a century-old established process.

Among the novel routes, it will be very interesting to look at the growth of the market share of CO₂-based methanol obtained from renewable energies as compared to fossil based methanol. Methanol is a base chemical with a direct connection to the energy sector and thus has tremendous potential. Several other Power to Fuels conversion processes are also emerging industrially, all of which use CO₂ as the key shuttle molecule between renewable energy and the fuel molecule.

CO₂-containing polyurethanes could also become a “greener” alternative to the existing fossil-based ones, which are omnipresent polymers used, for example, in most foams.

Finally, inorganic carbonates obtained from CO₂ and, for example, ashes and other end of pipe materials, for use in the construction business as a substitute for mined rocks and cementitious materials, are very interesting products.

What projects currently being implemented in Europe offer the most exciting CCUS solutions?

All the examples I just cited are from European-based companies, either spin-offs from well-established large groups, or new ones. State-level projects (such as pledges to reduce, and eventually erase, the share of fossil fuel in electricity production), will de facto boost CDU deployment, since it is a key enabling technology for introducing renewable energy in the current infrastructure. Finally ambitious projects from several funding agencies can lead to exciting further solutions through research.

How do you see CCUS developing in Europe in the medium to long-term?

For all the reasons stated above, which range from the maturity of some technologies and the genuine political commitment to favour renewable energies and reduce our dependency on fossil fuels, to the economic soundness of some processes and the creativity of our research, I see a very positive outlook for CDU development in Europe.