Carbon Capture and Storage (CCS)
When I dug into the energy roadmaps looking for clues, it became clear to me that carbon capture utilization and storage technologies (CCUS) were fundamental to the net zero scenario although they still required a R&D and infrastructure push.
To begin with, CCS is a process that consists of the CO2 separation from industrial sources or sources related to energy production and its transport to a location where it is stored isolated from the atmosphere for a long period of time. If that stored CO2 is used in a subsequent process, the technologies are called CO2 capture for use (CCU).
In the petrochemical industry, this technology has a niche application since there are various processes that result in highly concentrated CO2 flows. It is applicable in the case of the production of ammonia and ethylene oxide. Being able to avoid the initial separation step, which represents 70-80% of the total cost, significantly reduces it. In the case of methanol, there are several studies that report the economic infeasibility under current conditions of applying CCU in the synthesis process.
Which are the main technologies?
Industrial CO2 capture: Absorbing chemicals are used to separate the CO2 stream. It is performed extensively on synthesis gas streams in ammonia production.
Post-combustion: Chemical absorption or scrubbing process is currently the technology most likely to be implemented in the near future. Membrane-based CO2 separation process in recent years appears to be a competitive substitution. In power generation plants it is economically viable under special conditions.
Pre-combustion capture: Carbon based fuel is refined before it enters the combustion chamber in order to produce a gas rich in CO2 and hydrogen, from which the CO2 is separated and the H2 is used as fuel. It is widely applied in fertilizer manufacturing and hydrogen production.
Oxyfuel: Pure oxygen generated by membranes is used, it is in the pilot phase.
There are two main challenges to determine the viability of these technologies, the first one relates to the wide range that still exists in the estimation of capture costs due to the complex design of each installation. For example, in a bottom-up approach study consulted, if post-combustion is used, a cost between $62-128/t CO2 is estimated and between $52-127/t CO2 if pre-combustion is used. The second challenge lies in the difficulty of estimating the minimum size of the reference facility for the economy of scale to be profitable.
In spite of the short term economic burden to the bottom line, by 2030 it is estimated that more than 60% of accumulated emissions from flows highly concentrated in CO2 will already be captured.
In the Global Status of CCS 2021 report, we can see how the projects are becoming more diverse. Until 2020, 10 relatively small plants are in operation in the production of fertilizers, ethanol and other chemicals. From 2020 to 2030 there are expected another 8 that currently are in construction or in advanced development, for the same application, but with a wider range of capture capacities.
Historically, CCS projects tended to be vertically integrated, with a capture plant having its own dedicated downstream transport system. The trend is sifting nowadays towards “CCS networks” where the transport and storage infrastructure are projected to be shared by different users. Living and working in the the Netherlands I must refer to the Porthos project as one of the European CCS networks.
Although in terms of regional developments, the US is one of the areas in the world with the most suitable storage regions. There, two large-scale CCS networks with biorefineries have been announced, facilitated by low CO2 capture costs from ethanol production and potential access to federal tax credits ("Section 45Q") and regulatory credits under California's Low Carbon Fuel Standard ("LCFS"). The potential of CCS may now be moving closer to realization as a result of these developing incentives. In general, all the pathways to industrial CCS deployment rely on support from sustained policies.
Finally, referring back to the bottom line, in the long run models suggest that when industrial CCS is not available, global costs of reaching the target may be higher by 71% in 2100. What seems a burden in the short term for a few, will become one of the inflexion point in the long term for all of us.
