Eni/Snam’s new Ravenna capture pilot plant may be using MHI’s older KS-1 solvent rather than the KS-21 solvent being proposed for UK and US projects
Eni / Snam S.p.A. are trying to do exactly the right thing by building and running a moderately large amine pilot plant designed to capture 25,000 tCO2/yr (~75 tCO2/day), also with a test storage injection, prior to committing to a much bigger project capturing, in aggregate, as much as 4 MtCO2/yr.
As identified by the U.S. Department of Energy (DOE) their own Carbon Capture Large Scale Pilot Program description, pilot plants like this can:
“represent the scale of technology necessary to gain the operational data needed to understand the technical and performance risks of the technology before the application of that technology at commercial scale or in commercial-scale demonstration."
More detailed considerations for derisking pilot plant tests are presented in a review of amine post-combustion capture as an emerging technology, available on the @UKCCSRC web site.
“This [i.e. project derisking pilot testing] differs from most pilot-scale PCC plant operation to date, which has been for R&D purposes, or for estimating short-term solvent performance relative to other solvents as a stage in solvent development.
Pilot testing for commercial applications will usually happen after one, or a small number, of solvents and associated PCC plant configurations have been selected.
It is intended to de-risk deployment by reproducing all salient features of operation, including:
A. the flue gas and its variations during extended operation,
B. the long term time/temperature/gas composition histories that will be experienced by the solvent,
C. the ways that solvent degradation and the solvent reclaiming and other management techniques that will be used on the full-scale plant will interact to evolve the solvent inventory to something different, and probably much more complex, than the fresh solvent initial charge and make-up.
The inclusion of solvent reclaiming, successfully treating solvent that is fully ‘dirty’ rather than fresh solvent, is the key to having a relevant test for commercial deployment. Test periods therefore need to be long enough to allow this, and in particular to be able to demonstrate the ability to maintain a STABLE solvent composition that gives satisfactory PCC performance (i.e. with respect to foaming, corrosion etc. as well as capture level and energy consumption).
As discussed at some length in this report, particularly Section 2.3.4, it is self-evident that it must be possible to remove all degradation products and flue gas impurities at the rates at which they are formed in, or added to, the solvent in a PCC system and still have satisfactory performance. If this is not demonstrated, under realistic conditions, in pilot tests that are aimed at de-risking deployment then satisfactory performance in service for this, and related, aspects of PCC plant performance has not been fully assessed.”
It appears, however, that the Ravenna pilot plant may be using the KS-1 solvent, which doesn’t seem to be being selected for currently-planned CCS projects. In an Mitsubishi Heavy Industries (MHI) press release in 2022 it was stated:
“･ Eni’s Project aims to capture 25,000 tons of CO2 per year from plant’s turbo compressor flue gas”
“･ MHIENG will license “KM CDR Process™” carbon capture technology and provide process design package”
“MHIENG’s role in the project will be to provide licensing for its carbon capture technology, the KM CDR Process™, jointly developed with The Kansai Electric Power Co., Inc., which is a technology that captures the CO2 contained in flue gas by a process of chemical absorption using MHIENG’s proprietary KS-1™ solvent.”
But MHI’s newer KS-21 solvent is apparent being proposed for use in one of the UK’s Track 1 capture projects and one of the US Office of Clean Energy Demonstrations | U.S. Department of Energy (OCED) Carbon Capture Demonstration Projects as well as a number of other projects under development. The KS-21 solvent may also be being tested at a new (but much smaller than at Ravenna) slipstream pilot plant on a natural gas combined cycle in Japan, as described in another MHI press release:
“Tokyo, January 17, 2024 - Mitsubishi Heavy Industries, Ltd. (MHI) agreed today with The Kansai Electric Power Co., Inc. (KEPCO) to install a CO2 capture pilot plant at Himeji No.2 power plant in Hyogo, Japan. This new plant is being established to demonstrate the next-generation CO2 capture technology as a substitution of the existing pilot plant installed at Nanko Power Station in 1991, and MHI aims to start operation in FY2025.
The pilot plant will be installed for R&D of CO2 capture technology and will use flue gas from the gas turbine at Himeji No.2 Power Station, with a capture capacity at approximately 5 tons/day. By demonstrating the next-generation CO2 capture technology, which has been jointly developed under an agreement (Note) with ExxonMobil since 2022, the plant will accelerate R&D aimed at reducing environmental impact and costs, and further strengthen its competitiveness.”
Leaving aside the uncertainty about the solvent(s) to be tested and subsequently used in a future full-scale project, only limited information on the Ravenna pilot plant appears to be available in the public domain. The ENI press release has a relatively long-distance and partially-obscured photograph, although it interestingly reports that:
“The project is already delivering a reduction of over 90% in CO₂ emissions from the Casalborsetti plant's chimney, rising to peaks of 96% - a notable achievement given the conditions of a carbon concentration of less than 3% and the low level of atmospheric pressure making achieving success more challenging. This excellent performance makes Ravenna CCS the world’s first industrial-scale project with such high levels of carbon capture efficiency.”
Another article describes the reciprocating compressor used on the pilot plant and gives a CO2 flow of 25,000 tons (22,679 tonnes) per year of CO2, shows a picture of what looks like the absorber lift and also identifies suction and delivery pressures for the CO2. The suction pressure – presumably a little lower than the desorber operating pressure – is stated to be 0.45 barg.
But, as shown above, Google Maps, potentially a useful source of information, still has to catch with the commendably rapid pilot plant construction programme.
Google Map images could probably not, however, identify whether or not some key plant features are included, including comprehensive solvent reclaiming, some sort of management equipment for the nitrosamines that are otherwise likely to build up in the solvent inventory and, obviously, emissions countermeasures at the absorber exit. And it certainly could not ascertain how well these work.
But presumably Eni/Snam will be looking carefully at all of these aspects – which is why they have commissioned the test plant - and will be able to disclose the necessary data for large scale plant permitting, public communications and, hopefully, professional and scientific discussions in due course.