Many roads lead to Rome, as is the same for the transition towards a low carbon economy. There is not one single solution, there are several building blocks with several builders. Ship-based carbon capture (SBCC) is one of these blocks according to the project partners of the project DerisCO2: FME, TNO, Heerema Marine Contractors, Linde Gas Benelux BV and ourselves.

Another piece of the zero emission puzzle

The role of carbon based fuels will remain significant for a number of decades, most notably in the heavy user category (industry and shipping). A bigger role for LNG is forecasted, which reduces CO2 emissions per unit of energy by about twenty per cent relative to diesel. There are few options for reducing the CO2 emissions of ships. Battery powered propulsion has been studied for inland shipping, but for short-sea and maritime shipping, fully electric propulsion systems are not expected to be feasible in decades to come. Ammonia has recently gained attention as a potential zero CO2 fuel, but will take time to be implemented, if proven feasible. To drastically reduce the carbon footprint in the shorter term, the alternative is to add (post-combustion) CO2 capture technology to existing diesel or LNG propulsion trains. DNV GL has theoretically proven the feasibility of ship-based carbon capture in 2013. Since 2017, TNO has been researching the adaptation of existing land-based carbon capture technologies for the purpose of application onboard ships. Next steps focus on adaptation and integration of technology onboard ships, as well as reduction of costs.

DerisCO2

The DerisCO2 project will contribute to the goal of a reduction of direct CO2 emissions from ships and other sea going units by up to ninety per cent compared to current emissions, through capturing the carbon dioxide and temporarily storing it on board at a cost price of less than fifty euros per tonne. The project is being implemented with a Topsector Energy subsidy from the Dutch Ministry of Economic Affairs (TCCU118008).

Focus of the research is on LNG-fuelled vessels, for two reasons. Firstly, gas-fuelled engines produce relatively clean exhaust gases, reducing the complexity of the CO2 capture system. Secondly, the captured CO2 needs to be cooled in order to store it as a liquid. The LNG, stored onboard at very low temperatures, can be used for this liquefaction process, reducing both the energy required for SBCC and the cost of the capture system itself.
The DerisCO2 project focuses on the following results:
1. An improved concept of a ship-based CO2 capture system, combining the use of a novel solvent system, optimised for LNGbased SBCC.
2. CO2 capture pre-piloting tests supporting the credibility of the proposed concept, including the effect of ship motions on the capture process, thereby closing technological gaps for piloting.
3. Techno-economic analyses stating the economic feasibility of SBCC for Heerema’s new LNG-fuelled semi-submersible crane vessel Sleipnir.
If feasibility is shown for Heerema’s Sleipnir use case, a follow-up project could be initiated towards a piloting and demonstrator phase.

Stepping stone to nearly closed CO2 cycle

Although the DerisCO2 project focuses on the onboard integration of SBCC, the results of this project may provide a stepping stone towards the development of a nearly closed CO2 cycle for shipping, including the production of synthetic “e-fuels” like synthetic methane (CH4) from hydrogen (produced with “green” electricity) and the captured CO2. Liquefied synthetic methane can directly be used in the LNG installations of LNG-fuelled vessels, as LNG typically consists for up to 95 per cent of (fossil) methane. By capturing the CO2 from using this e-fuel, cooling it down to liquid CO2 and returning it as feedstock to the producer of the synthetic methane, the CO2 cycle is closed and the e-fuel acts as a “hydrogen-carrier”. In this way, the installation of SBCC-systems enables existing LNG-fuelled vessels to adapt to a “green hydrogen economy” in the future.

Design challenges

SBCC does not require the development of new types of propulsion engines. This enables a quick introduction of the technology in shipping, for both newbuilds and retrofits. Application of SBCC does, however, come with several design challenges: space will have to be reserved for several ten to fifteen metre high columns that are part of the CO2 capture unit. Moreover, the captured CO2 will have to be stored. Considering that the volume of the captured and liquefied CO2 is in the same order of magnitude as the volume of the fuel that is spent producing the CO2, one can imagine that the impact of this on the vessel design is significant.
Although CO2 is not explosive, high concentrations of the colourless and odourless gas are dangerous to people. Hence, attention should be paid to safety and risk management throughout the design process. The same applies to the heat integration between the SBCC system and the fuel supply system, which drastically reduces the energy requirement of the system. Care should be taken with the design of this heat integration, so that the reliability of the propulsion system is guaranteed.

Project partners

The project partners play an essential role in laying the foundation for SBCC. Heerema Marine Contractors will provide one use case based on the Sleipnir. This ship features 96 megawatts of LNGfuelled engines and provides an excellent potential follow-up location for the pilot phase. Conoship International will inspire the project with its ship design knowledge related to carbon capture and perform the economic evaluation for the intended use case. Linde Gas Benelux will provide its extensive knowledge on CO2 transport and extraction. The research capabilities and test facilities of TNO related to carbon capture in conjunction with the dissemination and collaboration expertise of FME provides a complete storyline to resolve the barriers for carbon capture technology implementation within the coming years.

For the duration of the project, the possibility to join as advisor remains open for industry partners, with the aim to further increase the applicability of SBCC and widespread implementation of the technology. DerisCO2 is being coordinated by Jurrit Bergsma,Business Developer Maritime Energy Transition at TNO.