Value of combining methanol fuel and CCS still a topic of discussion

From a tank-to-wake perspective, the use of methanol fuel on board the ship counts as a GHG emission since methanol contains carbon. This applies to both fossil-based methanol and synthetic/bio-methanol.

Even if green hydrogen is used to produce methanol, if the source of the carbon is based on fossil fuels, it is challenging to label the resulting methanol as truly clean, says Dr Song Kanghyun, Senior Vice President & Head of KR Decarbonization, Ship R&D Center at Korean Register. This is because carbon emissions from fossil fuels are released into the atmosphere during the methanol utilisation phase, which occurs after its synthesis. “However, when fossil fuel-based carbon is captured and processed by onboard CCS, it is believed that it can be considered clean methanol, equivalent to green methanol.”

Depending on the fuel used in the propulsion system, onboard CCS could be implemented in two ways: either the ship is propelled by methanol, or hydrogen produced by reforming methanol is used to power an internal combustion engine or fuel cell.

“In both cases, the impact on the design and performance of the engine and fuel cell propulsion systems is expected to be extremely minimal. However, cargo losses due to the installation of onboard CCS equipment such as CO2 capture system, reboiler system, CO2 compressor, CO2 storage tank should be considered, as well as additional CO2 emissions resulting from the power consumption required to operate this equipment,” says Song.

“Furthermore, if regulatory guidelines are established based on the criteria for recognising GHG reduction effectiveness within the context of GHG regulation, specifically concerning the extent to which GHG reduction effects can be credited in each of the two cases described above, a plan for implementing onboard CCS in methanol-powered ships can be established.”

Kjeld Aabo, Consultant for The Methanol Institute, says the ability to capture carbon emissions generated from use of conventional methanol creates an incentive that could increase its uptake. Fossil natural gas-based methanol is widely available and cost competitive against MGO. Being able to capture carbon emissions efficiently would encourage its adoption, while necessary volumes of blue and green methanol are developed.

“As the global economy transitions towards a circular model, we will increasingly see fuel production units built around port facilities. Alongside cargo handling and distribution, ports will in future be home to production sites for e-methanol produced using captured carbon offloaded either from dedicated carbon carriers or from CCS systems,” he says. “Such projects reflect and expand on the regional role that ports play in their local economies, providing employment into the logistics chain, and in supporting the local workforce as well as related manufacturing and skills.”

However, he says it should be remembered that despite the assumption that CCS is a mature technology, shipping is still in the knowledge-building phase. “CCS appears an attractive option for shipowners who are seeking to future proof their vessels to meet GHG regulations, but its suitability for deployment onboard ship has not yet truly been demonstrated.”

There are at least three different proven CCS technologies and despite there being pilot projects underway, none has yet been trialled at full scale onboard ship. The Motorship notes that a trial of a Chinese solution on board a vessel reportedly achieved technical objectives, but the energy consumption was uneconomically high.

Early stage projects tend to be sponsored or supported, and while shipowners understand the sustainability case, they are unlikely to invest before the business case is also clear.

“Whatever the design of the CCS system used, there will be a need for energy. Will this come from waste heat, auxiliary generators, batteries or a different source? There needs to be better understanding of the efficiency of the proposed CCS and the power requirements to run it. In other words, does the value of the carbon captured outweigh the power consumed in doing so?”

Aabo believes that the issues clearly present some challenges for vessel designers and engine manufacturers. “We expect this conversation to continue.”

MAN Energy Solutions also notes that no full-scale installations of carbon capture plants exist on ships today. The OEM does not foresee onboard CCS for methanol fuelled vessels, as there will be very little CO2 emissions, and the energy demand is large.

Sigurd Jenssen, Director, Wärtsilä Exhaust Treatment, says Wärtsilä’s CCS solution can be applied to any exhaust stream containing CO2, including exhaust from the combustion of methanol. “Indeed, the combination of burning methanol as a marine fuel and CCS presents exciting opportunities. This is because, in theory, the CO2 that is captured from the exhaust could be used to make new methanol, thereby creating a circular CO2 chain. Alternatively, the captured CO2 can be permanently sequestered, potentially opening the door to a net-negative scenario.”

There are minor differences in the exact composition of the exhaust gas with the combustion of methanol compared to a standard diesel or LNG engine, but the CCS systems would fundamentally be very similar, he says.

“Already we are seeing interest from all segments for our solutions as ship owners seek to futureproof their assets and are looking for ways to extend the lifetime of their vessels. Space efficiency is key onboard a vessel. The storage capacity of our CCS technology can be flexible, depending on the vessel type and customer needs. We take a modular view to each project, taking into consideration factors, such as the energy demand required to capture carbon, the desired capture rate, and the trading pattern of the vessel.”

These considerations will be factored in at the very earliest stage of design work. Also, when a customer opts for a Wärtsilä CCS-Ready scrubber, the company takes measures during the scrubber installation process to ensure adequate space for the future installation of CCS system.

The alternatives to onboard CCS, says Jenssen are not simple. Even methanol and ammonia propulsion alternatives are space demanding, as they will require two to three times more tank space, and back-up fuels will need to be fitted, which will take up additional space.

“It is crucial that CCS systems for ships do not impact overall profitability or constrain operational flexibility. Each vessel type will face different challenges; for example, container liners will have to sacrifice some space, but these will be the easiest to install. In comparison, the bulk and tanker segments will have more space but require more complex CCS infrastructure to be installed.

“Despite these challenges, there remain many opportunities in this marketplace. Many owners and charterers are already aware of the challenges but want to talk through them and work on a solution together. They want to prepare their fleets and are actively making enquires and investigating solutions.”

Wärtsilä Exhaust Treatment is now offering CCS feasibility studies. These CCS feasibility studies encompass both newbuild and existing vessels, and they have already been conducted on a range of vessel types including ro-ro and ro-pax vessels, a drill ship, a container vessel, and a gas carrier. The process takes four to six months of study and design work. Wärtsilä Exhaust Treatment’s experts are involved in ship design at an early stage to conduct engineering work to understand how CCS can be smoothly integrated once the technology is launched to market.

Once completed, the CCS feasibility study work enables Wärtsilä to provide customers with a fully rounded commercial offer that can be shared with shipyards to get an exact quote for installation. During the feasibility studies, Wärtsilä’s experts closely examine the existing naval architecture of the ship and work to understand how the power, space and exhaust demands of CCS can be accommodated onboard. Owners will receive a qualified analysis on the costs of CCS integration, and a clear list of considerations on how a potential retrofit would be conducted in the least intrusive way.

Conducting the studies enables Wärtsilä to bring forward the early stages of CCS integration and, in doing so, lower the barrier to entry once the technology is commercialised in the near future. The studies also serve to educate customers of the upsides and particular considerations associated with installing CCS onboard their vessels, says Jenssen. “Additionally, as the studies will run in parallel with the implementation of new environmental regulations for shipping, owners who conduct them today will be ‘ahead of the curve’ versus their peers.”

Wärtsilä Exhaust Treatment plans to introduce its CCS product to the market by 2025.