EverLoNG CCS trials show real promise for LNG-fuelled shipping

Sleipnir hosted the second EverLoNG SBCC campaign, including CO2 liquefaction and storage integration. (source: Heerema Marine)

Results from a three-year, multi-vessel project show shipboard carbon capture is feasible for LNG-powered vessels, but cost and integration hurdles remain.

The EverLoNG project was conceived to address a clear need: provide an effective short-to-mid-term option for reducing greenhouse gas (GHG) emissions from existing and new LNG-fuelled ships. With regulatory pressure mounting from IMO and the EU, and low-carbon fuels still commercially and logistically constrained, shipboard carbon capture (SBCC) offers an attractive, scalable alternative to limit tank-to-wake CO2 emissions.

"We wanted to accelerate the implementation of onboard carbon capture," said TNO project coordinator Marco Linders. "We did this by demonstrating SBCC on two LNG-fuelled ships, integrating it with CO2 logistics and port infrastructure, and examining lifecycle and regulatory factors."

The three-year, EU-funded project, backed by 16 partners from the Netherlands, Norway, Germany, the UK and the US, carried out technical demonstrations aboard Heerema’s crane vessel Sleipnir and the Seapeak Arwa, an LNG carrier chartered by TotalEnergies.

The stated aim was to bring SBCC to Technology Readiness Level 7 by installing, operating and evaluating a complete capture, liquefaction and storage system in live shipboard conditions.

The prototype comprised three 20-foot containers: one for MEA-based capture, another for CO2 drying and liquefaction, and a third for onboard CO2 storage at 15 bara and –27.7°C. The unit captured around 10 kg of CO2 per hour, using a 30% monoethanolamine (MEA) solution for post-combustion absorption. It was a mobile unit designed to test the integration of carbon capture under real vessel operating conditions.

The capture technology was tested over 1,539 operating hours aboard the LNG carrier and 418 hours aboard the crasne vessel. Both vessels used four-stroke dual-fuel engines running primarily on LNG, with the LNGC fitted with a Wärtsilä 12V50DF engine and the crane vessel using a MAN 8L51/60DF. While the LNG carrier campaign focused solely on CO2 capture, the crane vessel trial included both capture and liquefaction.

"Ship motion, which we originally saw as a major risk, turned out to have negligible effect on capture performance," said TNO senior scientist Juliana Monteiro. "Even in rougher weather aboard the LNGC, the capture rate and system performance remained stable."

However, challenges did emerge. The exhaust gas from the LNGC was found to contain elevated NO2 levels, ranging from 50 to 200 ppm, an order of magnitude higher than typical onshore pilot plants. This caused increased oxidative degradation of the MEA solvent. As a result, more degradation products - such as formic and acetic acid – were emitted. "This high NO2 content significantly increased solvent degradation," said Ms Monteiro. "On Sleipnir, where NO2 was fully removed prior to the capture unit, the degradation levels were much lower."

She explained that the EverLoNG project observed NO2 removal rates of 100% in the Sleipnir configuration, which brought solvent degradation down to levels comparable with land-based facilities. This underscored the need for NOx removal equipment, such as SCR, to be integrated into the SBCC chain.

In the second campaign aboard the crane vessel, the project also detected aerosol-based emissions of MEA, attributed to particles in the engine exhaust. "If particles are present, countermeasures to prevent aerosol-based emissions must be integrated into the capture system design," she added. Countermeasures included upstream particle filtration or design modifications to reduce the formation of solvent-rich aerosols, which were measured in the hundreds of milligrams per cubic metre.

source: riviera news