First study to measure total methane and CO2 emissions from liquefied natural gas carriers
The results of a first-of-its-kind study to quantify greenhouse gas (GHG) emissions from liquefied natural gas (LNG) carriers were released today, providing actionable data for the LNG shipping industry on methane emissions. The study, led by Queen Mary University of London (QMUL), helps improve the understanding of GHG emission profiles of LNG carriers to meet national and international climate targets and corporate climate strategies.
In 2021, a team of researchers from Queen Mary and SLR Consultants took direct measurements onboard the Cheniere-chartered GasLog Galveston for a roundtrip voyage from Cheniere’s Corpus Christi liquefaction facility to a discharge port in Europe. The research covered all sources of methane and CO2emissions, including engine exhausts, venting and fugitive emissions. The study also sheds light on the best methods to directly measure methane emissions from LNG carriers, for future studies or retrofitting on-board continuous emissions monitors.
The results and recommendations were published today following peer-review in the journal Environmental Science and Technology (American Chemical Society) and include:
CO2 emissions were lower than other studies have assumed, while venting and fugitive emissions of methane were also extremely low.Uncombusted methane emissions from engine exhaust were in line with manufacturers’ test data, but higher than other studies due to higher methane slip from the generator (non-propulsion) engines.These engine methane slip emissions can be reduced drastically (as much as by half) by operating the engines at higher loads. The study notes that this was the Galveston’s second voyage, and multiple engines were used at lower loads for operational reasons, and that carriers often utilize engines at higher loads.The study recommends installation of methane emissions monitors on engine exhausts to monitor and report more accurate methane emissions estimates and to support methane mitigation operational practices.
Dr. Paul Balcombe, the Principal Investigator and lecturer in Chemical Engineering and Renewable Energy from Queen Mary University of London, said: “This study helps to fill a big data gap when it comes to methane emissions from LNG shipping. It’s vital that we understand what their emissions profile is at a time when LNG imports are likely to grow substantially to reduce Europe’s reliance on Russian gas.
“This study is the first-of-a-kind to measure total methane emissions from engines aboard LNG carriers, including venting and fugitive emissions, but we need to do much more to get a representative sample of the approximately 600-strong LNG fleet. As well as these academic measurement studies, increased monitoring of emissions from engines, vents and fugitives would allow us to identify and implement effective reduction measures as hotspots are found.”
Fiji George, Cheniere’s Senior Director for Climate and Sustainability, said: “This study provides actionable recommendations to monitor and reduce LNG shipping emissions to further strengthen the climate benefits of LNG. Following the recommendations by the study, Cheniere is expanding our emissions monitoring on the majority of our chartered carriers to further put this science into action. We appreciate the work done by CAMS, QMUL and GasLog to help deliver data-driven transparency that can guide mitigation strategies.”
Kostas Karathanos, Gaslog’s COO said: “Gaslog is committed to support climate action and is investing in partnerships, research and development to achieve this. GHG and air emissions reduction is a priority for us, as reflected in our ESG focus areas; we therefore enthusiastically joined this initiative aiming to better understand and monitor methane emissions from LNG carriers. The industry needs similar studies to gather concrete data and establish confidence in the operational emissions. This is essential in determining impactful mitigating measures and pursue realistic reduction targets.”
Paul Balcombe et al, Total Methane and CO2 Emissions from Liquefied Natural Gas Carrier Ships: The First Primary Measurements, Environmental Science & Technology (2022). DOI: 10.1021/acs.est.2c01383
Queen Mary, University of London
First study to measure total methane and CO2 emissions from liquefied natural gas carriers (2022, June 14)