LNG Ships Face Shore Power Problem: NABU Questions the Future of LNG Technology

LNG is not a bridging technology, but threatens to become a dead end for climate protection in shipping

LNG (Liquefied Natural Gas) is frequently promoted as a more climate-friendly alternative to heavy fuel oil and marine diesel. At the same time, shore power is considered a key measure for reducing greenhouse gas and air pollutant emissions in ports – and will become mandatory for many ship types in the EU from 2030.

However, a new study commissioned by NABU from the research institute CE Delft shows that these two approaches can conflict: Many LNG-powered ships cannot easily switch off their engines while docked without risking new emissions or safety issues.

“The results clearly show that LNG is not a viable bridging technology for shipping. Many LNG vessels can only implement the mandatory use of shore power to a limited extent. This is due to the so-called boil-off gas, which is inevitably produced during LNG storage and must be continuously discharged. If this gas is not used by the ship's engines while in port, it can lead to additional methane emissions or safety problems due to pressure increases in the tanks. This means that LNG threatens to undermine key emission reduction measures in ports,” says NABU shipping expert Sönke Diesener.

Shipping is responsible for around three percent of global greenhouse gas emissions and contributes significantly to air pollution. LNG has been discussed as an alternative to conventional marine fuels, particularly because of its lower air pollutant emissions. However, from a climate perspective, the overall picture is critical: methane, which has a short-term global warming potential roughly 85 times greater than CO₂, escapes during the operation of LNG ships. Studies show that LNG therefore often offers no climate advantage over conventional fuels.

The study also makes it clear that the technical design of ships and the regulatory requirements for emission-free port operations are not yet sufficiently aligned. A particular problem is that LNG ships must continue to safely discharge excess gas even when connected to shore power, without being able to use it effectively for energy generation.

"The maritime energy transition needs solutions that are compatible with climate neutrality in the long term. Investments in LNG could lock in fossil fuel infrastructure for decades and stifle innovation. Instead, political frameworks must be consistently geared towards truly climate-neutral propulsion systems such as green ammonia or methanol. At the same time, it is essential to better integrate technical standards, port infrastructure, and regulatory requirements so that emission reduction in ports actually works," says Diesener.

Background

The study, commissioned by NABU and conducted by the research institute CE Delft, examines the technical possibilities of LNG-powered ships for using shore power. Different ship types and tank configurations were analyzed. The results show that LNG technology and future requirements for emission-free port operations are not yet sufficiently aligned. Particularly with membrane and Type B tanks with large tank volumes and high boil-off gas quantities, significant technical and operational challenges arise.

Download the report here…