IVL Swedish Environmental Research Institute

The decarbonization of the maritime sector is driven by a combination of voluntary initiatives and binding regulations aimed at reducing greenhouse gas emissions and increasing the use of renewable fuels, where the use of liquified biomethane (LBG) has grown in interest and is the focus for this study. Voluntary climate targets, such as those defined by the Science Based Targets initiative (SBTi), the GHG Protocol, and ISO standards, enable companies to demonstrate climate ambition and build credibility with customers and investors.

These targets are often linked to internationally recognized frameworks that support structured emissions reporting and strategic goal-setting. At the same time, international and European regulations—such as FuelEU Maritime, the EU Emissions Trading System (EU ETS), the Renewable Energy Directive (RED III), and the International Maritime Organization’s (IMO) climate strategy—have introduced quantified requirements for emissions reductions and renewable energy shares. These instruments influence the shipping industry through financial incentives, technical requirements, and reporting obligations, creating strong pressure for investment in sustainable solutions. To enable the allocation of climate benefits in systems where renewable and fossil fuels are mixed, the mass balance principle is applied. This method allows for accounting of renewable shares without physical separation of molecules, which is particularly relevant in shared distribution infrastructures. Complementary mechanisms such as book & claim, insetting, and offsetting offer additional tools for recognizing emissions reductions, especially within Scope 1 and Scope 3. Certification systems like ISCC (International Sustainability and Carbon Certification) and RSB (Roundtable on Sustainable Biomaterials) ensure traceability and verification of climate benefits and are aligned with EU sustainability directives.

A survey of Swedish transport buyers shows that awareness of mass balance is relatively widespread, though actual usage remains limited. Road transport dominates, but maritime applications are also significant. Commercial offerings based on mass balance principles are increasingly available, often provided by energy companies and typically structured as book & claim solutions. This study focuses on the potential of using LBG in shipping and the findings indicate that mass balance principles have strong potential to support the maritime sector’s possibilities to use this fuel. However, clearer regulations, greater transparency, and harmonized certification systems are needed to ensure effective and credible implementation. The interplay of technical solutions, market initiatives, and policy instruments is shaping a new framework for sustainable shipping, where climate benefits can be allocated, reported, and verified even in complex fuel systems.