This document discusses four terms: ‘net-zero’, ‘near-zero’, ‘zero’, and ‘absolute zero’; frequently used in GHG-related discussions in the IMO and other fora.
This document is submitted to promote greater clarity in the use of these terms and a better understanding of what GHG emission reductions can be expected with the use of certain fuels (many of which are commonly referenced as potential fuels to be used in the maritime sector) when produced using 100% renewable energy.
This document also highlights the important role of renewable energy in the production of certain fuels and why this is critical to achieving a major energy transition with minimal GHG emissions.
"The Organization is currently engaged in an effort to identify mid- and long-term measures that will be critical to implement the Initial IMO GHG Strategy.
Discussions within MEPC and outside IMO often refer to zero-GHG emissions and zero-GHG ships. To facilitate effective deliberation of these important topics, WSC believes it is useful to have a clear and common understanding of the technical potential of a given fuel to reach zero-GHG emissions based on known technologies and a full Well-to-Wake lifecycle analysis (LCA) of the fuel in question," says WSC.
The difference between ‘net-zero’ and ‘absolute zero’
"In this context, it is important to understand the difference between ‘net-zero’ and ‘absolute zero’.
Given the practical realities and limits of known fuel production technologies, it is also important to understand the concept of ‘near-zero’ GHG emissions because many of the fuels offering the greatest reduction in GHG emissions do not achieve ‘absolute zero’, but rather achieve a GHG footprint (again using Well-to-Wake LCA) that achieves ‘near-zero’ emissions, but results in a GHG footprint that while small, is not ‘absolute zero’," claims World Shipping Council.
"Climate discussions within IMO, UNFCCC, and others often include different references to zero emissions. These include ‘net-zero’, ‘near-zero’, ‘absolute zero’, and ‘zero’.
Not surprisingly, the understanding of each of these terms may not be common to all stakeholders, and there are circumstances where some terms are used interchangeably which understandably adds confusion to what is already a complicated discussion," says WSC.
In the interest of facilitating greater clarity and understanding, we examine each of the terms concerning zero emissions and attempt to provide a practical, plain-English, distinction that is based on accepted definitions and current state-of-the-art modelling of GHG emissions.
Where established definitions are lacking, we offer an informal explanation and practical description. A very brief explanation follows for each of the terms relating to zero emissions.
This document has been published on October 21st, 2022, and the meeting (13th Session) of the IMO's Intersessional Working Group on Reduction of GHG Emissions from Ships (ISWG-GHG) will be held from December 5th to 9th, 2022.