ISO/PWI 19870-4

Hydrogen technologies — Methodology for determining the greenhouse gas emissions — Part 4: Methodology for determining the greenhouse gas emissions – Part 4: Emissions associated with the bi-directional conditioning of hydrogen into LOHC and back, and transport of LOHC and hydrogen up to consumption gate

Scope

ISO 14044 requires the goal and scope of an LCA to be clearly defined and be consistent with the intended application. Due to the iterative nature of LCA, it is possible that the LCA scope needs to be refined during the study.
This document specifies methodologies that can be applied to determine the carbon footprint of a product (CFP) or partial CFP of a hydrogen product in line with ISO 14067. The goals and scopes of the methodologies correspond to either approach a) or b), given below, that ISO 14040:2006, A.2 gives as two possible approaches to LCA.
a)    An approach that assigns elementary flows and potential environmental impacts to a specific product system, typically as an account of the history of the product.
b)    An approach that studies the environmental consequences of possible (future) changes between alternative product systems.
Approaches a) and b) have become known as attributional and consequential, respectively, with complementary information accessible in the ILCD handbook.[1]
There are numerous pathways to produce hydrogen from various primary energy sources. This document describes the requirements and evaluation methods applied to several hydrogen production pathways of interest: electrolysis, steam methane reforming (with carbon capture and storage), co-production and coal gasification (with carbon capture and storage), auto-thermal reforming (with carbon capture and storage), hydrogen as a co-product in industrial applications and hydrogen from biomass waste as feedstock.
This document also considers the GHG emissions due to the conditioning or conversion of hydrogen into different physical forms and chemical carriers:
—    hydrogen liquefaction;
—    production, transport and cracking of ammonia as a hydrogen carrier;
—    hydrogenation, transport and dehydrogenation of liquid organic hydrogen carriers (LOHCs).
This document considers the GHG emissions due to hydrogen and/or hydrogen carriers’ transport up to the consumption gate.
It is possible that future revisions of this document will consider additional hydrogen production, conditioning, conversion and transport methods.
This document applies to and includes every delivery along the supply chain up to the final delivery to the consumption gate (see Figure 2 in the Introduction).
This document also provides additional information related to evaluation principles, system boundaries and expected reported metrics in the form of Annexes A to K, that are accessible via the online ISO portal (https://standards.iso.org/iso/ts/19870/ed-1/en).