Policy Note 1 – GH2 methodology for GHG emissions measurement

1. The Green Hydrogen Standard applies the methodology for the electrolysis production pathway being developed by the International Partnership for Hydrogen and Fuel Cells in the Economy (IPHE) as outlined in the Working Paper Methodology for Determining the Greenhouse Gas Emissions Associated with the Production of Hydrogen. Based on discussions with stakeholders, some minor refinements have been adopted. This policy note will be reviewed on a regular basis, taking into account feedback from project operators and other stakeholders and subsequent refinements to the IPHE methodology. This will include a clarification of the methods to be followed for calculating GHG emissions for Green Hydrogen derivates, such as Green Ammonia.

2. Technology Scope (as per IPHE). There are currently three main electrolyser technologies, distinguished by the electrolyte (and associated production temperatures): alkaline electrolyser, polymer electrolyte membrane (PEM) electrolyser and solid oxide (SOEC) electrolyser. This methodology may be applied to any other electrolysis technologies.

3. Electrolysis Process Description (as per IPHE). A water electrolysis cell consists of an anode and a cathode separated by a membrane immerged in an electrolyte (a conductive solution). When connected to a direct current power supply, electricity flows through the electrolyte and causes the water to split into hydrogen and oxygen. Each electrolyser system consists of a stack of electrolysis units, a gas purifier and dryer and an apparatus for heat removal

Hydrogen and oxygen gas products must be purified, dried and cooled prior to storage and/or delivery to market, subject to required product specifications. The oxygen gas must be safely vented to the atmosphere. Alternatively, pending availability of appropriate markets, this oxygen may be sold as a co-product

Within this emissions accounting framework, electrolysers are assumed to have an outlet pressure of 3 MP.*

* For technologies whose typical hydrogen output pressure at gate is 1 MPa or lower, one can also report in addition to the 3 MPa, GHG emission at 1 MPa with the calculation result of GHG emission adjusted to 3 MPa which requires additional energy to increase the output pressure.
 

4. Emissions Sources in Electrolysis (as per IPHE). GHG emissions associated with electrolysis are subject to the nature of electricity supply for electrolysis as electricity can be sourced from the grid (noting that this may be impacted by contracting of renewable electricity supply and associated instruments), generated on-site via the combustion of liquid, gaseous and/or solid fuels (in this case, this would be the key emissions source) or supplied from an off-grid on-site system. Each process unit or stage in the electrolysis process contains emissions sources outlined below.

GHG emissions summary for electrolysis

5.    The process, methods and requirements of hydrogen life cycle impact assessment are as per IPHE §6.3 (and ISO 14044) with two modifications. Specifically: 

(a)    GHG impact of electricity used for H2 production. The IPHE methodology stipulates: “GHG impact of electricity used for H2 production shall be restricted to Scope 1 and 2 emissions, and partial Scope 3 assumptions (not including emissions associated with manufacturing of power generation facilities). As a result of this assumption, the GHG impact of electricity generation from wind, solar photovoltaic, hydropower and geothermal will be assumed to be zero” (§6.2.3 p32). GH2 notes that these emissions associated with renewable electricity may be > 0, and requires that these emissions are quantified as per requirement 5e.

(b)    Fugitive hydrogen emissions. The IPHE methodology stipulates: “The impacts of hydrogen as an indirect GHG have not been considered … given [the] current focus on (direct) GHG emissions accounting”. GH2 is developing guidance to address fugitive hydrogen emissions.

6.    Information to be reported. GH2 recommends alignment with the parameters specified by the IPHE (Table P1.5). 

The Green Ammonia Protocol 

1.    Summary. This protocol provides guidance to green hydrogen project developers in measuring greenhouse gas emissions associated with green ammonia production in accordance with requirement 5E of the Green Hydrogen Standard. As per requirement 5e, GH2 will review the performance of GH2 accredited projects on an annual basis, with the expectation that the boundaries of the emissions assessment framework can be widened, and that the emissions thresholds can be lowered in accordance with emerging best practice.

2.    Background. Requirement 5E of the Green Hydrogen Standard includes provisions focussed on demonstrating that green hydrogen is produced from renewable energy sources with close to zero emissions. The Green Hydrogen Standard applies the methodology for the electrolysis production pathway being developed by the International Partnership for Hydrogen and Fuel Cells in the Economy (IPHE) as outlined in the Working Paper Methodology for Determining the Greenhouse Gas Emissions Associated with the Production of Hydrogen.  Requirement 5E expects project operators to calculate and report on the emissions associated with the storage, conversion and delivery of H2 and its derivatives. Noting that the majority of export-oriented green hydrogen projects plan to ship green ammonia, GH2 has prioritised providing guidance on this topic. The IPHE working paper was recently revised to ammonia as a hydrogen carrier (Appendix C1). The current guidance focuses on ammonia production (“module 3” in the IPHE). GH2’s guidance will be revised taking into account ongoing work by the IPHE and others. Additional guidance materials addressing ammonia transportation and storage is under consideration. Guidance will be prepared for other green hydrogen derivatives. 

3.    GH2’s Definition of Green Ammonia. GH2 accreditation and certification requires that green hydrogen projects that operate at <=1 kg CO2e per kg H2 (taken as an average over a 12-month period) as per the electrolysis production pathway defined by the International Partnership for Hydrogen and Fuel Cells in the Economy (IPHE). Noting the typical electricity requirements for ammonia production, GH2’s definition of Green Ammonia is:
Green ammonia is ammonia produced using green hydrogen (as defined above) with 100% or near 100% renewable energy with close to zero greenhouse gas emissions (<=.3kg CO2e per kg NH3 taken as an average over a 12-month period).
The GH2 Board will review the performance of GH2 accredited projects on an annual basis, with the expectation that the boundaries of the emissions assessment framework can be widened, and that the emissions thresholds will be lowered in accordance with emerging best practice. 

4.    Technology Scope. The Haber Bosch (HB) process (also called Haber ammonia process, or synthetic ammonia process) for synthesizing ammonia from hydrogen and nitrogen (C1.5 in the IPHE).  

5.    Process Description

High purity nitrogen (N2) is obtained by separating air. There are three main methods of separating N2 from air: cryogenic distillation, pressure swing adsorption (PSA), and membrane separation. The electrolysis process is outlined in Policy Note 1 (above). The gas mixture containing N2 and H2 is compressed to the operating pressure of the HB reactor and enters the electricity-driven HB synthesis loop. There is a pressure drop around the HB synthesis loop. To overcome this, the recycled gas mixture needs to be recompressed to the operating pressure of the HB reactor. In the HB synthesis loop, the electricity is required almost exclusively for syngas/recycle gas compression. Energy is also required to circulate cooling water. 

6.    Emissions Sources in Green Ammonia production. The major component relates to the electricity supply as outlined below. GH2 is preparing guidance on the emission factors that should be applied for electrolysis, with the expectation that the same standards would be applied to green ammonia production.

GHG emissions summary for green ammonia

7.    Fugitive emissions. GH2 is developing guidance to address fugitive hydrogen emissions, which would also apply to ammonia production.

8.    Co-products. Where oxygen is a co-product, GH2 recommends alignment with the allocation factors specified in the Ecoinvent database, as further described in the IPHE “Methodology for determining the greenhouse gas emissions associated with the production of hydrogen”. 

9.    Embodied emissions. GH2 encourages project operators to calculate and report on the embodied emissions associated with green ammonia production, including embodied emissions associated with: (i) purchased energy (grid) and energy produced on site (off grid); (ii) construction of green ammonia production facilities, and (iii) construction of storage, conversion and delivery infrastructure. These emissions are not included in the threshold as per §3 above. GH2 will collaborate with partner organizations to develop and apply methods consistently to all energy providers.

10.    Information to be reported. GH2 recommends alignment with the parameters specified by the IPHE (Table C1.9).