ISO/TS 19870: The “Gold Standard” for Hydrogen Emissions Accounting – Critical Points Vietnamese Businesses and Policymakers Must Dissect Now
April 12, 2026 by VAHC Secretariat
Viena April 12, 2026 – As the world races toward a net-zero future, hydrogen is hailed as the fuel of tomorrow. Yet one question looms large: which hydrogen is truly “green”? The answer lies not in slogans but in cold, hard numbers – and the new international benchmark that sets the rules is ISO/TS 19870. Released by ISO and UNIDO in 2024, this is no dry technical manual. It is a practical, game-changing guide that standardizes how to calculate the partial carbon footprint of hydrogen from wellhead to consumption gate. For Vietnam, now drafting its national hydrogen strategy, ignoring this document could prove costly.
1. What exactly is ISO/TS 19870 and why does it matter?
ISO/TS 19870 – full title: Hydrogen technologies – Methodology for determining the greenhouse gas emissions associated with the production, conditioning and transport of hydrogen to consumption gate – is a Technical Specification developed by ISO/TC 197/SC 1. Published in 2023 and launched at COP28, it provides the world’s first unified methodology to measure greenhouse gas (GHG) emissions across the entire hydrogen value chain up to the point of use.
Key takeaway #1: This is not a mandatory law. ISO standards are voluntary. However, an increasing number of countries are embedding it into national legislation to define “low-emission hydrogen.” If Vietnam fails to align early, domestically produced hydrogen risks being labelled non-transparent on global markets, jeopardizing exports and foreign investment.
2. Two approaches – Attributional vs Consequential: Choose wrong and you’re lost
One of the most important innovations in ISO/TS 19870 is its explicit recognition of two LCA/CFP approaches:
- Attributional Approach: A “snapshot” of current emissions within the defined value chain. Ideal for product certification and reporting.
- Consequential Approach: Evaluates the broader environmental consequences of a decision or change (e.g., producing hydrogen from municipal waste instead of landfilling it). This is the powerful tool for policy-making and strategic planning.
Critical note: Vietnamese project developers must decide which approach to use from day one. Relying solely on the simpler Attributional method to “beautify” numbers may force a complete recalculation later when the government demands policy-level analysis. The Consequential route is more complex but delivers credible, future-proof results.
3. System boundary: “Well to consumption gate” – Never forget CAPEX and upstream methane
The standard draws a crystal-clear boundary: well-to-consumption gate. It covers production, conditioning (compression, liquefaction), conversion (to ammonia or LOHCs), and transport.
Two “hidden” points every stakeholder must watch:
- CAPEX emissions (capital expenditure emissions from plant construction and equipment): Must be reported separately unless proven immaterial. Many older projects conveniently ignore them, but ISO/TS 19870 demands transparency to ensure fair comparison with other energy vectors.
- Upstream methane emissions: For hydrogen produced from natural gas (SMR + CCS), methane leakage from extraction and transport is mandatory to include. Methane’s global warming potential is 28–36 times higher than CO₂ over 100 years – a make-or-break factor.
Vietnam-specific warning: With several planned projects based on natural gas reforming and coal gasification, failing to account for upstream methane could make Vietnamese “green” hydrogen appear dirtier than it actually is, undermining competitiveness against European electrolysis-based hydrogen.
4. Carbon capture (CCS/CCU) and hydrogen leakage – Don’t be complacent
- CCS (Carbon Capture and Storage): Captured CO₂ is treated as waste; no emissions are allocated to it, but the energy used for capture and storage still counts toward the hydrogen footprint.
- CCU (Carbon Capture and Utilization): Under Attributional, it is excluded; under Consequential, system boundaries may be expanded to include later emissions.
Crucial point: The standard does not directly count hydrogen releases as GHG, but leakage indirectly inflates the footprint because calculations are based on total hydrogen produced. Companies must transparently report production, storage, and delivery quantities at every gate.
Both governments and industry now agree: investing in advanced monitoring, measurement, and repair systems is non-negotiable for credible data.
5. Emission allocation and the 11 informative annexes – A detailed roadmap for every technology
ISO/TS 19870 provides a clear decision tree for allocating emissions to co-products (oxygen from electrolysis, ammonia, etc.). It includes 11 annexes with practical examples for:
- Seven production pathways (electrolysis, SMR+CCS, chlor-alkali, steam cracking, coal gasification+CCS, biomass waste+CCS, auto-thermal reforming+CCS)
- Conversion (ammonia, LOHCs)
- Conditioning (liquid hydrogen)
Important caveat: All annexes are currently informative only. ISO is now developing the first normative standard (ISO 19870-1) with binding annexes for mature technologies. Vietnamese companies adopting the guide today must stay updated to avoid costly revisions later.
6. What this means for Vietnam
Vietnam’s emerging hydrogen strategy now has a ready-made international tool to:
- Build a credible national certification scheme
- Attract serious foreign investment (European, Japanese, and Korean investors place high value on ISO alignment)
- Ensure fair comparison between electrolysis (renewable-powered) and blue hydrogen (natural gas + CCS)
Risk alert: Relying solely on domestic standards without harmonizing with ISO/TS 19870 could exclude Vietnamese hydrogen from global supply chains – just as certain agricultural exports once faced environmental barriers.
Final word: Act now or pay later
ISO/TS 19870 is far more than a technical document – it is a strategic instrument that determines whether hydrogen will genuinely help decarbonize the planet or remain “green on paper only.” For Vietnam, mastering and applying this standard early will decide whether the country becomes a regional hydrogen hub or merely a follower.
Businesses need training programs, the government needs clear implementation guidelines, and both must work closely with ISO and UNIDO. True green hydrogen is not about rhetoric – it is about transparent, verifiable numbers. Those who get this right will lead the game.
(This analysis is based on the official UNIDO-ISO publication “Global programme for hydrogen in industry – Guide on ISO/TS 19870” (2024). It is for reference purposes only. Stakeholders are strongly advised to consult the original document for precise application.)
