ISO 19694-4:2023

Overview

ISO 19694-4:2023 - Stationary source emissions: Determination of greenhouse gas emissions in energy‑intensive industries - Part 4: Aluminium industry - specifies a harmonized method for calculating greenhouse gas (GHG) emissions from the electrolysis section of primary aluminium smelters and aluminium anode baking plants. The standard defines sector‑specific rules, terminologies and symbols, and sets out key performance indicators (KPIs) and boundary definitions for benchmarking aluminium production sites. Note: direct fuel‑based emissions are excluded here (see ISO 19694‑1).

Keywords: ISO 19694-4:2023, aluminium industry, greenhouse gas emissions, primary aluminium smelters, electrolysis, anode baking, PFC, CO2, GHG benchmarking.

Key Topics and Requirements

• Scope and definitions: Precise sector terms (e.g., aluminium electrolysis, anode baking plant, PFC gases) and standard symbols/chemical formulae (CF4, C2F6).
• Structured calculation methods: Tiered approaches for process GHG emissions:
  • Tier 1 - process‑specific formulae with technology‑typical parameters (simpler, default values).
  • Tier 2 - process‑specific formulae with facility‑specific parameters (higher accuracy).
• Process coverage:
  • CO2 emissions from electrolysis (prebake and Søderberg processes) and anode baking furnaces.
  • PFC (perfluorocarbon) emissions from reduction processes, including stepwise calculation of kg PFC/t Al and CO2‑equivalent conversion.
  • Supporting processes and sources (e.g., alumina refining, baking furnace fuel and packing coke treatment).
• Verification and validation: Requirements and methods to validate CO2 and PFC calculation accuracy for reporting and external verification.
• KPIs for benchmarking: Metrics to compare GHG performance across facilities and over time, including use of a grid‑specific CO2 factor for electricity-related emissions.
• Reference framework: Aligns with ISO 19694‑1 (general aspects) and follows IPCC guidance where applicable.

Practical Applications and Users

• Environmental and sustainability managers in aluminium producers for GHG accounting, performance tracking and internal benchmarking.
• Regulatory compliance teams and permitting authorities assessing process emissions reporting.
• Third‑party verifiers and auditors conducting independent validation of reported GHG inventories.
• Investors, consultants and ESG analysts evaluating operational carbon intensity and reduction opportunities.
• R&D and process engineers targeting emission reduction projects (PFC minimization, anode management, energy efficiency).

Related Standards and Guidance

• ISO 19694‑1 - Stationary source emissions: General aspects for GHG emissions in energy‑intensive industries.
• IPCC guidelines (2006 and subsequent updates) for GHG accounting and global warming potentials.
• Other parts of the ISO 19694 series for sector‑specific methods.

This standard helps ensure consistent, transparent and comparable GHG reporting for the aluminium sector, supporting emissions management, benchmarking and credible verification.