Introduction

The steel industry recognizes the urgent need to take actions concerning climate change. Slowing and halting global warming requires reductions in GHG emissions on a global scale. To play a part in achieving these reductions, it is necessary for steel plants to identify the amount of CO₂ emitted during the production of steel products, in order to identify next opportunities for reduction of CO₂.

As the calculation methods for CO₂ emission and intensity in iron and steel industry, ISO 14404‑1 (for steel plants with blast furnace) and ISO 14404‑2 (for steel plants with electric arc furnace) were published in 2013, and ISO 14404‑3 (for steel plants with electric arc furnace and coal-based or gas-based direct reduction iron facility) was published in 2017.

The ISO 14404 series specifies calculation methods for the carbon dioxide (CO₂) intensity of a steel plant from the amounts of the major inputs (purchased items) and outputs (sold items), such as natural resources, intermediate products, and energy. The concept is shown in Figure 1.

Figure 1 — Conceptual diagram of calculation method in the ISO 14404 series

This calculation method only uses basic imports and exports that are commonly measured and recorded by the plants; thus, the method requires neither the measurement of the specific efficiency of individual equipment or processes nor dedicated measurements of the complex flow and recycling of materials and waste heat. In this way, the calculation method ensures its simplicity and universal applicability without requiring steel plants to install additional dedicated measuring devices or to collect additional dedicated data other than commonly used data in the management of plants.

In addition, the ISO 14404 series provides the guidance to consider the activities in the boundary that are located outside of the site boundary by considering the upstream emissions of the intermediate products produced in such “outsourced steel production activities”. The conceptual diagram of boundary and site boundary is shown in Figure 2.

Figure 2 — Conceptual diagram of boundary and site boundary

Intermediate products with possibilities of considering upstream emissions include the following:

— Electricity / steam;
— Substances produced in the basic activities existing in the target process route (e.g. purchased coke used in the BF - BOF route);
— Substances that substitute the iron source of the process route even if they do not exist in the target process route (e.g. purchased DRI used in the BF - BOF route).

The ISO 14404 series is based on “CO₂ Emissions Data Collection User Guide” established by the World Steel Association (worldsteel), which consists more than 161 major steel companies in 60 countries and regions of the world. Actual data collection among worldsteel members has been conducted yearly based upon this guide since 2007. While the ISO 14404 series of standards and worldsteel "CO₂ Emissions Data Collection User Guide" share the same concept, they have different characteristics where the worldsteel’s User Guide provides the method suitable for collecting data from steel plants across the world in a uniform way, and the ISO 14404 series provide methods suitable for the evaluation of CO₂ intensity of steel plant for each process route (i.e. combination of iron source and steelmaking process).

Therefore, while worldsteel method applies common boundary and CO₂ emission factors to all steelworks regardless of their process routes, the ISO 14404 series defines the boundary, CO₂ emission factors and intermediate products for which upstream emissions are considered for each of the process routes, such as BF-BOF (14404-1), Scrap-EAF (14404-2) and DRI-EAF (14404-3).

This document provides the guidance for calculating the CO₂ intensity at all types of steel plants, including steel plants with process routes not covered in ISO 14404‑1, ISO 14404‑2 and ISO 14404‑3 (steel plants with process routes other than BF - BOF, Scrap - EAF, DRI - EAF) as well as steel plants with multiple process routes, by defining the boundary, CO₂ emission factors and the intermediate products for which upstream emissions are considered for each of all types of steel plants. This document also includes Universal Calculation Sheet, which covers all relevant emission sources from ISO 14404‑1, ISO 14404‑2 and ISO 14404‑3 to assist the calculation of CO₂ emissions.

Moreover, this document provides additional guidance to the entire ISO 14404 series for the following topics, which have not been covered by ISO 14404‑1, ISO 14404‑2 and ISO 14404‑3.

a) Evaluation of exported slags
b) Evaluation of by-product gas
c) Evaluation of stock
d) Selection of calorific values and emission factors for electricity and fuel

BS ISO 14404-4:2020

Calculation method of carbon dioxide emission intensity from iron and steel production - Guidance for using the ISO 14404 series

Current, Under Review

Published:

31 Jan 2021