About LCI/LCA
- 01 What are LCI and LCA?
- Life Cycle Inventory (LCI) is one of the phases of a Life Cycle Assessment (LCA).
LCA is a tool to assist with the quantification and evaluation of environmental burdens and impacts associated with product systems and activities, from the extraction of raw materials in the earth to end-of-life and waste disposal. The tool is increasingly used by industries, governments, and environmental groups to assist with decision-making for environment-related strategies and materials selection.
The initial phase of LCA includes defining the goals and scope of a study, and the collection and calculation of Life Cycle Inventory data. LCI data quantify the material, energy and emissions associated with a functional system (for example, the manufacture of 1 kg of hot rolled coil). This phase precedes the Life Cycle Impact Assessment phase (LCIA) which involves the classification, characterisation and evaluation of these data in relation to ecological impacts. The fourth and last phase is the interpretation where the data resulting from the LCI and LCIA phases are analysed in the context of the scope and study goals and the quality of any study conclusions assessed. However, LCA is generally an iterative process where each phase has implications for the other phases.
- 02 What were the main goals of the LCI study?
- LCA has been a topic of growing interest to the steel and other industries. Several steel companies and associations have already independently carried out LCA studies, each different in purpose, system boundary and methodology. The Board of Directors therefore initiated a global 'LCI on Steel Industry Products', in order to avoid inconsistency and duplicated effort.
One of the primary aims of the project was to build a database and develop a common worldwide methodology for cradle-to-gate steel product LCI's across a representative sample of member companies. This database may subsequently form the basis for full LCA's across broader boundaries and complete product life cycles.
The purposes of the project were to:
- Produce worldwide LCI data for steel industry products
- Assist industry benchmarking and environmental improvement programmes
- Provide a basis for carrying out impact assessments
- Obtain life cycle information requested by customers
- Support communication with industry stakeholders
- Support responses to environmental claims against steel
- Train industry people in the field of life cycle assessment.
- 03 What products were included and how representative is the study?
- The LCI study quantifies resources use, energy and environmental emissions associated with the processing of fourteen steel industry products, from the extraction of raw materials in the ground through to the steel factory gate ("cradle-to-gate"), and produced via the blast furnace/basic oxygen furnace and the electric arc furnace routes. The fourteen products included in the study were: hot rolled coil; pickled hot rolled coil; cold rolled coil; finished cold rolled coil; tinplated coil; tin-free steel; hot-dipped galvanised; electrogalvanised; organic coated flat; plate; tubes; rebar/wire rod; engineering steel and sections. These products represent more than 80% of steel production by product category.
In total, 50 sites operated by 28 companies participated (34 blast furnace, 13 electric arc furnace and three direct reduction operations), representing most areas of the world and a range of operating configurations. These companies account for 39.7% of global crude steel production outside of the former USSR and China.
- 04 Who conducted the study?
- The original study was defined and run by the LCI Expert Group (chaired by Louis Brimacombe, Corus Group), which was appointed by the Working Group on LCA and composed of 25 steel industry representatives. The subsequent update was carried out by the LCA Forum set up following the original study (chaired by Norbert Prüm, ArcelorMittal), and consists of 53 companies.
The original study was undertaken by the independent consultancy firm Ecobilan, selected as a world class company in the field of LCA, having carried out studies for many material industries, including plastics, paper and steel. The update study was completed by IISI (now worldsteel).
A Critical Review Panel comprising of recognised, independent experts was formed to review the methodology, data quality and data presentation aspects of both studies.
- 05 How did the Critical Review Panel reacted to the LCI Study?
- The Critical Review Panel has presented a report that is in the main highly favourable to the Study (similarly for the original study). A copy of the Panel's report is provided in the Methodology Report.
- 06 In what way is the study is technically rigorous?
- The LCI study is one of the most comprehensive and rigorous LCI studies ever carried out for a material, and was probably one of the first completed in accordance with the ISO standards on LCA (ISO 14040 series). It involved an exhaustive process to collate some twenty thousand items of data from the participating steel companies and the creation of various models and calculations for upstream processes. Therefore, it offers enormous scope for data analysis, trending, benchmarking and investigating environmental significance. This approach has been repeated and improved for the update study, to include key upstream processes.
The data quality is excellent: data are recent and from reliable sources, and in general their range and variance is small. Every item of data is documented and verifiable. Furthermore, the study included a procedure for random auditing of data to ensure that participating steel plants met the data quality standards set for the study. Measures were also taken to verify apparent inconsistencies, and to ensure the consistent application of the study methodology, including training and technical support to ensure correct procedures for completion of the questionnaires. The database includes information on whether data were measured, calculated or estimated. The process of generating LCI results is transparent and extensively documented, and therefore reproducible. Finally, independent critical review panels reviewed each study.
- 07 Why is used system expansion used to account for by-products?
- The treatment of co-products is one of the key methodological issues for most LCA studies and is especially true for this LCI study because of the process gases, slags and many other co-products arising from the steelmaking processes. How to account for these useful co-products, in order to obtain the LCI of steel only is, therefore, a critical issue.
There are essentially two methods of accounting for co-products: allocation (also called partitioning) and system expansion.
'Allocation' consists of allocating the process in/outputs proportionally to the product and to the co-products, according to a parameter such as mass, feedstock energy or even monetary value.
For instance, assuming the BOF generates three mass units of steel and one mass unit of recovered slags, three-quarters of every BOF in/output is allocated to the steel and the remaining quarter to the slags.
'System expansion' assumes credits for co-products that render it unnecessary to produce functionally equivalent products by other means. For example, process gases that are exported and used to generate electricity are assumed to replace coal mining and combustion for electricity generation. The difference between the environmental burden associated with the coal and process gas combustion are then credited, or in some cases debited, to the steel LCI.
System expansion was applied in the study primarily because ISO recommends the use of system expansion and the avoidance of allocation whenever possible.
In addition, it is considered that there is no scientifically justifiable parameter to allocate in/outputs of the steelmaking process. In view of these and other relevant factors, the Working Group found the system expansion method to be the most scientific and fair way of accounting for most steel by-products. Most importantly, it does not result in unfairly favourable or misrepresentative LCI results for the steel industry.
- 08 What was the source and quality of upstream inventories?
- As an LCI is a cradle-to-gate study, the database includes upstream data (that is, iron ore mining, electricity production, etc.). Iron ore mining & pellet-making data was received directly from operations around the world; a disappointing response to the request for LCI data from coal and electricity producers meant that these were obtained mainly from commercial databases and literature sources, but the quality and transparency of methods to derive these data are less well defined than the steel industry specific data in terms of reliability, geographical relevance, methodology and completeness. In order to avoid potential data quality problems arising from this, certain steel sites acquired data directly from representative sites for the upstream processes not mentioned above that were judged to have a significant contribution to the global LCI results (for example, limestone quarrying, lime production and sea transport).
The inventory includes:
- All non-mass inputs (including electricity, steam, compressed air and water)
- More than 98% of steelworks material inputs (including raw
materials, energy and consumables, as well as minor inputs which may have significant environmental burdens). For more than 98% of these inputs, upstream production was accounted for.
Transport was taken into account for 95 percent of steelworks material inputs.
- 09 What are the principal areas covered by the data?
- The major material flows covered are quantified and categorised under five headings: resource use including energy and water; air emissions; water emissions; by-product and wastes. The range of data collected from different sites reflects different ironmaking and steelmaking practices, energy efficiencies, national power mixes and efficiencies, and the complexity of the finishing operations.
The inventory includes at least 99% of the total waste tonnage for given process stages and that are treated on site.
Certain data are included in the study but not accounted in the global averages (see section 3.3).
- 10 How reliable are the study results?
- The quality of data input in the LCI study is excellent (as outlined in Section 2.3). As transparency was a fundamental issue of the study, measures were taken to adopt fair assumptions and allocation rules in accordance with ISO standards, and the methodological assumptions, boundaries and allocation principles that were made are transparent and fully documented. In consequence, all results obtained are totally verifiable and reproducible.
The study was designed to represent the real interactions of steel production routes with the environment and avoid unsound theoretical scenarios. Most importantly, it does not result in unfairly favourable or misrepresentative LCI results for the steel industry. In addition, the software provides the flexibility to analyse and, if necessary, switch off specific scenarios and/or replace them with alternative functional systems. This facility allows sensitivity analysis of different scenarios, and can be adapted to future data inputs or assumptions as required.
However, as for any LCA studies of this magnitude, there is still further scope to improve the database including the improvement of upstream and by-product data especially where generic databases have been used which do not represent relevant regional/local practices. Data for specific flow categories such as water usage; waterborne emissions; and air emission of particulates, can also be improved by extending and more clearly defining site data collection requirements. The database would also benefit from a larger number of participating sites for certain products since this would provide more reliable averages and statistical confidence. A large program of work is managed through the LCA Forum to continue improving and updating the database.
- 11 The LCI does not list air emissions for PM10, PAH, etc. Why is this?
- Such data are listed in the database, but not accounted in the global averages, as in certain cases not enough data were available to do so. Some emissions are not measured routinely for the demands of local regulation, and therefore not all data categories were fully accounted across the participating sites. Another factor was that upstream data used in the LCI calculations did not necessarily contain all the emissions included in the steel plant questionnaires. It is anticipated that as measurement techniques become more established and widespread globally, an increasing number of emissions will be accounted in the global averaging. In addition, data for upstream operations will be sought directly from suppliers and so reduce the dependence on data from generalised databases.
- 12 Does the study indicate LCI benefits of recycling steel?
- Whether used in the BOF (basic oxygen furnace) or EAF (electric arc furnace) route, there is no doubt that the recycling of steel is beneficial, saving raw materials and other resources. Scrap recycled via the BOF and the EAF effectively displaces the energy and emissions associated with primary iron production mainly from the blast furnace.
- 13 Does steel recycling degrade the product quality: is there a limitation to steel recycling?
- Steel is 100% recyclable, 50% of world steel production is made from scrap and the infrastructure for scrap recycling is well established. There is no limit to the level of steel that can be recycled and steel can be recycled repeatedly without downgrading to a lower quality product.
Scrap is used in both the BF and the EAF steelmaking routes. Merchant scrap (as opposed to internally arising scrap) can contain some residual (tramp) elements such as copper and tin. Steelmakers are selective in their purchasing of scrap, manage the input of different quality scraps and use processes to eliminate or reduce the levels of tramp elements. Such treatment is a normal part of the steelmaking process and ensures that all steel recovered can be reused to make new steel.
- 14 Is the EAF route "better" than the BOF route?
- Both EAF and BOF routes provide essential capacity for scrap recycling and the impacts of converting scrap to steel are similar for each route.
At current levels of demand, there is insufficient scrap supply. Therefore there is a need to produce steel from virgin material. In life cycle terms, what is essential is that steel recycling is optimised so that the use of virgin material resources can be reduced and this makes the two routes complementary.
- 15 For what products do you provide LCI?
- For a complete list see the LCI Product Descriptions page. You can also download a PDF file that contains a complete list of the products from this page.
