Descarbonização do setor siderúrgico a partir da utilização de hidrogênio: desempenho ambiental e potencial

Abstract

Due to the use of coal and the high energy demand, the steel sector represents 30% of the total emissions of greenhouse gases (GHG) in the industrial sector and around 10% of the total emissions from the energy sector. Therefore, the decarbonization of the steel sector involves changes in its processes and the energy transition of all sectors involved. The use of hydrogen (H2) in the context of steelmaking decarbonization implies its role as a reducer and as fuel. Aiming the potential for reducing GHG in steelmaking, considering the use of H2 as a reducer, conventional steel routes were compared under two aspects: environmental performance and current and future potential for the use of H2. First, the carbon footprint was estimated, in a life cycle analysis (LCA) using IPCC method, ECOINVENT data in comparison to GHG protocol, considering 3 scenarios in Brazilian conditions: steelmaking using coke (Scenario 1), steelmaking using charcoal (Scenario 2) and the direct reduction route with gray and green H2 (Scenario 3). Second, trends in the steel sector were discussed based on sectoral and corporate reports from the biggest players. When discussing the results, Scenario 2 resulted in 51% less GHG emissions than Scenario 1. Scenario 3, with gray H2, implied 65% less emissions than Scenario 1 and, with green H2, the result was 89% less. Benefits have been realized in using LCA to calculate carbon footprint. Furthermore, it was possible to identify advantages of the Brazilian context regarding the pioneering use of charcoal in steelmaking and the 80% share of renewable energy in the country's electricity mix. Evaluating the decarbonization plans, 54% cite H2 as a step to be taken to meet the targets, but just 31% mention the investment in direct reduction with H2 reducer. Despite the prospects for decarbonizing the steel industry pointing to disruptive technologies, it is unanimous that the first step should be the best available techniques for existing scenarios, the energy efficiency, the preference for renewable energies and incentives for research and technology.