Thermophotovoltaics (TPVs), solar and wind assisted hydrogen production and utilisation in iron and steel industry for low carbon productions

Abstract

To reduce greenhouse gas (GHG) emissions in high-grade steel production plants, this study developed a solar and wind assisted H2-fuelled blast furnace – basic oxygen furnace (BF-BOF) route coupled with the electrolysis of H2O and thermoelectric units. The developed model consists of heat recovery units, water gas shift (WGS), low-temperature electrolysis of H2O, thermophotovoltaic converter, CO2 capture by absorption and oxy-hydrogen firing ovens and furnaces. The recovered thermal energy generated steam and distilled H2O feedstocks for WGS and PEMEC (proton exchange membrane electrolyser cell) units. WGS converted CO to CO2 and increased the H2 production rate before separation from other by-products in the (PSA) pressure swing adsorption column. H2O electrolysis generated more H2 fuel for the coke oven, Fe-CaO oven-sinter, BF and BOF. The result of the proposed system reveals that by utilising H2 as fuel and O2 as oxidant instead of burning natural gas (NG) for thermal decomposition of feedstocks, 1111.4 kg/h of CO2 emission for every 626 kg/h of produced steel can be prevented. The application of CO2 capture by absorption process eliminated CO2 emission footprint from the process. Whereas 61.1 kW was recovered by installing TPV units on ovens and furnaces' walls for the conversion of waste heat into electricity. By incorporating either solar or wind renewable energy systems with a power output of 20 MW, 1290.4 kg/h of H2 fuel and 38.5 kg/h of CH4 were stored for later use and 6754.8 kg/h of CO2 emission was avoided. The steel purchase price of the proposed system is anticipated to be cheaper than the conventional BF-BOF route operating with a CCS unit as ≥10% energy efficiency was recorded. The recycling of more scrap steel is also viable in this developed system because of the high energy density of the utilised H2 fuel for the thermal decomposition of ovens and furnaces’ feeds.