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

To reduce greenhouse gas (GHG) emissions in high-grade steel production plants, this study developed a solar and wind assisted H_2-fuelled blast furnace – basic oxygen furnace (BF-BOF) route coupled with the electrolysis of H_2 O and thermoelectric units. The developed model consists of heat recovery units, water gas shift (WGS), low-temperature electrolysis of H_2 O, thermophotovoltaic converter, CO_2 capture by absorption and oxy-hydrogen firing ovens and furnaces. The recovered thermal energy generated steam and distilled H_2 O feedstocks for WGS and PEMEC (proton exchange membrane electrolyser cell) units. WGS converted CO to 〖CO〗_2 and increased the H_2 production rate before separation from other by-products in the pressure swing adsorption (PSA) column. H_2 O electrolysis generated more H_2 fuel for the coke oven, Fe-CaO oven-sinter, BF and BOF. The result of the proposed system reveals that by utilising H_2 as fuel and O_2 as oxidant instead of burning natural gas (NG) for thermal decomposition of feedstocks, 1111.4kg/hr of CO_2 emission for every 626kg/hr of produced steel can be prevented. The application of 〖CO〗_2 capture by absorption process eliminated 〖CO〗_2 emission footprint from the process. Whereas 61.1kW was recovered by installing TPV units on ovens and furnaces’ walls for conversion of waste heat to electricity. By incorporating either solar or wind renewable energy systems with a power output of 20MW, 1290.4kg/hr of H_2 fuel and 38.5kg/hr of CH_4 were stored for later use and 6754.8kg/hr of CO_2 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 utilised H_2 fuel for the thermal decomposition of ovens and furnaces’ feeds.