To combat global warming, industry needs to find ways to reduce its carbon footprint. One way this can be done is by re-use of industrial flue gasses to produce value-added chemicals. Prime example feedstocks for the chemical industry are the three flue gasses produced during conventional steel production: blast furnace gas (BFG), basic oxygen furnace gas (BOFG), and coke oven gas (COG), due to their relatively high CO, CO2, or H2 content, allowing the production of carbon-based chemicals such as methanol or polymers. It is essential to know for decision-makers if using steel mill gas as a feedstock is more economically favorable and offers a lower global warming impact than benchmark CO and H2. Also, crucial information is which of the three steel mill gasses is the most favorable and under what conditions. This study presents a method for the estimation of the economic value and global warming impact of steel mill gasses, depending on the amount of steel mill gas being utilized by the steel production plant for different purposes at a given time and the economic cost and greenhouse gas (GHG) emissions required to replace these usages. Furthermore, this paper investigates storage solutions for steel mill gas. Replacement cost per ton of CO is found to be less than the benchmark for both BFG (50–70 €/ton) and BOFG (100–130 €/ton), and replacement cost per ton of H2 (1800–2100 €/ton) is slightly less than the benchmark for COG. Of the three kinds of steel mill gas, blast furnace gas is found to be the most economically favorable while also requiring the least emissions to replace per ton of CO and CO2. The GHG emissions replacement required to use BFG (0.43–0.55 tons-CO2-eq./ton CO) is less than for conventional processes to produce CO and CO2, and therefore BFG, in particular, is a potentially desirable chemical feedstock. The method used by this model could also easily be used to determine the value of flue gasses from other industrial plants.

Hydrogen (H2) produced using renewable energy could be used to reduce greenhouse gas (GHG) emissions in industrial sectors such as steel, chemicals, transportation, and energy storage. Knowing the delivered cost of renewable H2 is essential to decision-makers looking to utilize it. The cheapest location to source it from, as well as the transport method and medium, are also crucial information. This study presents a Monte Carlo simulation to determine the delivered cost for renewable H2 for any usage location globally, as well as the most cost-effective production location and transport route from nearly 6,000 global locations. Several industrially dense locations are selected for case studies, the primary two being Cologne, Germany and Houston, United States. The minimum delivered H2 cost to Cologne is 9.4 €/kg for small scale (no pipelines considered), shipped from northern Egypt as a liquid organic hydrogen carrier (LOHC), and 7.6 €/kg piped directly as H2 gas from southern France for large scale (pipelines considered). For small-scale H2 in Houston, the minimum delivered cost is 8.6 €/kg trucked as H2 gas from the western Gulf of Mexico, and 7.6 €/kg for large-scale demand piped as H2 gas from southern California. The south-west United States and Mexico, northern Chile, the Middle East and north Africa, south-west Africa, and north-west Australia are identified as the regions with the lowest renewable H2 cost potential, with production costs ranging from 6.7—7.8 €/kg in these regions. Each is able to supply differing industrially dominant areas. Furthermore, the effect of parameters such as year of construction, electrolyser, and H2 demand is analysed. For the case studies in Houston and Cologne, the delivered H2 cost is expected to reduce to about 7.8 €/kg by 2050 in Cologne (no pipelines considered, PEM electrolyser) and 6.8 €/kg in Houston.

In order to reduce human-made global warming, the aviation industry is under pressure to reduce greenhouse gas (GHG) emissions. Production of sustainable aviation fuel (SAF) from steel mill gases could help reduce the emissions intensity of jet fuel. This study presents a simulation, techno-economic assessment, and GHG emissions assessment of a Fischer-Tropsch (FT) process using two steel mill gases (coke oven gas and blast furnace gas) as feedstock. The process was analysed both with and without carbon capture and storage (CCS) to reduce process emissions. The minimum viable selling price (MVSP) was determined to be 1,046 €/tonne for the standard scenario and 1,150 €/tonne for the CCS scenario, which is higher than the fossil-fuel-based benchmark (325–1,087 €/tonne since 2020), although similar to the lowest costs found for other SAF benchmarks. The GHG emissions intensity was found to be 49 gCO2-eq./MJ for the standard scenario and 21 gCO2-eq./MJ with CCS, far lower than the 88 gCO2-eq./MJ average for the conventional benchmark and in the mid-lower range of found emissions intensities for other SAF benchmarks. When a CO2 tax of 130 €/tonne is considered, the MVSP for the standard scenario increases to 1,320 €/tonne while the CCS scenario increases to 1,269 €/tonne, making them cost-competitive with the fossil-fuel benchmark (797–1,604 €/tonne). The studied process offers economically viable small-to-medium scale SAF plants (up to 50 kt/y SAF) at a CO2 tax of 190 €/tonne or higher for the CCS scenario and 290 €/tonne or higher for the standard scenario.

Four commercial titanium dioxide (TiO2) photocatalysts, namely P25, P90, PC105, and PC500, were immobilized onto steel plates using a sol-gel binder and investigated for phenol degradation under 365 nm UV-LED irradiation. High-performance liquid chromatography (HPLC) and total organic carbon (TOC) analyses were performed to study the impact of three types of oxygen sources (air, dispersed synthetic air, and hydrogen peroxide) on the photocatalytic performance. The photocatalyst films were stable and there were significant differences in their performance. The best result was obtained with the P90/UV/H2O2 system with 100% degradation and about 70% mineralization within 3 h of irradiation. The operating conditions varied, showing that water quality is crucial for the performance. A wastewater treatment plant was developed based on the lab-scale results and water treatment costs were estimated for two cases of irradiation: UV-LED (about 600 EUR/m3) and sunlight (about 60 EUR/m3). The data show the high potential of immobilized photocatalysts for pollutant degradation under advanced oxidation process (AOP) conditions, but there is still a need for optimization to further reduce treatment costs.