Hydrogen is currently enjoying a renewed and widespread momentum in many national and international climate strategies. This review paper is focused on analysing the challenges and opportunities that are related to green and blue hydrogen, which are at the basis of different perspectives of a potential hydrogen society. While many governments and private companies are putting significant resources on the development of hydrogen technologies, there still remains a high number of unsolved issues, including technical challenges, economic and geopolitical implications. The hydrogen supply chain includes a large number of steps, resulting in additional energy losses, and while much focus is put on hydrogen generation costs, its transport and storage should not be neglected. A low-carbon hydrogen economy offers promising opportunities not only to fight climate change, but also to enhance energy security and develop local industries in many countries. However, to face the huge challenges of a transition towards a zero-carbon energy system, all available technologies should be allowed to contribute based on measurable indicators, which require a strong international consensus based on transparent standards and targets.

The Role of Green and Blue Hydrogen in the Energy Transition—A Technological and Geopolitical Perspective

Hydrogen as a clean, reliable and potentially sustainable energy vector has attracted growing interest for promoting the sustainable development of both industry and society worldwide. Hydrogen is a rising enabler for a multisectorial transition toward a low-carbon economy based on renewable energy sources. Nevertheless, there is a lack of literature scientifically scrutinizing the relationships between a hydrogen economy and the United Nations Sustainable Development Goals. In this article, we argue that the new role of hydrogen takes effect as a game changer and review the policy framework for a hydrogen economy with respect to the prospects of success and its timing and to its role in supporting to reach the Goal 7, i.e. ‘affordable and clean energy’.

Hydrogen economy and sustainable development goals: Review and policy insights

The 2018 IPCC (The Intergovernmental Panel on Climate Change’s) report defined the goal to limit global warming to 1.5 °C by 2050. This will require “rapid and far-reaching transitions in land, energy, industry, buildings, transport, and cities”. The challenge falls on all sectors, especially energy production and industry. In this regard, the recent progress and future challenges of greenhouse gas emissions and energy supply are first briefly introduced. Then, the current situation of the steel industry is presented. Steel production is predicted to grow by 25–30% by 2050. The dominant iron-making route, blast furnace (BF), especially, is an energy-intensive process based on fossil fuel consumption; the steel sector is thus responsible for about 7% of all anthropogenic CO2 emissions. In order to take up the 2050 challenge, emissions should see significant cuts. Correspondingly, specific emissions (t CO2/t steel) should be radically decreased. Several large research programs in big steelmaking countries and the EU have been carried out over the last 10–15 years or are ongoing. All plausible measures to decrease CO2 emissions were explored here based on the published literature. The essential results are discussed and concluded. The specific emissions of “world steel” are currently at 1.8 t CO2/t steel. Improved energy efficiency by modernizing plants and adopting best available technologies in all process stages could decrease the emissions by 15–20%. Further reductions towards 1.0 t CO2/t steel level are achievable via novel technologies like top gas recycling in BF, oxygen BF, and maximal replacement of coke by biomass. These processes are, however, waiting for substantive industrialization. Generally, substituting hydrogen for carbon in reductants and fuels like natural gas and coke gas can decrease CO2 emissions remarkably. The same holds for direct reduction processes (DR), which have spread recently, exceeding 100 Mt annual capacity. More radical cut is possible via CO2 capture and storage (CCS). The technology is well-known in the oil industry; and potential applications in other sectors, including the steel industry, are being explored. While this might be a real solution in propitious circumstances, it is hardly universally applicable in the long run. More auspicious is the concept that aims at utilizing captured carbon in the production of chemicals, food, or fuels e.g., methanol (CCU, CCUS). The basic idea is smart, but in the early phase of its application, the high energy-consumption and costs are disincentives. The potential of hydrogen as a fuel and reductant is well-known, but it has a supporting role in iron metallurgy. In the current fight against climate warming, H2 has come into the “limelight” as a reductant, fuel, and energy storage. The hydrogen economy concept contains both production, storage, distribution, and uses. In ironmaking, several research programs have been launched for hydrogen production and reduction of iron oxides. Another global trend is the transfer from fossil fuel to electricity. “Green” electricity generation and hydrogen will be firmly linked together. The electrification of steel production is emphasized upon in this paper as the recycled scrap is estimated to grow from the 30% level to 50% by 2050. Finally, in this review, all means to reduce specific CO2 emissions have been summarized. By thorough modernization of production facilities and energy systems and by adopting new pioneering methods, “world steel” could reach the level of 0.4–0.5 t CO2/t steel and thus reduce two-thirds of current annual emissions.

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A General Vision for Reduction of Energy Consumption and CO2 Emissions from the Steel Industry

In this paper we present the first systematic review of Power to X processes applied to the iron and steel industry. These processes convert renewable electricity into valuable chemicals through an electrolysis stage that produces the final product or a necessary intermediate. We have classified them in five categories (Power to Iron, Power to Hydrogen, Power to Syngas, Power to Methane and Power to Methanol) to compare the results of the different studies published so far, gathering specific energy consumption, electrolysis power capacity, CO2 emissions, and technology readiness level. We also present, for the first time, novel concepts that integrate oxy-fuel ironmaking and Power to Gas. Lastly, we round the review off with a summary of the most important research projects on the topic, including relevant data on the largest pilot facilities (2–6 MW).

A review on CO2 mitigation in the Iron and Steel industry through Power to X processes

The iron and steel industry is the largest coal consumer and the most greenhouse gas intensive industry. It consumes about 7% of global energy supply, and conservative estimates report that it is responsible for 7–9% of global greenhouse gas emissions. Decarbonization of the iron and steel industry is thus vital to meet climate change mitigation targets and achieve a sustainable future for the industry. This paper presents a comprehensive and systematic review that considered more than 1.6 million pieces of literature and analyzes in depth a shortlist of 271 studies on the iron and steel industry's decarbonization. Applying a sociotechnical lens that investigates raw materials, iron and steel making processes, steel products making and usage, and waste and recycling, the review identifies the climate footprint of the iron and steel industry. The review also assesses current and emerging practices for decarbonization, identifying 86 potentially transformative technologies. The benefits of decarbonizing the iron and steel industry are considered through energy and carbon savings, financial savings, and other environmental and public health benefits. Barriers to decarbonization are considered across financial, organizational, and behavioral aspects. The review also discusses various financial tools and policy instruments that can help overcome the barriers. Lastly, research gaps are outlined. 

Decarbonizing the iron and steel industry: A systematic review of sociotechnical systems, technological innovations, and policy options

Production of iron and steel releases seven percent of the global greenhouse gas (GHG) emissions. Incremental changes in present primary steel production technologies would not be sufficient to meet the emission reduction targets. Replacing coke, used in the blast furnaces as a reducing agent, with hydrogen produced from water electrolysis has the potential to reduce emissions from iron and steel production substantially. Mass and energy flow model based on an open-source software (Python) has been developed in this work to explore the feasibility of using hydrogen direct reduction of iron ore (HDRI) coupled with electric arc furnace (EAF) for carbon-free steel production. Modeling results show that HDRI-EAF technology could reduce specific emissions from steel production in the EU by more than 35 % , at present grid emission levels (295 kgCO2/MWh). The energy consumption for 1 ton of liquid steel (tls) production through the HDRI-EAF route was found to be 3.72 MWh, which is slightly more than the 3.48 MWh required for steel production through the blast furnace (BF) basic oxygen furnace route (BOF). Pellet making and steel finishing processes have not been considered. Sensitivity analysis revealed that electrolyzer efficiency is the most important factor affecting the system energy consumption, while the grid emission factor is strongly correlated with the overall system emissions.

Decarbonization of the Iron and Steel Industry with Direct Reduction of Iron Ore with Green Hydrogen

Decarbonizing primary steel production : Techno-economic assessment of a hydrogen based green steel production plant in Norway

Decarbonisation of the iron and steel industry would require the use of innovative low-carbon production technologies. Use of 100% hydrogen in a shaft furnace (SF) to reduce iron ore has the potential to reduce emissions from iron and steel production significantly. In this work, results from the techno-economic assessment of a H2-SF connected to an electric arc furnace(EAF) for steel production are presented under two scenarios. In the first scenario H2 is produced from molten metal methane pyrolysis in an electrically heated liquid metal bubble column reactor. Grid connected low-temperature alkaline electrolyser was considered for H2 production in the second scenario. In both cases, 59.25 kgH2 was required for the production of one ton of liquid steel (tls). The specific energy consumption (SEC) for the methane pyrolysis based system was found to be 5.16 MWh/tls. The system used 1.51 MWh/tls of electricity, and required 263 kg/tls of methane, corresponding to an energy consumption of 3.65 MWh/tls. The water electrolysis based system consumed 3.96 MWh/tls of electricity, at an electrolyser efficiency of 50 KWh/kgH2. Both systems have direct emissions of 129.4 kgCO2/tls. The indirect emissions are dependent on the source of natural gas, pellet making process and the grid-emission factor. Indirect emissions for the electrolysis based system could be negligible, if the electricity is generated from renewable energy sources. The levellized cost of production(LCOP) was found to be $631, and $669 respectively at a discount rate of 8%, for a plant-life of 20 years. The LCOP of a natural gas reforming based direct reduction steelmaking plant of operating under similar conditions was found to be $414. Uncertainty analysis was conducted for the NPV and IRR values.

Abhinav Bhaskar

Papers

Decarbonization of the Iron and Steel Industry with Direct Reduction of Iron Ore with Green Hydrogen

Decarbonizing primary steel production : Techno-economic assessment of a hydrogen based green steel production plant in Norway

Can methane pyrolysis based hydrogen production lead to the decarbonisation of iron and steel industry