scholarly journals Production of Negative-Emissions Steel Using a Reducing Gas Derived from DFB Gasification

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4835
Author(s):  
Sébastien Pissot ◽  
Henrik Thunman ◽  
Peter Samuelsson ◽  
Martin Seemann

A dual fluidized bed (DFB) gasification process is proposed to produce sustainable reducing gas for the direct reduction (DR) of iron ore. This novel steelmaking route is compared with the established process for DR, which is based on natural gas, and with the emerging DR technology using electrolysis-generated hydrogen as the reducing gas. The DFB-DR route is found to produce reducing gas that meets the requirement of the DR reactor, based on existing MIDREX plants, and which is produced with an energetic efficiency comparable with the natural gas route. The DFB-DR path is the only route considered that allows negative CO2 emissions, enabling a 145% decrease in emissions relative to the traditional blast furnace–basic oxygen furnace (BF–BOF) route. A reducing gas cost between 45–60 EUR/MWh is obtained, which makes it competitive with the hydrogen route, but not the natural gas route. The cost estimation for liquid steel production shows that, in Sweden, the DFB-DR route cannot compete with the natural gas and BF–BOF routes without a cost associated with carbon emissions and a revenue attributed to negative emissions. When the cost and revenue are set as equal, the DFB-DR route becomes the most competitive for a carbon price >60 EUR/tCO2.

2021 ◽  
Author(s):  
Rutger Gyllenram ◽  
Niloofar Arzpeyma ◽  
Wenjing Wei ◽  
Pär G. Jönsson

AbstractThe pressure on the steel industry to reduce its carbon footprint has led to discussions to replace coke as the main reductant for iron ore and turn to natural gas, bio-syngas or hydrogen. Such a major transition from the blast furnace-basic oxygen furnace route, to the direct reduction-electric arc furnace route, for steel production would drastically increase the demand for both suitable iron ore pellets and high-quality scrap. The value for an EAF plant to reduce the SiO2 content in DRI by 2 percentage points and the dirt content of scrap by 0.3 percentage points Si was estimated by using the optimization and calculation tool RAWMATMIX®. Three plant types were studied: (i) an integrated plant using internal scrap, (ii) a plant using equal amounts of scrap and DRI and (iii) a plant using a smaller fraction of DRI in relation to the scrap amount. Also, the slag volume for each plant type was studied. Finally, the cost for upgrading was estimated based on using mainly heuristic values. A conservative estimation of the benefit of decreasing the silica content in DRI from 4 to 2% is 20 USD/t DRI or 15 USD/t DR pellets and a conservative figure for the benefit of decreasing the dirt in scrap by 0.3 percentage points Si is 9 USD/t scrap. An estimate on the costs for the necessary ore beneficiation is 2.5 USD/t pellet concentrate and for a scrap upgrade, it is 1-2 USD/t scrap.


Author(s):  
Martin Hammerschmid ◽  
Stefan Müller ◽  
Josef Fuchs ◽  
Hermann Hofbauer

Abstract The present paper focuses on the production of a below zero emission reducing gas for use in raw iron production. The biomass-based concept of sorption-enhanced reforming combined with oxyfuel combustion constitutes an additional opportunity for selective separation of CO2. First experimental results from the test plant at TU Wien (100 kW) have been implemented. Based on these results, it could be demonstrated that the biomass-based product gas fulfills all requirements for the use in direct reduction plants and a concept for the commercial-scale use was developed. Additionally, the profitability of the below zero emission reducing gas concept within a techno-economic assessment is investigated. The results of the techno-economic assessment show that the production of biomass-based reducing gas can compete with the conventional natural gas route, if the required oxygen is delivered by an existing air separation unit and the utilization of the separated CO2 is possible. The production costs of the biomass-based reducing gas are in the range of natural gas-based reducing gas and twice as high as the production of fossil coke in a coke oven plant. The CO2 footprint of a direct reduction plant fed with biomass-based reducing gas is more than 80% lower compared with the conventional blast furnace route and could be even more if carbon capture and utilization is applied. Therefore, the biomass-based production of reducing gas could definitely make a reasonable contribution to a reduction of fossil CO2 emissions within the iron and steel sector in Austria.


Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7395
Author(s):  
Francesco Facchini ◽  
Giorgio Mossa ◽  
Giovanni Mummolo ◽  
Micaela Vitti

The steelmaking processes are considered extremely energy-intensive and carbon-dependent processes. In 2018, it was estimated that the emissions from global steel production represented 7–9% of direct emissions generated by fossil fuels. It was estimated that a specific emissions value of 1.8 tCO2 per ton of steel was produced due to the carbon-dependent nature of the traditional blast furnace and basic oxygen furnace (BF-BOF) route. Therefore, it is necessary to find an alternative solution to the BF-BOF route for steel production to counteract this negative trend, resulting in being sustainable from an environmental and economic point of view. To this concern, the objective of this work consists of developing a total cost function to assess the economic convenience of steelmaking processes considering the variability of specific market conditions (i.e., iron ore price, scraps price, energy cost, etc.). To this purpose, a direct reduction (DR) process fueled with natural gas (NG) to feed an electric arc furnace (EAF) using recycled steel scrap was considered. The approach introduced is totally new; it enables practitioners, managers, and experts to conduct a preliminary economic assessment of innovative steelmaking solutions under market uncertainty. A numerical simulation has been conducted to evaluate the profitability of the investment considering the economic and environmental costs. It emerged that the investment is profitable in any case from an economic perspective. On the contrary, considering the environmental costs, the profitability of the investment is not guaranteed under certain circumstances.


Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8349
Author(s):  
Alla Toktarova ◽  
Lisa Göransson ◽  
Filip Johnsson

In Europe, electrification is considered a key option to obtain a cleaner production of steel at the same time as the electricity system production portfolio is expected to consist of an increasing share of varying renewable electricity (VRE) generation, mainly in the form of solar PV and wind power. We investigate cost-efficient designs of hydrogen-based steelmaking in electricity systems dominated by VRE. We develop and apply a linear cost-minimization model with an hourly time resolution, which determines cost-optimal operation and sizing of the units in hydrogen-based steelmaking including an electrolyser, direct reduction shaft, electric arc furnace, as well as storage for hydrogen and hot-briquetted iron pellets. We show that the electricity price following steelmaking leads to savings in running costs but to increased capital cost due to investments in the overcapacity of steel production units and storage units for hydrogen and hot-briquetted iron pellets. For two VRE-dominated regions, we show that the electricity price following steel production reduces the total steel production cost by 23% and 17%, respectively, as compared to continuous steel production at a constant level. We also show that the cost-optimal design of the steelmaking process is dependent upon the electricity system mix.


Author(s):  
Abhinav Bhaskar ◽  
Mohsen Assadi ◽  
Homam Nikpey Somehsaraei

Reducing emissions from the iron and steel industry is essential to achieve the Paris climate goals. A new system to reduce the carbon footprint of steel production is proposed in this article by coupling hydrogen direct reduction of iron ore (H-DRI) and natural gas pyrolysis on liquid metal surface inside a bubble column reactor. If grid electricity from EU is used, the emissions would be 435 kg CO2/tls without considering methane leakage from the extraction, storage and transport of natural gas. Solid carbon, produced as a by-product of natural gas decomposition, finds applications in many industrial sectors, including as a replacement for coal in coke ovens. Specific energy consumption (SEC) of the proposed system is approximately 6.3 MWh per ton of liquid steel(tls). It is higher than other competing technologies, 3.48 MWh/tls for water electrolysis based DRI, and, 4.3-4.5 MWh/tls for natural gas based DRI and blast furnace-basic oxygen furnace (BF-BOF) respectively. Utilization of large quantities of natural gas, where the carbon remains unused, is the major reason for high SEC. Preliminary analysis of the system revealed that it has the potential to compete with existing technologies to produce CO2 free steel, if renewable electricity is used. Further studies on the kinetics of the bubble column reactor, H-DRI shaft furnace, design and sizing of components, along with building of industrial prototypes are required to improve the understanding of the system performance.


Author(s):  
Alex E. S. Green ◽  
Sean M. Bell

Solid waste (SW), mostly now wasted biomass, could fuel approximately ten times more of USA’s increasing energy needs than it currently does. At the same time it would create good non-exportable jobs, and local industries. Twenty four examples of wasted or under-utilized solids that contain appreciable organic matter are listed. Estimates of their sustainable tonnage lead to a total SW exceeding 2 billion dry tons. Now usually disposal problems, most of these SW’s, can be pyrolyzed into substitutes for or supplements to expensive natural gas. The large proportion of biomass (carbon dioxide neutral plant matter) in the list reduces Greenhouse problems. Pyrolysis converts such solid waste into a medium heating value gaseous fuel usually with a small energy expenditure. With advanced gas cleaning technologies the pyrogas can be used in high efficiency gas turbines or fuel cells systems. This approach has important environmental and efficiency advantages with respect to direct combustion in boilers and even air blown or oxygen blown partial combustion gasifiers. Since pyrolysis is still not a predictive science the CCTL has used an analytical semi-empirical model (ASEM) to organize experimental measurements of the yields of various product {CaHbOc} yields vs temperature (T) for r dry ash, nitrogen and sulfur free (DANSF) feedstock having various weight % of oxygen [O] and hydrogen [H]. With this ASEM each product is assigned 5 parameters (W, T0, D, p, q) in a robust analytical Y(T) expression to represent yields vs. temperature of any specific product from any specified feedstock. Patterns in the dependence of these parameters upon [O], [H], a, b, and c suggest that there is some order in pyrolysis yields that might be useful in optimize the throughput of particular pyrolysis systems used for waste to energy conversion (WEC). An analytical cost estimation (ACE) model is used to calculate the cost of electricity (COE) vs the cost of fuel (COF) for a SW pyrogas fired combined cycle (CC) system for comparison with the COE vs COF for a natural gas fired CC system. It shows that high natural gas prices solid waste can be changed from a disposal cost item to a valuable asset. Comparing COEs when using other SW capable technologies are also facilitated by the ACE method. Implications of this work for programs that combine conservation with waste to energy conversion in efforts to reach Zero Waste are discussed.


Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 758 ◽  
Author(s):  
Abhinav Bhaskar ◽  
Mohsen Assadi ◽  
Homam Nikpey Somehsaraei

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.


2021 ◽  
Vol 11 (16) ◽  
pp. 7246
Author(s):  
Julius Moritz Berges ◽  
Georg Jacobs ◽  
Sebastian Stein ◽  
Jonathan Sprehe

Locally load-optimized fiber-based composites, the so-called tailored textiles (TT), offer the potential to reduce weight and cost compared to conventional fiber-reinforced plastics (FRP). However, the design of TT has a higher complexity compared to FRP. Current approaches, focusing on solving this complexity for multiple objectives (cost, weight, stiffness), require great effort and calculation time, which makes them unsuitable for serial applications. Therefore, in this paper, an approach for the efficient creation of simplified TT concept designs is presented. By combining simplified models for structural design and cost estimation, the most promising concepts, regarding the cost, weight, and stiffness of TT parts, can be identified. By performing a parameter study, the cost, weight, and stiffness optima of a sample part compared to a conventional FRP component can be determined. The cost and weight were reduced by 30% for the same stiffness. Applying this approach at an early stage of product development reduces the initial complexity of the subsequent detailed engineering design, e.g., by applying methods from the state of the art.


2021 ◽  
Vol 48 (4) ◽  
pp. 3-3
Author(s):  
Ingo Weber

Blockchain is a novel distributed ledger technology. Through its features and smart contract capabilities, a wide range of application areas opened up for blockchain-based innovation [5]. In order to analyse how concrete blockchain systems as well as blockchain applications are used, data must be extracted from these systems. Due to various complexities inherent in blockchain, the question how to interpret such data is non-trivial. Such interpretation should often be shared among parties, e.g., if they collaborate via a blockchain. To this end, we devised an approach codify the interpretation of blockchain data, to extract data from blockchains accordingly, and to output it in suitable formats [1, 2]. This work will be the main topic of the keynote. In addition, application developers and users of blockchain applications may want to estimate the cost of using or operating a blockchain application. In the keynote, I will also discuss our cost estimation method [3, 4]. This method was designed for the Ethereum blockchain platform, where cost also relates to transaction complexity, and therefore also to system throughput.


Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6236
Author(s):  
Michael Samsu Koroma ◽  
Nils Brown ◽  
Giuseppe Cardellini ◽  
Maarten Messagie

The potential environmental impacts of producing and using future electric vehicles (EVs) are important given their expected role in mitigating global climate change and local air pollutants. Recently, studies have begun assessing the effect of potential future changes in EVs supply chains on overall environmental performance. This study contributes by integrating expected changes in future energy, iron, and steel production in the life cycle assessment (LCA) of EVs. In this light, the study examines the impacts of changes in these parameters on producing and charging future EVs. Future battery electric vehicles (BEV) could have a 36–53% lower global warming potential (GWP) compared to current BEV. The change in source of electricity generation accounts for 89% of GWP reductions over the BEV’s life cycle. Thus, it presents the highest GWP reduction potential of 35–48%. The use of hydrogen for direct reduction of iron in steelmaking (HDR-I) is expected to reduce vehicle production GWP by 17% compared to current technology. By accounting for 9% of the life cycle GWP reductions, HDR-I has the second-highest reduction potential (1.3–4.8%). The results also show that the potential for energy efficiency improvement measures for GWP reduction in vehicle and battery manufacture would be more beneficial when applied now than in the distant future (2050), when the CO2 intensity of the EU electricity is expected to be lower. Interestingly, under the same conditions, the high share of renewable energy in vehicle supply chains contributed to a decrease in all air pollution-related impact categories, but an increase in toxicity-related categories, as well as land use and water consumption.


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