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Valorization of Off Gases in Steel Making?
The paper to which I'll briefly refer in this post is this one: Valorizing the Steel Industry Off-Gases: Proof of Concept and Plantwide Design of an Electrified and Catalyst-Free Reverse Water–Gas-Shift-Based Route to Methanol Evangelos Delikonstantis, Panagiotis Vettas, Fabio Cameli, Marco Scapinello, Anton Nikiforov, Guy B. Marin, Kevin M. Van Geem, and Georgios D. Stefanidis Environmental Science & Technology 2023 57 (40), 14961-14972.
Let me just quote the first sentence in this paper to begin:
1. Introduction
Iron and steelmaking rank among the most polluting processes along with cement and commodity chemicals production, (1) possessing a 7%–9% share of the global annual CO2 emissions.
Iron and steelmaking rank among the most polluting processes along with cement and commodity chemicals production, (1) possessing a 7%–9% share of the global annual CO2 emissions.
I'm sure that many people here, having been handed a bunch of hooey about how the useless fossil fuel dependent wind industry would save the world, are disappointed with the fact that Oersted pulled out of the plan to make New Jersey's continental shelf into an industrial park, but personally, as an opponent of that industry on environmental grounds I'm thrilled.
News item: Offshore Wind Firm Cancels N.J. Projects, as Industry’s Prospects Dim
Subtitle:
Denmark’s Orsted said it would be forced to write off as much as $5.6 billion as wind developers in the U.S. faced wrenching financing costs.
Unlike the membership of the modern Sierra Club, I'm a John Muir type environmentalist, that is I believe wilderness (including benthic wilderness) should be protected from development, including energy development. (The New York Times article above quotes former NJ Sierra Club President Jeff Tittle whining about this happy development; Jeff Tittle never saw a huge stretch of wilderness in New Jersey that he didn't want to render into a gas dependent industrial plant. The NY Times, with its curious interpretation of reality identifies Mr. Tittle as an "environmental advocate." He's no such thing; he's an industrialization advocate. )
Anyway. As I pointed out very recently in this space referring to the bald faced lie that's been flying around for decades that it is faster to build than nuclear power plants, the wind industry, which according to the 2023 issue of the World Energy Outlook, has never not once produced even 1/3 of the energy that nuclear power has been producing for decades, this in an atmosphere of insipid attacks based on irrational fear and dogmatic ignorance, deliberate destruction of intellectual and industrial nuclear infrastructure using technology largely developed 50 years ago and seldom updated.
I covered a few days ago here: The 2023 World Energy Outlook Has Been Released. 632 EJ, 15 EJ from Solar and Wind in 2022.
If you want to know why the planet was on fire in the Northern Hemisphere Summer This Year, it may be useful to look at the following table, Table A.1a on Page 264 of the 2023 World Energy Outlook published by the International Energy Agency (IEA).
The useless and ineffective mass intensive wind industry is heavily dependent on the two materials listed in the first sentence of the article cited at the top of this post. Moreover, wind turbines have short life times and require rapid turnover:
A Commentary on Failure, Delusion and Faith: Danish Data on Big Wind Turbines and Their Lifetimes.
Anyway, making steel requires energy, lots of it, and the form of that energy is precisely that that wind and solar have a very hard time producing, heat energy.
From the introduction of the paper repeating that first sentence:
Iron and steelmaking rank among the most polluting processes along with cement and commodity chemicals production, (1) possessing a 7%–9% share of the global annual CO2 emissions. (2) To drastically reduce the carbon footprint of the steel industry, development of new processes and technologies for low-CO2 iron and steel production are needed. Several tactics are currently investigated, i.e., use of iron-rich raw materials and alternative fuels (pulverized coal, natural gas, biomass, or hydrogen) in the blast furnace, CO2 capture and storage, recycle and reuse of iron and steel scrap, or utilization of direct reduced iron in electric arc furnaces. Each alternative has certain technical advantages and downsides, which significantly depend on the production frame, e.g., availability, ease of transportation and distribution of the alternative raw materials and utilities, plant revamping cost, space requirements, etc. Yet, all approaches aim at reducing either the direct or indirect CO2 emissions of the iron and steelmaking process.
Alternatively, valorization of the steel industry off-gases to added-value chemicals, particularly to methanol (MeOH) due to its potential use as a precursor for plenty of commercial chemicals and as clean fuel, (3) has recently become a megatrend toward steel industry decarbonization. (4−6) In lieu of combusting the off-gases, i.e., blast furnace gas (BFG) and coke oven gas (COG), which contain CO2, CO, and H2, to produce electricity, MeOH is produced in a stepwise process; thereby, the GHG emissions of a steel shop are considerably reduced. (7) In this context, the reverse water–gas-shift (RWGS) reaction, i.e., CO2 + H2 ↔ CO + H2O, for syngas (a mixture of carbon monoxide (CO) and hydrogen (H2)) production is one of the main routes for CO2-based MeOH synthesis, although there are challenges pertaining to the economic viability and environmental impact of this thermocatalytic route. (8) In regard to the former aspect, the cost of H2 drives the economics. (8) Excess H2, usually greater than3 times the stoichiometric amount, is applied to shift the chemical equilibrium and thereby increase the single-pass CO2 conversion. Regarding the environmental impact, direct CO2 emissions attributed to the fossil-based heat provided to satisfy the reaction heat duty mitigates the CO2 abatement potential of the RWGS reaction. (9) Therefore, alternative CO2-to-MeOH technologies with higher economic potential and lower environmental burden should be developed.
Plasma technology could offer a promising solution for this application. Electricity-based activation of small stable molecules, such as CO2, is feasible through application of a strong electric field that induces a gas discharge, generating a highly reactive mix of electrons, ions, and excited species. In nonthermal plasma reactors, the gas temperature is well below the electron temperature (1–10 eV, corresponding to about 11,000–110,000 K), allowing the process to run under mild conditions (few hundreds to a thousand K) and atmospheric pressure. (10) Owing to their dependence on electric energy to initiate the discharge, plasma reactors are amenable to modular decentralized processes integrated with intermittently generated renewable power. Nonetheless, attaining a high energy efficiency in plasma-assisted processes is paramount for their large-scale deployment. Particularly, nanosecond pulse discharge (NPD) reactors enable efficient energy delivery to the system, (11) overcoming equilibrium limitations of conventionally heated reactors. (12)
Literature on syngas production via plasma-assisted RWGS is scarce. Most works report on the performance of dielectric barrier discharge (DBD) plasma reactors, either alone or coupled with complex catalytic materials to achieve high CO2 single-pass conversions at temperatures below 423 K. (13−16) Although greater than50% conversion can be attained, the catalyst stability at industrially relevant conditions along with the excessive energy inputs (greater than12,000 kJ/mol CO2) undermine the economic feasibility of the process at industrial level. Higher energy efficiency can be reached by integrating DBD with calcium looping... (17)
Alternatively, valorization of the steel industry off-gases to added-value chemicals, particularly to methanol (MeOH) due to its potential use as a precursor for plenty of commercial chemicals and as clean fuel, (3) has recently become a megatrend toward steel industry decarbonization. (4−6) In lieu of combusting the off-gases, i.e., blast furnace gas (BFG) and coke oven gas (COG), which contain CO2, CO, and H2, to produce electricity, MeOH is produced in a stepwise process; thereby, the GHG emissions of a steel shop are considerably reduced. (7) In this context, the reverse water–gas-shift (RWGS) reaction, i.e., CO2 + H2 ↔ CO + H2O, for syngas (a mixture of carbon monoxide (CO) and hydrogen (H2)) production is one of the main routes for CO2-based MeOH synthesis, although there are challenges pertaining to the economic viability and environmental impact of this thermocatalytic route. (8) In regard to the former aspect, the cost of H2 drives the economics. (8) Excess H2, usually greater than3 times the stoichiometric amount, is applied to shift the chemical equilibrium and thereby increase the single-pass CO2 conversion. Regarding the environmental impact, direct CO2 emissions attributed to the fossil-based heat provided to satisfy the reaction heat duty mitigates the CO2 abatement potential of the RWGS reaction. (9) Therefore, alternative CO2-to-MeOH technologies with higher economic potential and lower environmental burden should be developed.
Plasma technology could offer a promising solution for this application. Electricity-based activation of small stable molecules, such as CO2, is feasible through application of a strong electric field that induces a gas discharge, generating a highly reactive mix of electrons, ions, and excited species. In nonthermal plasma reactors, the gas temperature is well below the electron temperature (1–10 eV, corresponding to about 11,000–110,000 K), allowing the process to run under mild conditions (few hundreds to a thousand K) and atmospheric pressure. (10) Owing to their dependence on electric energy to initiate the discharge, plasma reactors are amenable to modular decentralized processes integrated with intermittently generated renewable power. Nonetheless, attaining a high energy efficiency in plasma-assisted processes is paramount for their large-scale deployment. Particularly, nanosecond pulse discharge (NPD) reactors enable efficient energy delivery to the system, (11) overcoming equilibrium limitations of conventionally heated reactors. (12)
Literature on syngas production via plasma-assisted RWGS is scarce. Most works report on the performance of dielectric barrier discharge (DBD) plasma reactors, either alone or coupled with complex catalytic materials to achieve high CO2 single-pass conversions at temperatures below 423 K. (13−16) Although greater than50% conversion can be attained, the catalyst stability at industrially relevant conditions along with the excessive energy inputs (greater than12,000 kJ/mol CO2) undermine the economic feasibility of the process at industrial level. Higher energy efficiency can be reached by integrating DBD with calcium looping... (17)
Methanol is potentially a clean fuel, and I often muse here and elsewhere about it, and an even superior fuel that can be made from it, dimethyl ether (DME).
(cf. A paper by Nobel Laureate George Olah: Anthropogenic Chemical Carbon Cycle for a Sustainable Future George A. Olah, G. K. Surya Prakash, and Alain Goeppert Journal of the American Chemical Society 2011 133 (33), 12881-12898)
However methanol is not and never will be, primary energy. As is the case with all the stupid hydrogen rhetoric that flies around, it requires more energy to make it than it contains as a consequence of the Second Law of Thermodyanmics, which no amount of chanting can repeal.
In any case, the authors are rather vague, despite advancing in their paper considerable insight to plasma routes to increase energy efficiency, about the ultimate source of energy. It comes in the form of a black box, "electricity." Electricity, like hydrogen, like methanol, is a thermodynamically degraded form of energy, and the use of electricity to make either hydrogen or methanol involves the most thermodynamic degradation. (Hydrogen and methanol can be made directly from thermal energy at a lower thermodynamic cost, and cleanly if the heat source is nuclear, but that's another matter.)
Here's some graphics from the paper describing some of the energy costs of this process and it's carbon intensity:
The caption:
Figure 5. Calculated key performance indicators which affect the profitability of the whole CO2-based methanol production network in industrial environments. Methanol production, electric energy, cooling water, and low pressure steam demand are calculated for every set of nanosecond pulsed discharge (NPD) reactor operating conditions: (A) 1:1 H2:CO2 feed ratio and (B) 3:1 H2:CO2 feed ratio.
The caption:
Figure 7. Performance of the overall plasma-assisted MeOH production process in terms of utilities, i.e., low pressure steam, cooling water, and total electric energy demand, and MeOH throughput normalized by mass of feed CO2: (A) set of NPD operating conditions #1–#4 (H2:CO2 = 1) and (B) set of NPD operating conditions #5–#8 (H2:CO2 = 3).
The conditions discussed in Figure 7 are described in the text.
A note on plasma: My son and I were discussing fusion energy the other day on the phone, remarking on how it is unlikely to ever be commercially viable, although many of the people in his lab after obtaining their Ph.Ds go to work for the fusion companies that have been cropping up recently.
From the time my son was in Junior High School until his graduation from high school, and sometimes during his undergraduate winter breaks, we have often attended the marvelous Science on Saturday lectures at the Princeton Plasma Physics Laboratory now hosted by the marvelous NJ State Senator Andrew Zwicker. (I'd love to see Dr. Zwicker in Congress someday.) The raison d'être for the lab is, of course, belief that fusion energy will someday be commercially available, and usually two or three lectures in the series each winter touch on developments in that field.
As we enjoy the lectures, and have availed ourselves of the marvelous opportunity that the labs represent, we feel guilty about the fact that neither of us actually believe that fusion energy will ever be an economically viable thing, if only on the grounds of materials science.
However the point is also made at the lab that plasma as a state of matter is not only scientifically interesting, but it has many practical applications. Indeed in our discussion I raised this point. A heat exchange device in fission reactors about which I have long mused and which I am working to hand off to him as a subject of musing will involve gaseous radioactive plasmas, and thus the work at the Princeton Plasma Physics Laboratory is of high value to humanity for physics reasons alone, even if, as we suspect, fusion - which in any case is already too late as are all other schemes to address climate change - will never be a commercially viable technology.
Plasma methanol synthesis may be a good thing, but in any discussion of this type we should be aware that energy inputs are required, since perpetual motion machines do not and cannot exist.
Have a nice day tomorrow.