energies

Article
The Bio Steel Cycle: 7 Steps to Net-Zero CO2 Emissions
Steel Production
Sandra Kiessling, Hamidreza Gohari Darabkhani * and Abdel-Hamid Soliman

Department of Engineering, Staffordshire University, Mellor Building, College Road, Stoke-on-Trent ST4 2DE, UK
* Correspondence: h.g.darabkhani@staffs.ac.uk

Abstract: CO2 emissions have been identified as the main driver for climate change, with devastating
consequences for the global natural environment. The steel industry is responsible for ~7–11%
of global CO2 emissions, due to high fossil-fuel and energy consumption. The onus is therefore
on industry to remedy the environmental damage caused and to decarbonise production. This
desk research report explores the Bio Steel Cycle (BiSC) and proposes a seven-step-strategy to
overcome the emission challenges within the iron and steel industry. The true levels of combined CO2
emissions from the blast-furnace and basic-oxygen-furnace operation, at 4.61 t of CO2 emissions/t of
steel produced, are calculated in detail. The BiSC includes CO2 capture, implementing renewable
energy sources (solar, wind, green H2 ) and plantation for CO2 absorption and provision of biomass.
The 7-step-implementation-strategy starts with replacing energy sources, develops over process
improvement and installation of flue gas carbon capture, and concludes with utilising biogas-derived
hydrogen, as a product from anaerobic digestion of the grown agrifood in the cycle. In the past,
CO2 emissions have been seemingly underreported and underestimated in the heavy industries, and
implementing the BiSC, using the provided seven-steps-strategy will potentially result in achieving
net-zero CO2 emissions in steel manufacturing by 2030.

Citation: Kiessling, S.; Darabkhani, Keywords: net-zero steel; CO2 emissions; Bio Steel Cycle (BiSC); CAT; CCUS; flue stack gas scrubbing
H.G.; Soliman, A.-H. The Bio Steel
Cycle: 7 Steps to Net-Zero CO2
Emissions Steel Production. Energies
2022, 15, 8880. https:// 1. Introduction
doi.org/10.3390/en15238880
The requirement to drastically reduce GHG emissions, and particularly CO2 emissions,
Academic Editors: Francesco has never been greater than today. The Kyoto Protocol, the Paris Agreement, and recent
Corvaro, Barbara Marchetti and 2022 reports from the IPCC have clearly set out the impact that the highest-ever recorded
Matteo Vitali anthropogenic CO2 emissions are having on our environment and climate. With the
Received: 1 November 2022
iron and steel industry being responsible for at least between 7% and 11% of global CO2
Accepted: 19 November 2022
emissions [1–10] and China being responsible for 50% of these GHGs [2], the factual level
Published: 24 November 2022
of CO2 emissions for every t of steel produced currently stands at more than 4.6 t of CO2
emissions [11]. The onus is therefore on industry to remedy the environmental damage
Publisher’s Note: MDPI stays neutral
caused in the past two centuries [11–16]. The anthropogenic carbon emissions are at an
with regard to jurisdictional claims in
all-time-high with reported ~65.6 Gt CO2 -equivalent in 2019 [11–16]. The 64 steel producing
published maps and institutional affil-
countries reported 1.9 Gt of steel produced between January and December 2021 [17–21],
iations.
and—based on the current findings—are likely resulting in 8,806,211,400 t or ~8.8 Gt
CO2 -equivalent of CO2 emissions as a result of the current linear steel manufacturing.
The importance to significantly reduce GHGs and eliminate fossil fuel combustion and
Copyright: © 2022 by the authors.
usage has never been greater, and fast, practical solutions—on a global scale—are needed.
Licensee MDPI, Basel, Switzerland. Already in 1912, it was recognised that coal consumption is an environmental hazard and
This article is an open access article incompatible with keeping global temperatures at a balanced level to sustain life. Industrial
distributed under the terms and processes have for more than 200 years polluted the air we breathe, and this was already
conditions of the Creative Commons recognised in 1912 [22].
Attribution (CC BY) license (https:// It is worth pointing out that in this article [22], merely the in-furnace-coal-combustion
creativecommons.org/licenses/by/ process is mentioned in connection with carbon emissions. CO2 emissions from energy con-
4.0/). sumption, mining, pelletising, coking, sintering, steel smelting, casting, rolling, annealing,

Energies 2022, 15, 8880. https://doi.org/10.3390/en15238880 https://www.mdpi.com/journal/energies

Energies 2022, 15, 8880 2 of 22

finish machining and surface treatment and related processes were not considered at that
time. These authors have already, more than a hundred years ago, established the emission
factor as being 3.5: as 7,000,000,000/CO2 emissions./.2,000,000,000 t of steel equates to 3.5 t
of CO2 emissions in the blast furnace operations per tonnes of steel. These assumptions
and calculations were possibly based on the carbon content of coal (78–95%) [5,23,24] and
the release of CO2 into the atmosphere as a result of combustion processes. Although the
steelmaking process has undergone significant improvements, the basic oxygen furnace
(BOF) operation alone still stands at CO2 emissions of between 2.2 t and 1.6 t/CO2 /t of
steel produced. This begs the question why this knowledge has not been used to establish
the true CO2 emissions of the steelmaking process over the past 2 centuries. Why has the
iron and steel industry not reacted immediately after having been made aware in 1912 of
the devastating environmental consequences of their operations?
The current state of the decarbonisation of the iron and steel industry has been care-
fully reviewed and key publications have been identified. A direction-giving quality can be
attributed to Bataille et al.’s (2018/2021) publications [25,26], as this provided key compo-
nents to develop the BiSC model and strategy and set the foundations to establish the seven
steps to net-zero carbon steelmaking. Invaluable insights were provided regarding decar-
bonisation of the iron and steel industry, “green” steel in particular and the mechanisms
and processes necessary to achieve sustainable and carbon-free iron and steel production.
Setting the scene, Muslemani et al. (2021) [27] worked on identifying the opportunities and
challenges for decarbonising steel production by creating markets for “green” steel products.
Their in-depth investigation provides valuable insight into potential markets for green steel
products and their manufacturers and to make the economic case for sustainable produc-
tion. Arens, Åhman, and Vogl (2021) [28] researched which countries are factually prepared
to “green” their coal-based steel industry with electricity and reviewed respective climate
and energy policy. They subsequently published policy guidance by country for “green”
steelmaking. One of the key papers to provide the technical insight into the vital compo-
nents of sustainable steel is Wang et al.’s (2022) and Wang’s (2022) [29,30] investigations of
the opportunities for technology-driven decarbonisation and green steel for Australia. They
carried out economic modelling of a green steel value chain with wider implications for the
second- and third-tier small-to-medium enterprises and heavy industry. Models, pathways,
and roadmaps are guiding the industry on the path to decarbonisation, and therefore
Bataille, Nilsson, and Jotzo’s (2021) [26] study was considered a key paper. They provided
some components for the BiSC (Bio Steel Cycle) model [10] when they looked at the iron
and steel industry in a net-zero emissions world. They identified new mitigation pathways,
new supply chains, modelling needs, and policy implications. Their mitigation pathways
investigation towards decarbonisation of steelmaking provided invaluable analysis and
insight into supply chains and policy needs. Liu et al.’s (2022) and Liu et al.’s (2020) [31,32]
work created a technological roadmap towards optimal decarbonisation development of
China’s iron and steel industry. They developed policy guidance exploring the deep de-
carbonisation pathways. Richardson-Barlow et al. (2022) [33] identified policy and pricing
barriers to steel industry decarbonisation during their case study of the UK iron and steel
industry. They issued a guidance paper, exploring the decarbonisation pathways. One of
the paths towards decarbonisation of the iron and steel industry is using hydrogen, and
particularly hydrogen direct reduction. The discussion around H2 has gained more momen-
tum again, and Öhman, Karakaya, and Urban (2021) [34] researched the transition potential
into a fossil-free steel sector and identified the necessary conditions for technology transfer
to hydrogen-based steelmaking in Europe. Toktarova et al. (2020) [35] investigated the low-
carbon steel industry interactions between the H2 DR of steel and the electricity system via a
Swedish case study. Toktarova (2021) [36] created a cost-optimal design of the steelmaking
industry and electricity system with close to “0” CO2 and produced another key paper to-
wards the creation of the BiSC model. Matino and Colla (2021) [37] took a slightly different
approach when they endeavoured to issue a guidance paper and overview of the state of
the art, recent developments, and future trends regarding a hydrogen route for a green
Energies 2022, 15, 8880 3 of 22

steelmaking process. In their opinion, steel production based on hydrogen is one of the key
factors to improve the carbon footprint of the steel industry. A more global perspective was
taken by García-Herrero, Tagliapietra, and Vorsatz (2021) [38], within their development of
hydrogen development strategies. They see hydrogen as a candidate to fully decarbonise
European steelmaking, global aviation, and maritime transport. Grasa et al. (2022) [39]
investigated the blast furnace gas decarbonisation through calcium-assisted steel-mill off-
gas hydrogen production. They took an experimental and modelling approach to the
calcium-assisted steel-mill off-gas H2 production process (CASOH) in integrated steelmak-
ing plants. Devlin and Yang (2022) [40], however, focused more on regional issues when
researching supply chain implications and their potential for decarbonising steel. Their
focus was energy efficiency and green premium mitigation, green hydrogen-based iron ore
reduction, and renewable electricity-based steelmaking. Case studies, such as Gosens, Turn-
bull, and Jotzo’s (2021) [41] work concentrated on a highly granular model of China’s coal
production, transport, and consumption system. Their work shows how its decarbonisation
and energy security plans will affect coal production and the effect of decarbonisation
on coal imports. Griffin and Hammond (2019/2021) [42,43], however, cast the net wider
with the focus on global transitions and investigation into making UK steel production
more environmentally benign whilst advancing decarbonisation of the iron and steel sector.
Lu et al. (2022) [44] also provided insight into China’s iron and steel industry decarbonisa-
tion options, based on a 3-dimensional analysis. Whereas Steenbrink (2022) [45] focused on
the impact of the Carbon Border Adjustment Mechanism and conducted an economic and
geopolitical assessment of the German–Chinese aluminium trade flows. That paper pro-
vides a thorough assessment on how best to incentivise non-EU trade partners, and to adopt
measures comparable to the EU’s and—simultaneously—assessment of yield revenue to
reuse in accelerating decarbonisation of steelmaking. In terms of carbon avoidance, capture
and utilisation, Kempken et al. (2021) [46] identified possible decarbonisation barriers (De-
liverable 1.5). The isolation of major barriers to the decarbonisation process of the EU iron
and steel industry provides valuable insights into the reasons why the industry seems quite
reluctant to decarbonise its existing production and facilities. Williams et al. (2021) [47]
conducted a case study, during which they focused on CO2 capture and storage (CCS)
and presented the results of focus group discussions in a Welsh steelmaking community.
The topic of decarbonisation of steel production by switching to renewable sources was
welcomed during the local focus group discussions and showed widespread support in the
community for the company’s efforts in this direction. Tanzer, Blok, and Ramirez (2021) [48]
went one step further by focusing their research on integration of biomass when they in-
vestigated the decarbonisation opportunities via BECCS: promising sectors, challenges,
and techno–economic limits of negative emissions and BECCS in the iron and steel in-
dustry. Sarić, Dijkstra, and Van Delft (2021) [49] considered CO2 abatement in the steel
industry through carbon recycle and electrification by means of advanced polymer mem-
branes. For this, a conceptual process design and assessment was performed for a process
that is a combination of carbon recycling and electrification of the steelmaking process.
Wang (2022) [30] focused more on energy saving technologies and optimisation of energy
use for a decarbonised iron and steel industry. A valuable guidance paper was issued in
which suitable decarbonisation technologies are categorised. A different approach was
taken by Singh et al. (2022) [50], as they researched the opportunities of decarbonisation
of steel-mill gases in an energy-neutral chemical looping process, providing the technical
elements for carbon enrichment for plant stimulation (CEPS), which is based on flue-stack
gas scrubbing. In addition to CAT, CCUS, and BECCS, waste recycling is a vital part of the
decarbonisation process. Jacob, Sergeev, and Müller (2021) [51] provided a thorough review
when they investigated the potential of valorisation of waste materials for high temperature
thermal storage. An overview of the decarbonisation process was presented, of both the
electricity and steelmaking industry. Sun (2022) [52] seemed to have worked along the same
lines and developed a concept for the decarbonisation of the iron and steel sector for a 2◦ C
target, using inherent waste streams. Furthermore, other aspects of decarbonisation need to
Energies 2022, 15, 8880 4 of 22

be considered, as Antonazzo et al. (2021) [53] pointed out: A key component of the transi-
tion process to decarbonisation is the need for meeting green-skills needs for a sustainable
steel industry. They identified the skills required for a steel industry in transition to sustain-
ability. Zhiming et al. (2021) [54] researched material-based decarbonisation implications
and how lime quality affected metallurgical steel quality and the value in use of lime in the
BOF steelmaking process. Garvey, Norman, and Barrett (2022) [55], however, focused on
technology and material efficiency scenarios for net-zero emissions in the UK steel sector.
Their assessment included steel-plant retrofitting and grid electricity decarbonisation.
So far, high asset cost and long amortisation periods (in excess of 25 years) of capital
equipment are making it difficult for steel manufacturers to honour their obligation to
decarbonise and clean up their production processes. However, even if only parts of the
BiSC and 7-steps strategy are being implemented, carbon neutrality can be achieved in the
short-term: Switching energy suppliers to those who derive their energy from renewable
sources can achieve a 30% reduction in emissions. Adding filter and Geomimetic© systems
would capture the remaining CO2 .
The objectives of this multi-disciplinary and multi-industry overarching study are
to identify the most efficient implementation opportunities of the chosen processes and
technologies to reduce the current BF–BOF route 4.6 t CO2 emissions/t of steel produced to
factual ”0”. These are ordered in seven easy steps, from short-term to long-term solution
implementation. This work appears to be one of the first of its kind (to date), as it so
seems that neither in academia, nor industry, nor politics have suitable models, strategies
or guidance papers been published to explain how net-zero steelmaking can be achieved.
If only individual steps are being implemented, such as switching to renewable energy
suppliers, a 30% reduction of GHG emissions can be achieved.

2. Materials and Methods

The research used global steel data and literature on sustainability, decarbonisation,
and CAT, CCS, and CCUS technology. The main reason underpinning this choice and course
of research is that, as suggested by the Steel Yearbook 2018/2019 [17,19] the global iron and
steel industry is still heavily reliant on coal and is responsible for at least between 7% and
11% of global CO2 emissions [1–10,56], and China is responsible for 50% of these GHGs [2].
The impact of different technologies [35] on the processes at all stages in the steelmak-
ing process [43], decarbonisation of the iron and steel manufacturing [1–10,17–21,23–55],
and related databases and corresponding literature [56–145] were investigated. Addition-
ally, literature regarding CAT, CCS, and CCUS and the circular economy, sustainability, and
decarbonisation of the steel industry were categorised for ease of implementation, from
easy to more challenging and depending on duration.
An Excel database was used for data collection, modelling, and key calculations. The
parameters were defined as t of CO2 per t of steel produced, although further parameters for
future research are being allowed. The research works with metric tonnes only. Formulae
were developed and adjusted [57,58], as follows:
(1) CO2 Etotal = ∑(emissions per ton of steel) × Ω (output tons produced)
(2) 1 charge (400 tons in 40 min)

CO2 Etotal,1c = ∑(CO2 REcoal + CO2 REore +CO2 REoxy + CO2 PTcoal +CO2 PTlime + CO2 STsint +CO2Smelt +
CO2 BF + CO2 BOF + CO2 C + CO2 M + CO2 FM) × (CapBF × t)

In order to determine the BF/BOF-route CO2 emissions, the formula had to be adjusted,
accordingly, to [65,66,119]:
(3) CO2 Etotal = ∑(CO2 BF + CO2 BOF)
CO2 Etotal = Total CO2 emissions
CO2 REcoal = CO2 emissions resource extraction coal
CO2 REore = CO2 emissions resource extraction iron ore
CO2 REoxy = CO2 emissions resource extraction oxygen
 CO2REcoal = CO2 emissions resource extraction coal
CO2REore = CO2 emissions resource extraction iron ore
CO2REoxy = CO2 emissions resource extraction oxygen

Energies 2022, 15, 8880

CO2PTcoal = CO2 emissions primary resource transformation coal> coke 5 of 22
CO2PTlime = CO2 emissions primary resource transformation limestone> lime
CO2STsint = CO2 emissions secondary resource transformation coke/iron ore> sinter
CO22Smelt
CO PTcoal = CO
= CO 2 emissions
2 emissions primary resource transformation coal> coke
smelting
CO2 PTlime = CO2 emissions primary resource transformation limestone> lime
CO2BF = CO2 emissions blast furnace
CO2STsint = CO2 emissions secondary resource transformation coke/iron ore> sinter
CO 2BOF =
CO2Smelt = CO
CO22 emissions
emissions basic oxygen furnace
smelting
CO2C BF==CO
CO 2 emissions
2 emissions blast furnace
casting
CO BOF = CO
CO22M = CO2 emissions
2 emissions basic oxygen furnace
milling
CO2 C = CO2 emissions casting
CO
CO22FMM ==COCO2emissions
emissionsmilling
finish machining
2
CapBF
CO2 FM==Capacity blast furnace
CO2 emissions / basic oxygen furnace
finish machining
CapBF = Capacity blast furnace
t = time (charges per day) 400 tonnes / basic
peroxygen
chargefurnace
every 40 min,
t = time (charges per day) 400 tonnes per charge every 40 min,
Ø of 10,000 tonnes/day
Ø of 10,000 tonnes/day
Additionally, engineering simulation software was used, such as Simul8 and Aspen
Additionally, engineering simulation software was used, such as Simul8 and Aspen
Plus V11. The Simul8 and Aspen Plus V11 models are being adjusted continuously to meet
Plus V11. The Simul8 and Aspen Plus V11 models are being adjusted continuously to
the different applications of carbon avoidance, carbon saving, and carbon utilisation tech-
meet the different applications of carbon avoidance, carbon saving, and carbon utilisation
nologies, in accordance with the strategy flowchart in Figure 1:
technologies, in accordance with the strategy flowchart in Figure 1:

steel linear
Figure 1. Simul8 steel linear production
productionconfiguration.
configuration The
*. * The colour-coding
colour-coding within
within Figure
Figure 1 is
1 is identical
identical to the master database (Excel), which has been created to gather and display findings,
to the master database (Excel), which has been created to gather and display findings, facts, and
facts, and
figures, figures,
and and is to
is supposed supposed to signify
signify the energy the energyand
intensity intensity and heat development
heat development at the
at the different stages
different stages of the steelmaking
of the steelmaking process in C. ◦ process in °C.

3. The Bio Steel Cycle Components and 7-Steps Principles

The conventional linear steel manufacturing process, including all processes such as
coal, iron ore, and limestone extraction, crushing, pelletising, sintering, smelting, casting,
casting,
rolling, and finish machining, was investigated and resulted in establishing that the BF/BOF
route alone produces ~4.6 t of CO2 emissions, which are one of the undesired by-products
of every metric t of steel produced. The results to date of research into the CO2 emissions
at the various stages of the steelmaking process and related sub-processes have been
established, and the findings of the BF/BOF route are displayed in Appendix 5. CO2
emissions as a direct result of steel manufacture increased by 1.6% or 8.7 Gt/CO2 in 2020,
although in the Net-Zero-Emissions-by-2050 scenario, industry emissions are estimated to
decrease by 2.3% annually at 6.9 Gt/CO2 by 2030, despite expected industrial production
growth [4]. Improved material and energy efficiency, the increased utilisation of renewable
energy technologies, and development and deployment of low-carbon process routes
(including CCS and hydrogen) are considered to have an emission-reduction effect of
individually between 12 and 30%. Fossil-fuel-derived energy generation and combustion of
fossil fuels for transport (including aviation) are the two biggest sources of CO2 emissions,
worldwide [3–5,13,35,56,59]. Steel production is in close third place, followed by cement
production and the chemical and glass industries [3–5,13,35,56,59].
Energies 2022, 15, 8880 6 of 22

One possible solution to combat this issue is the Bio Steel Cycle (BiSC) as a model,
based on the circular tech economical principle. Steel scrap is considered a resource, and
similar to recycling waste and by-products, is an integral part of the circular production
process. Off-gases (CO2 and other GHGs) are being captured and reutilised, and alongside
implementation of steelmaking process improvements, furnace heat capture and utilisa-
tion, CAT, CCS, and CCUS technologies and processes, and multi-disciplinary external
components, are closing the circle [14,15,25,26,35,59,60].
Suitable literature was thoroughly investigated in regard to applied and innovative
steelmaking procedures, CAT, CCS, and CCUS processes, and improved management
systems such as industry 4.0 (I4.0) [61,62]. The literature investigating the most efficient
and effective technologies, process improvement suggestions, and technologies at suitable
technical readiness levels (TRL 6–9) was analysed, and the conclusions derived led to the
creation of the components within the Bio Steel Cycle and the 7-stepsstrategy to net-zero
steel manufacturing.
The most likely scenarios were considered, and the principles of the Bio Steel Cycle
model are applicable to most heavy industries, such as cement, chemical, glass, paper, and
transport. It includes using renewable energy technologies, avoiding CO2 emissions by
incorporating process improvement technologies, recycling waste and by-products,7 and
Energies 2022, 15, x FOR PEER REVIEW of 24
capturing post-combustion emissions where possible [14,15,25,26,35,59,60], as displayed
in Figure 2:

Figure 2.
Figure 2. The
The Bio
Bio Steel
Steel Cycle
Cycle concept
concept and
and cyclical
cyclical resource
resource utilisation
utilisationflow.
flow.

Analyses
Analysesof ofthe
thetechnical
technicalandandeconomical
economical long-term
long-term potential of novel
potential steel
of novel production
steel produc-
technologies CAT, CCS, and CCUS and in the UK [63–66], Germany [67]
tion technologies CAT, CCS, and CCUS and in the UK [63–66], Germany [67] and beyond and beyond used
techno–economic
used techno–economic models models
to modeltothree research-stage
model [35,43,59,64][35,43,59,64]
three research-stage ore-based steelmaking
ore-based
routes versusroutes
steelmaking the BF–BOF
versus route [68]. It route
the BF–BOF was concluded
[68]. It wasthat in comparison,
concluded the BF with
that in comparison,
CCS1
the BF(BFCCS)
with CCS1[6–9,67], hydrogen
(BFCCS) direct
[6–9,67], reduction
hydrogen (H-DR)
direct [6–9],
reduction and iron
(H-DR) oreand
[6–9], electrolysis
iron ore
(EW) [35,36],
electrolysis energy
(EW) andenergy
[35,36], raw material
and rawefficiency is significantly
material efficiency higher for
is significantly H-DRforand
higher H-
EW [6–9,67–70] and the 80% reduction target by 2050 [71] was thought
DR and EW [6–9,67–70] and the 80% reduction target by 2050 [71] was thought to be per- to be perfectly
achievable in the scenario,
fectly achievable as per as
in the scenario, Tata Steel’s
per Zeremis
Tata Steel’s vision much
Zeremis visionsooner, by 2045by
much sooner, [72].
2045It
was found that there are a sufficient number of viable CAT, CCS, and CCUS
[72]. It was found that there are a sufficient number of viable CAT, CCS, and CCUS tech- technologies,
methods, and strategies
nologies, methods, at TRL 7–9
and strategies available
at TRL for immediate
7–9 available BiSC implementation
for immediate BiSC implementa- and
achieving short- to medium-term
tion and achieving significant reduction
short- to medium-term significantofreduction
CO2 emissions
of COin steelmaking.
2 emissions in

steelmaking. The urgency for sufficient prioritisation throughout all industries and polit-
ical willingness (subsidies) cannot be emphasised enough [14,15,71]: the need to create a
viable commercial environment, due to the required high capital investment and a signif-
icant dependency on electricity prices [35,56,73,74].
Energies 2022, 15, 8880 7 of 22

The urgency for sufficient prioritisation throughout all industries and political willingness
(subsidies) cannot be emphasised enough [14,15,71]: the need to create a viable commercial
environment, due to the required high capital investment and a significant dependency on
electricity prices [35,56,73,74].
The following key components within the Bio Steel Cycle are based on a circular
production process and are functioning in an interactive manner. The basis for this system
is the BF/BOF route and involves the aforementioned CAT, CCS, and CCUS and process im-
provements where possible. Innovative technologies such as Hisarna [70] and GrInHy [75]
and hydrogen direct reduction (HDR) have CO2 saving potential in their own right, as
explained in more detail, as follows. By removing coal as a primary energy source or
using hydrogen direct reduction, an immediate 30% CO2 emissions reduction is possible,
and therefore [31,35,64,76–78], replacing coal with biomass or hydrogen would reduce
the CO2 emissions from steelmaking potentially by the same percentage. According to
Siemens (2022) [79], a 50% carbon emissions reduction is immediately possible via utilisa-
tion of green hydrogen direct reduction. The standard steel production (SSP) process in
combination with the currently operational newly developed technologies [35,69,70,72] also
achieves a reduction of more than 50% with successive implementation to less than three
metric tonnes/t of steel produced. By incorporating the BiSC components of CAT, CCS,
and CCUS into existing steel production sites, an almost 100% CO2 emission reduction can
be achieved, immediately.
The post-combustion capture of CO2 (CCS) and other GHGs and the exploration of
carbon scrubbing of flue gases were explored. There are several possible technologies and
processes to be considered for post-combustion carbon capture:
- Mechanical capture;
- Compression and dehydration;
- Membrane installation;
- Guiding off-gas through troughs of physical solvents/solid sorbents (such as Zeo-
lite13X) and chemical solvents;
- Utilising metal-/organic frameworks [25,26,43,59,80].
Renewable energy technologies are one of the key components within the Bio Steel
Cycle, as CO2 emissions in steelmaking could be reduced by more than 30% [81] if com-
mercial entities in iron and steel production [25,26,82] were to simply switch their energy
providers [59] to those that supply energy which was derived using 100% renewable energy
technology and produce their own energy by retrofitting their plants with renewable energy
technologies (wind, solar PV). The same applies to greenhouses, as there is a vast amount
of roof space available, which has to date not been utilised. The static requirements would
obviously have to be considered, but as the cost and weight of solar energy and solar PV
has decreased significantly over recent years (Dastoor, 2021) [92] to less than GBP 3/m2
and to a foil body in appearance, it can be considered an unmissable opportunity.
In the spirit of innovative, multi-disciplinary approaches to solving contemporary
CO2 emission issues, the positive effects of DAC (Direct Air Capture) and utilisation
of woodlands for carbon capture cannot be emphasised enough. As one of the critical
components of the BiSC, woodlands/trees for DAC would even be a profitable side-line
for steel producers, as illustrated in the following Figure 3:
Trees and vegetation as natural carbon sinks should ideally be planted around steel
production plants to absorb the remaining CO2 emissions via direct air capture (DAC) [83–85],
whilst at the same time, the plant matter could feed the anaerobic digester, biochar plants or
be directly used at selected quality in iron and steelmaking as readily available biomass. In
this respect, bamboo beats deciduous native plants with its carbon sequestration capacities:
on average, one hectare of bamboo stand absorbs ~17 tonnes of carbon per year [86]. Native
deciduous and non-deciduous trees have a carbon sequestration capacity of on average 9 t
of CO2 /ha of tree plantation [6–9,83–85]. Planting a sufficient number of trees should be
considered in the planning for the updating of existing steel production plants and for any
new development in order to meet the UK government’s zero emissions targets. The UK tree
 Cycle, as CO2 emissions in steelmaking could be reduced by more than 30% [81] if com-
mercial entities in iron and steel production [25,26,82] were to simply switch their energy
providers [59] to those that supply energy which was derived using 100% renewable en-
ergy technology and produce their own energy by retrofitting their plants with renewable
Energies 2022, 15, 8880 energy technologies (wind, solar PV). The same applies to greenhouses, as there is a vast 8 of 22
amount of roof space available, which has to date not been utilised. The static require-
ments would obviously have to be considered, but as the cost and weight of solar energy
and solarstands
cover PV hasatdecreased
13.2% (3.2significantly over recent
million ha, 66.65 m peopleyears (Dastoor,
= 0.048 2021)
ha per [92] [83,84],
capita) to less than
which
GBP 3/m2 and to a foil body in appearance, it can be considered an unmissable
is the lowest in the Northern hemisphere. In comparison, forests, and wooded land oppor-
cover
tunity.
over 182 million hectares in the EU, which is about 42% of the EU’s total land area. This
In thetospirit
equates of innovative,
0.36 hectares of forestmulti-disciplinary
per capita in the EUapproaches to solving
in comparison contemporary
[6]. Woodlands not only
COcapture
2 emission issues, the positive
post-combustion CO2 andeffects
createofbiomass
DAC (Direct Air Capture)
for anaerobic and
digestion, utilisation
but they also ofmay
woodlands for carbon
create recreation capture cannot
and employment be emphasised
opportunities enough. As
and additional one of
sources of the critical com-
commercial activity.
ponents of the they
Additionally, BiSC,offer
woodlands/trees for DACfor
a low-cost opportunity would even be a profitable
carbon-offsetting, which couldside-line
be seenfor
as a
steel producers, as illustrated
commercial opportunity in itself.in the following Figure 3:

Figure 3. Woodland creation graph.

Figure 3. Woodland creation graph.
Food production in greenhouses, anaerobic digestion, and sewage treatment plants
Trees and vegetation as natural carbon sinks should ideally be planted around steel
require a stable ambient temperature throughout the year, which requires a conventional
production plants to absorb the remaining CO2 emissions via direct air capture (DAC)
source of heating. Re-using heat from the steelmaking process, the expenditure of installing
[83–85], whilst at the same time, the plant matter could feed the anaerobic digester, bio-
heating systems and using fuel and energy is simply not required, as the air has already
char plants
been or be directly
heated. Although used
theatinstallation
selected quality
of a in iron and
suitable steelmaking would
infrastructure as readily avail-
have to be
able biomass. In this respect, bamboo beats deciduous native plants with its
considered, the economical case must be further investigated, and the financial viability, carbon se-
questration capacities: on average, one hectare of bamboo stand absorbs
such as the cost of ducts and pipework against the installation of a heating and cooling ~17 tonnes of
carbon per year [86]. Native deciduous and non-deciduous trees have a carbon
system including energy requirements, need to be solid to make a case for re-utilising sequestra-
tion capacity off-heat.
flue-stack of on average 9 t of CO2/ha
The flue-stack heatofcan
treebe
plantation
as high as [6–9,83–85]. Planting
1650 ◦ C and wouldahavesufficient
to cool
number of trees should be considered in the planning for the updating of
down, i.e., via travelling through adequately sized pipework, ducts, and possibly turbinesexisting steel
production
(which inplants and for
their own any
right new development
would possibly be able in order to meet
to generate the UK government’s
electricity, via convection,
zero emissions targets. The UK tree cover stands at 13.2%
baffle systems or plate-heat exchangers). The energy saved on heating(3.2 million ha, 66.65
food m people
production
= 0.048 ha per capita) [83,84], which is the lowest in the Northern hemisphere. In compar-
facilities is deserving of further investigation, as this will effectively contribute to achieving
ison, forests,
net-zero and wooded
carbon land
emissions coverproduction.
in steel over 182 million hectares in the EU, which is about
Additionally, incorporating the CEPS (Carbon Enrichment for Plant Stimulation) pro-
cess into the BiSC-based circular steelmaking process [30,80] involves CCUS by means
of driving CO2 -enriched flue-stack off-gas from combustion processes into CEPS units.
Subsequently, this at almost 100% carbon enriched air is then directed into greenhouses to
stimulate plant growth. The chosen CEPS model is deemed scalable and has the capacity
to provide 85 tonnes of CO2 p.a. in its current configuration [80]: concentrating CO2 from
ambient air (400 ppm) into an enriched product stream at 1000 ppm CO2 . Locating the
source of CO2 , i.e., flue gases from production in steel, cement [87] or energy production
and greenhouses in proximity of each other eliminates costs associated with filtering, deac-
tivation, compression, transportation, handling, distribution, and storage entirely. Every
successfully installed CEPS unit/greenhouse infrastructure is effectively a CO2 sequestra-
tion station, and the economic feasibility is based on 1 kWh = 3600 kWs = 3.6 MJ [88], costs
between GBP 0.11–0.21/kWh and 17.8 kJ/mol CO2 = 17.8 kJ/44 g CO2 [89,90] for pure CO2
versus 8.5 kJ/mol CO2 = 8.5 kJ/44 g CO2 for enriched, 1000 ppm CO2 , costing effectively
between USD15 and USD309/t CO2 . The efficiency, technical, and economic viability are
making the case for temperature-swing absorption/desorption flue-gas carbon capture.
The anaerobic digester and sewage treatment facility are vital components within in
the BiSC and would be ideally integrated into the steel mill or quite possibly be independent
Energies 2022, 15, 8880 9 of 22

businesses in their own right, conveniently located on site of the steel production facility.
These units would be able to accommodate debris from nearby woodland management
and additional biomass from surrounding residential and commercial entities. Steelmaking
by-products, such as brown water, can be treated at the sewage treatment facility. The
cleared sewage can subsequently be utilised to fertilise the food production units. The
anaerobic digestion process in itself produces biogas, which can be used in steel production,
but it also provides the base for extraction of hydrogen. The green hydrogen produced at
or nearby the anaerobic digestion facility can then be used in (steel) production within the
hydrogen direct reduction (HDR) process. As this has been derived from biogas as a result
of anaerobic digestions, this can therefore be considered green hydrogen. Hydrogen direct
reduction (HDR) has been piloted over recent years and has been shown to have great CO2
avoidance potential, and green hydrogen technologies are currently being developed by a
number of significant industry leaders, such as Mannesmann Salzgitter [75], in cooperation
with the European Commission and Tata Steel. Green HDR in blast furnace and electric-arc
furnace application is considered as having a significant impact on reducing CO2 emissions
in steel manufacturing, as this process uses 3.48 MWh of electricity per ton of steel product
and emits only 2.8% of blast furnace CO2 . However, as the prices of fossil-fuel-derived
energy have increased significantly, it is imperative to replace fossil-fuel-derived energy
with renewable energy technologies and biomass [35,36]. Technologies such as ReclaMet
(waste resource recovery, post-combustion) [69] electrolysis projects, i.e., GrInHy and
H2Future [6–9,75] (direct water splitting: biomass > hydrogen, pre-combustion) all have an
impact in the magnitude of between 12% and 25%, although further research is required to
establish not only the most effective technology in terms of environmental impact, but also
which technology can be deployed the fastest and be the most cost-efficient.
A further key component of the BiSC is the Geomimetic® process [91], as these units
are effectively recycling facilities for the recycling of reclaimed concrete and the reutilisation
of CO2 , filters, dust, sludge, and slack from (steel) production. These units have the capacity
to reduce post-combustion CO2 emission to effectively zero and should be on site of any
(steel) production plant. The workings of the Geomimetic® process are in its essence carbon
utilisation and sequestration processes at the same time, as these recycle CO2 from flue
gases and recycled concrete into synthetic limestone and aggregate in cement production,
with the potential of absorbing 100% of the CO2 emissions produced. This is a technique
suitable to be applied in any industrial production setting: energy, steel, concrete, chemical
industry, glass industry, paper, and transport, to name a few.

4. The 7 Steps to Net-Zero Carbon Emission Steel Manufacturing

The newly introduced concept “Bio Steel Cycle” (BiSC) [10] provided the elements
with which net-zero carbon emissions steel production can be made a reality, in the short-
term. The following key components within the Bio Steel Cycle are based on a circular
production process and are functioning in an interactive manner. The basis for this system
is the BF/BOF route and involves the aforementioned CAT, CCS, and CCUS, and process
improvements where possible. Innovative technologies such as Hisarna and GrInHy and
hydrogen direct reduction (HDR) have CO2 saving potential in their own right. Removing
coal as primary energy source or using hydrogen direct reduction, an immediate 30%
CO2 emissions reduction is possible [31,35,64,76–78], and therefore, replacing coal with
biomass or hydrogen would reduce the CO2 emissions from steelmaking potentially by the
same percentage. According to Siemens (2022) [79], a 50% carbon emissions reduction is
immediately possible via utilisation of green hydrogen direct reduction. The standard steel
production (SSP) process in combination with the currently operational newly developed
technologies can also achieve a reduction of more than 50% with successive implementation
to less than 3 metric tonnes per ton of steel produced. By incorporating the BiSC components
of CAT, CCS, and CCUS into existing steel production sites, an almost 100% CO2 emission
reduction can be achieved, immediately.
 Energies 2022, 15, 8880 10 of 22

The post-combustion capture of CO2 (CCS) and other GHGs and the exploration of
carbon scrubbing of flue gases were explored. Several possible technologies and processes
to be considered for post-combustion carbon capture were considered [25,26,42,43,59,80],
such as mechanical capture, compression and dehydration, membrane installation, off-gas
flow through physical solvents/solid sorbents (such as Zeolite13X) troughs and chemical
solvents and utilising metal-/organic frameworks.
Renewable energy technologies as one of the key components within the Bio Steel Cy-
cle, can reduce CO2 emissions in steelmaking by more than 30% [81] if commercial entities
in iron and steel production [25,26,82] were to simply switch their energy providers [59]
to those who are deriving their energy based on 100% renewable energy technology.
Energies 2022, 15, x FOR PEER REVIEW
Retrofitting existing plants to produce their own energy (wind, solar, PV) is the next
logical step. The same applies to greenhouses, as there is a vast amount of roof space avail-
able, which has to date not been utilised. The static requirements would obviously have to
be considered, but as the cost of solar energy and solar PV has decreased significantly over
recent years [92] to less than GBP3/m 2 , it can be considered an unmissable opportunity.
Figure 4 demonstrates the steps, built on the components within the BiSC, t
Figure 4 demonstrates the steps, built on the components within the BiSC, that should be
taken with the aim to achieve net-zero carbon emission steel production.
taken with the aim to achieve net-zero carbon emission steel production.

Figure 4. The seven steps to achieving net-zero carbon emissions steel production.
Figure 4. The seven steps to achieving net-zero carbon emissions steel production.
Steps 1–7 were introduced based on the level of ease of implementation and from short-
term toSteps 1–7project
long-term wereduration,
introduced
startingbased
with Stepon1 by
the level of
switching ease
energy of implementat
providers and
arriving at Step 7 with producing biogas as a result of full implementation of all elements
short-term to long-term project duration, starting with Step 1 by switching e
of the Bio Steel Cycle (BiSC), splitting green hydrogen from this biogas and using thus
ers and
gained arriving
hydrogen at Step
in steel 7 with for
manufacturing producing biogas
hydrogen direct as a result
reduction (HDR). of full implem
elements of athe
There are BioofSteel
range Cycle
energy (BiSC),
providers, splitting
which claim to green
producehydrogen from this bio
energy exclusively
based on renewable energy technologies. The image in Figure 5 demonstrates the flow of
thus gained hydrogen in steel manufacturing for hydrogen direct reduction
the seven steps in some detail:
There are a range of energy providers, which claim to produce energ
based on renewable energy technologies. The image in Figure 5 demonstra
the seven steps in some detail:
Energies 2022, 15, x FOR PEER REVIEW 12 of 24
Energies 2022, 15, 8880 11 of 22

Figure 5.
Figure Theseven
5. The sevensteps
steps to
tonet-zero
net-zero steel
steel production.
production.

Step 1:
Step 1: Switching
Switchingto toaa green
green energy
energy provider
provider is is probably
probably thethe easiest
easiest toto achieve.
achieve. AnyAny
steel producer will just have to make an informed choice to switch its energy contract to
steel producer will just have to make an informed choice to switch its energy contract to
an energy provider that produces energy solely relying on renewable energy technologies,
an energy provider that produces energy solely relying on renewable energy technologies,
and not—as it has been up to now—the companies that agree to the best deal, regardless of
and not—as it has been up to now—the companies that agree to the best deal, regardless
the consequences for the environment.
of the consequences for the environment.
Step 2: Installing renewable energy technology. This requires surveying of existing
Step 2: Installing renewable energy technology. This requires surveying of existing
steel plants, regarding static performance of buildings, ground parameters, and structures
steel plants, regarding static performance of buildings, ground parameters, and structures
in situ. Selection of the most suitable product from a range of technologies and producers
in situ. Selection of the most suitable product from a range of technologies and producers
is the most time-consuming step after surveying the locations.
is the most time-consuming step after surveying the locations.
Toktarova et al. (2020) [35] identified a 30% CO2 emissions savings potential by
Toktarova et al. (2020) [35] identified a 30% CO2 emissions savings potential by re-
replacing fossil-fuel-derived electricity with renewable-energy-derived. Most industrial
placing fossil-fuel-derived electricity with renewable-energy-derived. Most industrial
structures well-maintained under British Standards are suitable to accommodate the in-
structures
stallation of well-maintained
the mature technologyunder British Standards
solar energy are either
panels, suitable
as to accommodate
solar thermal (hotthe in-
water
stallation
production) of the mature technology
or photovoltaic panelssolar (PV)energy panels,There
(electricity). eitherisas solar
such thermal
a very wide(hot water
range of
production) or photovoltaic panels (PV) (electricity). There is such
solar and PV systems available that it would be beyond the scope of this paper to list these a very wide range of
solar andentirety.
in their PV systems available
It may sufficethat
at it would
this pointbetobeyond
mention thethat
scope of this
there arepaper to list
suitable these
systems
in their entirety. It may suffice at this point to mention that there
available for every type of setting, from on-roof, over to in-roof and wall-covering solar are suitable systems
available
panels and foreven
every typewhich
foils, of setting,
can be from on-roof,toover
retrofitted to in-roof
provide and source
a reliable wall-covering
of energysolar
all
panels and even
year round. Evenfoils, which
windows maycanconsist
be retrofitted
of solar to provide
panels, a reliable
as the newest source
known of energy all
development
year round. Even windows
are semi-transparent may consist
solar cells. Researchersof solar panels,
at the as the newest
University known
of Michigan development
have developed
are
a technique to manufacture highly efficient, semi-transparent solar cells at scale, devel-
semi-transparent solar cells. Researchers at the University of Michigan have which
oped a technique electrical
use micron-scale to manufacture
connectionshighly efficient,
between semi-transparent
individual cells that solar cells the
constitute at scale,
solar
which
modules use[93].
micron-scale electrical connections between individual cells that constitute the
solar Wind
modules [93].pylons are—besides solar—another effective way to produce electricity
energy
fromWind energy
a natural pylons
source are—besides
(wind). solar—another
This technology effective
is mature way to produce
and widely electricity
used, Again, there
from a natural
is a wide rangesource (wind).onThis
of products the technology
market, andisthe mature and widelywill
site parameters used, Again, there
determine whichis
asystem
wide range
wouldofbeproducts
suitable foron the location
market, in and the site parameters will determine which
question.
system Atwould be suitable
sites where solar for the location
or wind energyin question.
systems are unsuitable, open- and closed-loop
hydroAtenergy
sites where
systems solar or wind
might energy
have their systems
place are unsuitable,
to provide energy for open- and processes.
industrial closed-loop In
hydro energy
the United systems
States, might haveistheir
this technology widely place to provide
used, energyclosed-loop
where creating for industrial processes.
systems using
In the of
pairs United
existing States, this technology
or artificial is widely used,
lakes or reservoirs instead where creating
of rivers would closed-loop
avoid the systems
need for
Energies 2022, 15, x FOR PEER REVIEW 13 of 24
Energies 2022, 15, 8880 12 of 22

using pairs of existing or artificial lakes or reservoirs instead of rivers would avoid the
need
newfordams.
new dams.
ThereThere are currently
are currently projects
projects underway,
underway, wherewhere
in BellinCounty,
Bell County, Ken-for
Kentucky,
tucky, for example,
example, an old
an old coal coal
strip stripis mine
mine beingisre-used
being re-used
[94]. As[94]. Asin
Wales Wales in the
the UK has UK hasarray
a vast a
vast
ofarray
thoseof those locations,
locations, it shoulditbe
should be practical
practical to installtothese.
install these.6 Figure
Figure 6 provides
provides some(not
some details
details (not for
to scale) to scale) for the principles
the principles of this technology:
of this technology:

Figure 6. Pumped-storage hydropower, open loop.

Figure 6. Pumped-storage hydropower, open loop.
Step 3: Replacing coal and coke with biomass. Coal and energy derived from com-
Step 3:ofReplacing
bustion fossil fuels coal andbiggest
is the coke with biomass.
emitter of COCoal and energy derived from com-
2 emissions [2] and replacing coal with
bustion of fossil fuels is the biggest emitter of CO 2 emissions [2] and replacing coal with
biomass in steel production would quite easily achieve a 30% reduction in carbon emissions,
biomass
whichin is steel production
the reason would quite
why renewable easily
energy achieve a 30%
technologies and reduction in carbon
replacing coal emis-
and coke with
sions, which is the reason why renewable energy technologies
biomass are cornerstones in the Bio Steel Cycle. Replacing pre-combustion fossil and replacing coal and cokefuels
withwithbiomass
biomass are[6–9,35,59,67,95]
cornerstones inand theoperating
Bio Steel(green)
Cycle. hydrogen
Replacingdirect
pre-combustion
reduction (HDR)fossil as
fuels with biomass [6–9,35,59,67,95] and operating (green) hydrogen
well as capturing post-combustion CO2 emissions with the Geomimetic process [91] are direct
® reduction
(HDR) as well
efforts which ashave
capturing post-combustion
the potential to reduce CO the2CO emissions with the Geomimetic® process
2 emissions in steel production to almost
[91] are There
“0”. effortsiswhich have theoutreach
considerable potentialinto
to reduce the CO2 emissions
other industries, in steel
such as the production
application of the
to almost “0”. There
® is considerable outreach into other industries,
Geomimetic [91] process, which produces aggregates from CO2 emissions and recycled such as the application
of the Geomimetic
concrete ® [91] process, which produces aggregates from CO2 emissions and re-
to producing new concrete and utilisation of BOF slacks for road building.
cycled concrete to producingofnew
Step 4: Installation concrete andflue-stack
carbon-capture utilisationfilters
of BOF(CCUS).
slacks for roadtechnologies
These building.
Step 4: Installation of carbon-capture flue-stack filters (CCUS).
are wide ranging, and every production site has its own parameters and challenges These technologies are to
wide ranging, and every production site has its own parameters
overcome. Thorough surveying of the sites and greenhouse gas emission (GHG) points and challenges to over-
come.
need Thorough surveying
to be identified, andofdepending
the sites andon greenhouse
the situation, gas emissionGHG
a suitable (GHG) points need
capturing system
to be
canidentified,
be installed.andThere
depending on the situation,
are companies a suitable[146],
such as Yurcent© GHGwhichcapturing system
provide canrotors
Xeolite be
installed.
(disc-likeThere are companies
wheels that are working such asonYurcent© [146], which provide
the absorption/desorption Xeolite rotors
principle). These(disc-
types of
likefilters
wheels that are
consist working on thecrystals
of aluminosilicate absorption/desorption
with average pores principle).
measuringThese types of filters
9 angstrom (0.9 nm)
consist of aluminosilicate
and can be adapted to fit crystals
almostwith average pores
any industrial measuring
flu stack 9 angstrom
or off-gas outlet and (0.9
arenm)
partand
of the
canCEPS
be adapted
(carbontoenrichment
fit almost any industrial
for plant flu stack
stimulation) or off-gas
system outlet and are part of the
[25,26,42,43,59,80,146].
CEPS (carbon
Step 5: enrichment
Utilisation of for plant stimulation)
captured systemand
carbon in concrete [25,26,42,43,59,80,146].
food production. Blue Planet [91]
is Step
using5:the so-calledof“Geomimetic ® process”, in which recycled concrete and captured
Utilisation captured carbon in concrete and food production. Blue Planet
[91]carbon
is using arethe
being re-formed
so-called to make ®new
“Geomimetic concrete
process”, and aggregate.
in which In combination
recycled concrete and cap- with
manufacturing
tured carbon are being post-combustion
re-formed toflue-stack
make newcarbon concretecapture, the utilisation
and aggregate. of the hereby
In combination
withcaptured carbon ispost-combustion
manufacturing subsequently utilised in making
flue-stack carbon new concrete
capture, (carbon
the sequestration).
utilisation of the
This process has the capability to reduce the carbon
hereby captured carbon is subsequently utilised in making new concrete (carbon emissions from steel production
seques- by
almostThis
tration). 100%.
process has the capability to reduce the carbon emissions from steel produc-
Step 6: 100%.
tion by almost Process improvement in steel manufacturing. Greater material and energy ef-
ficiency, and deployment of low-carbon process routes are all critical. The steel production
process has been thoroughly investigated in every aspect from mining to recycling, and it can
Energies 2022, 15, 8880 13 of 22

be said that there is currently a global effort underway for developing more environmentally
friendly and resource-saving technologies in steel production, such as TGRBF (top gas recy-
cling blast furnace operation, coal mine methane recovery [25,26,35,60,64–66,69,70,72,96] and
HISARNA [20,69,70,78,89,90,95,97], which eliminates the need for the sintering process entirely.
HISARNA, implemented individually, has the potential to reduce CO2 emissions from steel
production by at least 30%.
Step 7: Biogas from anaerobic digestion—Green hydrogen from biogas—Utilisation in
steel production. Trees are natural carbon sinks [83–85] and ideally, woodlands would be
planted around steel production plants to absorb the remaining CO2 emissions via direct
air capture (DAC)—while simultaneously, the trees would provide some of the material
for producing biochar and organic matter to be fed into the anaerobic digester, alongside
agricultural businesses.
Planting a sufficient number of trees [6–9,83–85] and both anaerobic digester and
biochar plants [6–9] are vital components within the Bio Steel Cycle and instrumental
to meet the UK government’s zero emissions target. They should be considered in the
planning for the updating of existing steel production plants and for any new steel plant
development or refurbishment. As the UK tree cover stands at 13.2% (3.2 million ha, 66.65 m
people = 0.048 ha per capita) [83,84], it is fair to say that this is the lowest percentage in the
Northern hemisphere. EU forests and wooded land cover over 182 million hectares (42%)
of the EU’s total land area [83,84].
Biochar [98] can easily be used as a direct replacement for coke or coal. Biogas and
biomass also are an alternative to commercial gases and fossil fuels [6–9,35,62,81], as their
properties allow for 1:1 replacement. Using biochar instead of coke in (steel) production
could reduce the CO2 emissions by 30%.
Additionally, “green” hydrogen extraction from biogas, naturally produced by anaero-
bic digestion, offers additional carbon avoidance opportunities. Hydrogen direct reduction
(HDR) has been piloted over recent years and has been shown to have great CO2 avoidance
potential. (Green hydrogen technologies are currently developed by a number of significant
industry leaders, such as Mannesmann Salzgitter [75], in cooperation with the European
Commission and others [6–9]). Green hydrogen implies hydrogen production using energy
from renewable resources only, which is where the Bio Steel Cycle comes to full circle:
Biomass from trees used for DAC is converted to biogas in the anaerobic digester, which
produces biogas. The hydrogen is then extracted from the biogas, using renewable energy
technologies exclusively.

5. Results and Discussion

The results of this study are the identified levels of CO2 emissions during the BF/BOF
route in steelmaking, as per Table 1:

Table 1. CO2 emissions BF/BOF route.

SEC *
Step in Production CO2 CO2 Author
−t/t product
Blast furnace 0.288 2.1 [31,42,43,112,125]
Basic oxygen f. 0.018 2.2 [31,32,43,55,76,125]
Total ∑ 0.306 4.3
Total ∑ 4.606 Total t/CO2 /t steel produced
* SEC = Specific Energy Consumption.

The sum total of identified levels of CO2 emissions at ~4.61/CO2 /t steel is the result
of thorough investigation of research into every process step along the linear steelmaking
BF/BOF route, to date.
 The sum total of identified levels of CO2 emissions at ~4.61/CO2/t steel is the result of
thorough investigation of research into every process step along the linear steelmaking
BF/BOF route, to date.
The individual seven steps towards “0” carbon steel production have a different ef-
Energies 2022, 15, 8880 fect, based on the way they are being implemented, either individually or in sequence 14 of 22

(successive), as displayed in Table 2 and Figure 7:

TableThe
2. Individual/successive implementation
individual seven steps of thecarbon
towards “0” seven steps
steeltoproduction
0-carbon steel.
have a different
effect, based on the way they are being implemented, either individually or in sequence
Implementation
(successive), as displayed in Table 2 and Figure 7:
Individual % Reduction Successive
SSP * CO 2 CO 2 SSP * CO2
Table 2. Individual/successive implementation of the seven steps to 0-carbon steel.
BF/BOF-Route 4.61 - 4.61
Implementation Step 1 3.23 −30% 3.23
Step 2 Individual
3.23 %−30%
Reduction 2.26
Successive
Step 3 SSP * CO
3.232 CO
−30% 2 SSP
1.58* CO2
BF/BOF-Route Step 4 2.31
4.61 −50% - 0.79
4.61
Step 1 Step 5 3.23
0.00 −
−100%30% 3.23
0.00
Step 2 3.23 −30% 2.26
Step 6 3.23 −30% 0.00
Step 3 3.23 −30% 1.58
Step 4 Step 7 3.23
2.31 −30%
−50% 0.00
0.79
* Standard Steel Production.
Step 5 0.00 −100% 0.00
Step 6 3.23 −30% 0.00
Step 7 the sequential
Notably, during −30%
3.23 implementation of the seven steps to ”0”0.00
carbon steel
*production—already
Standard Steel Production.with step 5–100% carbon reduction has been achieved.

successive implementation
Figure 7. Individual and successive implementation of
of Steps
Steps 1–7.
1–7.

Notably, during the sequential implementation of the seven steps to ”0” carbon steel
production—already with step 5–100% carbon reduction has been achieved.
This would logically render Steps 6 and 7 obsolete, with successive implementation,
but the technical application of flue-stack scrubbing technology, processes or material is
quite challenging, and the efficiency is dependent on site factors and the quality of the
installation, as well as the execution.
Energies 2022, 15, 8880 15 of 22

The industrialisation processes have for more than 200 years caused significant damage
to the natural environment. Although the current UK government seems to have abandoned
their commitments to reducing carbon emissions in the UK and are instead issuing licences
for natural gas exploration (Shell/Jackdaw) [99] and new coal mines (Cumbria) [100],
industry seems to have understood the severity of the climate crisis we find ourselves
in. In 2018, Tata Steel announced a partnership with chemicals company Nourvon with
the aim of producing hydrogen and oxygen at Tata Steel Europe B.V.’s Ijmuiden plant in
the Netherlands. Using water electrolysis, this effort is part of the company’s drive to
be a carbon-neutral steel manufacturer by 2050. As they are using electricity generated
by using renewable energy technologies, the plant is set to save up to 350,000 t/p.a. of
CO2 . The aim is to use the hydrogen as a reductant in the direct reduced iron steelmaking
process [70]. Tata Steel have requested financial support to the tune of GBP1.5bn to fund
its transition to greener production from the UK government for investing in sustainable
technologies at their Port Talbot (Wales/UK) plant, which employs more than 4000 people
at present [72]. With the 2020 UK Government “UK Green Industrial Revolution” paper
still fresh in everyone’s mind [101], this might possibly come to pass.
Industry leaders have already recognised that the current linear steel production
process is detrimental for our environment [145], and they have taken already considerable
action by investing in R&D into production process improvement and infrastructure im-
provement towards sustainable and carbon-neutral steel production. The governments in
the respective countries might be inclined within their “green” agendas to award green
loans at favourable terms to enable businesses to reach their sustainability goals sooner
rather than later. Legal frameworks require adaptation to accommodate an attractive
solution for businesses—in the form of tax incentives and subsidies, possibly re-directed
from nuclear and fossil fuel subsidies—and to apportion a set percentage of gross profits
to drastically change their business models to sustainable, circular production processes.
Despite global pressure, making steel—even in the UK—is still a very attractive business
and it can be done sustainably.
Previous aforementioned studies have focused on the assessment of policy needs,
skills needs, supply-chain pressures on a regional and global scale, and the requirement for
models, strategies, and guidance papers, and investigated the technical solutions for the
decarbonisation of the iron and steel industry. This paper is the first of its kind to (a) assess
sustainability guidelines, (b) assess technical progress and viability of technical and process
solutions for CAT and CCUS, (c) identify the factual CO2 emissions of the BF/BOF route of
steelmaking, and (d) offer a multi-disciplinary model and strategy to achieve factual “0”
carbon emissions steel manufacturing in one research report.
The individual or successive implementation of the detailed BiSC components, accom-
panied by steel production process improvements and following the “7 steps to net-zero
carbon emissions steel production” strategy is quite possibly the mechanism which is set to
achieve between 50% and 100% CO2 emissions reduction, immediately.
The authors’ work on the decarbonisation of the steel industry and further investiga-
tion of the CO2 emissions along the whole steelmaking process, starting with coal and iron
ore extraction, are currently under way.

6. Conclusions
The 7 steps to net-zero carbon emissions steel production and the Bio Steel Cycle
components are providing a feasible strategy to reach net-zero carbon emissions steel
production in the short- to medium-term. Even if only sections of the BiSC or 7-steps
strategy are being implemented, at least 30% carbon emission reduction can be achieved in
the short-term. The BiSC seven steps to take for reaching net-zero carbon emission steel
production seem to be technically possible and practically implementable in the short-term.
The global anthropogenic ~65.6 Gt CO2 -equivalent emissions in 2019, reported by the
64 steel-producing countries and documented 1.9 Gt of steel produced between January
and December 2021, are set to be resulting in 8.8 Gt CO2 -equivalent of CO2 emissions.
Energies 2022, 15, 8880 16 of 22

This volume as the product of the current linear steel manufacturing process leads to the
conclusion that the iron and steel industry’s emissions might have possibly in the past
been heavily underestimated and underreported. One example is the issue that there are
contradictory publications that do not seem to agree with the percentage of global share
in CO2 emissions, as they range from at least 7% to 11%. Suitable literature has been
identified, but the level and range of discrepancy just demonstrates and emphasises the
point of uncertainty, and possible underreporting of emissions in the iron and steel industry.
Industry leaders have already recognised that the current linear steel production
process is detrimental for our environment, and they have taken considerable action by
investing in R&D into production process improvement and infrastructure improvement
towards sustainable and carbon-neutral steel production. The governments in the respec-
tive countries might be inclined within their “green” agendas to award green loans at
favourable terms to enable businesses to reach their sustainability goals sooner rather
than later. Legal frameworks require adaptation to accommodate an attractive solution for
businesses—in the form of tax incentives and subsidies, possibly re-directed from nuclear
and fossil fuel subsidies—and to apportion a set percentage of gross profits to drastically
change their business models to sustainable, circular production processes.
Despite global pressure, making steel—even in the UK—is still a very attractive
business and it can be done sustainably. This research has proposed a sustainable solution
to avoid and remove carbon emissions from the iron and steel industry by implementing
the Bio Steel Cycle in seven steps to achieve net-zero steelmaking, at the latest by 2050.
A road map needs to be prepared to show the correct direction and required actions for
government, policy makers, and steel manufacturers.

Author Contributions: Conceptualization, S.K.; methodology, S.K., H.G.D. and A.-H.S.; software,
S.K.; validation, H.G.D. and A.-H.S.; formal analysis, S.K.; investigation, S.K.; resources, S.K., H.G.D.
and A.-H.S.; data curation, S.K.; writing—original draft preparation, S.K.; writing—review and edit-
ing, H.G.D. and A.-H.S.; visualization, S.K.; supervision, H.G.D. and A.-H.S.; project administration,
A.-H.S.; funding acquisition, S.K. All authors have read and agreed to the published version of
the manuscript.
Funding: This research received no external funding.
Institutional Review Board Statement: The study was conducted in accordance with the Declaration
of Helsinki and approved by the Institutional Review Board (or Ethics Committee) Staffordshire
University (date of approval: 28 January 2022).
Informed Consent Statement: Not applicable.
Data Availability Statement: Not applicable.
Conflicts of Interest: The authors declare no conflict of interest.

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