closed material loops by reusing re-

sidual material and cogenerated

products. According to the company,

it is “working very close to the limits

of what science and technology per-

mits”, which puts it “among the

world’s most efcient producers of

steel”.

Nevertheless, production in the

Salzgitter steelworks generates about

8 million t of CO

per year, made

unavoidable by processes and by the

current status of technical conditions

and the facilities available. In order

to lower its CO

emissions, the

company has begun to implement its

SALCOS

programme – Salzgitter

Low CO

Steelmaking.

Although the ambition among steel

producers to cut emissions varies

from region to region, Sengupta says

that, overall, Siemens Energy’s cus-

tomers are “working very hard to

dene their own individual strategy”.

He added: “It depends on the pro-

cess they are using; how old the steel

plant is; and the different local re-

quirements, i.e. whether they are in

Europe, US, India or Japan. But most

of them want to become climate-

neutral by 2045 at the latest.”

Sengupta says that the most realistic

pathway is to rst optimise and elec-

trify. Historically, the most common

to the higher demand, things have

really gone south and the overall

amount of CO

emissions has gone

up in a way that now we really need

measures to meet the net zero emis-

sions target.”

“Figures from the Energy Informa-

tion Administration (EIA) show that

producing 1 t of steel produces about

1.9 t of CO

. And using coal means

that CO

emissions are not the only

problem – methane, nitrous oxides,

sulphur dioxide and particulates are

also an issue. So this is a very impor-

tant problem for us to solve.”

Siemens Energy has put reducing

carbon emissions from industrial

processes such as steel production,

and indeed its own processes and

products, at the heart of its opera-

tions. In what is one of the most im-

portant projects aimed at cutting CO

emissions from steel production, the

company has been collaborating

with Salzgitter AG on a programme

to make steel production more cli-

mate-friendly.

Salzgitter AG is one of Europe’s

leading steel and technology groups.

Apart from the carbon used, the

company operates its integrated

steelworks in Salzgitter, southeast

Lower Saxony, Germany, on a virtu-

ally energy autonomous basis and

Siemens Energy has secured the contract to deliver and install its advanced centrifugal

compressors for compressing hydrogen at Salzgitter. The compressor package features an

integrally-geared compressor design, allowing for more efcient compression

Sengupta: CO

emissions have gone up in a way that “now we

really need measures” to meet the net zero emissions target

Special Technology Supplement

he importance of decarbonising

the steel industry cannot be un-

derstated. According to a 2021

report by the World Steel Associa-

tion, steel production accounts for

between 7 and 9 per cent of global

emissions. More recently, in its

Tracking Clean Energy Progress

2023 report, the International Energy

Agency (IEA) estimates that it ac-

counts for 8 per cent of primary pro-

duction in 2030 in its NZE (Net Zero

Emissions) Scenario. The IEA there-

fore stresses that innovation is crucial

for the commercialisation of new

near zero emissions steel production

processes.

Fortunately, both the steel industry

and major players in the energy sec-

tor have not been sitting on their

hands. Although the current pipeline

of low- and near zero-emission

projects in the steel industry falls

short of what is required to meet the

NZE Scenario, important progress is

being made.

Commenting on the size of the

problem of CO

emissions from steel

production, Anand Sengupta, Vice

President and Head of Global Sales,

Compression at Siemens Energy, said:

“In a word, it’s as big as 8 per cent of

global emissions. The industry has

seen a big demand for steel in the last

few years. It’s a fundamental indica-

tor of economic growth… demand

will stay and the problem will grow

in size. But today steel production is

heavily dependent on coal, which is

primarily used for reducing iron ore

to so-called pig iron.

“But over the last decade, these

emissions have gone up. There has

been some improvement in terms of

efciency, i.e. the number of tonnes

of CO

per tonne(t) of steel. But due

THE ENERGY INDUSTRY TIMES - SEPTEMBER 2023

Reducing carbon emissions in steel production is crucial in achieving global net zero CO

targets. Siemens Energy

is collaborating with European steel producer Salzgitter AG to help reduce emissions from its steel production

process. But it is a partnership that is also helping Siemens Energy to cut its own Scope 3 emissions.

Junior Isles explains.

A steely resolve to cutting

carbon emissions

of Salzgitter AG, amounting to well

over €1 billion. The total investment

volume for the rst stage of SALCOS

is € 2.2-2.4 billion.

The SALCOS programme will be

implemented in three stages. The

rst – consisting of a direct reduction

plant, an electric arc furnace and a

100 MW electrolysis plant for hy-

drogen production – will be com-

pleted in 2026. Wind power genera-

tion has already been installed along

with the electrolyser, which produces

hydrogen for use in the electric arc

furnace. Phases two and three will

entail the increased use of scrap.

Salzgitter is targeting at least a 95

per cent reduction in CO

emissions

by 2033. The company noted: “By

setting ourselves the goal of avoid-

ing CO

directly rather than storing it

or making it usable at great expense

(carbon direct avoidance strategy),

our concept is sustainable and sets an

example for the industry.”

Transformation of the steel produc-

tion process at the Salzgitter site

should be completed by the end of

2033, well ahead of the regulatory

requirements.

In May this year Salzgitter reached

a major milestone in executing this

plan with the order of an ‘Energiron

ZR Direct Reduction’ plant from a

consortium of Tenova, Danieli and

DSD Steel Group. The consortium

will build the DRI plant on the site of

Salzgitter Flachstahl GmbH. The unit

is the largest sub-plant in the rst

stage of the SALCOS programme

and has a production capacity of

Special Technology Supplement

THE ENERGY INDUSTRY TIMES - SEPTEMBER 2023

Integrally-geared compressor

rotor

blast furnace used by steel producers

has been the Basic Oxygen Furnace

(BOF). A growing number are shift-

ing towards the electric arc furnace

(EAF) to implement a different pro-

duction route, which is easier to de-

carbonise. The second part, he says,

is “decarbonising operations”. This

means reducing the carbon in the

electricity supply, i.e. using renew-

ables. The third is carbon capture.

“We see some frontrunners – espe-

cially in Europe where we are trying

to implement, with the government,

some concrete actions. Most of the

major steel producing countries have

targets to reduce emissions by be-

tween 15 and 40 per cent by 2030.

But the EU has launched a strong

push for industries to transition from

a high carbon to a low carbon foot-

print,” he said.

“Beyond Europe, the Ination Re-

duction Act (IRA) in the US is pro-

viding a huge amount of funding [for

industries] – around $5.6-5.8 billion

– a large part of which will be avail-

able to some of the projects in the

steel industry.”

He noted, however, that the technol-

ogy aspect is also important, high-

lighting some of the new technologies

that are being deployed. “Sweden, for

example is doing a scrap waste steel

project that will help reduce carbon

footprint. We are also seeing some

hydrogen-based direct reduction of

iron (H

-DRI) that will demonstrate

the future of how the industry will

move forward.”

As part of its SALCOS programme,

Salzgitter is replacing its existing

blast furnaces with direct reduction

plants. The company currently pro-

duces pig iron, or crude iron, by us-

ing coal in its blast furnaces. This

releases CO

as a result of the pro-

cess. In direct reduction, iron ore is

reduced with the aid of hydrogen.

The hydrogen reacts with the oxygen

in the iron ore (iron oxide) directly in

the solid state and converts it into

sponge iron (almost pure iron).

Instead of CO

, this technology

produces water (H

O), which in turn

is reused in the integrated process. In

order to be able to process sponge

iron further, the porous material is

nally melted down together with

steel scrap in an electric arc furnace.

The SALCOS programme is al-

ready in the midst of implementa-

tion. The nancing of stage 1 of the

programm has been secured through

subsidies of about €1 billion from

the Federal Republic of Germany

(€700 million) and the State of

Lower Saxony (€300 million), as

well as through the substantial funds

more than 2 million t of direct re-

duced iron per year.

Sengupta commented: “SALCOS

has also announced that they will

stop using blast furnaces by mid-

2030s and replace their coal-based

process with a new hydrogen route.

That’s a massive change. It’s a huge

change in the plant itself. This trans-

formation is expected to achieve

emissions savings of 95 per cent,

which is actually 1 per cent of Ger-

many’s CO

emissions.”

Sengupta noted that blast furnaces

sites around the world can also use

DRI technology similar to that used

by Salzgitter. A key benet here is

that operators can switch from natu-

ral gas to hydrogen “on the y”. This

would allow them to make the transi-

tion from natural gas to hydrogen

slowly.

“You could initially start with, say

5 per cent hydrogen, and 95 per cent

natural gas; or you could have in

between 50:50 and switch over from

5:95 to the other way around,” said

Sengupta. “This is a huge advantage

because, without changing the

equipment or the process, you can

move from point A to point B almost

seamlessly.”

This is where Siemens Energy

compressors play a pivotal role.

Sengupta explained: “The process

uses natural gas, which has a certain

molecular composition, molecular

weight, uid dynamics, etc. But the

same process tomorrow has to use a

mix or pure hydrogen, which has a

different molecular weight and a

different kind of uid dynamics.

“So the compressors need to be

exible and adaptable to handle the

wide range of head – the compressor

power, the ow that is needed; the

pressure ratio that’s needed. And the

compressors need to be reliable

enough to move from a heavy, big

molecule, to a lighter, smaller, mol-

ecule; so it’s really important to un-

derstand how the compressors, from

a exibility standpoint, can handle

both the gases. Unlike Salzgitter, in

Example of an advanced rotor

hydrogen compressor

F-gas-free switchgear in an offshore wind turbine: it is important for the wind industry to reduce

its carbon footprint through developments such as GIS without SF

or other F-gases

THE ENERGY INDUSTRY TIMES - SEPTEMBER 2023

Special Technology Supplement

F-gas-free switchgear at the

Siemens Energy switchgear

factory in Berlin

allows more efcient compression,

further reducing the energy con-

sumption of the plant (and resultant

footprint).

“This lies at the heart of what we do

at Siemens Energy. We have a busi-

ness area that specically looks at

how we reduce the carbon footprint

of industrial processes; steel is one of

them,” said Sengupta.

Siemens Energy is building on its

Salzgitter compressor experience, with

plans to install an advanced rotor hy-

drogen compressor at another steel

production plant in Sweden. It will

meet the steel producer’s requirement

for a compressor with higher ow

rates.

“This will be phenomenal because

you won’t need to have multiple

compressors running in parallel; you

can have one large centrifugal com-

pressor, providing all the pressure

ratio and the ow rate at the same

time,” said Sengupta.

“It’s something we are very excited

about and are talking to multiple cus-

tomers about it. The future of green

steel will need a portfolio where we

are not looking at small multiple units

but reliable larger units.”

The use of fewer units, he says will

mean lower costs, higher reliability

and reduced footprint. “Each com-

pressor has its own balance-of-plant,

so each time you add one more

compressor, the average cost per

megawatt goes up.

“Also steel producers are convert-

ing in a browneld situation, so there

is a space constraint. If you have a

large ow there will at some point

not be enough room for multiple

compressors; so a larger single

compressor with a 1+1 conguration

would be a huge advantage.”

In addition to compressors, Siemens

Energy has also secured a contract to

build a substation on Salzgitter AG’s

premises to connect to the 380 kV

‘Salzgitter Industrial Line’.

The scope of the contract covers a

380 kV gas-insulated switchgear

(GIS); a 220 kV GIS; substation

auxiliary systems; and the entire de-

sign engineering. In addition, Sie-

mens Energy will provide four high

voltage and medium voltage trans-

formers for the rst step of SALCOS.

The substation will be connected via

the Bleckenstedt Süd substation of

TenneT TSO GmbH to the future 380

kV industrial line that in turn will

connect up Salzgitter with the Wahle-

Mecklar line. Going forward, this

grid connection will allow Salzgitter

AG to source the necessary volumes

of power from renewable energies.

GIS is in fact another area in which

Siemens Energy is already contribut-

ing to tackling climate change. The

company has launched a range of

GIS that has eliminated the use of

sulphur hexauoride (SF

) – a gas

which is used for insulation with a

global warming potential 24 300

times that of CO

Siemens Energy has been working

on its ‘Blue’ technology for more

than 12 years, initially focusing on

lower high-voltage levels, i.e. 72.5

kV. The technology is available for

GIS, circuit breakers and instrument

transformers all with absolutely zero

equivalent emissions over the

lifetime of the equipment. The tech-

nology has been in service around

the globe up to 145 kV for several

years and is currently being rolled

out across Siemens Energy’s entire

HV switching equipment portfolio

up to the highest transmission level

of 420 kV.

The company also emphasised that

several hundreds of switchgears with

Blue technology are already being

installed in wind turbines. Big off-

shore wind farms currently use 72.5

kV, so it developed switchgear espe-

cially for wind turbine applications

and rst installation started in 2017.

Wind power is one of the corner-

stones of the green energy transition.

With more than 600 GW of new ca-

pacity to be installed worldwide in

the next ve years, it is important for

the wind industry to reduce its car-

bon footprint through developments

such as GIS without SF

or other F-

gases. The work Siemens Energy is

doing with Salzgitter also feeds back

into this.

In April this year, Siemens Gamesa

announced the GreenerTower, a

wind turbine tower made of more

sustainable steel.

Towers consist of approximately

80 per cent steel plates. The new

GreenerTower will ensure a CO

re-

duction of at least 63 per cent in the

tower steel plates compared to con-

ventional steel. Siemens Gamesa’s

new thorough qualication process

will verify that only a maximum of

0.7 t of CO

-equivalent emissions

are permitted per tonne of steel,

while maintaining the same steel

properties and quality.

Salzgitter AG, with its heavy plate

mill Ilsenburger Grobblech GmbH,

is the rst supplier to be qualied,

something, which has also been rein-

forced by third-party certication.

Today, tower production accounts

for more than one-third of all wind-

turbine-related CO

emissions. If all

towers installed by the company in

one year were exchanged with

GreenerTowers, it would be the same

as removing more than 466 000 cars

from the roads in Europe for a year.

This new CO

-reduced tower will be

available as an option for both on-

shore and offshore wind turbines for

projects to be installed from 2024

onward.

The GreenerTower has already

closed its rst order. RWE and Sie-

mens Gamesa have agreed to intro-

duce 36 GreenerTowers at the 1000

MW Thor offshore wind power

project in Denmark. In total, 72 SG

14-236 DD offshore wind turbines

are planned to be installed starting in

2026. Sven Utermöhlen, CEO RWE

Offshore Wind, said: “Offshore wind

already has one of the lowest life-

cycle carbon footprints of power

generation technologies. At RWE we

are fully committed to working to-

wards circularity and net zero emis-

sions. We are already testing the

world’s rst recyclable wind turbine

blades by Siemens Gamesa under

real-life conditions.”

By piloting the GreenerTower at

our Thor offshore wind farm, RWE

is now looking to take the lead in

helping to signicantly reduce the

carbon footprint of wind turbines.

On average, 1.91 t of CO

is emit-

ted during the manufacturing process

for every tonne of steel. By setting a

threshold of 0.7 t CO

-equivalent

emissions per tonne of steel, Siemens

Gamesa says it “signicantly” re-

duces the footprint of the largest

component in terms of CO

-equiva-

lent emissions.

The use of green steel in its wind

towers goes a long way to closing the

loop in making its wind turbines

completely green.

It certainly feeds into Siemens En-

ergy’s strategy of cutting emissions

from its own operations. “Again, this

is at the heart of what we’re doing at

Siemens Energy and the goals that

we’ve set for ourselves. We look at

Scope 1, Scope 2 and Scope 3 emis-

sions. Every time we supply to the

steel industry, if it’s not green steel it

adds to our Scope 3 emissions,” said

Sengupta. “So we are very actively

engaged to reduce Scope 3 emis-

sions, which means we are actively

engaged to pursue the HDRI. So it

not only helps our customers, it helps

us as well. Ten years down the line,

this needs to be more the norm rather

than the exception.”

He concluded: “Technology is im-

portant but perhaps even more im-

portant is the relationship with our

customers. We have been working

with Salzgitter to build the solution

together, supporting them for the last

5-10 years. It’s partnerships that

make all of this come to life.”

most cases, the operators would like

to switch over from existing natural

gas to a mix of hydrogen before

completely turning over to hydrogen.

The exibility of not having to

change the compression system is a

huge advantage on continued pro-

duction and costs.”

Apart from hydrogen, compressors

are also used in steel plants to handle

nitrogen and oxygen.

Sengupta commented: “There are

compressors that handle dry oxygen

and these are different from the ones

that handle hydrogen and natural

gas, and different from compressors

that handle nitrogen.”

For nitrogen compressors, Siemens

Energy has extensive experience in

the air separation market. These, says

Sengupta, are fairly standard technol-

ogy but need to be extremely reliable.

The oxygen compressors are more

complicated: you don’t want any

ammable material inside. And this is

where we have the experience, with

years of reliable operation; very few

manufacturers can do it. For the natu-

ral gas/hydrogen compressors, this is

where we also have the experience

depending on the size.”

Siemens Energy has secured the

contract to deliver and install its ad-

vanced centrifugal compressors for

compressing hydrogen at Salzgitter,

with an integrally-geared compres-

sor design driving two compression

stages to achieve the required pres-

sure ratio. This portfolio of geared

compressors driving up to four shafts

at individually optimised speeds

The new GreenerTower will ensure a CO

reduction of at least 63 per cent in the tower steel plates compared to conventional steel

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