![](images/Logos/Sustainable%20Energy.jpg)
A nice
paper on history and practice of renewable ammonia, with good numbers
Kevin H. R. Rouwenhorst1,2,3,*,
Anthony S. Travis4and
Leon Lefferts1
1
Catalytic Processes & Materials, MESA+ Institute for Nanotechnology,
Department of Science & Technology,University
of Twente, P.O. Box 217, 7500 Enschede, The Netherlands;
l.lefferts@utwente.nl
2
Proton Ventures, Karel Doormanweg 5, 3115 Schiedam, The Netherlands
3
Ammonia Energy Association, 77 Sands Street, 6th Floor, Brooklyn, NY
11201, USA
4
Edelstein Center, The Hebrew University of Jerusalem, Jerusalem 91904,
Israel; tony.travis282@gmail.com
*Correspondence:
k.h.r.rouwenhorst@utwente.nl
Abstract:
Synthetic
ammonia, manufactured by the Haber–Bosch process and its variants, is
the key
to
securing global food security. Hydrogen is the most important
feedstock for all synthetic ammonia
processes.
Renewable ammonia production relies on hydrogen generated by water
electrolysis
using
electricity generated from hydropower. This was used commercially as
early as 1921. In the
present
work, we discuss how renewable ammonia production subsequently emerged
in those
countries
endowed with abundant hydropower, and in particular in regions with
limited or no oil,
gas,
and coal deposits. Thus, renewable ammonia played an important role in
national food security
for
countries without fossil fuel resources until after the mid-20th
century. For economic reasons,
renewable
ammonia production declined from the 1960s onward in favor of
fossil-based ammonia
production.
However, renewable ammonia has recently gained traction again as an
energy vector. It
is
an important component of the rapidly emerging hydrogen economy.
Renewable ammonia will
probably
play a significant role in maintaining national and global energy and
food security during
the
21st century
Keywords:
ammonia;
renewable; electrolysis; Haber–Bosch; hydropower; fertilizers; energy
1. Introduction
The
synthesis of ammonia (NH3)
from un reactive nitrogen (N2)
and hydrogen (H2),Equation
(1), is one of the most significant scientific–technical developments
in human
history.
Ammonia, as the precursor for various nitrogen-containing fertilizers,
currently
sustains
about half of the global population [1,2].
With new strains of wheat and rice, its
bulk
availability has, particularly since the 1960s, enabled an alleviation
of wide spread
famine
[3].
The ammonia synthesis method was invented by Fritz Haber and Robert LeRossignol
in 1909, and was scaled up by Carl Bosch and colleagues at the German
firm
BASF,
which opened the first commercial plant in 1913 at Oppau, near its
Ludwigshafen
works
[4]. The hydrogen was produced from a coal-based process.
3H2+
N22NH3with∆Hr
=−46
kJ mol-NH3−1,
(1)
However, 100 years ago, in 1921, the first viable commercial rival to
what became
known
as the Haber–Bosch process was introduced by the Italian chemist Luigi
Casale. His
synthetic
ammonia process originally relied on hydrogen generated by the
electrolysis of
water.
The Casale ammonia synthesis technology became the key to the
globalization of
the
synthetic ammonia industry.
Currently,
about 183 Mt of ammonia is produced annually, almost exclusively from
fossil
feed stocks, mainly natural gas and coal [5,6].
Renewable ammonia production today
accounts
for just 0.01% of global production [7].
It is estimated that current ammonia
production
accounts for 0.5 Gt of CO2-equivalent
emissions annually [8],
equivalent to 1.0%of
global CO2-equivalent
emissions.
Renewable ammonia production has recently gained traction again, due
to its potential
role
as a decarbonized hydrogen carrier and as a fuel in the hydrogen
economy. Historically,
nearly
all electrolysis-based hydrogen production capacity has been used for
ammonia
synthesis
[9],
making any discussion regarding renewable ammonia in the context of
the
hydrogen
economy relevant. Hydropower has historically been the renewable
electricity
source
for alkaline electrolyzers for hydrogen production [10].
In this paper, we discuss the historical commercialization of
renewable ammonia
synthesis
from 1921, its scale up in the late 1920s and beyond, and the demise
of renewable
ammonia
during the second half of the 20th century (1960s–2021). To our
knowledge,
this
is the first publication specifically discussing the history of
renewable ammonia. We
use
recent literature, as well as sources from the early 20th century,
covering a century of
renewable
ammonia production.
The
historical role of renewable ammonia synthesis is demonstrated in
Figure 1. The
only
renewable ammonia plant still in operation is located in Cuzco, Peru.
However,
various
renewable ammonia plants have recently been announced, mainly based on
solar
and
wind combined with electrolysis [7]
![](images/images_09_12_2022/pic1.jpg)
![](images/images_09_12_2022/pic2.jpg)
Figure 1.Historical
ammonia production by feedstock, and expected production until 2030.
Coal:
coal
gasification; HFO: heavy fuel oil gasification; Naphtha: naphtha
reforming; Natural gas: steam
methane
reforming; Blue: steam methane reforming with carbon capture and
storage (CCS); Renew-able:
electrolysis. The original data can be found in the Supplementary
Materials Section.
2. Early 1920s: Development and Small-Scale Technology
In
1913, the first ammonia plant began operation at the Oppau works of
BASF, in
Germany.
From 1913 until 1920, ammonia was synthesized only in Germany, based
on
the
BASF Haber–Bosch process, which used coal-based technology for gas
production.
Subsequently,
ammonia synthesis technology was developed outside Germany. From1921,
electrolysis-based hydrogen production was a relevant technology for
ammonia
synthesis
[10–12].
However, as at BASF, the majority of ammonia produced by similar
processes
in the 1920s was synthesized from hydrogen produced by coal
gasification
and
coking oven processes [10].
By 1930, about 30% of the total ammonia production
capacity
was based on electrolysis-based ammonia synthesis with individual
ammonia unit
capacities
up to 295 t-NH3d−1(at
Rjukan, Norway, see Supplementary Materials Section).
This
was the maximum rated capacity of individual ammonia units (synthesis
loops) until
the
mid-1960s, when centrifugal compressors were introduced. Hydrogen for
ammonia
was
also produced as a by-product from other electrochemical processes,
such as caustic
or
chlorine production [10],
although production volumes for these plants were limited
to≤10
t-NH3d−1.
Electrolysis-based ammonia production was mainly developed in
locations with cheap
and
abundant electricity from hydropower [12].
In fact, most of the regions that adopted
electrolysis-based
ammonia synthesis already had substantial hydropower capacity that
was
used for the fixation of atmospheric nitrogen for use in fertilizer
production. Before the
development
of the ammonia synthesis, nitrogen was industrially fixed with the
Birkeland–Eyde
electric arc process and the Frank–Caro calcium cyanamide process,
both dating
from
1905, and both of which consumed hydropower. The Birkeland–Eyde
process fixed
nitrogen
from the air by reacting atmospheric nitrogen (N2)
and oxygen (O2)
in a plasma
reactor,
thereby forming nitrogen oxides (NOX),
which were treated with water to form
nitric
acid (HNO3)
[13,14].
The Frank–Caro process fixed nitrogen from air by reacting
atmospheric nitrogen (N2)
with calcium carbide (CaC2),
thereby forming the final product
calcium
cyanamide (CaCN2),
and the by-product carbon (C) [10].Because
electrolysis-based ammonia synthesis was substantially more energy
efficient
than
the Birkeland–Eyde process and had a lower capital investment than the
Birkeland–Eyde
and Frank–Caro processes, the ammonia synthesis technology eventually
replaced the
Birkeland–Eyde
and Frank–Caro processes in locations with hydropower capacity [10,12].The
Birkeland–Eyde process, the Frank–Caro process, and the
electrolysis-based synthetic
ammonia
process consumed about 3.1, 0.7, and 0.8 MJ mol-N−1,
respectively, during
the
1920s [10].
The low-temperature electrolysis-based hydrogen production used in the
ammonia
process has in recent decades been further optimized to yield a
current energy
consumption
of about 0.6 MJ mol-N−1[7].
2.1. Renewable Ammonia Synthesis Technology
A schematic overview of electrolysis-based ammonia synthesis during
the 1920s is
shown
in Figure 2. At that time, electrolysis-based ammonia synthesis was
the technology
with the lowest energy consumption for ammonia synthesis, at about
48–50 GJt-NH3−1[10,11],
and far lower than coal-based ammonia synthesis at about 95–100 GJt-NH3−1[5].
However, coal and coke were readily available at a low cost in various
countries,
for example in Germany, Belgium, France, the Netherlands, and the
United
Kingdom
[12,15–18],
making fossil-based ammonia production in these countries more
economical
than renewable ammonia production. Fossil-based processes for hydrogen
production
required extensive purification equipment, making necessary
substantial capital
investment.
![](images/images_09_12_2022/pic3.jpg)
Ammonia is synthesized at considerably elevated temperatures and
under high pres-sures
in the presence of an iron-based catalyst which contained promoters.
Currently, this
technology
is commonly termed the Haber–Bosch process. However, various ammonia
processes
were developed and introduced during the 1920s, following the
refusal of the
German
company BASF to share the Haber–Bosch technology know how with
foreign firm sand
governments [12,16].
The alternative ammonia synthesis technologies include the
already
mentioned Casale process, the Claude process, the Fauser process,
the General
Chemical/Allied
process, the NEC (Nitrogen Engineering Corporation) process, the
MontCenis
process, and the Showa Fertilizer process. Various sources discuss
the subtle differences
regarding operating conditions and yields among the processes [11,12,18,24].
The
different
ammonia synthesis technologies are listed in Table 1.
It should be noted that hydrogen production typically accounts for
more than 90% of
the
required energy input. Furthermore, the compressors for feed gas
compression and the
recycling
of un-reacted gas in the ammonia synthesis loop can be operated with
renewable
electricity.
If renewable electricity is the economical method for hydrogen
production, it
will
also be favorable for gas compression and recirculation in the
synthesis loop. Thus,
ammonia
production using renewable hydrogen results in renewable ammonia. It
should
be
noted that the implicit assumption that the produced ammonia
converts completely
back
to N2is
reasonable when using ammonia as an energy carrier.
From
a thermodynamic point of view, ammonia synthesis benefits from a low
temperature
and a high pressure. However, the H2and
N2do
not spontaneously react to form
ammonia
unless the temperature is increased to several thousand Kelvin. This
is impracticable
in industry. Therefore, a catalyst is essential to increase the
ammonia synthesis rate
for
industrial application.
All
synthetic ammonia technologies developed during the 1920s relied on
a multi-component
iron-based catalyst, high temperatures and high pressures (400–650◦C
and200–1000
bar),
and ammonia removal by condensation. The exact formulation of theiron-based
catalyst varied among ammonia synthesis processes because most
companies
developed
their own catalysts due to a lack of international collaboration [12].
For this reason,
there was a certain amount of industrial espionage to obtain
intellectual property. For
example,
this enabled British investigators to gain access to details of the
BASF technology,
including
catalyst recipes.
The
catalyst formulation has a major impact on the activity. A less
active catalyst re-quires
a higher operating temperature to achieve sufficient activity for
ammonia formation.
However,
a higher temperature is not beneficial for the equilibrium, as
explained above.
Thus,
the pressure is increased to improve the equilibrium conversion to
ammonia.
Most
processes, including the original Haber–Bosch process, required
refrigeration to
sub-atmospheric
temperatures to produce liquid, anhydrous ammonia. However, the
Casale
and
Claude processes did not require such refrigeration to
sub-atmospheric temperatures to
produce
liquid, anhydrous ammonia due to their very high operating pressures
(800–1000
bar).
Thus,
the operating pressure influences both the thermodynamic equilibrium
and the liquefaction
temperature. It should be noted that increasing the pressure
increases the energy
requirement
for the compression of the hydrogen and nitrogen feed stock.
Apart
from the (original) Claude process, which was not continuous and did
not
incorporate
a gas recycle, the maximum yield of ammonia at a single pass was no
more
than
around 20% (see Table 1). The unconverted nitrogen and hydrogen were
recycled to the
ammonia
synthesis reactor with the continuous addition of new feed hydrogen
& nitrogen.
An
exception, as mentioned, was the Claude process, which operated at
extreme
pressures
of 900–1000 bar to bring about the ammonia synthesis in a series of
reactors
without
the recirculation of un-reacted nitrogen and hydrogen. Some 40%
conversion was
achieved
in the first pass [11,24–26].
After the removal of the ammonia by condensation,
the
unconverted feedstock was fed successively to two more reactors,
bringing the total
yield
for three reactors to around 85%. At first, issues with the steel
reactors due to the
extreme
pressures delayed the introduction of the Claude process until the
late 1920s [12,16].
From around 1940, the Claude process was redesigned as a continuous
process, with are
circulation
of un-reacted gas, similar to the other ammonia processes.
Table
1.Comparison
of reported yields for synthetic ammonia technologies. Values
adapted from
references
[12,27]
![](images/images_09_12_2022/pic4.jpg)
In the following sections, the development of renewable ammonia
production in
various
countries during the early 1920s is discussed. Historical accounts
of the ammonia
industry before the 1940s have been reported by Ernst [10,22],
Travis [12,16],
and
Van
Rooij [18].
These authors discussed the ammonia industry in general, mainly
focusing
on
fossil-based ammonia, in contrast to the current paper which focuses
on renewable
ammonia
production.2.2.
Italy
At
the turn of the 20th century, the Italian chemical industry was
poorly developed,
due
to limited coal resources [16].
Furthermore, there was limited arable land in Italy [16].Thus,
fertilizers were imported to increase crop yields. These included
Chile salt petre from
Latin
America and ammonium sulfate from Great Britain [16].
Hydroelectric power was developed in Italy by 1900 [16],
enabling the development
of
a chemical industry based on electrochemical processes. In 1905, the
first Frank–Carocalcium
cyanamide plant was opened in Italy [16].
Various hydropower-driven cyanamide
plants
were built in Italy prior to and during the 1920s.
Though cyanamide production remained significant in Italy, the main
growth was
in
renewable ammonia plants. In fact, the very first large-scale
electrolysis-based ammonia
plants were located in Italy. Ammonia was mainly produced with
Fauser ammonia
synthesis
technology (see Table 1) by the Montecatini corporation, which
monopolized
the
nitrogen fertilizer industry in Italy. However, there were smaller
contributions from
the
Casale and Claude processes (see Table 2). Significantly, the
ammonia synthesis technologies
of Casale and Fauser were both developed in Italy [16].
Moreover, the technology
for
electrolysis-based hydrogen production was invented by both Casale
and Fauser. The
Fauser
process was restricted to Italy until 1926, while the Casale process
was licensed
worldwide
from 1921.
![](images/images_09_12_2022/pic5.jpg)
The first renewable ammonia plant was built in Terni, Italy. This
semi-commercial
plant
was based on the electrolysis technology and the ammonia synthesis
technology
of
Luigi Casale [12,29].
By the autumn of 1922, the plant produced about 2 t-NH3d−1,equivalent
to 0.7 kt-NH3y−1[12].
The Terni plant, mainly used for R&D purposes, was
expanded
in 1923 and 1924, to produce about 7–8 t-NH3d−1[12].
Due to a higher ammonia
production
in other locations by the late 1920s (see Table 2), especially as a
result of
Montecatini’s
aforementioned monopoly over nitrogen fertilizer production in Italy,
Terni
declined
as an ammonia production facility and from 1925 became a leading
research center
for
Casale’s company [16].
Casale ammonia technology was used close to the hydro power
station
in Nera Montoro (see Figure 3).
![](images/images_09_12_2022/pic6.jpg)
Most important to this discussion is the Fauser–Montecatini renewable
ammonia plant
in
Merano, South Tyrol, located next to the Marlengo hydroelectric power
station. This
plant
produced about 108 t-NH3d−1by
1925. It was the largest ammonia plant outside
Germany
and at the time the largest renewable ammonia plant in the world.
Under the
state-sponsored
program of Mussolini, the chemical industry was a key pillar for the
fascist
government
in Italy at the time, and ammonia synthesis grew rapidly between 1925
and1927
[16].
Renewable ammonia production was not restricted to mainland Italy. In
1927, an
ammonia
plant was built on the island of Sardinia, next to a hydroelectric
power plant
across
the River Coghinas. The plant was, again, based on Fauser technology
and had a
production
capacity of 10 t-NH3d−1.
Numerous other renewable ammonia plants were constructed in Italy,
mainly based
on
Fauser technology. The Italian ammonia plants are listed in Table 2.
This clearly
demonstrates
that Italy has had the most renewable ammonia plants built to date.
2.3. Other European Countries
During
the early 1920s, various renewable ammonia plants were constructed in
other
European
countries, such as France, Spain, Sweden, and Switzerland. The
renewable
synthetic
ammonia plant at Rjukan, Norway, was constructed later, and is
discussed in
Section
3.1.
In Saint Auban, France, a renewable ammonia plant with Casale ammonia
synthesis
technology
was constructed sometime after 1922. In 1927, this plant was expanded
to a
daily
capacity of about 10 t-NH3d−1[22].
In 1925, a 5 kt-NH3y−1plant
was constructed in Sabiñánigo,
Spain, again based
on
Casale ammonia synthesis technology (see Figure 4) [12].
Another ammonia plant
with
Casale technology was opened in Visp, Switzerland, in 1927. Casale’s
3.5 t-NH3d−1converter
gave an actual production of about 4 t-NH3d−1[12].
Thus, the annual capacity
was
about 2.8 kt-NH3y−1,
based on two converters. Both plants relied on electrolysis
for
hydrogen. Casale converters of different-rated capacities of up to 20
t-NH3d−1wereavailable
by the late-1920s.
![](images/images_09_12_2022/pic7.jpg)
In Ljunga, Sweden, the Stockholms Superfosfat Fabrik replaced its
cyanamide process
with
a renewable ammonia plant based on Fauser ammonia synthesis technology
[10].Finally,
a government-owned renewable ammonia plant based on Casale technology
with
a
capacity of 11 t-NH3d−1was
located at Dugi Rat in Yugoslavia [12].
2.4. Japan
Like
Italy, Japan had scarce arable land but abundant water power. It also
developed
hydroelectric
power around the turn of the 20thcentury
[16].
During the early 1900s, the
main
nitrogen fertilizers were imported bean cake and ammonium sulfate.
However, this
nitrogen
fertilizer supply was gradually supplemented by calcium cyanamide
plants in
Japan
that were powered with hydropower, starting in Minamata in 1909 [16].
The calcium
cyanamide
had a dirty, dusty appearance, and farmers believed this would poison
crops.
Therefore,
the calcium cyanamide was converted to ammonia, which was reacted with
sulfuric
acid to produce the fertilizer ammonium sulfate [10,16].
Three Japanese delegations had traveled to Italy in 1921 to see the
electrolysis-based
ammonia
plant based on Casale technology in operation (see Section 2.2). As a
result, Japan
became
the first non-European country to build an electrolysis-based
synthetic ammonia
plant,
based on Casale technology.
In
late 1923, 7 kt-NH3y−1Casale
ammonia units were introduced at Nobeoka (see
Figure
5) [12].
At the time this was the largest renewable ammonia plant worldwide.
The
plant
was later expanded in 1927 with new Casale converters. By then, the
plant produced
about
19.5 kt-NH3y−1[22].
Other estimates include a total rated plant capacity, based on
larger
converters, of 62 t-NH3d−1[16].
![](images/images_09_12_2022/pic8.jpg)
In 1926, an even larger Japanese ammonia plant was built with a
capacity of21.5–32
kt-NH3y−1in
Minamata, also based on Casale ammonia synthesis technology[12,22].Capacity
was later increased to 100 t-NH3d−1.
Casale ammonia converters at Minimata are
shown
in Figure 5.
State sponsored programs for the chemical industry were key aspects of
colonial
modernization,
and Japan was no exception [16].
The Japanese Empire annexed Korea by1910,
and between 1927 and the early 1930s, two large Casale-based renewable
synthetic
ammonia
plants were also constructed there. In Hungnam in the northeast
(currently
North
Korea), an ammonia plant with a capacity of 120 t-NH3d−1began
operation in1930,
utilizing hydroelectric power [16].
By 1938, the ammonia capacity of this plant andthe
second nearby plant, both owned by Nitchitsu of Japan (operator of
Nobeoka and
Minamata),
was 480 t-NH3d−1
In 1934, Japan was the third largest producer of fixed nitrogen after
Germany and
the
United States, with an annual output of 200 kt ammonia [16].
The Haber–Boschtechnology
of IG Farben was introduced in Japan from the mid-1930s onwards, after
the
initial
successes of the Casale processes and the failings of the Claude
process. Show a
Fertilizers
operated a Japanese-designed synthetic ammonia process. During the
Second
World
War, various Japanese ammonia factories were destroyed by the US Army
Air Force;
from
1945, the Red Army removed equipment from the factory in Hungnam [16].
The
Hungnam
factory was a target during the Korean War, but was later rebuilt with
Chinese
and
Eastern Bloc assistance.
2.5. Canada
Canada
had operational renewable nitrogen-fixation technology as early as
1903, with
the
short-lived Bradley and Lovejoy process, a plasma process similar to
the Birkeland–Eyde
process, for NOX
production
located in Niagara Falls, with a power supply of about2.2
kW [10].
In practice, this plant was a failure. This plasma-based
nitrogen-fixation
technology
had a high energy consumption, and the emergence of the Frank–Caro process
and later the Haber–Bosch process brought about the demise of the
Birkeland–Eydeprocess
[12,13].
By the late 1920s, the American Cyanamid Company produced about54
kt-N y−1of
calcium cyanamide with the Frank–Caro process on the Canadian side of
the
Niagara Falls [30]. This facility opened around 1910.
Nitrogen-fixation capacity for synthetic ammonia was installed in two
sites in Canadian
1930. A renewable ammonia plant with Casale technology started
operating in Sandwich,
Ontario,
with an output of about 2.5 kt-NH3y−1.
A 38 kt-NH3y−1facility
based on Fauser
technology,
with hydrogen also obtained by electrolysis, was built in Trail,
British Columbia,
at
the forerunner of the company Cominco [12].
Later, this plant had a reported capacity of200
t-NH3d−1,
equivalent to about 70 kt-NH3y−1[31].
It was located near a hydro electric
power
station on the Kootenay River. Initially, this plant used unipolar
electrolyzers from
three
different companies, namely Fauser, Pechkranz, and Knowles & Stewart [31].
Later,
all
these electrolyzers were replaced by those supplied by Cominco [31].
The main growth
in
the Canadian synthetic ammonia industry took place from around 1950,
and was based
on
natural gas. Electrolysis-based hydrogen production at the Trail plant
was abandoned
after
the oil crisis of the 1970s, when the export of hydroelectric energy
to the USA became
feasible
[31].
The feedstock was switched to natural gas, which was abundant on the
west
coast
of Canada [31].
2.6. United States
The
United States is unique regarding the renewable hydrogen feedstock for
ammonia
production.
Renewable ammonia at first was limited to mainly small units of a
rated
capacity
of 3 t-NH3d−1designed
by the government’s Fixed Nitrogen Research Laboratory
(FNRL),
and drawing on the by-product hydrogen. Two renewable ammonia
production
facilities
were installed on the US side of the Niagara Falls. There, Roessler &
Hasslacher
Chemical
Company operated a FNRL 3 t-NH3d−1unit
with a hydrogen by-product from
electrolysis
[10].
Later, Roessler & Hasslacher erected a 6 t-NH3d−1plant,
using two FNRL
units,
to utilize by-product hydrogen available from the Hooker
Electrochemical Company.
Similarly,
Mathieson Alkali Company operated a 10–12 t-NH3d−1plant,
again based on
FNRL
units, at Niagara Falls, from by-product hydrogen. In Pittsburg,
California, by-product
hydrogen from chlorine manufacture was used by Great Western Electro
chemical
to
produce about 1 t-NH3d−1[22].
During 1924–1927, the Swiss Ammonia Casale Company
(now
Casale S.A.) operated a renewable ammonia facility at Niagara Falls.
Its Electrolab
corporation’s
electrolyzers for renewable hydrogen production were transferred to
there
new able
ammonia plant of Pacific Nitrogen in Seattle. By-product hydrogen was
used
by
General Chemical/Allied at Solvay’s Syracuse works for a
semi-commercial operation,
from
1927 until the early 1930s.
The renewable ammonia produced in the United States, however, was also
derived
from
biomass gasification with the subsequent formation of ammonia from
hydrogen and
nitrogen
[22].
A biomass-based ammonia plant was located in Peoria, Illinois
(Commercial
Solvents),
producing about 12.3 t-NH3d−1
by the end of 1926 [22].
In 1927, a similar plant
was
constructed in Terre Haute, Indiana, with a capacity of 12–15 t-NH3d−1[10].
The
hydrogen
was produced as a by-product from corn fermentation. However, these
plants,
though
successful, produced ammonia for less than a year. The converters were
used to
produce
methanol instead from 1928 onwards [12].
During the 2000s and early 2010s, interest in biomass-based ammonia
production
re-emerged
as an alternative for renewable ammonia production in the United
States [32].However,
these plants have not materialized so far.3.
Late 1920s–1960s: Scale-Up of Renewable Ammonia and Competition from
Fossil
Technology.
As
mentioned in the foregoing, electrolysis-based hydrogen production for
ammonia
synthesis
generally replaced nitrogen fixation by the Birkeland–Eyde process and
the
Frank–Caro
process. This was due to the lower energy consumption of ammonia
synthesis
compared
to the other processes. During the early 1920s, the feasibility of
operating
electrolysis-based
ammonia was established. As of 1930, electrolysis-based hydrogen
accounted
for about 30% of global ammonia production.
The
general interest in synthetic ammonia stimulated the scale-up of
ammonia synthesis
from a few tons of ammonia per day to hundreds of tons of ammonia per
day in
the
decades that followed. By the late 1920s, a small-scale plant
operating at the rate of
a
few tons of ammonia per day, based on electrolysis, or other feed
stocks, was no longer
competitive
with the larger fossil-based plants [10].
This was especially true during periods
of
fluctuation in demand, including overcapacity of ammonia, at first at
the end of the1920s
[16].
Nevertheless, until well after 1945, a number of large, more
cost-competitive
renewable
ammonia plants were built in various countries, including Egypt,
Iceland, India,
Norway, Peru, and Zimbabwe [9],
in order to benefit from economies of scale. The
operational
global renewable ammonia capacity over time is shown in Figure 6
![](images/images_09_12_2022/pic9.jpg)
As renewable ammonia capacity increased, so too did the requirement
for electrolyz-ers.
Furthermore, electrolyzers needed to be replaced within 5–10 years [21],
while the
renewable
ammonia plants typically operated for several decades. As a result,
various
companies
started developing and producing electrolyzers and electrolyzer
performances
improved
over time [33,34].
The energy consumption for renewable ammonia synthesis
decreased
from 48–50 GJ t-NH3−1during
the 1920s [10,11]
to 36 GJ t-NH3−1during
the1980s
[35].
3.1. Norway
Norway
was one of the first countries to introduce industrial nitrogen
fixation. In fact,
the
Birkeland–Eyde process was developed in Norway by the scientist
Kristian Birkelandand
the industrialist Samuel Eyde [36,37].
In Notodden, hydroelectric power was fed to
electric
arc furnaces to fix nitrogen from air with plasma [37].
In 1905, the plant had three500
kW electric arc furnaces, resulting in an annual capacity of 2 kt
calcium nitrate [12].Various
other factories were established by Norsk Hydro in the following
years. By 1927,Norway
was the country with the largest Birkeland–Eyde process capacity,
capable of
fixating
about 42 kt-N y−1[30].
Instead of transitioning to the Frank–Caro process, Norway changed to
electrolysis-based
ammonia synthesis in the late 1920s [10].
At the Rjukan site, which already had
Birkeland–Eyde
furnaces, a pilot plant for ammonia synthesis was operational by 1927,and
a year later the plant was working at full capacity. The ammonia
synthesis technology
was
provided by the BASF successor IG Farben, that is the original Haber–Bosch
ammonia
synthesis
technology [12].
With a capacity of about 295–340 t-NH3d−1,
the Rjukan plant
was
nearly triple the size of the Merano plant in Italy (see Section 2.2),
which was previously
the
largest renewable ammonia plant. The electrolyzers were provided by
Norsk Hydro(see
Figure 7). The plant remained in operation until 1971.
![](images/images_09_12_2022/pic10.jpg)
From 1953 until 1991, another electrolysis-based ammonia plant was
operated, in
Glomfjord,
producing about 330 t-NH3d−1.
The plant used the same electrolyzers as at
Norsk Hydro’s Rjukan site [35,38].
Due to the emergence of low-cost natural gas in Norway,
this
plant was closed down in 1991.
3.2. Egypt
The
first renewable ammonia plant in Egypt, and probably the country’s
first synthetic
ammonia
plant, was built in 1960. The plant was near the city of Aswan, close
to a
hydroelectric
power station on the Aswan River. The hydroelectric power station and
the
electrolyzers of the renewable ammonia plant are shown in Figure 8.
The reason for
building
the renewable ammonia plant in 1960 was national food security and the
absence
of
natural gas, which became commercially available in Egypt only from
1970 onwards [39].
With a production of 400–500 t-NH3d−1or
140–175 kt-NH3y−1,
the ammonia plant
in
Aswan was the largest renewable ammonia plant ever built. Initially,
the plant was
operated
with electrolyzers from De Nora, but these were replaced with
electrolyzers from
Brown
Boveri in 1977 [40].
This renewable ammonia plant, also known the KIMA plant, was still
operational
into
the 2000s [41].
However, a second ammonia plant was recently built in Aswan for the
production
of urea, based on natural gas. This fossil-based ammonia plant
replaced the
renewable
ammonia plant, which was closed down in 2019 [42].
![](images/images_09_12_2022/pic11.jpg)
In 1958, a renewable ammonia plant became operational in Nangal,
located in the
northern
part of India. The electricity was derived from the Bhakra Dam.
The
plant produced about 400 kt-CAN y−1(calcium
ammonium nitrate), equivalent to
about
285 t-NH3d−1or
100 kt-NH3y−1[44].
It was equipped with De Nora electrolyzers.
The
electrolyzers were operated at a reduced load from 1978 onwards, when
the
ammonia
plant was changed to fuel oil as feedstock [45].
The plant was converted to
natural
gas in 2013 [46].
3.4.Peru
A
renewable ammonia plant was built in Cusco, Peru, in 1962. By 1965,
the plant
had
a rated capacity of 5200 Nm3H2h−1from
seven parallel electrolyzers with a rated
capacity
of 3.5 MW, equivalent to about 60–65 t-NH3d−−1or
20 kt-NH3y−1[31].
These
electrolyzers
are of the high-pressure bipolar-electrolyzer type, operating at 90◦C
and30
bar, manufactured by Lurgi.
The
Cuzco plant is the only renewable ammonia plant that is currently
still in operation.
The plant is equipped with ThyssenKrupp electrolyzers, operating at an
energy
consumption of≤4.3
kWh Nm−3H2[47].
A typical module of 10 MW consists of three
stacks
of 3.3 MW. The hydrogen pressure at the electrolyzer outlet is about
0.3 bar. Assuming
an energy consumption of about 4 GJ t-NH3−1for
nitrogen purification and ammonia
synthesis
[48], this gives a total energy consumption of about 34 GJ t-NH3−1.
3.5. Zimbabwe
The
last electrolysis-based ammonia plant to be built, during 1972–1974,
is at Kwekwe,Zimbabwe
(see Figure 9). By 1975, the plant produced about 72.6 kt-NH3y−1.
Hydro electric
power
was delivered from the Kariba Dam. Twenty-eight alkaline electrolyzers
with
a
rated capacity of 3.5 MW were operated in parallel, based on
high-pressure bipolar
electrolyzers
manufactured by Lurgi. The total rated capacity of these electrolyzers
was
about
21,000 Nm3H2h−1.
The electrolyzer design was the same as for the Cusco plant in
Peru,
e.g., operating at 90◦C
and 30 bar. In 2015, the plant was decommissioned due to an
energy
deficit in Zimbabwe and the associated high electricity prices.
Given
that the plants in Peru and Zimbabwe used similar electrolysis
technology, the
energy
consumption of these plants is probably similar. The energy
consumption of the
electrolyzers
was about 4.5 kWh Nm−3-H2[20],
equivalent to about 32 GJ t-NH3−1.
The
nitrogen
purification and ammonia synthesis add another 4 GJ t-NH3−1[48],
yielding a
total
energy consumption of about 36 GJ t-NH3−1.
![](images/images_09_12_2022/pic12.jpg)
![](images/images_09_12_2022/pic13.jpg)
4. 1960s–2021: Natural Gas Out competes Renewable Ammonia Production
on
a Large Scale
During
the 1960s, renewable ammonia production reached its peak with an
annual
production
of 0.65 Mt (see Figure 6). This represented about 4% of global ammonia
production.
Only one renewable plant was built after the 1960s, namely that at
Kwekwe, in
Zimbabwe
(see Section 3.5).
The reasons for the decline of renewable ammonia synthesis in the
latter half of the20th
century are discussed in this section. Especially, the emergence of
abundant and
low-cost
natural gas was responsible for the decline in renewable ammonia
production.
Currently,
essentially all ammonia production outside China is based on natural
gas [7].The
four main reasons for the decline of renewable ammonia synthesis in
favor of natural
gas-based
ammonia synthesis are:
•Technology
improvements for fossil-based hydrogen production, especially for
natural
gas-based
hydrogen production (Section 4.1);
•Cost
reductions and availability of fossil-based feed stocks, especially
natural gas
(Section
4.2);
•Better
cost-scaling of fossil fuel-based technologies (Section 4.3);
•Globalization
of the fertilizer trade (Section 4.4).
4.1. Technology Improvements for Fossil Fuel-based Hydrogen Production
The
technology for large-scale natural gas-based hydrogen production was
introduced
for
ammonia synthesis during the 1940s–1950s. This began with the United
States war time
program,
when six new facilities adopted the primary and secondary
steam-reforming
of
natural gas (methane), a technology developed by ICI [15].
This was followed with
new
markets for pure hydrogen, namely for hydro treating in refineries. A
benefit of
natural
gas over coal-based hydrogen production is the lower sulfur content in
natural
gas,
requiring less clean up at the front end. Since then, the technology
for natural gas-based
hydrogen production has substantially improved. Initially, the energy
consumption
for
natural gas-based ammonia synthesis was 55 GJ t-NH3−1,
while the lowest current
energy
consumption is currently 26 GJ t-NH3−1[5].
The reasons for this decrease in energy
consumption include, for individual high-capacity ammonia units of
over 600 t-NH3d−1,the
introduction of pressure reforming and centrifugal compressors
(replacing reciprocating
compressors),
which enabled a tripling of the capacities of the individual
converters.
Improved
heat integration through process optimization enabled the scale-up in
single-train
energy-integrated ammonia units. In addition, there were advances in
improved
catalyst
activity for the lower temperature and pressure operations which
accompanied
the
scale-up [5].
There is an extensive literature describing historical developments in
fossil-based
ammonia production [49–52].
In contrast, the technology for electrolysis-based hydrogen production
has remained
remarkably
unchanged. Currently, the most efficient electrolysis-based ammonia
synthesis
technology
consumes about 33 GJ t-NH3−1[7],
compared with about 50 GJ t-NH3−1acentury
ago [11].
An indication of the changes in energy consumption for coal-based
ammonia
synthesis, electrolysis-based ammonia synthesis, and natural gas-based
ammonia
synthesis
is shown in Figure 10.
![](images/images_09_12_2022/pic14.jpg)
4.2. Cost Reductions of Fossil Feed stocks
Though
in the late 1920s electricity was more costly than coal as a source of
power, in
the
case of ammonia synthesis the energy consumption from coal was
substantially higher
than
for electrolysis-based ammonia production (see Figure 10). This made
renewable
ammonia
production competitive except for in the large plants (IG Farben, ICI,
Du Pont,and
Allied Chemical). However, because the energy consumption of
coal-based ammonia
synthesis,
and especially natural gas-based ammonia synthesis, decreased after
the mid-1940s
(see Figure 10), electrolysis-based ammonia production became less
competitive. This
was
notably the case from the mid-1960s following the introduction of the
novel single-train
high-capacity
energy-saving units by the engineering contractor M.W. Kellogg.
Hydropower
costs at least 30 USD/MWh [53,54],
equivalent to about 8.3 USD/GJor
7.9 USD/MMBtu, resulting in an electricity price of at least 300 USD/t
for ammonia
production.
This does not include other expenditures, such as capital investment
and
operational
costs, which also easily add 200 USD/t [55].
This is not competitive, given that
ammonia
market prices have typically been 200–300 USD/t. For comparison, the
cost of
natural
gas can be as low as 2 USD/MMBtu in various locations, equivalent to
an ammonia
feedstock
cost of 54 USD/t ammonia [51].
4.3. Better Cost-Scaling of Fossil Fuel-Based Technologies
During
the 1920s, most ammonia synthesis plants were small, typically with a
capacity
< 100 t-NH3d−1,
with few exceptions [22].
At this process scale, the investment cost fora
coal-based ammonia plant and an electrolysis-based ammonia plant was
similar at about4560
USD/t-NH3/y
and 4940 USD/t-NH3/y,
respectively in 2020 USD equivalent [10].
During the early 1960s, the largest individual fossil-based ammonia
units had reported
capacities
of about 455 t-NH3d−1[15].
However, typical unit sizes at the time were250–300
t-NH3d−1.
Several loops, or trains, each one a single ammonia synthesis unit,
typically
operated side by side to increase the capacity of a factory.
The
largest renewable ammonia factory to date was also built during the
1960s, in
Aswan,
Egypt, with a capacity of 400–500 t-NH3d−1.
Since the 1960s, the size of typical
fossil-based
ammonia units have been scaled-up substantially, as mentioned above,
due
to
technological developments and economies of scale [5].
With scale-up, more heat
integration
was possible, resulting in a lower overall energy consumption (Figure
10).
Currently, typical ammonia units have a capacity of 1000–3300 t-NH3d−1[15].
The
largest
fossil fuel-based ammonia synthesis unit currently in operation has a
capacity
of
3670 t-NH3d−1[56].
A historical overview of ammonia unit capacities is shown in
Figure
11.
![](images/images_09_12_2022/pic15.jpg)
Figure 11.Ammonia
production, individual unit capacities, through the years,
fossil-based ammonia
production
(brown squares), and renewable ammonia production (green triangles).
Estimates for
the
largest fossil-based ammonia units between 1913 and 1918 are from
Travis [12],
and between themid-1960s
and 2019 from Brightling [15]
and ThyssenKrupp [56].
Estimates for renewable ammonia
units
are discussed in this article.
The
cost of fossil-based technologies for hydrogen production scales
substantially,
with
cost-scaling factors typically of 0.6. In contrast, electrolyzers are
produced in modules
with
a few MW, which are increased in cases of higher hydrogen demand.
Thus, the
cost
benefit of large-scale production is less substantial than for
fossil-based hydrogen
production
technologies [35,57].
The cost-scaling for the ammonia synthesis loop still
applies
for renewable ammonia production [58].
The typical investment requirements of
various
ammonia synthesis technologies are shown in Figure 12.
![](images/images_09_12_2022/pic16.jpg)
4.4. Globalization of the Fertilizer Trade
During
the 1920s, renewable ammonia was manufactured to provide national food
security,
especially in Italy and Japan. Ammonia and derived fertilizers
increasingly be-came
global commodities in the decades that followed. Given that
fossil-based ammonia
production
is often more cost-competitive (especially at large scales) than
renewable ammonia
production, and that the cost of ammonia transport is typically low,
renewable
ammonia
was eventually unable to compete in the global ammonia fertilizer
market [7,59].In
addition, urea, a fertilizer with the chemical formula CO(NH2)2,
accounts for 55% of
current
ammonia utilization [6].
Urea synthesis requires a carbon feedstock, such as natural
gas
or coal, which is processed to yield synthesis gas (hydrogen and
carbon monoxide),
which
is the source of carbon dioxide (from carbon monoxide by the shift
reaction), that is
reacted
with ammonia. Decarbonized carbon feed stocks are currently expensive.
Recent
events such as the COVID-19 pandemic and extreme climatic conditions
reduced
ammonia production in 2020, resulting in major supply problems for
natural gas and
high
fertilizer prices in late 2021, and even more in early 2022 [60].
In light of this supply
problem,
a project has recently been announced in Kenya for the domestic
production
of
a renewable fertilizer from renewable solar and wind energy [61].
This food security
situation
is similar to that of Italy and Japan during the 1920s (see Sections
2.2 and 2.4).Providing
domestic food security and thus economic security may ‘outcompete’ or
at least
rival
the global market again in certain cases.5.
2021 and Beyond: Renewed Interest in Renewable Ammonia
During
the 1980s, in the wake of the oil crises, ammonia gained interest as
an energy
vector
in the hydrogen economy [62,63].
The interest in ammonia as an energy vectorre
emerged in the early 2000s, due to growing concerns regarding the
environmental
impact
of fossil fuels. Various authors have discussed the central role of
ammonia in the
hydrogen
economy [64,65].
In 2004, the NH3Fuel
Association (now the Ammonia Energy
Association)
organized its first NH3Fuel
Conference in West Des Moines, Iowa. Since then,
conferences
on ammonia as a decarbonized energy vector and as a hydrogen carrier
have
been
organized at least annually, with activities intensifying in recent
years.
Especially
since 2020, the momentum towards renewable ammonia has been substantial,
with various world-scale renewable ammonia plants being announced for
the present
decade
[7].
Several authors have reviewed the central role of ammonia in a
hydrogen
economy
[59,66–70].
Furthermore, a consortium of industrial companies has indicated
that
ammonia will play a central role in decarbonizing the shipping sector
[71].
Key factors
for the renaissance of renewable ammonia production include: (1)
increasing carbon
emission penalties, (2) the decreasing cost of renewable electricity
from solar and wind,(3)
the decreasing cost of electrolyzers and scale-up of electrolyzer
capacity, and (4) the
development
of novel electrolysis technologies [7,21,72].
In fact, Saygin and Gielen [73]estimated
a renewable ammonia production of 495 Mt by 2050 in their 1.5◦C
scenario,
which
is nearly three times the current global ammonia production.
Novel
approaches to electricity-driven nitrogen fixation are currently
extensively
researched,
including electrochemical ammonia synthesis [67,74–77] and
plasma-catalytic
ammonia
synthesis [78–81].
Such technologies can follow the load fluctuations of renewable
electricity,
and are more easily scaled down than an electrolysis-based Haber–Bosch
plant.
However,
scientific challenges remain for these technologies [82–84],
and the economics
are
not (yet) competitive with an electrolysis-based Haber–Bosch process
[85–87].
A century ago, in 1921, renewable ammonia production stimulated not
only the global
production
of synthetic ammonia but also the development and scale-up of the
electrolyzer
industry.
Today, the electrolyzer industry is once more spurred on by the
development of
large-scale
renewable ammonia projects [7].
A current technological challenge is the fluctuation in renewable
electricity from solar
and
wind. The typical solution for this is over sizing the electrolyzers
for hydrogen production,
and storing compressed hydrogen [88].
This allows the operation of the ammonia
synthesis
loop with minimal fluctuations. Such a facility is already under
construction
in
Puertollano, Spain, where fossil-based hydrogen production was
partially replaced by
renewable
hydrogen from solar PV electricity, a battery, water electrolysis, and
compressed
hydrogen
storage [89].
Alternatively, the natural gas feedstock of a gas-based ammonia plant
can be replaced
with,
for instance, biogas, to decrease the carbon footprint of the ammonia
product [7].Furthermore,
biomass can be gasified for hydrogen production, with the subsequent
conversion
to ammonia [90].In
conclusion, renewable ammonia is set to make a major comeback and play
a key
role
in the decarbonized energy landscape and in the hydrogen economy.
While renewable
ammonia
played a key role in national food security for countries without
fossil resources
during
the 20th century, it promises, in addition, national and global energy
security during
the
21st century.
Green Play Ammonia™, Yielder® NFuel Energy.
Spokane, Washington. 99212
www.exactrix.com
509 995 1879 cell, Pacific.
exactrix@exactrix.com
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