ENERGY HIGHLIGHTS - No16 2021 - NATO ENERGY SECURITY CENTRE OF EXCELLENCE
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ERGY SEC
EN U
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NA NATO ENERGY SECURITY
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CENTRE OF EXCELLENCE
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F E XC E
ENERGY HIGHLIGHTS
No 16 2021
ENERGY H IG HLIG HTS No 16 1
This is a product of the NATO Energy Security Centre of Excellence (NATO ENSEC COE). It is produced
for NATO, NATO member countries, NATO partners, related private and public institutions and related
individuals. It does not represent the opinions or policies of NATO or NATO ENSEC COE. The views
presented in the articles are those of the authors alone.
© All rights reserved by the NATO ENSEC COE. Articles may not be copied, reproduced, distributed or
publicly displayed without reference to the NATO ENSEC COE and the respective publication.
2 No 16 ENERGY H IG HLIG HTS
Content
4 Editorial
5 Nitrogen based propellants as substitute for
carbon containing fuels
BY DR. JUTTA LAUF, WSEWOLOD RUSOW, DR. REINER ZIMMERMANN
22 The hidden costs of solar photovoltaic power
BY THOMAS A. TROSZAK
34 What to expect from an energy transition for
Australia’s energy security and its Defence Force?
BY CAMILLE FOURMEAU, NICOLAS MAZZUCCHI, REINER ZIMMERMANN
44 The Synchronization of the Baltic States’:
Geopolitical Implications on the Baltic Sea Region and Beyond
BY JUSTINAS JUOZAITIS
ENERGY H IG HLIG HTS No 16 3
Editorial
By COL Romualdas Petkevičius (LTU-AF)
Director of the NATO ENSEC COE
T
he clean energy Meanwhile, in his piece Thomas Troszak exam-
transition is with- ines the environmental impact of solar photo-
out a doubt one voltaics (PV) production. More specifically, the
of the greatest author introduces the readers to the many types
challenges of the 21st cen- of fossil fuels that are used in PV production and
tury. The reasons for that notes how some other environmentally hazard-
are myriad, complex and ous inputs are required before the delivery of a
sometimes overlapping. solar PV array can take place.
There are significant chal-
lenges associated with In the third article, Camille Fourmeau, Nicolas
some of the new and innovative energy tech- Mazzucchi and Dr. Reiner Zimmermann analyse
nologies that could help to decarbonise hard-to- Australia’s energy transition challenges and its
abate sectors. And, due to a number of reasons, implications for the country’s military. The au-
even some of the more established technologies thors place particular emphasis on the difficulties
have flaws that often are easily overlooked. Canberra faces while trying to reconcile its cur-
rent dependency on fossil fuels, the negative im-
In addition to these technological problems, in plications of climate change and the urgent need
some countries historical path dependencies can to expand investments in renewable sources of
hinder the clean energy transition from gaining energy.
momentum. Or, alternatively, traditional energy
security issues may at times divert some of the Finally, Justinas Juozaitis explains why it is
attention that could otherwise be spent on mak- important for the Baltic States to disconnect
ing the energy systems greener. their power systems from the Soviet-era BRELL
power grid and to synchronize with the Con-
This issue of Energy Highlights will tackle some tinental European Network. The author not
of these challenges head on. only provides a comprehensive account of
the historical development of the BRELL grid,
In their contribution, Dr. Jutta Lauf, Wsewolod highlights the synchronization significance for
Rusow and Dr. Reiner Zimmermann examine the Baltic energy security, but also points out how
utility of nitrogen-based fuels. They argue that Russia and Belarus have been pursuing various
these fuels have significant advantages over car- strategies to deter the Baltics from leaving the
bon-based fuels because they do not emit green- BRELL grid.
house gases or any other hazardous compounds
during combustion. While the authors agree that In the end, we hope that these articles would
it may take a while before nitrogen-based fu- provide you, the readers, not only with a better
els can become adopted on a wider scale, they grasp of the clean energy transition challenges
are confident that in the near future these fuels that many governments face, but would also in-
could play a meaningful role in the global decar- spire you to be part of the change.
bonisation effort.
4 No 16 ENERGY H IG HLIG HTS
Nitrogen based propellants
as substitute for carbon
containing fuels
by Dr. Jutta Lauf, Wsewolod Rusow and Dr. Reiner Zimmermann
1. ABSTRACT
N
itrogen based fuels have several ad- and plants are existing in all major agricultural
vantages over carbon-based fuels. No countries, the upscaling of ammonia production
greenhouse gases (GHG) or health seems easily possible. The prime advantage of ni-
compromising compounds are emit- trogen based fuels are both, the intrinsic lack of
ted during the combustion and the subsequent carbon as well as the technological maturity of
waste gas treatment of most nitrogen bases their production, transport and storage. As the
fuels. When nitrogen based fuels are produced various propulsion engines and the combustion
with power from renewable sources, no GHG technologies reach technical maturity, nitrogen
are emitted during the production process either. based fuels will certainly become attractive for a
All nitrogen based fuels originate from ammonia decarbonizing world.
(NH3), which is produced via the Haber-Bosch-
Process. Ammonia combustion engines have 2. INTRODUCTION
been developed and tested as prototypes for sev-
eral decades. In recent years the interest mainly Nitrogen based fuels are well known since several
for use in naval propulsion systems has grown. decades but rarely used for transportation pur-
Marketable fuels cells using ammonia are now poses. Their inherent environmental advantage
commercially available, as well as fuel cells using is the absence of any carbon dioxide (CO2) emis-
hydrogen which was stripped from the ammonia. sions during combustion. Therefore, they may
Hydrazine is a commonly used rocket propellant contribute significantly to the internationally
but is not used in civil environments due to its demanded decarbonisation of the transport sec-
high toxicity. Ammonium nitrate and urea en- tor. However, easy access to fossil carbon-based
gines are fringe applications which were currently gas (methane) and liquid fuels (derived from
tested in laboratory environments. Production of crude oil) during the past decades as well as their
nitrogen based fuels by using renewable power cheapness, low safety risks and established pro-
sources would be most economically feasible cessing infrastructure made them the almost ex-
with energy produced in the global Sunbelt. Since clusive propulsion energy for transportation pur-
the necessary Haber-Bosch technology is mature poses. Crude oil is easily refined to e. g. kerosene,
by Dr. Jutta Lauf, Wsewolod Rusow and Dr. Reiner Zimmermann
Dr. Jutta Lauf works at the department of Renewable Energy Management at the University of Applied
Sciences Erfurt. She is also a Fellow at the NATO ENSEC COE.
Wsewolod Rusow works at the Doctrine and Concept Development Division of the NATO ENSEC COE.
Dr. Reiner Zimmermann was the Head of the Research and Lessons Learned Division of the NATO ENSEC COE.
ENERGY H IG HLIG HTS No 16 5
diesel, or gasoline. In the next decade the need actions were taken to reduce the dependency
to move away from fossil carbon-based energy from fossil carbon fuels in the transportation or
may favour – at least in part - nitrogen as fuel in heating sectors on a global scale and only the nu-
the transportation sector due to its ecologic ad- clear power generation sector gained importance
vantages, the technological practicability and the since the end of the 1970ies, mainly in techno-
relatively moderate changes needed to existing logically advanced countries (Roser 2020).
infrastructure for production and logistics.
Even today most attempts to reduce or mini-
As early as 1943, during the fossil fuel shortages mise the usage of carbon-based fossil fuels are
in WW II, a retrofitted bus engine was propelled not price driven. In fact, global oil prices have
by ammonia (NH3) in Belgium (Kroch 1945) (Fig- reached a relatively stable minimum caused by
ure 1). In the 1950ies an Austrian inventor rede- the increased application of fracking techniques
signed a motor bike to run on hydrazine (N2H4) in North America, political discord of the oil
in a fuel cell (Figure 2). Hydrazine in combina- producing countries about production quanti-
tion with other fuels was used during WW II as ties and the current economic slow-down due
a propellant for the German A4 rocket and the to the SARS-CoV-2 pandemic (BP 2020; BBC
rocket engine driven German Me-163 interceptor 09.06.2020). Current attempts to reduce the us-
airplane (Ziegler 1976). Hydrazine is still com- age of fossil fuels and to replace them with carbon
mon in the Titan and Ariane rockets as well as in free fuels are due to mounting concerns regarding
satellites and space ships (Haidn 2008). However the negative environmental consequences of ris-
hydrazine is not widely used because of its high ing global temperatures which are caused by the
toxicity (Table 1) (Bundesanstalt für Arbeitss- increasing atmospheric concentration of CO2 and
chutz und Arbeitsmedizin 1991). Nitrous oxide other greenhouse gases. The increasing global
(N2O) injection in piston driven engines was used temperatures cause rising sea levels, more se-
by high performance airplanes during WWII as an vere droughts, raging wildfires and the melting of
additional power booster. permafrost areas. The resulting natural disasters,
economic disruptions, social unrest and mass
Non-fossil originated carbon-based fuels (often migrations will result in more refugee and rescue
called “synthetic carbon fuels”) are very expen- missions for the military forces (Reinhardt and
sive in production and are currently used for niche Toffel 2017; Fourmeau and Zimmerman 2020).
applications only. Even after the global oil price
shocks in 1973 and 1979/80, which were caused The present article will provide an overview of
by geo-political disruptions (BP 2020), no serious the chemical production processes of nitrogen-
based fuels using power from renewable energy
sources as well as cover the safety issues of nitro-
gen fuels in comparison with carbon-based fuels.
Also, propulsion technologies for nitrogen based
fuels and possible global NH3 production capaci-
ties will be discussed.
3. NITROGEN BASED FUELS IN
POWER-TO-FUEL PROCESSES
Power–to-fuel (PtF) is an umbrella term for pro-
cesses using electricity from renewable sources
for the production of gaseous or liquid fuels. Liq-
uid fuels are the most attractive and cost-effec-
tive approach for storing and delivering energy
Figure 1: Retrofitted bus with an ammonia driven for large scale applications. They are unmatched
internal combustion engine in 1943 during WWII in in terms of transportability and energy density
Belgium (Kroch 1945).
6 No 16 ENERGY H IG HLIG HTS
(Andersson and Grönkvist 2019) compared with quires a significant amount of energy and safety
gaseous fuels (Table 1). precautions to reach these states (Table 1) (An-
dersson and Grönkvist 2019). H2 is also a valua-
Liquid fuels come with higher production costs ble base chemical, leading to further applications
compared to gaseous fuels because more steps in fuel syntheses.
are required to produce them. Due to the second
law of thermodynamics each energy conversion (1) Electricity production from renewable sourc-
process – of which chemical synthesis is one - re- es. Electricity can be used directly in electric en-
sults in a loss of energy available to perform work gines. (2) Electrolysis of water and production of
(free energy). This fact leads with each additional hydrogen (H2). (3) Synthetic gas (syngas) or am-
step of synthesis to substantial losses in the monia (NH3) can be produced with H2. Syngas
useable fuel energy content (Atkins et al. 1990; requires a CO2 source from fossil or non-fossil
Perner et al. 2018). Consequently, the number of sources. NH3 requires nitrogen (N2) from ambi-
production or energy conversion steps should al- ent air. (4) Reactors for the synthesis of organic
ways be kept as low as possible. compounds (synthetic fuels or methanol) or hy-
drazine. (6) Fuel cell for electricity production. (7)
A selection of production pathways for nitrogen- Engine technologies useable for different types
based fuels is presented in Figure 2 . All processes of fuels. Electricity from the producing plants can
start with the production of electricity from re- be used directly in electric engines. H2, NH3 and
newable sources (1). Electricity can be directly hydrazine can be either used in fuels cells, which
used in electric engines via battery storage. power electric engines or in internal combustion
Electricity driven electrolysers produce hydro- and rocket engines. Modified after (Sterner 2019;
gen (H2), from water, which is the first possible Perner et al. 2018; Grinberg Dana et al. 2016).
chemical storage (Holleman et al. 1985). H2 is a
nontoxic gas under normal conditions, but han- NH3 produced by the Haber-Bosch process (Hol-
dling is difficult due to its flammable and ex- leman et al. 1985) is the first of several possible
plosive properties (Table 1) (Bundesanstalt für nitrogen based fuels (3). Nitrogen (N2) is needed
Arbeitsschutz und Arbeitsmedizin 2020). The as a base component (Formula 1) and normally
volumetric and gravimetric energy density of H2 extracted from ambient air. NH3 can be used as
in compressed or liquefied form is high but it re- a base chemical for further synthesis (4), in fuel
cells (6) or in internal combustion or jet engines
(7). Hydrazine and its methyl derivatives are used
as long term storable rocket fuels (Haidn 2008).
Because hydrazine is extremely toxic (Bundesan-
stalt für Arbeitsschutz und Arbeitsmedizin 1991)
(Table 1), its usage is only allowed in environ-
ments where no substitutes are possible, e.g. in
military and space technologies. Fuels which are
based on nitrates (NO3-) - including aqueous so-
lutions of urea, ammonium nitrate and their mix-
tures - are currently tested in laboratory environ-
ments (Grinberg Dana et al. 2016).
Carbon based fuels (often simply called synthetic
fuels) derived from the Fischer-Tropsch pro-
cess or methanol from methanol synthesis can
be obtained via the production of synthetic gas
Figure 2: Schematic of power- to-X (PtX) produc- (syngas) (Holleman et al. 1985). These chemical
tion pathways and the usage of the products for processes require CO2 as the carbon source. Non
mobility. fossil CO2 sources (secondary carbon sources) as
ENERGY H IG HLIG HTS No 16 7
well as their production costs were discussed in mans to leave a contaminated area before health
(Lauf 2020b). Methanol can be used in fuel cells risks occur. However, if suddenly exposed to high
and methanol or synthetic fuels can also be used concentrations, the human nose can no longer
in internal combustion and jet engines. detect it. Hydrazine is the most toxic and inflam-
mable of the fuels discussed. Ammonia is 200
Ammonia and hydrazine are generally more toxic times less toxic than hydrazine and not inflam-
than conventional fossil or synthetic fuels (Table mable. The smell of hydrazine is similar to that of
1). Many countries define maximum workplace NH3, but less intense. Ammonium nitrate is not
air concentrations for mean daily exposure to toxic but explosive in solid state while urea is nei-
humans (e.g for Germany: Bundesanstalt für Ar- ther toxic nor inflammable.
beitsschutz und Arbeitsmedizin 1991; Bundesan-
stalt für Arbeitsschutz und Arbeitsmedizin 2020). The carbon-based methanol and diesel fuels are
Hydrogen as the first fuel generated from elec- less toxic than NH3 but inflammable. A maxi-
tricity is not toxic but extremely inflammable mum workplace air concentration for diesel is
and explosive. It is odourless and can only be de- not given, as it is a mixture of many components.
tected by elaborate technical devices. NH3 is also The most toxic component is benzene. Synthetic
toxic but self-alarming due its pungent smell. diesel may differ from its fossil counterpart, as
The limit of detection (LOD) by the human nose the Fischer-Tropsch synthesis can be managed to
is about 4 times lower than the allowed work- result in less toxic by-products.
place air concentration (Assumpção et al. 2014).
The unpleasant smell of NH3 normally forces hu- The so-called inferior heating values or net ca-
Maximum workplace
Inflammable Energy content, Hi
air concentration
and/or explosive [kWh/kg]
[ppm]
Hydrogen (g) (H2) - (1) Yes (3) 33,3 (6)
Ammonia (g) (NH3) 20 (1) No (3) 5,2 (6)
Hydrazine (l) (N2H4) 0.1 (2) Yes (3) 5,5 (6)
Urea (s) (H2NCONH2) - (1) No (3, 4) 2,6 (6)
Ammonium nitrate (NH4NO3)
- Solid - (1) Yes (5) -
- Aqueous solution - (1) No (5) -
Methanol (l) (CH3OH) 100 (1) Yes (4) 6,3 (6)
Ethanol (l) (CH3-CH2OH) 200 (1) Yes (4) 7,5 (6)
Diesel fuel (l) (analogue to F-34) - (1) Yes (1) 11,8 (7)
Carbon dioxide (g) (CO2) 5 000 (1) No -
Table 1: Maximum workplace air concentrations in parts per million [ppm], flammability and energy densi-
ty for selected alternative fuels as well as for ethanol and carbon dioxide. State of aggregation at ambient
air temperature and pressure: g = gaseous, l = liquid, s = solid). Energy content expressed as the so called
inferior heating value (net caloric value, Hi) Citations: (1) (Bundesanstalt für Arbeitsschutz und Arbeits-
medizin 2020); (2) (Bundesanstalt für Arbeitsschutz und Arbeitsmedizin 1991); (3) (Holleman et al. 1985);
(4) (Beyer and Walter 1988); (5) (Grinberg Dana et al. 2016); (6) (Beilicke 2010); (7) (Reitmair 2013).
8 No 16 ENERGY H IG HLIG HTS
loric value Hi of a selection of fuels (referenced to Large scale electrochemical storage in batteries
weight) are shown in Table 1. H2 shows the highest is not yet economic and affordable, although a
Hi value. The nitrogen-based fuels NH3 and N2H4 as pilot project in Australia shows promising results
well as methanol and ethanol show inferior heating in levelling fluctuations and peaks in the elec-
values within the same order of magnitude. Hi is tricity demand during the summer months for a
rising with the increasing number of chemical bonds community of 30 000 households (DER SPIEGEL
of the respective compound. The energy content 2017). Physical storage using pumped hydro
of diesel fuel is highest, as it contains much more power stations is a mature technology but lim-
chemical bonds. From the perspective of Hi values, ited by topographic conditions. Environmental
diesel appears to be the most promising fuel to pro- and social problems invoked in building them are
duce. However, the Hi does not reflect the amount paramount and have led to an almost complete
of energy needed – or, in other words, the amount construction freeze during the past decades in
of free energy lost - to produce these components the western world (Sinn 2017; Bundesministe-
from steps (3) to (5) in Figure 2. If the energy con- rium der Justiz und für Verbraucherschutz 2020).
tent of the product and the energy needed for its Chemical storage of electricity is currently in-
synthesis are accounted for, H2 is the best fuel to tensely studied. It is the preferred storage solu-
use and NH3 is the second best. tion because the energy carrier can be directly re-
transformed into electricity by fuel cells, internal
FLUCTUATING POWER SUPPLY FROM combustion engines, jet engines etc or used as
RENEWABLE PLANTS AND STORAGE OF fuel for mobility.
ELECTRIC ENERGY
The focus of the following sections is on the pro-
Electricity is difficult to store on a large scale. It
duction steps of nitrogen based fuels from re-
has to be provided “on time” to enable efficient
newable electric power, in comparison with car-
and effective processes in all sectors of society.
bon bases fuels.
Most providers ensure this flexibility by provid-
ing excess production capacity in plants with in-
4. INDUSTRIAL SCALE PRODUCTION OF
herent ultralow response times (e.g. gas powered
NITROGEN-BASED FUELS
plants). Power from renewable sources usually
can’t be managed in this way as it has to be pro- AMMONIA
duced when e.g. the wind blows or the sun shines.
Ammonia is a poisonous (Table 1), colourless
Therefore, the key enablers for the shift to re-
and lighter-than-air gas with a characteristic
newable energy sources are efficient means of
pungent smell. Its synthesis (artificial nitrogen
storing renewable electricity for times when it is
fixation) from atmospheric nitrogen (N2) and
not generated and distributing the stored energy
hydrogen (H2) was invented before WWI by the
effectively over large distances. Hydro powered
German scientists Fritz Haber and Carl Bosch.
dams and biogas plants are the only renewable
The so called Haber-Bosch process was imple-
energy producing technologies which are adjust-
mented at an industrial scale during WWI (Hol-
able to fluctuating electricity demands. Howev-
leman et al. 1985) and provided the German
er, they are not available on a scale needed for
Empire with nitrate (NO3-) which could not be
many industrial processes.
obtain from the mines in Chile as they were con-
trolled by the Allied forces. Nitrate was needed
Three forms of storage are considered in this arti-
for the production of explosives like nitroglyc-
cle: a) batteries, b) physical storage and c) chemi-
erine and dynamite. Since more than 100 years
cal storage. This scheme is not the conventional
the Haber-Bosch process remains virtually un-
classification of physics and chemistry. Energy in
changed and this mature technology provides
batteries is stored due to electrochemical process-
NH3 at low costs. Nowadays about 70 % of the
es. Physical storage in this article means gravita-
global ammonia production of about 11,3 * 109 t
tional, kinetic and thermal energy. Chemical stor-
in 2014 is used for fertilizer production (Ritchie
age means the synthesis of new compounds where
and Roser 2020).
the energy is stored in chemical bonds.
ENERGY H IG HLIG HTS No 16 9
The chemical reaction is performed using cat- sodium salt of hypochloric acid (NaClO) is used as
alysators at >10 MPa pressure and temperatures oxidant for NH3 (Holleman et al. 1985).
between 400 – 500 °C (Holleman et al. 1985).
NH3 + ClO- NH2Cl + OH- (4)
91.8 kJ + 3 H2 + N2 2 NH3 (1)
NH2Cl + NH3 + OH- N2H4 + Cl- + OH- (5)
Currently about 90% of the hydrogen needed
for the process is obtained via synthetic gas by
steam gas reformation of fossil resources (typi- AMMONIUM NITRATE
cally gas or coal) which releases huge amounts of Ammonium nitrate (NH4NO3) is globally pro-
CO2 (Holleman et al. 1985). duced in large quantities as a raw material for
most common nitrogen fertilizers. It is produced
in two steps: Nitric acid (HNO3) production from
206.2 kJ + CH4 + H2O CO + 3 H2 (2) NH3 and subsequently NH4NO3 production from
nitric acid. Both steps are often performed at the
same industrial site. The production and handling
Hydrogen can also be obtained by the expensive of NH4NO3 involves mature technologies.
process of electrolysis of water (Holleman et al.
1985) which requires large amounts of electric Ammonia as a gas (g) from the Haber-Bosch pro-
energy (Lauf 2020a). cess is oxidised with oxygen (g) in the presence of
platinum/rhodium catalysts in solid state (s) to
nitric acid (HNO3) which is dissolved in the water
286.02 kJ + H2O (liquid) H2 + ½ O2 (3) formed during the reaction and which results in
an aqueous solution (aq). This process is called
Ostwald process.
Industrial sized Haber-Bosch plants have their
own on-site N2 supply, which is obtained from
ambient air (78% N2, 21% O2 and other gases). 2 NH3 (g) + 4 O2 (g) + H2O (l)
In steam gas reforming plants, the ambient air
2 HNO3 (aq) + 3 H2O (g) + 740 kJ (6)
is used in the clean-up of the synthetic gas (For-
mula 1) resulting in a pure N2 gas. In electrolyser
plants, pure N2 gas can be generated either by
Ammonium nitrate is produced by the acid-base
cryogenic distillation of liquified air or by mem-
reaction of NH3 in aqueous solution and HNO3 in
brane filtered compressed ambient air. The lat-
aqueous solution. The dissolved salt is then dried
ter is less expensive and delivers lower, but suf-
and handled in solid state.
ficient, N2 purity grades. (Holleman et al. 1985;
thyssenkrupp Industrial Solutions AG 2020)
NH3 + HNO3 NH4NO3 (7)
HYDRAZINE
Hydrazine is a toxic and carcinogenic oily liquid. Its
smell resembles that of NH3. For safety reasons it is Ammonium nitrate is explosive and therefore
mostly used in the form of hydrazine hydrate which widely used in mining and quarrying. As fertilizer
is unstable and even as in aqueous solution danger- it is mixed with lime (calcium carbonate, CaCO3)
ous to handle. At industrial scale three pathways and oil to prevent its explosive properties (Holle-
for hydrazine (N2H4) are in common use which all man et al. 1985). However, several catastrophic
use NH3 as base chemical. The most common path- accidents have occurred ever since the Haber-
way is the two step Raschig synthesis in which the Bosch- and Ostwald processes were first estab-
10 No 16 ENERGY H IG HLIG HTS2 NH3 + CO2 H2NCONH2 + H2O (8)
5. WASTE GAS PROPERTIES AND APPLICA-
TIONS OF NITROGEN-BASED FUELS
The composition of waste gases are defined by
the energy conversion technology used. Waste
gases from fuel cells contain only the products of
a complete combustion with no side products. In
the case of carbon-based fuels these are carbon di-
Figure 3: Aerial photo of the BASF Oppenau/Lud- oxide (CO2) and water (H2O) in the case of ammo-
wigshafen (Germany) production plant after the nia- and nitrate-based fuels these are N2 and H2O.
devastating explosion of 400 tonnes of ammoni- The waste gases of urea contain CO2, N2 and H2O.
um sulphate nitrate in 1921 causing 559 fatalities
(Abelshauser 2003). The crater in the foreground
Fossil fuels do contain varying amounts of sul-
indicates the location of the storage area where the
explosion happened.
phur. The maximum sulphur concentration of fu-
els is often regulated by local laws. Sulphur burns
into a mixture of sulphur oxides (SOx). In carbon-
lished in Germany on an industrial scale. In 1921 based fuels volatile organic compounds (VOC’s)
at the BASF Oppenau/Ludwigshafen manufac- and particulate matter (PM) are formed during
turing plant in Germany approx. 400 tonnes of incomplete combustion. Depending on the com-
stored ammonium sulphate nitrate exploded and bustion temperature, the nitrogen (N2) and oxy-
killed 559 persons, mostly workers of the plant gen (O2) from the air form a mixture of nitrogen
(Figure 3) (Abelshauser 2003). The most recent oxides (NOx). This process occurs for both, car-
explosion occurred in 2020 in Beirut (Lebanon), bon- and nitrogen-based fuels and sparked an in-
when approx. 2750 tonnes of stored ammonium tense environmental debate over the future use
nitrate exploded in a warehouse at the harbour of diesel engines. In nitrogen based fuels nitrous
(BBC 05.08.2020). oxide (N2O) and NOx may form as products of an
incomplete fuel combustion.(Baird 1995; Holle-
UREA man et al. 1985; Pavlos and Rahat 2020)
Pure urea is a non-toxic and non-explosive crystal-
line solid which easily dissolves in water or alco- AMMONIA
hols. It is used as fertilizer in agriculture and for the The complete combustion of ammonia under
reduction of NOx in power plants and combus- laboratory conditions is shown in Formula 9. No
tion engines. Sold under the trademark “AdBlue” greenhouse gases (CO2, N2O, NOx) and no toxic
it contains one third of urea mixed with water. components (NOx, SOx, VOC’s and PM) are re-
Other applications are as a pharmaceutical for the leased to the atmosphere (Holleman et al. 1985).
treatment of skin diseases. The production of urea
at an industrial scale became possible after the
Haber-Bosch process was established. Carl Bosch 4 NH3 + 3 O2 2 N2 + 6 H2O + 1 267 kJ (9)
and Wilhelm Meiser established an urea produc-
tion site in 1922 (Holleman et al. 1985).
A selection of ready to use solutions as well as de-
For urea production NH3 and CO2 are mixed at velopment projects in early and advanced stages
temperatures of 170 – 220 °C and at pressures with emphasis on NATO members and partners is
between 12.5 – 25.0 * 106 Pa (125 – 220 bar). The given below. Intensive research and development
reaction is in equilibrium and can be pushed to- work in this field is also done by the Peoples Re-
wards the desired urea product by adding NH3 in public of China, the Republic of Korea and Japan.
excess (Holleman et al. 1985).
ENERGY H IG HLIG HTS No 16 11Ammonia in NH3-fuel cells diesel engines retrofitted in commercially avail-
Fuel cells provide optimal combustion conditions able cars and trucks to run on pure NH3, as well
with no secondary reactions. However, NH3-fuel as standard carbon-based fuels mixed with NH3.
cells are not yet a mature technology and re- Prototype cars and trucks are operating (Vezina
search and development efforts are being under- 2020). Ammonia is also tested under laboratory
taken on a global scale (Assumpção et al. 2014; conditions as sole fuel in internal combustion en-
Cinti et al. 2016; Holleman et al. 1985).Currently gines in the shipping sector by the Finnish ship-
a pilot project which is partly financed by the EU ping company Wärtsilä. Results are not available
Horizon 2020 SHIPFC program is upscaling a 100 yet, but first tests seem promising (Figure 4 a)
kW NH3-fuel cell to a 2 000 kW version. It will (Wärtsilä Helsinki Campus 2020). The German
be installed the long haul vessel “Viking Energy”, engineering company MAN has already devel-
allowing emission free sailing for 3 000 hours an- oped a NH3 driven internal combustion engine
nually. The system should be operative on the and is currently building cooperations with ship-
vessel by the end of 2023. The NH3 needed will yard companies for its implementation (Figure 4
be produced by electrolysis.(SHIPFC 2020) b). (MAN Energy Solutions 2019)
Ammonia in H2-fuel cells While NH3 as fuel shows no CO2, PM, VOC’s or
SOx emissions, other emissions from unburnt
Ammonia is also useable in H2-fuel cells. The NH3
NH3, N2O and NOx are significant. Therefore
is catalytically split into N2 and H2. The N2 is re-
post treatment technologies for cleaning these
leased directly into the air while the H2 is fed into
exhaust gases are needed. Mature technologies
the fuel cell. No secondary products are formed.
like selective catalytic reduction, SCRare avail-
Such H2-fuel cells systems powered by NH3 can
able (MAN Energy Solutions 2019; Pavlos and
be purchased for private sector applications
Rahat 2020).
(GENCELL, Israel). They provide uninterruptable
power supply (UPS) for critical infrastructure
Ammonia and diesel in dual fuel internal
i. e. hospitals or main power supply for remote
combustion engines
communities or remote telecommunications
infrastructure(GENCELL WORLDWILD 2020). In recent years the diesel engine has received a
great deal of scrutiny with respect to NOx and
Ammonia in internal combustion engines PM emissions. Emission treatment systems (i.
e. AdBlue injection) are now widely available to
A Canadian inventor showed the feasibility of
Figure 4: A)Test engine for using NH3 as fuel in an internal combustion engine in a laboratory at the Wärt-
silä Helsinki Campus of the Wärtsilä Corporation (Finland) (Wärtsilä Helsinki Campus 2020). B) Engine test
room at MAN Energy Solutions (The Maritime Executive 2020)
12 No 16 ENERGY H IG HLIG HTSminimise these emissions and became standard thus requiring no external ignition devices or
in many truck engines. With respect to the decar- chemicals. Hydrazine based liquid fuels are e. g.
bonisation of the economy, dual fuels of NH3 and Aerozin 50 used in the USA built Titan rockets
lower auto-ignition temperature fuels like die- and UH 25 used in the European Ariane rocket. It
sel fuels are in early testing phases. Preliminary is estimated that currently about 500 satellites
results show that conventional diesel engines in orbit use hydrazine based small control rockets
can use NH3/diesel mixtures but produce high for position and orbit control. In the NASA Space
amounts of NH3 and NOx emissions. Adjust- Shuttles missions, the high toxicity of hydrazine
ments on the injection system may reduce the required careful pre-launch and post-touchdown
emissions, but the implementation of an after- checks for N2H4 leaks by teams wearing protec-
treatment system is required to meet emission tive gear and self-contained breathing equipment
standards.(Pavlos and Rahat 2020) (Jenkins 2016).
Ammonia in new settings Many naval forces currently use hydrazine in their
Ammonia as carrier for H2 is a versatile agent for submarine rescue systems for emergency sur-
innovative energy solutions. The decomposition facing by rapid displacement of the ballast tank
of NH3 into N2 and H2 is a well-known process water upon injection. The RESUS (REscue system
(see above, NH3 in H2 fuel cells). The H2 gained for SUbmarineS) uses hydrazine which catalyti-
may be used either in pure H2 combustion en- cally decomposes in the ballast tanks and creates
gines or in dual fuel (H2/diesel) combustion en- buoyance. (ArianeGroup 2020)
gines (Wang et al. 2013).
NITRATE AND UREA-BASED FUELS
HYDRAZINE Nitrate-based fuels burn under optimal laborato-
As early as in May of 1944 the German Luftwaffe ry conditions without releasing CO2, VOC, PM or
put a rocket engine powered interceptor aircraft NOx. Urea-based fuels do not release NOx under
into active service. The Messerschmitt Me-163 optimal laboratory conditions but always release
“Komet” used a volatile fuel mixture of T-Stoff CO2. (Grinberg Dana et al. 2014; Grinberg Dana
(80% hydrogen peroxide and 20% water) and C- et al. 2016). Whether this can be also achieved
Stoff (hydrazine hydrate, methyl alcohol and wa- in service engines has not been tested yet. A fuel
ter), which provided a maximum thrust of 1 500 infrastructure is not existing but ammonium
kp (3 300 lb.). The airplane set the speed record nitrate could be transported as non-toxic sub-
for its time at 1 170 km/h or 700 mph. A surviving stance in solid state or in aqueous solutions. The
airplane is on display in at the Smithsonian’s Boe- solid state – when handled properly – is also non-
ing Aviation Hangar at the Steven F. Udvar-Hazy explosive. However, accidents occur on a regular
Center in Chantilly, VA (USA) (National Air and basis (c.f. Fig 3).
Space Museum 2021). The first operational mili-
tary use of hydrazine as rocket propellant was in 6. AMMONIA COMBUSTION IN INTERNAL
the German A4 ballistic long range artillery rock- COMBUSTION ENGINES FROM AN
ets (also known as V-2) which were launched in ENGINEERING POINT OF VIEW
late 1944. The same A4 type rocket started suc- If the question is the feasibility of using ammo-
cessfully from the deck of a US aircraft carrier in nia in internal combustion engines there is only
1947 initiating the era of seaborne rocket launch- one simple answer: yes, an internal combustion
es. (Zaloga 2003). engine can be driven with either ammonia or its
mixtures. This answer remains valid for Compres-
Hydrazine (pure or in mixture with e. g. dimethyl sion-Ignition Engines (CIE) and Spark-Ignition En-
hydrazine) is a very commonly used liquid rocket gines (SIE) likewise. A gas turbine can be “fired”
fuel. It ignites as a hypergolic fuel (self-igniting with ammonia blends as well. This has been
fuel mixture) if brought in contact with an oxi- proven several times through basic research,
dizer like dinitrogen tetroxide (NO2 N2O4) feasibility studies, experiments and prototypes.
ENERGY H IG HLIG HTS No 16 13Nevertheless, the challenge is not to offer a new compression ratios as much as 35:1 are needed
propulsion technology to the public or markets, for ammonia as fuel in CI-engines (Kong and Re-
it rather is to suggest a new propulsion technol- iter 2011). Therefore, the use of a pilot fuel is re-
ogy which can replace the existing technology. quired in order to achieve and maintain a certain
ignition temperature and compression ratio. Very
In the following, the focus is more on feasibil- common and useful pilot fuels are diesel or Di-
ity and less on economic competition, which is methyl Ether (DME) – a synthetic substitute for
discussed separately. While it is not very diffi- diesel fuel. Fuels with higher cetane numbers
cult to replace passenger cars after a couple of show generally better ignition characteristics
years of service it is more difficult to modify a with ammonia (Pearsall and Garabedian 1967).
fleet of hundreds of container freighters where An ammonia content up to 95% was feasible with
the life cycle of the asset is 25 years and more. only 5% diesel fuel when used in a John Deere en-
The logical solution is a dual use technology that gine. However, the optimal mixture is 40% diesel
provides a sufficient transition period for the new with 60% ammonia since a diesel amount larger
technology with a minimum of drawbacks on the than that would limit the ammonia´s flammabil-
overall performance. A dual use technology in ity (Reiter and S.-C. Kong 2008). Due to the DME
this context means that either one or the other chemical characteristics it can be mixed directly
fuel is used for combustion. No mixtures of fuels with liquid ammonia and injected into a CI en-
are used. gine. Researchers at the Iowa State University
(USA) demonstrated this in 2013 when they suc-
COMPRESSION-IGNITION ENGINES (CIE) cessfully used it in an off-the-shelf diesel engine.
Ammonia is flammable, but the ignition temper-
ature is higher than for petroleum-based fuels. The original setup used for the exploration of
Thus, it is not possible to use ammonia as a sole highly advanced liquid ammonia direct injection
fuel in a CI-engine due to the high compression was designed very similar to a diesel direct injec-
ratios needed for ignition/combustion (Pearsall tion system. A fuel combination of ammonia and
and Garabedian 1967; Brohi 2014). Very high DME was directly injected into the engine, using
C-RIO Fuel Controller
C-RIO Engine Controller
Computer
Ocilloscope
Charge
amplifier
Common-Rail
High Pressure
Fuel pump
Smoke meter
Mixing Fuel Tank 5 Gas Analyzer NOx/NH3 Analyzer
Injector Pressure Sensor
Ammonia
DME
Intake Air Flow Measurement
N2
Exhaust Out
Intake Air Heating control
Encoder
Laminar Flow Intake Air In Dynamometer
Diesel engine
Meter
Surge Tank
Speed and Torque signal
Figure 5: Schematic of an experimental apparatus for highly advanced liquid ammonia direct injection
testing (Zacharakis-Jutz 2013).
14 No 16 ENERGY H IG HLIG HTSconventional to slightly early diesel injection tim- do not avoid CO2 emissions completely but rath-
ings. However, it was observed that conventional er reduce them substantially.
injection timing or even earlier injection timing
was insufficient to achieve more than 40% am- SPARK-IGNITION ENGINES (SIE)
monia content in fuel. Thus, in an attempt to The use of ammonia as sole fuel for SE-engines
increase the operating range and maximum per- is possible but requires significant changes to the
cent of ammonia in the fuel, highly advanced ignition hardware. For instance, ammonia as sole
injection timing was used. Such highly advanced fuel has been patented by Toyota where they
injection timing transforms conventional diesel suggest that several plasma jet igniters arranged
combustion into a homogeneous charge com- inside the combustion chamber or plural spark
pression ignition (HCCI) combustion. The highly plugs that ignite the ammonia at several points
advanced injection allows the heat loss due to will facilitate ammonia combustion (EP 2378105
the vaporization of the ammonia to be mitigated A; EP 2 378 094 A1). Those changes are not trivial
over a longer time period thus reducing its nega- and would probably require the redesign of the
tive effects (Zacharakis-Jutz 2013). entire cylinder head. As of now, there is no sin-
gle fuel asset on the market which would be at
The technical retrofitting efforts will have to the serial production level or even close to that.
include additional fuel installations (tank, mix- More promising are double-fuel applications. Hy-
ing tank, pumps, and valves), inject assembly drogen dissociates at 400 °C and can be used as a
upgrade, engine management software (com- combustion promoter for ammonia as fuel. A hy-
pression ignition timings) and extensive exhaust drogen content of 3-5% weight basis is the mini-
treatment system. The implementation of CI en- mum amount of hydrogen required as combus-
gine technology is feasible and requires moderate tion promoter (Starkman and Samuelsen 1967).
retrofitting only. A significant drawback, how- For comparison: Using gasoline as a combustion
ever, is the unstable performance at alternating promoter requires a compression ratio of 10:1
loads. The use of pilot fuels for NH3 engines is a for optimal operation with a gasoline content of
double fuel technology. Therefore, these engines 30% (Grannell et al. 2008).
C-RIO NH3 Fuel Controller
Supercharged 2 Stage
Surge Tank Surge Tank Data Acquisition
System
Ocilloscope
Intake Air In Gas Analyzer
Charge
Pressure Amplifier
Relief Valve
Fuel line Heating Controller NH3 Injector
Pressure Sensor
Ammonia Gas Constant
Temperature Spark Plug Exhaust Out
Container
Ammonia
Ammonia Liquid
Cooling Water
Speed and Torque Signal
138.17 g
Gasoline
Electronic Balance
Fuel
25.76 g Pump Encoder
Dynamometer
Electronic Balance CFR Engine
Figure 6: Schematic of an experimental setup for testing gaseous ammonia direct injection (Zacharakis-Jutz 2013).
ENERGY H IG HLIG HTS No 16 15Figure 7: Ammonia storage facility in Japan (Harding 2020).
Researchers from Iowa State University (USA) and comprehensive exhaust after-treatment sub-
conducted a trial with a Cooperative Fuel re- systems. This automatically reduces the number
search (CFR) Engine and had to overcome signifi- of possible applications. The large space demand
cant upgrade challenges while adjusting the in- paired with a limited response time to fast chang-
jection assembly for the gaseous ammonia usage. ing load demands indicates that two common
applications are likely: In stationary power gen-
Furthermore, they (Zacharakis-Jutz 2013) as- eration facilities and as naval propulsion systems.
sessed that the required changes and add-ons Both applications could provide a significant con-
for the ammonia injection such as an ammonia tribution towards global GHG emission reduction
vaporizing unit, an ammonia gas preheating and if implemented at a large scale.
ammonia direct injection system, are not suit-
able for small-scale engines. With respect to While the usage of ammonia for power gen-
retrofitting efforts, the statements made about eration may sound like fiction for the European
CI engines apply as well: The subsystems to be audience, it does play an essential role in Asian
modified are injection assembly, engine manage- (Japan, Korea, China) future energy strategies
ment and exhaust after treatment. In the case (Figure 7) (Harding 2020). Japan for instance is
of SI engines the injection assemblies are more strongly heading towards ammonia usage in the
complex and voluminous. near future. Green ammonia is supposed to be
generated by renewables (though imports are
NH3 AS A FUEL OF THE FUTURE needed) and used in gas turbines for power gen-
As of today, it is not easy to say how the future eration. Japanese industries conducted successful
for ammonia as a fuel for combustion engines may tests and are now able to engage 100% ammonia
look like. From an engineering perspective, the an- driven turbines (without any pilot fuels). Within
swer is positive. All the challenges and setbacks the near future, ammonia will cover at least 1%
described above are manageable issues and all of the country’s electricity demand.
these issues can be solved with state-of-the-art
technologies. All required technologies are avail- In general, NH3 represents a very economic stor-
able and the only thing to do is to find applications age option for renewable power. It is also much
where the advantages of ammonia combustion easier to handle than storing electric power in
dominate over the existing disadvantages. secondary cells or hydrogen. Another promising
application is in the maritime sector. The future
Based on the research discussed above, it is obvious of naval propulsion systems is on the brink of un-
that when using ammonia a volumetric enlarge- dergoing significant changes. Political and public
ment of equipment is unavoidable: larger tanks demands result in national and international en-
with additional equipment, the usage of pilot fuels vironmental regulations and expect the industry
16 No 16 ENERGY H IG HLIG HTSto provide solutions. Ammonia is one of several dropower stations is possible if certain geological
mature solutions to address these challenges and and topographic conditions are met, but public
will compete with LNG, LPG, hydrogen, biofuels acceptance is low. Flywheel storage technology
and synfuels. From many points of view ammo- is not yet widely established but appears prom-
nia is a strong competitor and makes especially ising. Chemical energy storage in newly synthe-
sense if being implemented with a strategic ap- sised compounds seems an interesting pathway.
proach and not in a case-by-case scenario. Sev-
eral research activities provided prove of concept According to the second law of thermodynamics,
for ammonia technologies but did not go beyond each conversion is ultimately coupled with loss-
laboratory and test environments yet. The next es in free energy (Atkins et al. 1990). Therefore,
step could be the presentation of a fully function- the number of production steps for fuels should
ing device as a minimum viable product being always be kept to a minimum. Hydrogen is the
able to serve the market requirements. first fuel product of the electrolysis of water and
shows the least loss of free energy (Holleman
The project performed by Wärtsilä Corporation et al. 1985). Hydrogen can be used as a fuel in (a)
with the support of the Norwegian Government fuel cells – as currently tested in pilot projects in
(see chapter 5) might deliver such a device. The public transportation buses (Waterstofnet 2020)
project successfully passed the laboratory trials and trains (VDI 2018), (b) blended into natural
in Finland in 2020 and was then moved to Norway gas pipelines for heating purposes (Atlantic Coun-
for further development. A maritime vessel with cil 2020; Sadler 2016) or (c) used as pure H2 as
ammonia propulsion is expected to sail in 2023. If an chemical basic material (Gasunie Waterstof
successful, that vessel would be much more than Services B.V. 2020). In The Netherlands, a consor-
just a working prototype. It will be able to provide tium of the Gasunie pipeline operator, Groningen
information on the necessary depth and the vol- harbour and Shell Netherland built a wind farm to
ume of retrofitting naval engines for use of am- power electrolysers for H2 production. The pro-
monia. Besides that, the vessel will allow both, to ject was started at the beginning of 2020 (N.V.
formulate the ammonia supply infrastructure re- Nederlandse Gasunie 27.02.2020). In all those
quirements and to evaluate the economic frame- technologies mentioned, the final product of the
work conditions of using ammonia as fuel. incineration process is H2O. The disadvantages of
using H2 are its highly inflammable and explo-
Today, it is difficult to predict whether ammonia sive properties as well as its low energy density
will win the competition for the fuel of the future as gas. Thus, before transport and storage, a liq-
or will end up in scientific libraries as a “missed uefaction or pressurisation is necessary which is
chance”. What is sure, however, is that if ammo- expensive and energy consuming (Table 1).
nia propulsion will reach the market, it is going to
be first in the maritime sector. Hydrogen can be further on processed to am-
monia which is mostly known as a precursor for
7. CONCLUSIONS AND OUTLOOK nitrogen fertiliser production (nitrates and urea),
but is also used as fuel since many decades. NH3
Electricity production from renewable sources
may also serve as a chemical storage substance
is well established. From 2018 on it became
for H2. Catalytic dissociation of ammonia produc-
cheaper on the international energy market than
es N2 and H2. The hydrogen can then be used in all
electricity produced by fossil power plants (Kost
applications mentioned in the paragraph above.
et al. 2018; The International Renewable Energy
NH3 is easier and safer to handle and to transport
Agency 2019). Decarbonising the economy de-
than H2. Applications supplying power in remote
mands both, energy storage options for time
areas are already established (GENCELL WORLD-
periods when renewable energy sources are not
WILD 2020). Since additional transformation
available and production of carbon neutral or no-
steps cause further energy losses, direct uses of
carbon fuels for mobility and e.g. heating. Large
ammonia should be preferred. The most prom-
scale storage of electricity in batteries is current-
ising short term NH3 applications are in marine
ly not economic. Physical storage in pumped hy-
ENERGY H IG HLIG HTS No 16 17vessels. Both, ammonia driven fuel cells (SHIPFC Fischer-Tropsch syntheses. On the source to tank
2020) and internal combustion engines (Wärtsilä basis, NH3 as a fuel is superior to H2 and metha-
Helsinki Campus 2020) are on the brink of their nol. The efficiency of the NH3 fuel cells, however,
first real life tests. Both technologies will provide has to be improved to sustain the cost advantage
CO2- and SOx- emission free mobility. However, of NH3.(Zhao et al. 2019)
such internal combustion engines need selective
catalytic reduction (SCR) treatment systems) be- Ammonia is toxic but self-alarming to humans due
cause the NH3, N2O and NOx emissions are high. to its pungent smell and it is neither inflammable
These treatment systems are mature and well nor explosive. Ammonia is widely used as a cooling
established technologies in ships, as they are al- agent in the food industry, in sporting arenas and
ready used with carbon based fuels for reducing in emission treatment systems in ships. NH3 pro-
NOx emissions (MAN Energy Solutions 2019). duction, transportation and distribution by ships
These combined technologies would have a huge and trucks is common practise. Safety routines are
positive impact on decreasing the pollution with well established during maintenance and repair
SOx, PM and heavy metals in harbours and coast- works (Bundesministerium für Umwelt, Natur-
al regions since the fuels currently used in most schutz und nukleare Sicherheit 2018; MAN Energy
large ships are waste products from the crude Solutions 2019). The practical obstacles for large
oil refining processes and are highly enriched in scale NH3 usage seem smaller than for H2 usage.
substances hazardous to health. The concentra-
tions permitted for these hazardous substances Ammonia is one of the most commonly produced
in shipping fuels are currently much higher than commodities on a global scale. In 2014 approx.
for land based mobility fuels (Umweltbundesamt 113 x 106 tonnes of NH3 were produced glob-
- UBA) - but this may change soon. ally. Production, transportation and distribution
capacities are available on all continents (Figure
Zhao et.al. (2019) estimated the costs for differ- 8) (Ritchie and Roser 2020). Countries with large
ent non-fossil fuels from source-to tank in cars. agricultural and industrial sectors show high lev-
He compared several hydrogen-, nitrogen and els of production.
carbon-based fuels produced from renewable
electricity, H2 from electrolysis, methanol and Using NH3 as fuel would require a significant upscal-
Figure 8: Global nitrogen fertilizer production in 2014. Global production in 2014 was 113.31 * 106 tonnes
(Ritchie and Roser 2020).
18 No 16 ENERGY H IG HLIG HTSFigure 9: Global map of photovoltaic power potential(THE WORLD BANK, 1818 H Street, NW Washington,
DC 20433 USA 2020).
ing of the production capacities. Under the given In the future we will surely experience intensified
conditions this seems a manageable task and vari- research and development for using fuels on a
ous CO2-free or low CO2- routes are thinkable. On a nitrogen basis. The prime advantages of nitrogen
larger scale, additional plants for ammonia produc- based fuels are both, the intrinsic lack of carbon –
tion would be needed. If powered with renewable with exception of urea - as well as the technolog-
electricity for the electrolysis of water, the overall ical maturity of their production, transport and
CO2 emission could be substantially reduced. Many storage. As the various propulsion engine and
of the countries with a large NH3 production output combustion technologies reach technical matu-
are located in the global Sunbelt (Figure 9) between rity, nitrogen based fuels will certainly become
35th degrees of northern and southern latitude, attractive fuels for a decarbonizing world.
where global yearly irradiation is the highest. These
regions are very well suited for solar electricity pro- For the next years it appears to be a prudent di-
duction. The German plant manufacturer Thyssen- versification strategy for NATO nations and part-
Krupp already offers small scale Ammonia pro- ners to establish a balanced strategy of invest-
duction plants with H2 obtained by electrolysis of ments in Power to Liquid technologies at home
water with electricity gained from renewable sourc- and in politically stable regions and to include
es (thyssenkrupp Industrial Solutions AG 2020). nitrogen fuel research in their portfolio. This will
Upscaling of these plants is surely possible. MAN ensure own technological competence and lead-
Energy Solutions (Denmark), the producer of two- ership for promising technologies.
stroke NH3 internal combustion engines for ships,
proposes the production of NH3 fuel in plants in the ACKNOWLEDGMENTS
Australian deserts, powered by electricity from so-
The lead author thanks the NATO Energy Security
lar parks (MAN Energy Solutions 2019).
Centre of Excellence for a fellowship grant as well
as the librarians of the University of Bayreuth and
Hydrazine is highly toxic and applications for the
Dr. Gintaras Labutis from the Lithuanian Military
general public are unlikely. It is currently used as a
academy for help in obtaining literature and sta-
fuel in space travel and military applications only.
tistical information. Thanks also go to Cpt Juozas
Nitrate and urea based fuels are in early laboratory
Latvys (LTU) for excellent support during the ed-
testing phases. Whether these fuel-technologies
iting process.
will reach marketability is not yet conceivable.
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