Ammonia as a Hydrogen Carrier

March 2019
Ammonia (NH3) contains about 17.5% hydrogen by molecular weight.
The process of cracking hydrogen from ammonia usually results in about 15% of the ammonia mass being available as useable hydrogen.
Road Tankers
Hydrogen is usually transported as high pressure gas, at between 200 and 700 Bar in Tube Tanker Trailers. The high pressure tubes are made from high strength materials including carbon fibre. The current large Tube Tanker Trailers have a capacity of around 1100 Kg at a pressure of 500 Bar.
Ammonia is usually transported as liquid in carbon steel or stainless steel tankers at 15 to 20 Bar. There are ISO tanks which are built into a 20 foot container frame, each having a capacity of about 12,000 Kg of ammonia. A normal container trailer can accommodate two ISO containers giving a total capacity of 24,000 Kg of ammonia which translates to 3,600 Kg of hydrogen.
It is fair to say that using ammonia as a hydrogen carrier will result in 3 to 5 times as much hydrogen being transported per truckload and the capital cost of the ammonia tanks will be very much cheaper than the high pressure tube tankers. Transporting hydrogen as ammonia therefore, has the potential to dramatically reduce the transport cost component of hydrogen fuel at the filling station.
Marine Transport
There have been fleets of ammonia tankers plying the high seas for decades. One such fleet transports 5 million tonnes of liquid ammonia around the world every year. These ships typically contain 15,000 to 25,000 tonnes of ammonia liquid in insulated steel hold tanks held at 3 kpag and -33C. There are many ports around the globe which have been using ammonia liquid loading and unloading infrastructure as well as large scale ammonia terminal storage at 3 kpag/-33C , for many decades. The efficient and safe systems and infrastructure already exist and can be greatly expanded to allow ammonia to be traded internationally as an energy commodity.
Energy Storage
A typical ammonia liquid storage terminal comprising two 50M diameter insulated storage tanks will occupy approximately 1.5 Hectares and contain 36,000 tonnes of ammonia. Conversion of the energy contained into electricity via gas turbines will realise in excess of 60,000 MWHr of electrical output. (Based on a conversion efficiency of 28%) Conversion via cracking the hydrogen from the ammonia and feeding fuel cells will realise a higher output, probably in excess of 80,000 MWHr. All of this electrical output will be generated with zero carbon emissions provided the liquid supplied to the terminal is green ammonia. Given that the biggest conventional battery in the world has a storage capacity of 130 MWHr , this “ammonia battery” offers massive carbon free energy storage capacity in the order of 500 times that of conventional technology.
Ammonia as a hydrogen vector
Hydrogen is very difficult and expensive to store and transport. There are two main ways to improve the energy density of hydrogen, compress the gas to very high pressures of up to 700 atmospheres or liquefy it by cooling it to very low temperatures below -240C. Using ammonia as a hydrogen carrier is more efficient and cost effective than either of these options.
In the next instalment we will discuss progress and the way forward for ammonia in various energy applications.
Until then
Kind Regards

Green and Blue Ammonia

January 2019
Blue Ammonia
Ammonia has been manufactured for the past century using the Haber-Bosch process into which are fed nitrogen and hydrogen gas streams. At the right temperature and pressure, and in the presence of a catalyst, ammonia is produced. Traditionally, Haber-Bosch processes are fueled by hydrocarbons and release a lot of carbon dioxide. Blue ammonia is defined as ammonia produced by this traditional process however with the addition of CCS (Carbon Capture and Storage) to sequester all of the carbon dioxide generated rather than allowing it to enter the atmosphere. Achieving effective and permanent CCS will be very challenging due to the technical issues, energy consumption and high cost. There are some proposals to “sequester” the CO2 into existing oil wells and in doing so, achieve enhanced oil recovery (EOR) however this would seem to be counterproductive from an environmental point of view as it releases more hydrocarbons to be burnt in the future. Therefore blue ammonia production will probably be an interim solution only, until green ammonia production can be brought on line.
Green Ammonia
Green ammonia can be manufactured in the Haber-Bosch process using renewable energy rather than hydrocarbons. This will result in no CO2 emissions. Renewable electrical energy is used to separate hydrogen from water with electrolysers and separate nitrogen from air with air separation units. The bulk of the energy input is used to generate the hydrogen whilst a minor part is used for the air separation and Haber-Bosch processes. There are a number of pilot green ammonia plants operating in several countries.
It is likely that any new large scale green ammonia production plants will operate on the Haber-Bosch system. These systems operate most efficiently and produce lowest cost ammonia when they are continuously supplied with renewable electrical energy. Therefore the best forms of continuous renewable energy for green ammonia production are likely to be hydroelectricity, geothermal electricity or similar. Manufacturing ammonia from intermittent forms of renewable electrical energy (solar, wind, wave, tidal etc.) will be viable, but less efficient. It may be possible to use a combination of two or more of these intermittent sources to provide a virtually continuous supply and thereby improve the efficiency.
Green ammonia is the most likely contender to fulfil future global non-nuclear, carbon-free energy requirements in areas including:
– A vector to transport hydrogen over long distances
– An internationally traded energy commodity
– Grid scale energy storage
In the next instalment we will discuss ammonia as an internationally traded energy commodity.
Until then
Kind Regards

Ammonia & Fuel Cells

January 2019

PEM Fuel Cell Electric Vehicles
A number of the world’s leading automobile manufacturers have commenced making Fuel Cell Electric Vehicles (FCEV’s) in recent years. These vehicles have PEM (Proton Exchange Membrane) fuel cells which are fueled by hydrogen gas carried on board in high pressure gas tanks. The fuel cells provide a very efficient conversion of the energy contained in the hydrogen fuel, into electricity to propel the vehicle. This conversion efficiency is much higher than that achieved using the hydrogen fuel in an internal combustion engine and it is therefore likely that the FCEV’s will be the carbon free way forward rather than hydrogen fueled combustion engines. The leading manufacturers of FCEV’s are:
– Toyota with their Mirai
– Hyundai with their Nexo
These FCEV’s have high pressure 700 bar hydrogen gas tanks on board to achieve a reasonable energy density. The vehicles can be re fueled from a hydrogen filling station in several minutes and when full, hold around 5 or 6 Kg of hydrogen, which gives them a range of 500 to 800 km.
Liquid hydrogen fuel is generally not commercially viable due to the amount of energy it takes to liquefy it. Liquefaction consumes about one third of the hydrogen energy stream which means only about 66% comes out as liquid and the rest is lost. This is due to the fact that it must be cooled to well below the critical point (-240C) to about -253C (20K) and this process is very energy hungry and expensive. Consequentially the hydrogen FCEV’s use high pressure compressed hydrogen gas tanks rather than cryogenic liquid hydrogen tanks.
Ammonia is a very good carrier of hydrogen and is easily and cheaply liquefied (+132C critical point) to provide a much higher transportable energy density than hydrogen gas. In August 2018, the CSIRO in Australia demonstrated it’s groundbreaking technology which is able to provide high purity hydrogen gas derived from ammonia to re fuel the FCEV’s. This technology provides a system to crack the hydrogen out of the ammonia then put it thru a metal membrane filter to achieve very high purity hydrogen to comply with the FCEV manufacturers specifications.
This CSIRO development paves the way for hydrogen to be shipped , stored , transported and distributed to the fueling stations as ammonia liquid, and then the hydrogen is cracked and filtered from the ammonia at the fueling station to re fuel the FCEV’s. This will be a far more efficient and cost effective way of distributing the hydrogen than the existing system of using hydrogen gas tube tankers.
Solid Oxide Fuel Cells
In 2017 the Green Ammonia Consortium was formed in Japan and now involves 28 companies. One of the priorities of this consortium is the development of a solid oxide fuel cell which will run directly on ammonia. There is rapid progress on this project and they already have prototypes operating in the lab. The aim is to produce a commercially viable fuel cell with at least similar efficiencies to the PEM fuel cells. Once this new fuel cell is developed, it will open a multitude of options for ammonia energy in areas including transport and electricity generation. We will watch this exciting development with great interest.
In the next instalment we will discuss the manufacture of green and blue ammonia.
Until then
Kind Regards

Ammonia Manufacture

January 2015

Ammonia as a logical and viable contender for a carbon free fuel and energy future. Ammonia and hydrogen derived from it, can be used in many applications where hydrocarbon fuels are traditionally used. Ground transport, power generation, energy storage, maritime transport, heating furnaces and international energy trading are some of the areas where ammonia/hydrogen can be used. Ammonia is a naturally occurring substance and is one of the most popular industrial chemicals in the world. The manufacture of ammonia in commercial quantities without releasing carbon (Green Ammonia) is the subject of research and development around the globe.

A Material Safety Data Sheet (MSDS) for ammonia is readily available. The Physiological effects of various concentrations of ammonia in air are also included (SAA AS/NZS 2022) The IDLH (Immediately Dangerous to Life and Health) for ammonia is currently listed as 300 ppm.

Ammonia air mixtures are flammable in a fairly narrow range of concentrations between 16% and 25%. The LFL for ammonia of 16% is very high when compared with other popular fuels.

Ammonia has been commercially manufactured for over a century and currently over 100 million tonnes is produced globally per annum.

Ammonia is relatively straight forward to store, transport and handle. As it is highly corrosive to zinc and copper or it’s alloys, only steel, stainless steel or aluminium can normally be used.

Where ammonia is referred to as “anhydrous ammonia” this indicates it has a water content of less than 0.2%. Ammonia liquid is usually stored in large or medium sized tanks manufactured from carbon steel and it is necessary to have a small water content of this magnitude to avoid stress corrosion cracking in these tanks.

Where ammonia is stored as a liquid at ambient temperatures it needs to be in a pressure vessel with a design pressure of 2100 kpag (saturated temperature of 53 C max). Where ammonia is stored as a liquid at atmospheric pressure it will need to be in an insulated, refrigerated vessel and will exist at a temperature of -33C.

Ammonia has a very pungent odour which is quite offensive to mammals and it will drive them away at concentrations of about one tenth of that which would do them harm. It is for this reason ammonia is known as a self-alarming substance.

Ammonia can be used as a fuel including in internal combustion engines and gas turbines, however the development of fuel cells is likely to take over as a more efficient solution for transport and electricity generation.

Ammonia is an excellent carrier of hydrogen, however it is very much easier to store, transport, handle and dispense than liquid hydrogen. At one atmosphere liquid hydrogen exists at -253C (20K) whereas liquid ammonia exists at -33C (240K). Hydrogen has a very low molecular weight and it will permeate many materials which means it is very difficult and expensive to contain. Hydrogen is also incredibly expensive and energy hungry to liquefy.

An internal combustion engine operating on ammonia fuel will emit nitrogen, water and Nitrous oxide, however no CO2 or CO will be emitted as ammonia contains no carbon. A fuel cell running on hydrogen gas derived from ammonia will emit water.

The oil in an internal combustion engine operating on ammonia fuel is much cleaner than that in a hydrocarbon fuelled engine as there is no carbon present in the fuel.

There are many examples of where ammonia has been used as a fuel including:

  • Public transport buses in Belgium during the Second World War.
  • Chevrolet powered by “hydrofuel” in Toronto in 1981
  • Toyota GT 86 converted by Bigas to duel fuel ( ammonia and gasoline) in 2013
  • Hydrofuel Canada 2012 duel fuel vehicle ( ammonia and gasoline)
  • Garbage truck in Pisa Italy
  • Gas turbines in the USA

The fuel system required for an ammonia powered passenger vehicle is not unlike that used for an LPG  (propane) powered vehicle. The following table shows the saturated pressure – temperature relationship for ammonia and propane.


The main areas of difference are:

  • Design pressure of fuel tank, piping and components.
  • Materials for the ammonia fuel system cannot include zinc or copper or it’s alloys.
  • The evacuation of the small amount of ammonia liquid contained between the handpiece valve and the check valve in the neck of the fuel connection at the point of disconnect cannot be discharged to atmosphere as is the case with LPG. This would need to be recovered and contained or treated.

Fuel systems for the storage and dispensing of ammonia fuel at the vehicle filling station would not be unlike those used for LPG.

All of the vessels, pumps, check valves, excess flow valves, safety valves and other safety devices used in the LPG fuel systems will generally be appropriate for ammonia subject to obvious pressure rating and material changes.


Data from the International Fertilizer Association (IFA) indicates that a modern ammonia production facility using natural gas consumes around 30GJ of energy per tonne of ammonia produced.

Scientific modelling indicates, with present technology, ammonia manufactured using electrical energy and heat recovery with hydrogen sourced from water electrolysis, would consume somewhere around 40 to 60 GJ per tonne of ammonia produced.

The manufacture of ammonia fuel without releasing carbon from energy sources such as solar, wind, geothermal or hydroelectricity will be the way forward into a carbon free energy future.

Research is required into large scale, highly efficient, carbon free, ammonia manufacture using existing or new technologies. The development of micro ammonia fuel manufacturing systems will also need to be a high priority.

Ammonia fuel offers a solution to the stranded energy problem. The surplus renewable energy generated at times of low demand can be used to manufacture ammonia which is stored for later consumption.

The following are a selection of literature items found to be relevant to this subject:

  1. Techno-Economic Feasibility Study of Ammonia Plants Powered by Offshore Wind.                 A thesis by Dr. Eric R. Morgan. University of Massachusetts – Amherst. 2013.                                     This thesis reviews the technologies required for all-electric, offshore wind powered ammonia production and offers a simple design of such a system. The cost models provided, are capable of calculating the capital costs of small industrial sized ammonia plants coupled with an offshore wind farm. Whilst the levelized cost per tonne of ammonia is high relative to ammonia produced with natural gas or coal, major cost reductions are possible for systems having long life, low operating and maintenance costs, or for systems that qualify for Renewable Energy Credits.
  2. A feasibility study of implementing an Ammonia Economy.                                                         A thesis by Jeffrey Ralph Bartels. Iowa State University.  2008.                                                                                              This thesis reports the results of a feasibility study performed on the concept of an Ammonia Economy, which treats ammonia as an alternative fuel and energy storage mechanism. The results showed that ammonia sourced using alternative renewable fuels was more expensive than ammonia sourced from coal, gasoline or natural gas, however it may become economical as fossil fuel costs increase and technological advances improve the alternative energy technologies.
  3. Planning for Hundred –Fold Increase in Global Ammonia Production.                                        A paper by William L. Ahlgren. California Polytechnic State University, San Luis Obispo. 2013.   The use of ammonia as fuel offers a path to effective climate change mitigation. To meet the projected demand, the ammonia industry must scale up from the second or third largest non-petroleum commodity chemical business, to the largest economic enterprise on earth, surpassing even the petroleum industry. This presents an enormous challenge, and also an unprecedented opportunity.
  4. Synthesis of ammonia directly from air and water at ambient temperature and pressure.    A paper by Rong Lan, Shanwen Tao. University of Strathclyde, and John T.S. Ervine, University of St.Andrews.      2012.                                                                                                 Considering climate change and the depletion of fossil fuels used for synthesis of ammonia by conventional methods, this is a renewable and sustainable chemical synthesis process for future.
  5. A hybrid vehicle powered by ammonia and hydrogen.                                                                    A paper by Stefano Frigo and Roberto Gentili. Destec- Universita di Pisa , Italy .2013             An attractive solution is represented by the possibility of storing hydrogen in the form of ammonia that, at environmental temperature is liquid at roughly 0.9 MPa and therefore involves relatively low-cost and light tanks. Ammonia represents an alternative fuel to feed IC engines and, if produced in a “green” way, it could lead to a really “zero emission vehicle”.

Ammonia has been used widely in many industries for over a century. Mankind knows how to store, distribute, transport, dispense and use it safely. There is now an urgent need to start manufacturing ammonia without releasing carbon. When this is achieved we will truly be able to enter a zero emissions fuel and energy future.

Table 2


  1. Coregas Pty Ltd (Prepared by Risk Management Technologies) December 2008. Ammonia

Material Safety Data Sheet No: 40831002

  1. Standards Australia. AS/NZS 2022:2003
  2. ASHRAE Handbook Fundamentals 2013 Chapter 30
  3. International Fertilizer Association: Global Energy Energy efficiency benchmark 2012
  4. E.R Morgan 2013. Techno-Economic Feasibility Study of Ammonia Plants Powered by Offshore Wind.
  1. J.R Bartels 2008. A feasibility study of implementing an Ammonia Economy.
  2. W.L Ahlgren 2013. Planning for Hundred – Fold Increase in Global Ammonia Production.
  3. Rong Lan, Shanwen Tao and J.T.S Ervine 2012. Synthesis of ammonia directly from air and water at ambient temperature and pressure
  1. S Frigo and R Gentili 2013. A hybrid vehicle powered by ammonia and hydrogen

Until then

Kind Regards


Ammonia as a Fuel

October 2013

Ammonia-air mixtures are flammable in a narrow zone of concentrations between 16% and 25%. The products of combustion from burning ammonia are predominately nitrogen and water. No CO2 or CO are produced as ammonia does not contain any carbon. Ammonia is an excellent carrier of hydrogen and it is far easier to store, distribute and use than hydrogen.

Ammonia can be used as a fuel in many applications where hydrocarbons are currently used. These applications include internal combustion engines, gas turbines, boilers and furnaces. Engines running on ammonia may produce NOx however in quantities , certainly no greater than those produced by an equivalent hydrocarbon fuelled engine. An engine running on ammonia can therefore be classified as producing zero carbon emissions.

Ammonia has been successfully used as a ground transport fuel dating as far back as the 1940’s where it was used to fuel public motor buses in Belgium. One of the more recent applications has been the conversion of a 2013 model popular sports car, to a dual fuel vehicle which runs on ammonia at low speeds.

The development of fuel cells to run on hydrogen or ammonia are likely to surpass combustion engines or turbines, due to their superior efficiency.

The technology and means are rapidly being established to store, distribute and use ammonia as a zero emissions fuel for transport and energy systems. The challenge now is to develop processes to cost effectively manufacture ammonia using renewable energy. That is, to discontinue using hydrocarbons for the ammonia manufacturing process, and develop other zero carbon emission systems to efficiently produce ammonia. When this is achieved, it will “close the loop” on the ammonia carbon free fuel cycle and pave the way for a clean energy future.

A concerted global research effort is required to develop ways of “closing the loop” on the ammonia carbon free energy cycle.

Ammonia has been least exploited as a fuel and energy source however this is where it has the most potential in attaining humanity’s dream of a carbon free energy future.

The next instalment will discuss ammonia manufacture.

Until then

Kind Regards


Ammonia as a Fertilizer

October 2013

Ammonia is one of the most commonly produced industrial chemicals worldwide. More than 100 million tonnes of ammonia is produced each year and the bulk of this is used in the agricultural fertilizer industry. Anhydrous ammonia liquid is direct drilled into the soil in many areas around the world. This method is said to be a cost effective delivery of nitrogen to the subsoil which encourages crop growth. In other situations the fertilizer is delivered to the plants as an aqueous-ammonia solution typically 25% ammonia in water. Ammonia is also widely used in the manufacture of a range of granular fertilizers.

In the US Midwest there is a network of more than 40 ammonia storage terminals interconnected with over 5000 km of piping to facilitate the distribution of anhydrous ammonia for use as a fertilizer. This network spans from Louisiana in the south to Minnesota in the north and from Indiana to Texas. Large quantities of ammonia are also transported by sea, rail and road. The US uses around 15 Million tonnes of ammonia per year in the fertilizer industry.

China is currently the largest producer of ammonia. Most ammonia is at present produced using natural gas or coal. It is possible to manufacture ammonia using renewable energy like solar, wind, hydroelectricity etc. rather than using hydrocarbons.

At present, ammonia is a massive contributor and essential to efficient world food production.

In the next session we will discuss the potential for ammonia as a carbon free, zero emission fuel. This is where ammonia has the most to offer in preserving the future of our planet.

Until then,

Kind Regards


Ammonia as a refrigerant

September 2013

Prior to 1850, a brilliant Australian Engineer, James Harrison invented the vapour compression refrigeration system by “closing the loop”. He was aware that when ether evaporated it made printing type set cold when used for cleaning. His invention collected the evaporated gas, compressed it, condensed it and fed it back as a liquid to be re-evaporated, thereby forming a closed loop. Refrigeration was born. By 1855, Harrison was manufacturing  ice machines operating on ether in the closed refrigeration circuit, while the rest of the world were still cutting ice blocks from frozen rivers and lakes. In 1856, Harrison was awarded patent No. 747 for his invention.

In the 1860’s, ammonia started to be used in refrigeration as it was seen as a much safer alternative than ether.  Ammonia quickly gained popularity and by 1900 it dominated the world of refrigeration as the refrigerant of choice. The ammonia domination remained through until the 1930’s when the first synthetic refrigerants known as CFC’s were introduced.  CFC’s and subsequently HCFC’s and HFC’s then took over and dominated the commercial, domestic and transport refrigeration and air conditioning sectors, confining ammonia to the Industrial refrigeration world. Recent decades have seen the phasing out of the synthetic refrigerants in recognition of their extreme environmental damage.  There has been a resurgence of the use of ammonia as one of three naturally occurring refrigerants attracting huge support worldwide, the other two being carbon dioxide and hydrocarbons.

From a thermal engineering point of view, ammonia is an excellent refrigerant achieving vapour compression, cycle efficiencies better than virtually all other refrigerants.

In a refrigeration system, the refrigerant is a working fluid which circulates around a closed loop, carrying heat from one location to another. The refrigerant is not consumed, and only needs topping up if some leaks out. Therefore the consumption of anhydrous ammonia for refrigeration purposes is only a tiny fraction of the amount of ammonia manufactured each year. The amount would be in the order of a fraction of one per cent. The total amount of ammonia manufactured worldwide each year is in excess of one hundred million  tonnes, whilst that used in refrigeration would be in the order of tens of thousands of tonnes.

The world has been using ammonia as a refrigerant for 150 years; it has proven itself as a star performer from an efficiency, environmental and safety point of view. For these reasons, it can do nothing but grow in popularity into the future.

In the next instalment we will discuss the profound impact ammonia has on the world as a fertilizer

Until then, Kind Regards


Introduction to Ammonia

September 2013

Welcome to the world of Ammonia.

Ammonia is a naturally occurring substance with a molecular structure comprising one Nitrogen atom and three hydrogen atoms expressed as NH3.

Ammonia has also been manufactured in commercial quantities around the world for over a century.

Its properties are very well known with full MSDS details readily available. It is usually referred to as “Anhydrous Ammonia” which describes it’s very low or negligible water content. The Salient features of ammonia are that it is highly alkaline, it is toxic in medium concentrations and it has medium flammability when mixed with air in relatively high concentrations.

The world wide manufacture of ammonia presently runs at over one hundred million tonnes per year, and the manufacturing process currently used involves the consumption of hydrocarbons.

The bulk of Anhydrous Ammonia manufactured at present is used in the fertilizer industry to efficiently deliver nitrogen fertilizer for agriculture world wide. Much smaller amounts are used in refrigeration , water treatment and other forms of gas treatment.

In future I will try to convey the benefits and enormous potential of this wonderfully versatile substance we call Ammonia. In the next installment I will attempt to cover the huge contribution Ammonia has made to the world of refrigeration.

Until then ,  Kind Regards

Ammonia Man