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:
- 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.
- 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.
- 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.
- 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.
- 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.
- Coregas Pty Ltd (Prepared by Risk Management Technologies) December 2008. Ammonia
Material Safety Data Sheet No: 40831002
- Standards Australia. AS/NZS 2022:2003
- ASHRAE Handbook Fundamentals 2013 Chapter 30
- International Fertilizer Association: Global Energy Energy efficiency benchmark 2012
- E.R Morgan 2013. Techno-Economic Feasibility Study of Ammonia Plants Powered by Offshore Wind.
- J.R Bartels 2008. A feasibility study of implementing an Ammonia Economy.
- W.L Ahlgren 2013. Planning for Hundred – Fold Increase in Global Ammonia Production.
- Rong Lan, Shanwen Tao and J.T.S Ervine 2012. Synthesis of ammonia directly from air and water at ambient temperature and pressure
- S Frigo and R Gentili 2013. A hybrid vehicle powered by ammonia and hydrogen