We've heard lots about fertilizer bombs since the federal building in OK city blew up, but not so much about fertilizer as a fuel for internal combustion engines.

Hydrogen Engine Center will work together with Sawtelle & Rosprim to design and build the world’s first Ammonia-Fueled Irrigation Pump System . . .

Plans include integrating HEC’s ammonia-powered engines with Sawtelle’s pump technologies and expertise . . .

Ammonia (NH3), also known as anhydrous ammonia, which the agricultural industry has relied on as a fertilizer for many years, contains no carbon, stores like propane and is the second most prevalent chemical in the world. Ammonia contains more hydrogen per cubic foot than liquid H2. . .

An infrastructure for ammonia is already in place, as transporting and storing the fuel is much like that of propane. Usage and safety regulations for ammonia are already in place, therefore, the process of obtaining a permit to use ammonia is usually relatively simple. Ammonia pipelines can be found in many areas of the United States, including Iowa, and distribution of the fuel is already established. . .

Work done on advanced internal combustion engines by Sandia National Laboratories in 2000 found that:

The combustion of ammonia exhibits ideal Otto cycle performance in our free piston combustion experiment, and produces conversion efficiencies comparable to hydrogen.

Ammonia is comparable to gasoline as a fuel for combustion engines. Three gallons of ammonia is equivalent to one gallon of gasoline in energy content. In other terms, 2.35 pounds of ammonia is equivalent to one pound of gasoline in energy content.

See this post from last year that expands on that a bit by referencing this document: Ammonia as Hydrogen Source for an Alkaline Fuel Cell–Battery Hybrid System.

Facts on Ammonia

Almost all of the ammonia produced today comes from Haber-Bosch synthesis out of its constituent elements, whereby the total production quantity grows continuously (e.g. 1980: 70 million tons per year; 2000: 105 million tons per year). Although the main raw material for ammonia production today is natural gas (especially methane, CH4) via a steam cracking process and hydrogen as intermittent product, ammonia can also be produced from any other source of hydrogen. Especially regarding hydrogen economy, renewable sources like water, wind or solar energy via electrolysis could be considered (minimizing the CO2 problem). Being produced in very high quantities, ammonia is of very low total cost ($ 1,20 per kWh; for comparison: methanol: $ 3,80; hydrogen: $ 25,40) [1].

Pure ammonia is used today as fertilizer, most commonly it is applied directly to the soil from anhydrous ammonia tanks. Also, ammonia is widely used in various branches of chemical industry as catalyst, neutralizing agent or reactant in rubber, plastic and textile industry, ammonia-soda (Solvay) process, fertilizer industry (nitrate, phosphate …), metallurgy… One gram of ammonia absorbs approx. 1,4 kJ of heat when vaporizing, therefore it is also frequently used as cooling agent in air-conditioning systems, ice skating rinks and refrigeration (especially in bigger ships, therefore many harbors are equipped with ammonia fueling stations).

Due to that wide use, the infrastructure as well as standards for the use of ammonia is well established. It is either transported in cylinders at -33 deg.C (~ -27 deg.F) at ambient pressure or at approx. 8 bar (120 psi) at ambient temperature. In addition, pipelines for ammonia exist all around the world.

Using the ammonia for an AFC seems more attractive than an ICE. But either way, or both ways, ammonia has so many uses, is safe and clean compared to other fuels and is so common that it seems an attractive substance for fuel. Though currently made most often from methane there are other and arguably better ways that use no fossil fuels. Those who argue that hydrogen is only an energy storage system miss the multiple uses of this particular hydrogen rich substance. It can store energy from intermittent sources such as wind mills, but it can also transport energy from steadier sources. Emerging technologies for an order of magnitude cheaper electrolysis just add to the attractiveness of this hydrogen rich substance.

Those who mistakenly whinge about "petroleum fertilizer" might benefit from a little education on this subject too. The methane was just a cheap source of hydrogen. That is changing, so water is looking like a better source. Will we then hear whingeing about "water fertilizer"?