Thursday, May 17, 2012

Ammonia can substitute Gasoline


Ammonia is a well known industrial chemical that is manufactured worldwide as a precursor for the production of Urea. The chemistry and technology of Ammonia synthesis is well known and well established. It was a land mark achievement to fix atmospheric Nitrogen into the soil in the form of Urea as a fertilizer. It has 17.6% Hydrogen and 82.4% Nitrogen making it an ideal fuel for combustion when compared to Gasoline in terms of greenhouse gas emission because Ammonia no carbon. Handling free Hydrogen has always been a concern due to its explosive nature and lightness. Transportation of Hydrogen in the form of Ammonia is relatively cheaper and safer. A non-regulated Ammonia nursing tank at 265 psi pressure holds 3025kg Ammonia, containing 534kg Hydrogen, whereas a 5900 gallon Hydrogen tube trailer at 3200 psi pressure, contain only 350kgs of Hydrogen. Low pressure Ammonia tank with less than 25% volume contain more than 53% Hydrogen than a high pressure tube trailer. Ammonia has a lower volumetric energy density compared to other fuels.However, after subtracting energy required to elicit hydrogen from each fuel, hydrogen emerges with highest energy density compared to other fuels, and it is the only fuel which is carbon free. These qualities make Ammonia, a potential substitute for Gasoline. Ammonia need not be used as direct combustible fuel in internal combustion engines but it can be used as Hydrogen carrier safely and economically. The Hydrogen resulting from the decomposition of Ammonia can be used as fuel in a Fuel cell car as well as in a combustion engine. It can also be used to generate small onsite power using a Fuel cell or IC engine. For example, 534kg Hydrogen can generate Electricity up to 10 MW and up to 6Mw thermal energy using a Fuel cell. Currently ammonia is manufactured using fossil fuel source such as natural gas or naphtha to generate Hydrogen in the form of Syngas.But this can be effectively substituted with renewable source of Hydrogen such as Electrolysis of water using renewable solar thermal power or wind energy. Alternatively a biogas can be steam reformed to generate Hydrogen similar to natural gas. The generated Hydrogen can be compressed and stored. Nitrogen constitutes 79% of atmospheric air and it can be obtained by air liquefaction and separation by distillation or by simple membrane separation method to separate air into Nitrogen and Oxygen. The resulting Nitrogen can be compressed and stored for Ammonia sysnthsis.Production of Ammonia using Bosch Haber process is well known. Ammonia can be transported in pipelines, in tankers by road, rail or ship to various destinations. Ammonia can be readily be used as fuel using a spark ignited combustion engine with little modifications because Ammonia is classified as non-combustible fuel. Alternatively, it can be decomposed in a catalytic bed reactor and separated into Hydrogen and Nitrogen using PSA (pressure swing adsorption) system. The resulting Hydrogen can be stored to run a Fuel cell car similar to Honda FCX. Ammonia, as a Hydrogen carrier can substitute gasoline as an alternative fuel for transportation and power generation. All necessary technologies and systems are commercially available to make it a commercial reality.