Ammonia as a fuel is one of main contenders for replacing fossil-fuels because of its wasteless combustion (Nitrogen and water) and, in many ways, it is better that hydrogen including its technical, economical and infraestructurals aspects. At technical level, ammonia is a gas at standard conditions but becomes liquid when exposed to higher temperatures. This property allows it to store more hydrogen per volume unit than compressed hydrogen, in other words, ammonia can produce 3 times more energy per liter than hydrogen at a determined pressure.
At a economical or infrastructural level, ammonia is 5 times cheaper than hydrogen and there exists a complete transport and supply infrastructure as a result of ammonia production for agricultural applications in the last 90 years. It can be delivered through pipelines in an easy and safe way at a relatively low pressure. It has several advantages over bioethanol which competes with the food industry.
This technology consists in the use of biological waste with a composition based on urea to produce ammonia (NH3) as an energetic vector. Because of the nature of its precursors it is considered a renewable energy source. This process is mainly based on the catabolic reaction of urease enzyme that is used to undergo the reaction.
Urease is an enzyme capable of catalyze the hydrolysis of urea. It tends to increase the pH of its surroundings because of its production of ammonia, it is normally found in numerous bacteria, algae, fungi, plants and some invertebrates. This enzyme has an optimum pH at 7.4 and an optimum temperature at 60 degrees celsius and its functions can be inactivated with heavy metals like lead.
As there are not microorganisms involved, there are no consumptions or nitrogen metabolization cycle losses. The only losses are related to possible leaks and other non-biological issues.
The ammonia can be mixed with water which results in ammonia hydroxide. (Dissociated form is shown in equation)
Ammonia hydroxide can be reduced with a Fe catalyst. Ammonia hydroxide molecule can be regenerated this way and hydrogen is produced. Both products can be used a fuels, their combustion does not generates harmful waste.
It is expected that enough ammonia may be created and with a conversion high enough so that the expected costs of separation of products from subproducts and other impurities still make the process profitable.