Ammonia as fuel for internal combustion engines?

Examensarbete för masterexamen
Master Thesis
Brohi, Emtiaz
Although alternative fuels are being widely discussed for Internal Combustion Engines (ICE), little attention and knowledge is available on nitrogen based fuel. An interesting idea is if it´s possible get into the worlds natural nitrogen cycle, instead of the carbon cycle. That means capturing nitrogen in a similar, but easier fashion as capturing CO2 from air. Therefore, the aim of the study is to investigate nitrogen based fuels to be used in existing ICE with as small modifications of the engine design as possible. The criteria of nitrogen based, closed loop produced fuel compatible with the design of an existing ICE utilizing small design modifications would be a breakthrough in the global vehicle fleet. A theoretical study was conducted in order to investigate the possibility of using nitrogen-based fuels in internal combustion engines. This idea prompted up since ammonia has been used as fuel for buses in Belgium during World War II [Kroch E]. Modern time issues such as climate change and depletion of fossil fuels could be solved by using a possible carbon-free nitrogen-based fuel. There are several nitrogen based fuel/fuel mixtures but not all are suitable for use in existing engine designs since many of these are aimed for use as rocket fuel. Our judgement is that ammonia, mainly used in dual fuel concepts, is the only convenient nitrogen based fuel for possible use in internal combustion engines in an reasonable future unless a major scientific breakthrough occurs. Ammonia is today mainly produced from natural gas that emits a large amount of carbon dioxide when combusted. It is thus more convenient to use natural gas direct in a natural gas vehicle rather than producing ammonia of it. Alternative production processes based on sustainable sources, i.e. solar and wind (electricity) can´t compete economically with hydrocarbons. A possible competitive carbon-neutral production method for future is to produce ammonia by biomass gasification that would enable almost zero carbon emission propulsion when considering Well-To-Tank. Using biomass for ammonia is better than using it for bio-fuel (hydrocarbon) production considering corn as feedstock. This is due to the larger amount of corn needed for bio-fuel production compared to ammonia production. A future use of biomass for ammonia production opens a window of opportunity to realize a carbon-free Well-To-Wheel chain. There are no engines currently that can run on ammonia, or ammonia as dual-fuel, at today’s standards and with the same operating conditions. The work performed are rather at research level, mainly as fuel research on Cooperative Fuel Research (CFR) II engines, and have some way to go before being possible for engine application in transport vehicles. There is no engine architecture at present that supports ammonia as fuel. Ammonia as fuel for internal combustion engines is not possible in the near-term future if a carbon-free Well-To-Wheel chain is required. It might be possible, if further research is conducted in future. Nitrogen based fuels do not seem to be an alternative for low Green House Gas (GHG) emissions in automotive engines. Currently, only ammonia seems feasible as fuel in engines. Being locally “low-carbon”, meaning emitting no or low GHG emissions, it cannot compete on the total Well-to-Wheel chain. Additionally there is a large gap in the engine technology and application to meet todays and future requirements.
Energi, Transport, Hållbar utveckling, Farkostteknik, Energiteknik, Energy, Transport, Sustainable Development, Vehicle Engineering, Energy Engineering
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