Life Cycle Analysis Of Energy Efficiency And Environmental Benefits Using Ammonia As Fuel And Hydrogen Carrier

Due to its high hydrogen content,high octane number,ease of storage and transport,mature synthetic technology and zero carbon emissions(only water and nitrogen are produced),ammonia is considered as an ideal energy storage medium and one of the most suitable clean alternative fuels in the future.With the rapid development of ammonia synthesis technologies and ammonia fuel application,it is necessary to carry out assessment of ammonia energy system immediately.The green ammonia synthesized from renewable energy provides the base for ammonia fuel to be applied in boilers,gas turbines and reciprocal internal combustion engines,among others.In this paper,the whole Life Cycle of ammonia from"birth"to"death"is evaluated from the perspectives of energy efficiency and environmental benefits.Firstly,this thesis analyzes the feasibility of utilizing ammonia as a fuel instead of common chemicals from theoretical analysis.This thesis compares the emissions and energy efficiency of anmmonia,hydrogen and traditional fossil fuels through theoretical calculation.Then,potential application pathways of ammonia energy system that may be industrialized in the short term will be evaluated in the stages of synthesis,transportation and application,and optimal solution is selected from the perspectives of energy efficiency and environmental benefits.Improvement pathways are also discussed.At the same time,experiments are performed in order to supplement the abovementioned theoretical analysis.Ammonia fueled boiler experiments were designed and performed,and experimental results are analyzed.Finally,the potential routes of the green ammonia energy system are evaluated and summarized,and future research direction for an in-depth evaluation of ammonia energy system is prospected.The main results of this thesis are as follows:(1)Twelve ammonia energy pathways are compared and analyzed after considering short-term industrialization and the demand for large-scale renewable energy consumption.Among them,the highest energy utilization efficiency is 31.1%and the lowest is 10.8%.(2)Compared to the reciprocal internal combustion engine,the gas turbine is more suitable for ammonia fuel for power generation in terms of energy efficiency and pollutant emissions.The conversion rate of the life-cycle system from electricity to electricity is about 5.(3)Ammonia energy system can effectively reduce greenhouse gases,particulate matters,sulfide and other pollutants in exhaust gases.Providing the same energy,ammonia combustion emits 0.06 to O.11kg/MJ less carbon dioxide than conventional fossil fuels.Besides,the NOx emissions are around 500 ppm in practical boiler application,so reducing the concentration of NOx emissions is an important task of ammonia energy application research.In summary,this thesis analyzes four stages of ammonia life cycle,i.e.,synthesis,storages,transportation,and applications.Energy efficiency and emissions are analyzed for each stage theoretically and experimentally.It is expected that the results and recommendations are valuable for the promotion of ammonia fuel and hence hydrogen energy in China,which may compromise the environmental issues and fossil fuel supply crisis.