Vinsamlegast notið þetta auðkenni þegar þið vitnið til verksins eða tengið í það: http://hdl.handle.net/1946/7003
Backup systems are crucial elements of modern electrical grids. They are used in places where an interruption in power supply can cause significant damage, e.g. in hospitals, banks or telecommunication towers. There are many solutions for how emergency power can be delivered. Hydrogen fuel cells are an emerging technology with great potential for the future. Fuel cells combine the advantages of batteries and diesel generators, and eliminate some of their significant disadvantages. They can work as long as they are supplied with fuel via a simple and efficient electrochemical reaction and at the same time they are quiet, produce no emissions and require minimum maintenance.
The aim of this thesis is to present the idea of hydrogen fuel cells as reliable backup power systems. The work consisted of two parts: one practical, the other theoretical. The first part includes the background of energy security, emergency power sources, fuel cell systems backup power market, as well as an introduction to fuel cell technology, principles of operation and hydrogen safety. The practical part of this project is focused on the Plug Power GenCore 5B48 fuel cell backup power unit, its description, installation, operation, safety precautions and performance characteristics.
The necessary hydrogen infrastructure was built according to safety codes and standards. The performance and reliability of the system was assessed. The system’s behavior was stable except for several minor problems during start-up which required intervention. The measured efficiency of the fuel cell stack and the whole system at the maximum available load of 1.65kW was 42.5% and 35.8% respectively. It was noted that the auxiliary load of the system has great influence on the overall performance of the system, especially at low output power. Noted fuel consumption was 13slm at 1kW and fuel utilization efficiency was estimated at around 99%. A cold start-up analysis was conducted and described based on the output data. During the first few minutes of operation the system required additional power to warm the fuel cell stack. The transition analysis focused on the ability of the system to provide power in case of a sudden outage. It was working well with batteries, as the fuel cell needed approximately 15 seconds to be ready to completely take over the power demand. Reliability and availability were assessed to be 96.8% and 79.9% respectively. It has to be pointed out that it was not possible to completely determine the system’s performance during some of the failure scenario and operation under different load because of the limitations of time and budget.