Thesis
Development of an ambient temperature alkaline electrolyser for integrating with the electrical grid and renewable energy system
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2013
- Thesis identifier
- T13454
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Electrolytic hydrogen production from an alkaline electrolyser is considered a promising energy storage technology that integrates renewable energy sources such as wind, solar, wave and tidal energy with the electrical grid. Hydrogen energy systems consisting of conventional temperature (at 80°C) alkaline electrolysers have been widely demonstrated by industry and their collaborators in academic institutions to minimise dependence on fossil fuels especially in the transport sector and thus help to ultimately reduce carbon emissions. However, the conventional temperature alkaline electrolysers are limited in terms of reliability, dynamic and fast-response operation when powered by renewable energy sources. Also, cost and safety concerns are barriers to decentralise and distribute the technology. As a result of this adds to the scepticism about the feasibility of a so called future 'hydrogen economy'. In this PhD study, an ambient temperature (at 23°C) alkaline electrolyser was investigated as part of a future integrated renewable energy system and compared with existing conventional temperature alkaline electrolyser system. The ambient temperature alkaline electrolyser is identified as a low-cost, reliable, and safe technology that is suitable for dynamic, intermittent, continuous and fast-response operation with renewable energy sources and the electrical grid. This also means the ambient temperature alkaline electrolyser is capable of wider operational range at 5%-100% of rated electrical power and faster response time in less than 1 second when powered by renewable energy sources. The auxiliary equipment are significantly reduced in the operation of ambient temperature alkaline electrolyser thereby reducing the cost of hydrogen and oxygen production and also making the technology reliable and safe for portable, stationary, transport and renewable energy system applications.;Equally important is the capability of the alkaline electrolyser to efficiently convert electricity and water into hydrogen and oxygen. This is demonstrated by DC polarisation and Electrochemical Impedance Spectroscopy (EIS) analysis of the alkaline electrolyser. EIS is used to determine resistance and capacitance which are basic electrical circuit elements of the alkaline electrolyser, and thus provides useful knowledge to the electrical engineer who is interested in modelling and optimisation of alkaline electrolysers as electrical loads. Additionally, the thesis provides a systematic approach to fabricating and characterising the electrodes for the ambient temperature alkaline electrolyser that is powered directly by either renewable energy sources such as wind turbine or the electrical grid. As such, EIS has become invaluable to characterise the electrodes based on exchange current density and corrosion rates. The objective is not only to enhance energy efficiency of the cell but to develop low-cost and durable electrodes. During this PhD work the electrodes have been characterised in an 'open-system' and flow-cell alkaline electrolyser. The 'open-system' simulates the monopolar tank-type alkaline electrolyser cell, and consists of stainless steel coated with nickel and molybdenum (SS-Ni-Mo) electro-catalyst that enhances the efficiencies for hydrogen and oxygen production. The flow-cell alkaline electrolyser has the unique advantage of modularity because the electrodes can be configured in either monopolar or bi-polar filter press arrangements. The flow-cell alkaline electrolyser is manifolded in order to capture the hydrogen and oxygen product gases that can be subsequently utilised in an alkaline fuel cell to essentially generate back electricity. It is demonstrated in this research work that, through electro-catalysis, appropriate cell design and good electrochemical engineering, efficiency and durability of the ambient temperature alkaline electrolyser can be enhanced by about 13 % and 50 % respectively.
- Resource Type
- Note
- Strathclyde theses - ask staff. Thesis no. : T13454
- DOI
- Date Created
- 2013
- Former identifier
- 991369
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