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Alkaline Electrolysis

(University of Strathclyde - Douglas Tamunosaki, Mahdi Kiaee, Dr. Andy Cruden & Prof. David Infield)

Hydrogen production by alkaline electrolysis involves the break-down of water (H2O) using electricity, into its basic elements of hydrogen (H2) and oxygen (½O2) generated as gases.

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Figure 1: Schematic diagram of an alkaline electrolyser cell1

 We are interested in development of alkaline electrolysers of improved energy efficiency  ≤ 4.0-4.5kWh/Nm3 hydrogen and low unit hydrogen production cost  ≤ £2.25/kg that is also able to perform efficiently under operating conditions of low temperature and variable electrical power supply for large scale commercialisation of the technology by the year 20152.

Our research approach is systematically planned as to build an alkaline electrolyser test cell for use in investigating and developing low cost materials for superior performance of hydrogen production. We are investigating materials such as electrodes, bi-polar plates, membrane separators and electrolytes that can be highly responsive to variable power supply characteristic of renewable energy from dynamic sources such as wind, solar and wave energy, and also reducing electrolytic energy demand for high rate of hydrogen production. The test cell which would be subsequently scaled into a multi-cell stack similar with commercial alkaline electrolyser systems will be used to further develop technical and economic models for system improvement.

The electrodes are manufactured from epoxy resins by cast and compression mould technique. Initial design and fabricated single test cell unit are shown in figures 2-4:

 

Figure 2: Design of single test cell unit         Figure 3: Electrode mould            

Figure 4: 2cm diameter ‘button’ electrode test cell
The second part of the work aims to investigate the demand side management potential of highly distributed alkaline electrolyser loads, connected to the UK electricity system. The potential aggregated electrical load of such future electrolyser plants will be considerable, and this work will analyse the use of such a 'controllable load' for frequency reserve, load levelling, reduction of power station emissions via reduction of 'spinning reserve', improved energy trading and so forth. This study will require an accurate and validated electrical model of typical alkaline electrolyser units, which may include laboratory testing and characterisation of these plant items to facilitate 'grid scale' demand side management.

As a part of this work two electrolysers and two wind farms were added to the standard IEEE30 power system model, and then the possibility of consuming the extra wind energy from these wind farms using two electrolysers were investigated. Software was developed using MATLAB and MATPOWER to simulate the standard IEEE30 model. Figure 5 shows the IEEE30 bus system plus wind farms and electrolysers.

Figure 5: the IEEE30 bus system plus wind farms and electrolysers

An experiment was carried out to measure the AC and DC harmonics and the efficiency of the electrical parts of an operational 1Nm3/hr electrolyser. Figure 6 shows the side view of the PEM electrolyser.

Fig. 6: The side view of the PEM electrolyser

[1] ┬┐ystein Ulleberg, “Modelling of advanced alkaline electrolyser; a system simulation approach”  International Journal of Hydrogen Energy 28 (2003) 1, 21-33.

[2] Marcello Contestabile, “Critical review of the state of the art and international development targets for selected hydrogen production and delivery technologies H-Delivery WP 3-Task 3.1 Benchmarking” Imperial College London (2009).