An inexpensive bipolar alkaline electrolyser
“The objective of this work was to develop a low cost and portable device to produce an alternative form of fuel or a fuel that can be used to improve combustion efficiency on internal combustion engines and reduce emissions of PM, CO, CO2 and NOx with an incentive to users of improved fuel efficiency.
A technology suitable for the users of today.
Much research work is available on Hydrogen IC engines, water injection, and emulsified fuel but few have been shown to address suitability for use on heavy goods vehicles and public transport. Water injection has been shown to reduce combustion temperature and thereby reduce harmful NOx emissions but a practical device has not yet materialised.
Emulsified fuel (water in diesel) is currently in use for public transport in some European cities and is generally used in conjunction with hydrogen. This emulsified fuel has limited applications as it is unstable and will separate and is therefore only suitable for high fuel users. Its use has been shown to substantially reduce particulates and NOx emissions.
The cost of going “Green” will remain a burden on taxpayers and users of public transport. London Transport are using some electric buses and for every route two buses are required as one must stop to recharge. Governments continue to impose carbon taxes instead of funding a solution.
On most commercial and industrial electrolysers, the catalyst used is 25%/35% wt/wt potassium hydroxide (KOH) and in this volume the gas cannot be used in engines due to corrosion.
The methodology in this work was to identify a balance between the multiple variables involved in water electrolysis which include a suitable low cost electrode, electrode surface area, variable voltage, current density, electrical resistance, temperature and the type and volume of electrolyte. Reliability of such device and with no electrode erosion could only be achieved with minimal electrolyte concentration and with a low current density.
The design result was achieved by using low cost stainless steel electrodes in a bi-polar configuration whereby electrodes are of solid state in the absence of any perforations and with exposed perimeter edges concealed from the electrolyte, to avoid current loss. This was achieved by the slotted gables in the polypropylene enclosure.
When power is applied the top edge of electrodes become exposed in a gas void. An electronic controller was developed in-house and is used to control current/ gas volume to a prescribed setting. The initial voltage per electrode is 2.3 volts which ensures a fast warm up of the electrolyte and as it begins to heat, the voltage reduces by change in resistance, which improves energy efficiency as the electrolyte heats to approx. 60 deg C.
We are now producing a combustible gas of H2/O2 which has almost three times more heat energy than gasoline but we also have a form of water injection with the vapour.
This result can be achieved with 0.12M KOH catalyst with laboratory analysis showing no trace in the evolved gas and therefore will not cause engine corrosion. This was also confirmed by analysis of the electrolyte after hours of operation when electrolyte had depleted and the catalyst concentration increased. This result is of particular interest to users as replenishment is carried out with de-ionised water only.
The polypropylene enclosure is designed to accommodate a PEM to separate the oxygen from the evolved gas to permit storage of the H2. Due to the high efficiency the gas can now be produced using solar PV. Testing has been carried out on most vehicles types and the result is significant.
The new administration in the Irish Government has shown considerable interest and we are ready to commence trials using the Reformer on Public Transport where efficiency and emissions testing will be carried out by an independent specialist. ”
About the author:
Professor John Cassidy was awarded a diploma in Applied Science by Dublin Institute of Technology, his BSc (Applied Sciences) by University of Dublin, and completed his PhD at the University of Utah, USA. He has since lectured in Analytical Chemistry in DIT, Kevin Street. He was appointed Assistant Head of School in 2001 and awarded Professorship of DIT in 2009.