Development of Electrolysis System Powered by Solar-Cell Array to Supply Hydrogen Gas for Fuel-Cell Energy Resource Systems Priambodo, P; Yusivar, F; Subiantoro, A; Gunawan, R. INTERNATIONAL WORKSHOP ON ADVANCED MATERIAL FOR NEW AND RENEWABLE ENERGY.

Background Electrolysis The process of separating water into hydrogen and oxygen Requires a direct electric current An electrolyte is required to increase the conductivity of water Produces two times the amount of hydrogen than oxygen

Background Hydrogen Simplest and lightest element Contains one electron and one proton Doesn’t exist naturally on Earth as a gas The most plentiful gas in the universe Has the highest energy content per unit weight

Background Most of the energy we use today comes from fossil fuels Only six percent of our energy comes from renewable energy resources In the mid of the 21st century the world could face an energy crisis

Background Fossil fuels need to be replaced by renewable resource to avoid crisis Alternative energy resources Nuclear Bio-fuel or Bio-diesel Biomass Hydro energy Wind energy Ocean wave energy Solar cell Fuel cell

P.S.Priambodo et. al. 2008 We need energy storing systems which capably store large scale energy and are also transportable. The promising way to store energy easily, efficiently and in large scale is by storing hydrogen gas in bottles.

T.M. Maloney et. al. 2005 Electrolysis uses an electric current to split water into hydrogen and oxygen gases. The electric current has to itself be produced. Of course, for the reason of pollution free and renewable energy system, the electrical energy used to support electrolysis system must by produced by renewable energy resources such as solar, wind, hydro, or ocean wave energies.

T. Mizuno, T. Akimoto and T. Ohmori et. al. 2003 The obvious method to store such energy carrier is by storing it as possible in the form of small volume storage such as gas bottle. However, there is still a problem because hydrogen gas is explosive.

Purpose To propose a method to develop an efficient electrolysis system supplied by solar cell array to support fuel-cells in a renewable energy resource system

Methods Two different tests were conducted to test if the distance between electrodes correlated with the resistance between electrodes In the first test, two plate electrodes were tested at distances between 0.5-14 cm in a plastic box 27x18x10 cm^3

Methods The next test was conducted almost the same as the first using cylindrical electrodes each 1.2-cm diameter and 10-cm length instead of plate electrodes. In each test a mixture of 8-parts pure water to 1-part sulfuric acid was used.

Methods With the results of the previous tests, a design was created for a space efficient, compact electrolysis system. This system was created to use a 50-Watt-peak solar cell with a resistance maximum of 4-Ohms and a mixture of 36-parts pure water to 1-part sulfuric acid.

Methods To capture the hydrogen created by the system, a two stage storage system The gas goes through silica gel to separate it from contaminating water vapor A vacuumed bottle would be used to pull the hydrogen from the silica gel A second high pressure bottle would be filled from the first using a vacuum pump

Results Figure-3. Electrolysis resistance (Ohm) vs electrode distance (cm), 8-part pure water and 1-part sulfuric acid (H2SO4) and 5x5 cm electrode-area [ 1 ] "

Results Figure-6. Electrolysis resistance (Ohm) vs electrode distance (cm), 8-part pure water and 1-part sulfuric-acid (H2SO4) and 1.2-cm diameter cylindrical electrodes and 5-cm length

Discussion It can be expected that the electrolysis-cell with 4-Ohm resistance can be achieved by dimension of about 10x10x10 cm^3, and increasing the ratio pure-water: H2SO4 = 36 : 1. In 400 ml water there is an approximate 500 liters of hydrogen and 250 liters of oxygen at room temperature. The required energy for 400-ml water conversion is about 2 kWh or equal to 40 hours of 50-Wpeak.

Discussion In order to increase space efficiency to obtain a compact electrolysis system, it is proposed to use four or more electrolysis systems into one box system. It is also recommended to use cylindrical shape electrodes instead of plate electrodes due to a more compact size. To collect hydrogen produced by this system, it is proposed that a two stage collection system be used.

Further Research Developing FEM for better visualization of electrical-current flow inside the electrolysis system. This visualization will help optimize the structure of the multiple-electrolysis cell box.

Conclusion Characterization of electrolysis system has been done. It is concluded that there are at least 3 different parameters determining the required criterion maximum load-Ohmic resistance of typical solar-cell. Those 3 parameters are, distance between electrodes, acid, base/salt electrolyte concentration and the area of electrodes. As already been discussed in this paper that to obtain the optimum load-Ohmic resistance of typical solar-cell, the maximum current allowed at the solar panel must be determined first. Then the 3 parameters can be determined. In order to make the overall electrolysis system become more compact and efficient, it has been proposed to use multi-electrode electrolysis system. To store the hydrogen gas, it has been proposed to use two-stage hydrogen gas storage.

Article Citation Priambodo, P; Yusivar, F; Subiantoro, A; Gunawan, R. (2009) Development of Electrolysis System Powered by Solar-Cell Array to Supply Hydrogen Gas for Fuel-Cell Energy Resource Systems. INTERNATIONAL WORKSHOP ON ADVANCED MATERIAL FOR NEW AND RENEWABLE ENERGY. Volume 1169: pp. 206-213 http://web.ebscohost.com.proxybz.lib.montana.edu/ehost/pdfviewer/pdfviewer?sid=955bc97c-4d0a-4d21-b3af-bb49dce1c8ce%40sessionmgr4&vid=4&hid=10

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