With a little help from the sun

Ask any expert and they will tell you the future of mobility lies in hydrogen. Everybody agrees that there is a need to leapfrog battery-based mobility and move into hydrogen, simply because while batteries need to be disposed, hydrogen only ends up as water in the tailpipes. But the problem is, how to produce large quantities of hydrogen and keep it in cylinders to power automobile engines?

It is impractical to keep the gas in cylinders and then burn it in the combustion chambers — it is neither economical nor safe to do that. The hydrogen way is to push the gas into fuel cells that generate electricity (and water).

But as researchers grapple with the problem of storing large enough quantities of the gas in cylinders and making the fuel cells smaller, economical and efficient, there is another problem left unattended — how do you produce the gas in an environment-friendly manner?

Among the many ways to produce hydrogen is electrolysis, or splitting of water into hydrogen and oxygen. This process uses a lot of electricity. Now, the Central Electro Chemical Research Institute (CECRI), one of the units under the Council for Industrial and Scientific Research (CSIR), has come up with a contrivance that marries solar panels to electrolysis equipment so as to produce hydrogen from sunshine.

The device is basically a cathode and an anode separated by a membrane (proton exchange membrane or PEM), the whole thing held in position by titanium plates in a bath of water. When electricity is passed through the titanium plates, hydrogen emerges at the membrane. It is roughly the reverse of a fuel cell in a car. You inject hydrogen to the membrane to get electricity and water; here you pass electricity through water to get hydrogen and oxygen.

“Water electrolysis by PEM concept is the most suited process for onsite production of hydrogen, because of its simplicity of operation and maintenance, compactness, absence of corrosive liquids and purity of hydrogen,” says Dr Subramanyan Vasudevan, Senior Principal Scientist at CECRI, Karaikudi, who is the head of the team that invented the machine.

The source of electricity is solar panels. You need 5 kWhr of electricity to produce one cubic metre of hydrogen in an hour, and half a cubic metre of oxygen, at atmospheric pressure. Both gases are of 99.99 per cent purity and the oxygen can be used in hospitals, Vasudevan says.

The device costs around ₹1 lakh, but that is because the anode and cathode are made of iridium and platinum respectively. Now CECRI is trying out different materials for the electrodes to make it less expensive. The electricity, of course, is free once the cost of the solar panels is paid for.

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