The future, it seems, may just be hydrogen-powered. A few years back, electric power generation through rooftop solar units was envisioned to mitigate power losses along transmission and distribution lines and also control greenhouse gas emissions. However, rooftop solar power projects in India failed to take off due to the intransigence of various state-owned electricity distribution companies. Other factors, like poor offtake for surplus energy generated and the low prices offered, conspired to hamper the growth of rooftop solar power in India.

As solar energy is subject to periodic interruption, traditional batteries are used to store energy, which is an expensive proposition. Traditional batteries have several drawbacks, such as low storage capacity and limited lifespan. With the world swiftly moving to hydrogen, many in the industry and scientific community believe hydrogen generators are a more viable alternative.

Also read: L&T and ReNew to jointly develop, operate green hydrogen projects in India

What are rooftop hydrogen generators?

A rooftop hydrogen generator is a machine set up on the terrace that uses a process called electrolysis to produce hydrogen from water. Unlike a cylinder, a hydrogen generator does not store vast quantities of the gas inside it. Hence, only a very small quantity of hydrogen is likely to escape if the generator leaks.

How do they work?

Imagine this: A device on your rooftop, which has a chamber filled with water. The water in the tank gets converted to hydrogen, which you can conveniently use as fuel for your car or the cooking stove. This is what a hydrogen generator does. The generator uses electricity to split the hydrogen atoms in the water molecule from the oxygen atom through a process called electrolysis. The process is performed in a cell inside the hydrogen generator.

Although one can use the electricity from the rooftop solar plant to split water and produce hydrogen, scientists are working on technologies that can make photolysis or splitting of water directly using sunlight, using photoelectrochemical cells without the use of electricity.

Also read: All you need to know about the $2.6-bn green hydrogen project planned for Europe

Emerging technologies

In August, Aravind Kumar Chandiran, head of the Solar Energy Research Group at IIT Madras, said “a new material” had been developed that could be used to split water under sunlight, the Business Line reported.

Mohammed Qureshi of IIT Guwahati claimed his team had developed a catalyst that could be used as a “photoanode” to split water into oxygen and hydrogen, the report added.

With these emerging technologies, many in the academia and industry believe small-sized hydrogen generators are not too far away from reality.

Work in progress

“Demand for hydrogen is expected to grow by a factor of 1,000 or more by 2030 and decentralised systems producing the gas on-site, with no transportation cost, will make a huge difference,” Sebastian-Justus Schmidt, Chairman of German company Enapter, that produces electrolysers, was quoted as saying by Business Line.

Also read: India’s hydrogen fuel journey – from 2006 to 2021 – where are we now?

Many companies like Enapter are making devices that can be attached to a rooftop solar plant for making hydrogen.

Meanwhile, another company Hydrogenium Resources is already deliberating with rooftop solar installers to use electrolysers with the solar plants to produce hydrogen from surplus solar power.

Cost factor

Due to the high cost of electrolysers, right now, the estimated cost of the rooftop hydrogen is around $7.50 (around Rs 560) a kg. However, industry experts believe the price could come down once the manufacturing gains ground.

(Edited by : Shoma Bhattacharjee)