29 Aug 2018 21:46 IST

Energy for free; well, almost

We’d love to think that free energy is what powers EVs. And this may be no Utopian dream.

We are hearing two words more and more frequently these days: electric vehicles. In the coming years, we are likely to hear two other words as frequently: fuel cells. If we don’t, it would be a shame.

But first, why electric vehicles? Because there is, quite literally, no other go. Two broad areas are responsible for greenhouse gas emissions, and they are energy and transport. Something is being done in energy — there is a global movement towards elimination of coal, even if it is running like a lame horse, and increased use of renewables such as wind and solar. And for transport — electric vehicles; since they don’t burn fossil fuels, they don’t spew carbon dioxide.

However, electric vehicles still need energy to run, right? Where will the energy come from? From batteries. Batteries are made with cells that store energy electro-chemically — energy can be put in and drawn back when required. Battery-powered vehicles — I’m sure many of you have travelled in these quiet auto-rickshaws, or golf carts or very local transport vehicles such as those in zoos.

They may look, feel and sound nice, but, well, they are still not good enough. Forget about aspects like range (how far they can run before needing to be plugged in for charge again), or charging time, which are the hurdles the EV industry is working hard to overcome. There is one crucial aspect impacting climate change. The electricity that is put into these batteries will needs to be produced somewhere, and if it is not produced through renewable sources, the EVs solve no problem. Furthermore, this input electricity also costs money. But we all want electricity that is available free, or nearly free. Now, is that an utopian dream?

Turns out it is not. Read on.

Free hydrogen

Fuel cells are devices that make electricity from hydrogen gas. Hydrogen is the most abundant element in the world. Two-thirds of all water is made of it. A lot of free hydrogen exists in the upper atmosphere and, being extremely light (if you remember, it is the very first element in the Periodic Table, which means it is the lightest element ever), some of it keeps escaping into space all the time. As a result Earth’s weight is coming down year after year, though the loss is more than compensated by the rocks that fly into the earth’s atmosphere, burn to dust due to friction and settle down on the planet. But I digress.

Hydrogen is freely available, and if you can separate it from other elements, it lives jointly with (such as water) you have an excellent energy carrier. Fuel cells are machines in which, on the input side, you put in hydrogen, and on the output side you get electricity and water. Sounds like magic, yes, but the science is that, in a fuel cell, the proton and the electron in a hydrogen atom (it has no neutron) are separated at a membrane. The electrons are made to flow, and a flow of electrons is electricity. After doing some useful work, such as running the car, the flowing electrons are allowed to rejoin the electron-less hydrogen atom, which eventually mixes with the oxygen in the air and comes out as water.

The world is furiously working on fuel cells and in due course, EVs will be powered by fuel cells rather than batteries.

Solar-powered electrolysers

Now, why do I say this energy is almost free? Because hydrogen can be produced by splitting water. Water splitting machines, or ‘electrolysers’ need electricity to do their job, but this electricity can be easily provided by solar panels.

I recently visited the Central Electro-Chemical Research Institute, (CECRI), Karaikudi (Tamil Nadu), which is one of the 38 units of the Council of Scientific and Industrial Research (CSIR). CECRI has developed a solar-powered water-splitter.

Their literature describing the machine sounds all technical gobbledygook. To give you an example, one sentence goes like this: “The Proton Exchange Membrane electrolyser consists of Membrane Electrode Assembly (MEA) coated on both sides by catalysts sandwiched between anode and cathode current distributors, which are held in position by titanium plates as main current leads.”

Head spinning? Well, that is how these scientists write, but the central message is of weight. Solar powered hydrogen producers are a reality.

Positive numbers

On a sunny day, 1 kW of solar panels can produce enough electricity to power this machine and produce 1,000 litres of hydrogen. Therefore, if you have a 100 kW rooftop solar plant, you can produce 100,000 litres of hydrogen. Imagine a battery of electrolysers — you could have tens of thousands of litres of hydrogen.

Solar energy is free. The machines cost money, but once they are paid back, in about 5-7 years, all the hydrogen that comes out is free. It takes a bit of money to pack them into cylinders and attach the cylinders to fuel cells in cars, but that’s why the energy is said to be “almost” free.

Fuel-cell powered vehicles are already on the roads. Some examples are Toyota’s Mirai and Hyundai’s Ioniq. It is very early days now and nobody knows how the numbers will pan out — except that the costs will go down dramatically. In future, most vehicles will be powered by fuel cells that will run on almost-free hydrogen.

Which is why I say we are bound to hear the words “fuel cell” more frequently in the coming years.

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