In a small industrial unit on the outskirts of Birmingham - where a company called Chad Valley used to make toys - a small group of technicians are now making hydrogen fuel cells.

The idea of using the most plentiful element in the universe to produce energy has been around for more than two hundred years, but the urgent need to decarbonise our current energy system means its time as a mainstream energy source may finally have come.

Dr Michaela Kendall, CEO of Adelan technologies, which designs and builds small fuel cells to power all sorts of devices says: "It's a very exciting point because people have suddenly discovered it. We discovered it really. And people are looking to use hydrogen to decarbonise the energy infrastructure.

"And it's happening in lots of different ways. So there's a general enthusiasm for hydrogen, the use of the fuel and the use of the technologies.

"Decarbonisation has accelerated people's interest in clean energy. We've seen that solar power is commercially viable and dropping in price continuing to drop wind power, the same batteries are emerging as technology that can be put everywhere.

"So I think people are now looking for another type of generation to add to that suite of technologies if you like, and fuel cells fit the bill. So fuel cells are this hardware and hydrogen is the fuel or one of the fuels that can also deliver no carbon."

This photo taken last week shows Toyota's Mirai hydrogen-powered car, which was originally launched in 2014 but has only sold 17,000 units, on display at a showroom in Tokyo

Michaela takes us to one of just a dozen hydrogen filling stations in the UK. She drives a Toyota Mirai - a car that generates electricity from a hydrogen fuel cell.

It works by drawing off the electric charge created when hydrogen atoms combine with oxygen in the air. The exhaust that comes out the back of the car is H20 - pure water.

Hyundai, Honda and Mercedes have started to offer cars - mostly for rental contract - that are powered by hydrogen fuel cells. Prices are from around €60,000 in Germany.

"We think that the hydrogen can really be a solution because you can fuel hydrogen like normal petrol today."

Filling up the tank with hydrogen gas is just like filling up with petrol - simple and quick. The hydrogen at the Birmingham station is made on site using electricity from the waste incinerator next door to break water into hydrogen and oxygen. The oxygen is also used for industrial and health service uses.

But the next step is to make hydrogen from clean energy sources like wind or hydro power - known as green hydrogen. This way energy can be stored until it's needed, something that can't be done with renewable power alone.

Which is why big chemical companies are interested in linking their existing plants to wind farms to make hydrogen, and petrol companies can sell it through their existing forecourts.

Wouter Bleukx speaks to the media during an event to unveil the first hydrogen-fuelled double-decker bus in London last month

"We think that the hydrogen can really be a solution because you can fuel hydrogen like normal petrol today," says Wouter Bleukx, a Belgian engineer who is the hydrogen business unit manager for Ineos, a British chemicals and engineering multinational.

"Also you have a very long driving distance much longer than batteries. And what could be a problem in the future - if everybody is going to batteries, and everybody is going to plug in their car at home, the grid is simply not able to cope with all this energy demand. And therefore hydrogen can be a very valid alternative."

We meet in front of a Hyundai passenger car that runs on a hydrogen fuel cell, but he tells me that commercial vehicles, especially heavy trucks, will pioneer the route to widespread hydrogen use.

"We think it will probably start more with commercial transport. So at the moment, we think that we should invest in heavy trucks, in buses, in garbage vehicles, and in taxis - to create a mass scale. We can then put fuelling stations at the depots where these buses and taxis work.

"And then in the next phase, we think that the passenger cars will follow once the (refuelling) infrastructure in the country is developed.

Although some truck makers are experimenting with battery powered trucks - that would mainly rely on overhead wires along main motorway routes, rather like trams - Bleukx thinks hydrogen fuel cell technology is more practical.

"If you would use batteries on the truck, the batteries would be far too heavy and take too much room, reducing the payload of your truck. And that is why we see now a lot of developments, for instance, in Norway, but also in other countries of the world, where we see hydrogen trucks being developed."

He also points to one of the most polluting forms of transport - shipping: "We see small barges, where normal diesel motors are replaced by fuel cells and hydrogen, but also big maritime vessels will drive or will sail on hydrogen in the future. Maybe not on hydrogen itself, but maybe on green ammonia, which is produced with green hydrogen. So there is a lot changing in this world, going away from from diesel to alternatives in hydrogen or ammonia."

"I didn't understand that the construction industry, for example, would be so enthusiastic about going for fuel cells. But they really need them."

Germany has around half of all the 200 or so hydrogen filling stations in Europe: France has the fastest growing network of hydrogen stations.

In the US, California is leading the development of hydrogen fuel cells with the roll-out of a filling station network.

Japans first hydrogen import terminal in Kobe, Hyogo Prefecture

Globally, Japan is the leader in hydrogen infrastructure roll-out. The EU has set an end of decade target of having a hydrogen fuelling station every 150km along the main motorway trunks of Europe - the so-called TEN-T network. In Ireland that means the motorway connecting cork with Belfast, via Dublin.

And there is a strategic reason why Japan and Germany are pushing deep into hydrogen as a transport solution:

China - the world's biggest automobile maker and market - now controls about two thirds of the global supply of the metals and chemicals needed to make batteries.

Putting all the transport energy eggs into the battery vehicle basket means increasing dependence on China: a hydrogen energy transport system gives more strategic autonomy and options.

The EU produced a far reaching hydrogen strategy last year, part of the EU Green Deal industrial strategy to decarbonise the economy, backed by money from the massive investment programme known as the Covid Recovery Fund.

The aim is to convert the problem of climate change into an opportunity for industrial renewal. The British government produced its own hydrogen policy over the summer.

Alstom's Coradia iLint train, the first in the world to be powered by hydrogen, during its inauguration in September

In Germany, the French engineering company Alstom is testing a train that runs on hydrogen - a fuel cell replacing a diesel engine to give the quiet, clean power of electric trains without the need for overhead cables. Airbus is promising hydrogen powered aircraft in about fifteen years' time.

And it's not just the vehicles that use fuel cells - construction offices for a high speed rail line, the temporary signage for motorways - even a drone have used fuel cells from Adelan in Birmingham.

"I didn't understand that the construction industry, for example, would be so enthusiastic about going for fuel cells. But they really need them. And in vehicles, we started to see hydrogen vehicles.

"I drive a hydrogen car - and that's a product on the road right now. You can see them in (home heating company) Worcester Bosch making hydrogen boilers, you can start to see in different sectors, different parts of the economy, these products creeping in, and hydrogen and other fuels like bio-fuels, creeping in as well," says Michaela Kendall.

If the last decade in transport was all about batteries, the decade to come may be all about hydrogen.