Image copyright Christ Clijsen Image caption Team Fast sitting in front of their prototype bus that runs on formic acid

A group of students has developed a way of storing energy that could be cheaper to make, more practical and more sustainable than alternative renewable fuels.

They are young and clever, and they want to change the world - one bus at a time.

"We've created the world's first bus that runs on formic acid, which is a much cheaper solution than hydrogen, yet it delivers the same environmental benefits," says Lucas van Cappellen from Team Fast, a spin-off company from Eindhoven University of Technology in the Netherlands.

"We're building our own future."

Around 40 of his fellow students are endeavouring to develop emissions-free transport that will help in the global battle against climate change. And they're also trying to create careers for themselves.

Formic acid is found in nature, delivered in the stings and bites of ants and other insects - the Latin word for ant is formica.

And this simple carboxylic acid (chemical formula HCOOH) is already used in textiles and leather processing, as a livestock feed preservative, and is also found in some household limescale removers.

Image copyright Team Fast Image caption The hydrozine-filled trailer will attach to the back of the bus

But Team Fast has found a way the acid can efficiently carry the ingredients needed for hydrogen fuel cells, used to power electric vehicles.

The fuel, which the team has dubbed hydrozine (not to be confused with hydrazine), is a liquid, which means you can transport it easily and refill vehicles quickly, as with conventional fuels.

The difference is that it is much cleaner.

"The tailpipe emissions are only CO2 and water," explains Mr van Cappellen. "No other harmful gases like nitric oxides, soot or sulphuric oxides are emitted."

To prove the concept in the real world, an electric bus is set to hit the road in the Netherlands later this year, where it will shuttle between running on conventional bus routes and appearing at promotional events and industry fairs.

The bus has an electric drive system, developed by bus builder VDL, that receives additional power from the formic acid fuel cell system mounted in a range-extender trailer, towed behind.

"Our tank is around 300 litres, so we will extend the range of the bus by 200km (180 miles). However, we could of course make the tank bigger very easily," says Mr van Cappellen.

Image copyright Bart van Overbeeke Fotografie Image caption Team Fast tested its concept in a one-metre length model car in January 2016

Current hydrogen fuel cell buses have a range of up to 400km.

But why develop a bus rather than a car?

"If we built a car, we would compete with electric cars, but we believe battery-powered cars are a good solution for a lot of people," says Mr van Cappellen.

"But if we prove that we can build a bus that meets the needs of bus companies, with a range of around 400km and quick refuelling, we will have shown the potential of hydrozine in a segment where there is no sustainable competition yet."

Hydrozine is created through a chemical reaction between water (H2O) and carbon dioxide (CO2).

More Technology of Business

"In a reactor, water and CO2 are bonded using sustainable electricity. This is a direct, sustainable electrochemical process," explains Mr van Cappellen.

The hydrozine is then broken down by a catalyst into hydrogen and carbon dioxide inside a piece of kit called a reformer that Team Fast is attempting to patent.

Its newly designed reformer is a tenth of the size of reformers of the past, which is why "it is now applicable in transport applications for the first time".

The hydrogen is then added to a fuel cell where it reacts with oxygen to generate the electricity that powers the electric motor.

Image caption Zero-emission hydrogen fuel cell buses are becoming more common on our city streets

"We are continuously looking for new technologies that can extend the range of zero emissions traffic in a simple way," says Menno Kleingeld, managing director, VDL Enabling Transport Solutions.

"The decomposition of formic acid into hydrogen gas is one of these new, promising technologies."

But does it really stand a chance of becoming commercially viable?

"It costs about 35,000 euros (£30,000) to convert a conventional petrol filling station to a hydrozine filling station, a process that essentially involves replacing the pipes and coating the tanks," says Mr van Cappellen.

As such, it is "100 times cheaper" to roll out a fuelling network for hydrozine than for gaseous hydrogen, he maintains.

"Hydrozine is currently cheaper than petrol and more expensive than diesel in the Netherlands, and in future we expect prices to come down so it will be cheaper than both," he adds.

Although the bus emits CO2, Team Fast argues that the original CO2 used to create the hydrozine is taken from existing sources, such as air or exhaust fumes, so that no additional CO2 is produced - it's a closed carbon cycle in the jargon.

Image copyright Getty Images Image caption Some types of ant squirt formic acid as a defence mechanism

Some experts believe the technology shows promise.

"Team Fast has a very good project," says Professor Richard van de Sanden, head of the Dutch Institute for Fundamental Energy Research.

"It works on a very important issue: the storing of renewable energy in a transportable form and in a form which can actually be used."

And several companies are supporting the project.

"What we're working on together is a version of renewable energy that can combine renewable energy with CO2 capture," says Martijn de Graaff, senior business development manager at TNO Industry.

"If we achieve this it will give us a stable future."

The students' own commitment is impressive, with 15 of the 40 working full time on the project, and the rest contributing at least 20-25 hours per week.

"We don't get study points for it, but you can only learn so much at university about the practical experience of things," Mr van Cappellen says.

"It's our own future we're making."