Scientists have developed a new method for producing hydrogen in a clean, carbon-free way, boosting its chances of becoming the sustainable fuel of the future.

The technique produces hydrogen using untreated biomass, sunlight, and special nanoparticles called quantum dots as the catalyst, removing the need for the high levels of heat (and energy) that usually power the process of getting fuel from biomass.

Less heat and less energy in the conversion process means fewer demands on the planet's resources, and no need for polluting chemicals, says the team from the University of Cambridge, potentially increasing the number of ways hydrogen can be used.

"Our sunlight-powered technology is exciting as it enables the production of clean hydrogen from unprocessed biomass under ambient conditions," says one of the researchers, Erwin Reisner.

"We see it as a new and viable alternative to high temperature gasification and other renewable means of hydrogen production."

The potential of hydrogen as a clean, renewable fuel is huge - its only waste product is water when used in cars - but scientists are still trying to figure out how to produce it using as little resources as possible.

The key could be biomass (organic matter) such lignocellulose, which contains the tiny fibres that protect trees and plants from wear and tear.

Lignocellulose has already been identified as a good biofuel source, but here the researchers were able to improve the conversion process using quantum dots - more specifically, cadmium sulphide quantum dots suspended in alkaline water.

These very tiny particles react with sunlight to kick off a complex series of chemical reactions, ultimately rearranging the atoms in the water and biomass solution to form hydrogen fuel and other organic chemicals, including formic acid and carbonate.

The hydrogen gas rises out of the solution and can be collected ready for any purpose - such as powering the cars of the future.

Even better, the team got positive results from different types of biomass, including wood, paper, and leaves, and say the process can be used in small-scale and large-scale projects alike - it's versatile, as well as environmentally friendly.

While biomass has been used as fuel for centuries, the modern techniques explored here and in other studies could finally make it suitable for the technology of the 21st century, the researchers suggest.

"There's a lot of chemical energy stored in raw biomass, but it's unrefined, so you can't expect it to work in complicated machinery, such as a car engine," explains one of the team, David Wakerley.

"Our system is able to convert the long, messy structures that make up biomass into hydrogen gas, which is much more useful. ... With this in place, we can simply add organic matter to the system and then, provided it's a sunny day, produce hydrogen fuel."

The findings have been published in Nature Energy.