The world’s demand of energy is increasing rapidly, leading scientists into aggressively searching for alternative methods such as renewable energy to assist with energy supply.

There are two methods used to convert biomass energy which are gasification and pyrolysis. The process of gasification places solid or liquid biomass at temperatures around 1000°C which assists with converting it into gas called syngas and solid compounds known as biochar.

Syngas is a mixture of hydrogen, methane, carbon monoxide and other hydrocarbons which are used as biofuel to generate power. Biochar is often regarded as a solid carbon waste, even though it can be used in agriculture applications.

Another method is that biomass pyrolysis is similar to gasification and the only difference is that biomass is heated at lower temperatures which are between 400-800°C and at pressures up to 5 bar in an inert atmosphere. The three types of pyrolysis are known as conventional, fast which take the longest time and have the most char production and flash pyrolysis.

Scientists led by Professor Hubert Girault at EPFL’s School of Basic Sciences have developed a new method for biomass photo-pyrolysis that produces not only valuable syngas, but also a biochar of solid carbon that can be repurposed in other applications. The work is published in Chemical Science.

The method performs flash-light pyrolysis using a Xenon lamp, commonly used for curing metallic inks for printed electronics. Girault’s group has also used the system in the last few years for ther purposes, like synthesizing nanoparticles.

The lamp’s white flashlight provides a high-power energy source as well as short pulses that promote photo-thermal chemical reactions. The idea is to generate a powerful flashlight shot, which the biomass absorb and which instantaneously triggers a photothermal biomass conversion into syngas and biochar.

What stands out in this method is that both its end products, hydrogen and solid-carbon biochar, are valuable. The hydrogen can be used as green fuel, while the carbon biochar, can either be buried and used as a fertilizer or it can be used to manufacture conductive electrodes.