A guest blog by Alice Llewellyn from UCell, the electrochemical outreach group at UCL

Shortly after the invention of the battery in the form of a voltaic pile by Alessandro Volta in 1800, William Nicholson (1753-1815) and Anthony Carlisle (1768-1840) discovered that water can be split into its constituent elements (hydrogen and oxygen) by using electrical energy.This phenomena is termed electrolysis and is the process of using electricity to produce a chemical change. Electrolysis was a critical discovery, which shook the scientific community at the time. It directly demonstrated a relationship between electricity and chemical elements. This fact helped scientific legends – Faraday, Arrhenius, Otswald and van’t Hoff develop the basics of physical chemistry as we know them.

Fast forward to today, and we are faced with one of the greatest challenges – climate change. This effect has accelerated the search for alternative fuels and energy storage devices fin order to decarbonise the energy sector. Burning fossil fuels (coal, oil and natural gas) for energy is the main cause of climate change as it produces carbon dioxide gas which leads to a greenhouse effect and the warming of our atmosphere.

A huge contender for alternative fuels is hydrogen. Hydrogen is the most abundant element in the universe. However, it does not typically exist as itself in nature and is most commonly bonded to other molecules, such as oxygen in water (H₂O). This is where electrolysis plays a key role. Electrolysis can be used to extract hydrogen from the compound which can then go on to be used as a fuel. Moreover, if a renewable source of energy is used (for example wind or solar) to provide the electricity required to split the water, then there is no carbon footprint associated with this hydrogen production.

Hydrogen can then be used in fuel cells to produce electricity. Fuel cells are electrochemical energy devices, they convert chemical energy directly into electrical energy without any combustion. The way in which a fuel cell works is in fact the reverse process of electrolysis. In a fuel cell, hydrogen is split into its protons and electrons which then react with oxygen to produce water, electricity and a little bit of heat. As the only side product of this reaction is water, fuel cells are a very clean way to produce electricity.

Energy from renewable sources (wind, solar…) is intrinsically intermittent. Depending on the season or time of the day more or less energy is produced. To make sure the supply of energy is secure and stable, energy needs to be stored when an excess is produced and later fed back into the grid when needed. Water electrolysis offers grid stabilization. When a surplus of energy is available, e.g. during the day when the sun is shining, some of this energy is used to produce hydrogen. This hydrogen can then easily be stored in tanks. Whenever more energy is needed, e.g. when it is dark, hydrogen is taken from tanks and fuelcells are used to release the energy stored in the hydrogen.  

Not only can hydrogen be used for grid stabilisation, but this can also be used to transform the transport sector, which contributes to around a quarter of the UK’s greenhouse gas emissions. Fuel cell vehicles are one of the solutions that have been adopted to tackle this problem and are classed as zero-emission vehicles (only water comes out of the exhaust). 

In 2019, London adopted a fleet of hydrogen-powered double decker buses – a world first! As more people start to learn about this technology, more fuel cell vehicles can be spotted on our roads.

Without the discovery of electrolysis by Nicholson and Carlisle in 1800, it might not be possible to produce pure hydrogen for these applications in such an environmentally-friendly way, making the fight against climate change a more difficult task.

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About our guest author Alice Llewellyn

Following a masters project synthesizing and testing novel battery negative electrodes, Alice Llewellyn, started her PhD project in the electrochemical innovation lab at UCL, primarily using X-ray diffraction to study atomic lattice changes in transition metal oxide cathodes during battery degradation. Alice co-runs the electrochemical outreach group UCell.

UCell is a group of PhD and masters students based at University College London, who are passionate about hydrogen, clean technologies and electricity storage and love sharing their knowledge and experience to the general public through outreach, taking their 3 kW fuel cell stack to power stages, thermal cameras and, well, anything that needs powering!  In a time of a changing energy landscape, they aim to show how these technologies are starting to become a regular feature in our everyday lives.

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