Hydrogen: somewhere over the rainbow?
Finbar Percy
Introduction
Many things come to people’s minds when they think of rainbows: positivity, happiness and equality. But does hydrogen? Surely there is no correlation between a colourless gas and a spectrum of colours. The hydrogen rainbow is a series of colour codes, or nicknames, used in industry to differentiate between the different types and origins of the gas. For example, all naturally occurring hydrogen is white. Most hydrogen made today is from natural gas through reforming, so is grey. If you capture the carbon dioxide produced from this reaction, it is now blue hydrogen. Other colours include pink, created by nuclear power, and black, the most environmentally damaging as it is made from coal, through combustion and gasification. However, the colour with the biggest interest, the greatest investment and the brightest future is green hydrogen, as it could play a vital role in helping us live sustainably. Sustainability is, and will be, the biggest talking point of the 21 st century. Now we know we are warming the planet; how can we change to live sustainably? Unlike other problems humankind has had in the past, global warming could be catastrophic for the planet. The UK is committed to becoming net zero by 2050 (National Grid, 2022) and a recent study conducted by the University of Minnesota concluded that one in three species could be threatened with extinction at the turn of the century if we continue to warm the planet (Daily Mail, 2022). So, it is essential to focus on solving this problem now. I believe using green hydrogen and creating a hydrogen economy could be the perfect answer.
What is a fuel cell?
The fuel cell is crucial to this future. It is not the newest or most complex technology. Early versions of the direct coal fuel cell date back to the 19 th century when, in 1896, W.W Jacques created one which could provide up to 1.5 kW of power (Perry & Fuller, 2002). However, the seemingly perfect energy producer, crude oil, hindered progression of fuel cell technology in the first half of the 20 th century. Now we know burning fossil fuels is harmful, the fuel cell is making a comeback and hydrogen could be the best replacement. All hydrogen fuel cells separate the reaction of hydrogen and oxygen into two stages, so we can use the electrons generated to make a current (see Figure 1).
Figure 1: The mechanics of a fuel cell in its simplest form (self-made)
The first stage is the oxidation of hydrogen at an anode producing two hydrogen ions and two electrons. The second is the reduction of oxygen at a
cathode and the combining of hydrogen and oxide ions to produce water, the only by-product. This can happen at either the anode or the cathode depending on the electrolyte placed between them. An electrolyte is a material or fluid which allows the movement of ions but inhibits the movement of
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