Derived from the most abundant element in the universe, hydrogen fuel is clean, flexible, and energy efficient. Current projections indicate that by 2030 the hydrogen economy could be worth $500bn. Yet hydrogen power has had a historically rough ride—and there are still obstacles to overcome until commonplace use. Could recent innovations, the obligation to decarbonise the energy sector, and global interest in reaching a “net zero” world, at last, make hydrogen commercially viable? In this article, we will be examining four potential types of hydrogen fuel: Green, Blue, Purple and Turquoise.
Many experts believe hydrogen holds great promise as a clean energy resource that can help nations achieve carbon-free goals. There are many different types of hydrogen, for example, the main type is green hydrogen, which is made from water through renewable-powered electrolysis. This form of hydrogen could be used to decarbonize a wide range of hard-to-mitigate industries, including petrochemical, cement, and steel, which often require high temperatures and combustion that cannot be achieved with standard wind and solar power. Hydrogen can also be used in mobility applications, such as air travel, for example Rolls Royce (partnered with EasyJet) have just released the world's first aero engine running completely on hydrogen. Hydrogen can also be used as an energy storage medium as it has an exceptional energy density, so the future looks very bright for this up-and-coming energy sector.
However, there is one main issue; most of the hydrogen used today (green hydrogen) is extracted from natural gas in an energy-intensive process and emits huge amounts of carbon dioxide. Producing natural gas also releases methane, a particularly potent greenhouse gas with a twenty-year global warming potential (GWP) of around eighty-four that of carbon dioxide. However, due to its short life span methane has a one-hundred-year GWP of around twenty-eight. Nevertheless, this still means for every one kilogram of methane released this is equivalent to that of eighty-four kilograms of carbon dioxide.
And while the natural gas industry has proposed capturing that carbon dioxide — creating what it promotes as emissions-free, “blue” hydrogen — even that fuel still emits more across its entire supply chain than simply burning natural gas, according to a paper published in the Energy Science & Engineering journal by researchers from Cornell and Stanford Universities. “To call it a zero-emissions fuel is totally wrong,” said Robert W. Howarth, a biogeochemist and ecosystem scientist at Cornell. “What we found is that it’s not even a low-emissions fuel, either.” The scientists involved in the production of this report examined the life cycle of the greenhouse gas emissions of blue hydrogen accounting for both carbon dioxide emissions and the methane that leaks from wells and other equipment during natural gas production. The researchers assumed that a considerable percentage of the gas drilled from the ground in fact leaks into the atmosphere, an assumption that draws on mounting research that has found that drilling for natural gas emits far more methane than previously known. Conclusively, they found that the greenhouse gas footprint of blue hydrogen was more than twenty per cent greater than burning natural gas or coal for heat.
However, there is promise for hydrogen energy, this is with both turquoise and purple hydrogen. Purple hydrogen is made with nuclear energy-powered electrolysis and is being considered by the European Commission. According to Euroactiv, "Using nuclear power for hydrogen production is known as “purple hydrogen” and offers the benefit of low-carbon emissions compared to the sort produced from natural gas – or grey hydrogen – which is currently the most widely available." The French are pushing for this to be considered green and sustainable. This paired with the recent breakthroughs in nuclear fusion such as the National Ignition Facility’s net gain reaction, could potentially help the world move towards a more sustainable future.
However, turquoise on the other hand is made with super-heated plasma in an oxygen-vacant vessel whereby the carbon is stripped off methane leaving hydrogen. Due to the absence of oxygen, the stripped carbon is in the form of a solid and is therefore known as carbon black, this can be recycled and used in industry making the process ‘greener’. Thus, making this process favourable if and only if super-heated plasmas can be created economically which they can. In actual fact plasma electrolysis produces more hydrogen with less energy consumption than hydrocarbon or Faraday electrolysis, therefore making this process yet again feasible and favourable.
Global energy demands are increasing day by day, and without radical change, governments won’t reach the requirements needed to fulfil the Paris 2050 agreement. Hydrogen energy, albeit purple, turquoise, or whatever colour will play a key role in this transition to a greener, cleaner, and eco-friendly world, however, this won’t be the only change required. To complete this move to net zero and fulfilment of the agreement, energy production will have to move towards a synergic platform whereby all methods of energy fabrication work together to maximise total outputs. For example, fusion (or fission as this method is currently unavailable) could work together with a hydrogen production platform to both power the plant and provide hydrogen to other industries. The opportunities are endless.
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