This technology is based on the generation of hydrogen a universal, light and highly reactive fuel through a chemical process known as electrolysis. This method uses an electrical current to separate the hydrogen from the oxygen in water. [1] If this electricity is obtained from renewable sources we will, therefore, produce energy without emitting carbon dioxide into the atmosphere. The figure 1 shows the green hydrogen.

Figure 1: The Green Hydrogen [2]

As the IEA points out, this method of obtaining green hydrogen would save the 830 million tonnes of CO2 that are emitted annually when this gas is produced using fossil fuels. Likewise, replacing all grey hydrogen in the world would require 3,000 TWh/year from new renewables — equivalent to current demand of Europe. However, there are some questions about the viability of green hydrogen because of its high production cost; reasonable doubts that will disappear as the decarbonisation of the earth progresses and, consequently, the generation of renewable energy becomes cheaper.

Green hydrogen is an important piece of the energy transition. It is not the next immediate step, as we first need to further accelerate the deployment of renewable electricity to decarbonize existing power systems, accelerate electrification of the energy sector to leverage low-cost renewable electricity, [3] before finally decarbonize sectors that are difficult to electrify – like heavy industry, shipping and aviation – through green hydrogen.

It is important to note that today we produce significant amount of grey hydrogen, with high CO2 (and methane) emissions: priority would be to start decarbonizing existing hydrogen demand, for example by replacing ammonia from natural gas with green ammonia.

In the age-old debate between fossil fuels and renewable energies, there are fewer and fewer arguments against the latter. [4] Although there are several misconceptions surrounding renewable energies, one of their main drawbacks is their reliance on natural elements. Before, if there was no wind, there was no wind power. If it was night-time, there was no solar power.

In the absence of being able to compel the sun to shine at night or summon winds that propel the blades of windmills at our will, efforts are focused on finding a suitable tool that allows excess energy generated by good weather conditions to be stored so that it can be used for when conditions are less favourable.

Green hydrogen is obtained from renewable sources through electrolysis. Well, we can store this clean hydrogen compressed in specific tanks. And later, when we need energy, this element is channelled into a fuel cell, where we combine hydrogen with oxygen from the air to produce electricity and the only by-product produced is water.

References:

1. https://www.iberdrola.com/sustainability/green-hydrogen
2. https://group.bureauveritas.com/magazine/supporting-shift-toward-green-hydrogen
3. https://www.weforum.org/agenda/2021/12/what-is-green-hydrogen-expert-explains-benefits/
4. https://www.activesustainability.com/sustainable-development/what-is-green-hydrogen-used-for/?_adin=02021864894

Cite this article:

Vinotha D (2022), The Review of the Green Hydrogen Technology, AnaTechMaz, pp.209