Hydrogen is often touted as the future of green industry, heating and fuels. It certainly has the capability to be just that, but there are many hurdles along the way to be overcome.  

In truth, while there are many methods to produce hydrogen, only four could potentially reach carbon zero.

The methods of hydrogen production give rise to the hydrogen rainbow: 

1. Black and brown hydrogen are produced from different types of coal by gasification -this is the dirtiest form of hydrogen production
2. Grey hydrogen is produced from natural gas using steam reformation. At present this is the most common type of hydrogen production, but carbon dioxide is produced as a biproduct
3. Blue hydrogen is a variant of grey hydrogen, but importantly the process includes carbon capture systems (“CCS”) to catch and store any carbon dioxide produced
4. Green hydrogen is the holy grail of sustainable hydrogen production. It is produced by electrolysing water using clean sources of energy. No carbon dioxide is produced at any stage of the process

Beyond these basic colours the kaleidoscope becomes more specific and includes pink (produced using nuclear power), turquoise (produced by a new technique called methane pyrolysis which produces solid carbon as a by-product), yellow (produced by electrolysis using solar power) and white (naturally occurring geological hydrogen).

As we can see  from the rainbow of colours, it is critical to know how that hydrogen is being produced to understand just how sustainable and environmentally friendly the hydrogen really is. Thus, while pink and blue hydrogen could become carbon zero, either the CCS technology would have to be absolutely perfect (in the case of blue) or we would have to live with the other problems that nuclear power creates (in the case of pink).

The focus of hydrogen production is generally green hydrogen (yellow being a relatively new technology). The problem facing green hydrogen production is that it is an energy intense process, and we simply do not have sufficient renewable energy at the moment.  

The World Bank has estimated that by 2050 the demand for hydrogen will reach between 500 to 680 million metric tonnes per year. Producing this quantity of green hydrogen would require around 22,000 TWh (22 PWh) of green energy. To put this in context, annual worldwide renewable energy generation in 2021 was around 8,300 TWh, with few if any green hydrogen facilities operating at significant scale.  

The challenge ahead is how to generate three times as much green energy (without considering everything else that we need this for) in the next 27 years, and how to store it so that production can continue when the sun is not shining and the wind is not blowing.  

Longer term perhaps hydrogen fusion will provide some answers, though even with recent announcements from the National Ignition Facility in California and the completion of ITER in the next few years, this still seems some long way off. In the short term, therefore, we must look to our current technologies. This may include deep water wind turbines and greater use of other technologies such as tidal power. 

Irrespective of how it is produced, it’sclear that there needs to be a significant increase in the amount of green power available. Shaping the development of this infrastructure will be one of the biggest challenges in ensuring hydrogen’s potential is fully realised.