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Hydrogen explained: what is hydrogen and how can it support net zero?

Hydrogen has been touted for many years as a key option for decarbonisation – yet it’s used only at a tiny scale. Now, though, it’s attracting fresh interest as part of the global journey to net zero. So what is hydrogen, and how could it develop in future?

Learn about the Hydrogen Colour Swatch

What is hydrogen?

Hydrogen is a colourless gas which is highly reactive and burns readily in air. Because of this, its potential as an energy source has long been recognised. Its greatest attraction is that you can burn it without emitting any carbon or greenhouse gases (GHGs) at the point of use.

Hydrogen can also be used in a “fuel cell” to convert its energy into electricity. In either case, the only waste product is water so, in this sense, hydrogen energy is clean energy.

For this reason, hydrogen is attracting attention as a possible long-term part of the sustainable energy mix – and is likely to be part of the journey to net zero for many organisations in future.

What are the challenges of using hydrogen?

Hydrogen is one of the most abundant elements in the universe – but ironically, because of its reactivity, there are almost no abundant natural sources of pure hydrogen found on Earth. So a challenge is that hydrogen has to be manufactured from compounds which contain it, such as methane and water.

Unfortunately, this uses energy intensively and, in most current hydrogen production, results in carbon and GHG emissions.

So, while hydrogen is a clean energy when burned by itself, the “lifecycle emissions” of producing hydrogen are a major challenge – notwithstanding other issues such as expense, safety and the availability of infrastructure.

Can we produce hydrogen without carbon emissions? 

There are many ways to produce hydrogen, and some are more carbon-emitting than others. With many processes available, the industry informally gives each one a “colour code”.

Of course, the hydrogen produced is still a colourless gas, so the names of the processes have nothing to do with the colour of the hydrogen itself; nor are there universally agreed definition for the colours used. These are the three most commonly seen:

Grey hydrogen
Grey hydrogen
The main process of creating hydrogen today is steam methane reformation (SMR), known as “grey hydrogen”. This process combines steam and methane at a high temperature to create hydrogen – but unfortunately, the chemical reaction releases carbon dioxide (CO2) as a waste product, so this process cannot be considered low-carbon.
Blue hydrogen
Blue hydrogen
This process uses the same method as grey hydrogen, with one significant adaptation: the CO₂ emissions are captured, stored and used. The idea is that this reduces the carbon emissions on a lifecycle basis.
Green hydrogen
Green hydrogen
“Green hydrogen” is a more environmentally friendly production method. In this process, hydrogen is produced by electrolysis of water – in other words, you use electricity to split water (H20) into hydrogen and oxygen. If the energy used to power this process is renewable, then the green hydrogen is emission-free.

There are other possible ways to produce hydrogen. For example, in November 2021 Centrica took a minority stake in HiiROC, a company whose hydrogen technology converts methane into hydrogen and carbon black (a solid form of carbon). This turquoise hydrogen technology has a comparable cost to grey hydrogen, without the emissions.


How widely used are blue and green hydrogen?

Unfortunately, according to the UK Hydrogen Strategy published in August 2021, there is “almost no low-carbon production of hydrogen in the UK or globally today”. Yet that’s not to say that things will stay that way, because hydrogen does have the potential to be part of the shift to a sustainable energy system.

In its strategy, the UK government says it wants to see the decarbonisation of hydrogen supply, with 5GW of low-carbon hydrogen production capacity by 2030. It admits that this means a “rapid and significant scale-up” of low-carbon hydrogen production.

The UK government also says it will follow a “twin-track” approach to hydrogen production – in other words, supporting both blue and green hydrogen at the same time. The idea is to build the hydrogen economy by supporting blue hydrogen in the 2020s, providing “lead-in time” for green hydrogen from the 2030s onwards.

In the EU, meanwhile, the European Clean Hydrogen Alliance is also supporting investments in clean hydrogen.

What about hydrogen infrastructure?

Hydrogen, like natural gas, is highly flammable, so it has to be produced, stored and transported safely. Currently there is little hydrogen-specific energy infrastructure, which would be necessary if the hydrogen economy is to develop. Infrastructure requirements mean hydrogen technology is challenging to roll out at scale.

At the moment, work is under way to convert iron gas distribution pipelines to plastic, which will support their use to carry hydrogen. Hydrogen can be blended with natural gas and transported in existing plastic pipelines.

We’re part of a project to support the National Grid in establishing methods for injecting green hydrogen into the National Transmission System (NTS), the UK’s national network of transmission gas pipelines. This project is part of work to understand what’s needed to set up a “connections process” for injecting green hydrogen into the gas transmission system.

We’ve also joined the Hydrogen Taskforce, which has provided evidence to the UK government on how hydrogen can support the UK’s economic recovery after Covid-19. 

What is the potential of hydrogen for organisations?

Many large organisations are, of course, thinking seriously about how to decarbonise and move forward to net zero – and in the medium to long term, hydrogen looks set to be part of that mix. Hydrogen technology is at least part of government thinking.

Making hydrogen a part of your long-term Energy Pathway planning is important. It means you will be ready to take advantage of hydrogen technologies when they become commercially available at scale, and harness this new approach to fully decarbonise.

To discuss your net zero strategy and how hydrogen and other innovative new technologies could provide a pathway to decarbonisation, speak to our expert team.

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