Last reviewed 30 May 2022

Low-carbon hydrogen will play a crucial role in reducing carbon emissions and meeting net zero targets by the end of this decade, the Government claims. But producing hydrogen as a source of heat and power at scale comes with its own unique challenges, as John Barwise explains in the first part of a two-part article.

The Government is committed to achieving net zero carbon emissions by 2050. This will involve increasing the proportion of electricity coming from renewables and low-carbon nuclear power and a major expansion of energy efficiency. This will go some way to reduce dependency on fossil fuels, but the Government knows this is still not enough to fully decarbonise the energy system.

The Government published the UK’s first hydrogen strategy less than a year ago with a commitment to deliver 5GW by 2030. Since then, it has revised its plans to double hydrogen production capacity to 10GW by 2030 — with longer term projections of delivering up to 35% of UK final energy consumption by 2050.

The added sense of urgency follows recent volatility in global fossil fuel supplies, coupled with rising energy prices that have heightened the UK’s vulnerability to global energy markets and forced the Government to redouble its efforts for more “home grown” energy supply options, including hydrogen.

But building a new hydrogen energy sector at scale is a major undertaking, not least because of the technical complexities of producing low-carbon hydrogen, but also how it will be distributed and what appliances will be capable of using it, as this article explains.

The case for hydrogen

Hydrogen is the most abundant element in the universe and has a high energy content per unit of weight. It is a flexible energy source that can be used to produce heat and power, or it can be stored in fuel cells to provide energy when it is needed. It produces zero carbon emissions at the point of delivery and can also be blended with natural gas to heat homes and for industrial processes.

Hydrogen has played a role in the UK’s energy mix for years, although not always as a “clean” source of power. Town gas, produced by burning coal, contains hydrogen and methane, and was used for street lighting and heating homes until the 1960s, when it was abandoned in favour of cleaner and cheaper natural gas from new reserves in the North Sea.

In a foreword to the Government’s Energy Security Strategy, the prime minister, Boris Johnson, described hydrogen as a “low carbon super fuel of the future” that is “easy to store and ready to use whenever it is needed”.

The Government’s wider ambition is for a fully decarbonised power sector by 2035, with electrification, supported by low-carbon hydrogen, and phasing out all fossil fuels from road transport, home heating and much of industry. Further details of the UK’s energy security strategy can be found here.

In the short term, the plan is to move quickly to develop a strong UK hydrogen economy by 2030, which the Government says will help ensure security of energy supply, unlock over £4 billion of private sector co-investment and create over 9000 high-quality and sustainable jobs.

The challenges

Pure hydrogen (H) is a low-carbon energy carrier, but it doesn't typically exist by itself in nature and must be split from elements that contain it — elements such as water (H2O) or Methane (CH4).

The problem is that it takes more energy to separate hydrogen from other elements than it provides as an energy carrier and costs more to produce than fossil fuels or renewables, although costs are expected to fall over time as deployment expands.

But the big challenge is finding ways to produce hydrogen that avoids releasing excessive carbon emissions during the production process. There’s also concern over fugitive emissions which can add to greenhouse gas emissions: hydrogen in a compressed gas cylinder can lose between 0.12% and 0.24% a day; it can also leak out of pipes and valves during transfer operations.

A more controversial plan is the recent announcement by BEIS secretary Kwasi Kwarteng to classify as natural gas as a “green investment” in a bid to increase North Sea production. This is partly to mitigate risks from volatile fossil fuel markets, but also to support emerging new industries such as hydrogen, but it does raise questions over the Government’s commitment to phase out fossil fuel subsidies.

Colour coding hydrogen

Hydrogen is a colourless gas — colour coding is simply a way of defining the various processes used to make it. Town gas, for example, would be coded “black” or “brown” hydrogen.

  • Grey hydrogen — steam reacts with natural gas to produce hydrogen in a process called steam methane reformation (SMR), but without capturing the carbon dioxide produced in the process. SMR accounts for around 95% of all hydrogen produced today.

  • Blue hydrogen — also uses SMR to produce hydrogen, but the carbon dioxide biproduct is captured in a process known as carbon capture, usage and storage (CCUS).

  • Pink hydrogen — is generated through electrolysis using nuclear power as the energy source to split water into its basic elements, water and hydrogen.

  • Green hydrogen — also uses electrolysis but uses electricity from renewable sources to split water into water and hydrogen.

The Government’s preferred option is for a twin track approach, supporting both electrolytic green hydrogen and blue hydrogen production with carbon capture and storage (CCS).

Two pilot projects have been established to test both blue and green hydrogen systems.

  • H100 Fife — a green hydrogen project aiming to demonstrate hydrogen’s role in decarbonising heat as an alternative to natural gas. H100 Fife will be the first project of its kind to use electricity from offshore wind turbines to power the production of hydrogen gas for domestic heating. The green hydrogen gas network will supply up to 300 households initially but has the capacity to supply up to 900 homes as part of the planned future expansion of the H100 Fife project.

  • Humber Hub Blue Project — a blue hydrogen project from Uniper and Shell who plan to develop a hydrogen hub with up to 720MW of blue hydrogen production and up to 100MW of green hydrogen production at Uniper’s Killingholme site in North Lincolnshire. Uniper is also a partner in the Zero Carbon Humber project, which will deliver a storage network for blue hydrogen which will then be transported to permanent storage offshore in the North Sea.

The Committee on Climate Change (CCC), which advises the Government on energy strategy, says that to meet 2050 net zero commitments, green hydrogen should start replacing blue hydrogen in the 2030s.


  • Hydrogen is the most abundant element in the universe and has a key role to play in achieving net zero carbon emissions.

  • The Government aims to deliver a strong UK hydrogen economy, producing 5GW by 2030.

  • However, it currently takes more energy to separate hydrogen from other elements than it provides.

  • Pilot projects using so-called green and blue hydrogen are in place in Fife and Lincolnshire.