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Hydrogen Explainer: ‘What’s all the fuss about?’

Hydrogen technology has secured increasing support from both government and the private sector alike. But what is it all about? 

Hydrogen is said to be ‘the next big thing’, touted as the fuel of the future for homes and heavy industry alike. It has great potential for high-temperature processes such as ceramic and cement production, for example, can be injected directly into the existing gas grid and used to power heavy vehicles. Hydrogen is also one of the few feasible options for zero-carbon aviation, either burning it directly in a jet engine or using it in a fuel cell to power a propeller. 

As it can be produced using solar power- dubbed yellow hydrogen – the technology is something that developers should at least key an eye on. 

However, critics such as the think tank E3G consider that cost and practicalities will preclude hydrogen from ever entering widespread use. It found last year that using ‘green hydrogen’ (see below) to keep our homes warm implies a 30-fold increase in offshore wind power deployment. Plans to expand hydrogen production have also been described as little more than a way to keep fossil fuels on life support, by manufacturing it from natural gas. 

As highlighted in an Imperial College report earlier in the year, injecting hydrogen into natural gas infrastructure would also mean having to retrofit vast lengths of old steel gas pipes, air pollution from nitrogen oxides, the need for huge hydrogen stores, safety risks – and consequently enormous costs. 

Hydrogen’s use in vehicles has not taken off either, partly due to electric battery technologies improving so quickly and the lack of refuelling stations. 

Nevertheless, the government is still enthusiastic about hydrogen in industry, having recently doubled targets for the sector that it put forward only last year. The technology is central to projects supported by £171m of government funding for industrial decarbonisation, on top of a further £240m Net Zero Hydrogen Fund and £250m for clean steel production. 

Last August’s Hydrogen Strategy set a target to have five gigawatts of low-carbon hydrogen production capacity by 2030, explaining that this is equivalent to the natural gas consumed by more than three million households each year. “We are aware of a potential pipeline of over 15GW of projects, from large scale [carbon capture]-enabled production plants in our industrial heartlands, to wind or solar powered electrolysers in every corner of the UK,” it states. 

The passage was one of the few mentions of solar power in the strategy, which assumed that natural gas would remain cheap and therefore dominate the sector. Then Vladimir Putin intervened. 

The British Energy Security Strategy, written in response to the Russian invasion of Ukraine, was rather more even handed. It doubled the earlier strategy’s objective to 10GW by 2030, setting an ambition for at least half of that of that to be from electrolysis. It added that up to a gigawatt of green hydrogen capacity should be operational or under construction by 2025. 

The hydrogen rainbow 

Hydrogen is currently used almost entirely in refineries and for the production of chemicals, manufactured on site from natural gas – a process known as grey hydrogen. This releases one molecule of carbon dioxide for every two molecules of hydrogen, so is an inherently unsustainable process.  

There is an entire rainbow of other colours used to describe other methods, which vary in their practicality and state of development. 

  • Blue hydrogen: The same as grey hydrogen, but with its associated CO2 emissions captured and stored. Billions of pounds are going into plans to build CO2 transport pipelines and storage systems offshore. 
  • Green hydrogen: Electrolysis is the cleanest but – as things stand at least – the most expensive method of production. Renewably produced electricity is passed through water, releasing hydrogen at one terminal and oxygen at the other. Electrolyser technology is improving rapidly, in terms of efficiency, cost and scale, in much the same way that renewable energy has over recent decades. 
  • Yellow hydrogen: Green hydrogen from solar power. There are already some projects in the pipeline in the UK. For example, EDF is planning to use its proposed 49.9MW Tees Solar Farm near Redcar, combined with an offshore wind farm, to power an electrolyser system of 30-50MW capacity. It could scale up to 500MW as demand grows. There is also experimental technology that can produce hydrogen directly from water and sunlight, bypassing the need for electrolysers. 
  • Pink hydrogen: Hydrogen from nuclear-powered electrolysis. 
  • Turquoise hydrogen: Like grey and blue hydrogen, this also uses natural gas. But it instead passes it through a molten metal, resulting in hydrogen with solid carbon as a by-product. For now, this is a purely theoretical process. 
  • White hydrogen: Hydrogen obtained through drilling, in the same manner as oil or natural gas. It may not be economically viable. 
  • Black hydrogen: Made from the gasification of coal, similar to how ‘town gas’ was made before natural gas from the North Sea replaced it.