Times are changing: hydrogen energy

Dr Jenifer Baxter examines the changing conversation around hydrogen and climate change.

The concept of using hydrogen as an energy vector is not a new one, in fact, as far back as 1839, Welsh judge and physical scientist Sir William Grove invented the ‘gas battery’, the first fuel cell. Jules Verne in his novel of 1874, 'Mysterious Island' put forward the idea that water split into its component parts would someday replace coal in steamers and locomotives and provide enormous calorific value.

Since the 19^th century the concepts and innovations around hydrogen for transport, heat and power have continued to develop, but have not been able to oust the incumbent fossil based system. Another factor that was not such a concern to these trailblazers is that we also know that hydrogen does not give off greenhouse gas emissions at the point of use.

Moving swiftly through time to 2019, we are now living in a time of Greta Thunberg, the IPPC’s 5^th Assessment report and Extinction Rebellion; the climate change bug has finally bitten and our communities are waking up to the challenges a globally warmer future will present. Here in the UK, there has been, within the last 12 months, a dramatic shift in the way governments in the UK and globally are talking about hydrogen and its potential to help solve some of our challenges around providing energy in a low carbon environment.

In May of this year, the Committee on Climate Change (CCC) reviewed the carbon targets for the U.K, concluding that we could and should aim for net zero carbon dioxide equivalent emissions by 2050 and this was committed to law in the UK in June. As part of the CCC’s scenarios to achieve net zero, hydrogen plays a big part in transport, industry, back up electricity generation and potentially heating on the coldest days, although I am not clear on how that final part would work. Starting now, the CCC have suggested that we begin large scale hydrogen production using carbon capture and storage and that means using natural gas aka methane CH₄.

Hot on the CCC’s heels we heard from National Grid who recently released their scenarios stating that net zero emissions would be possible, but would require immediate action across key technologies including hydrogen. They state that the gas system will need to be transformed to accommodate hydrogen and that gas appliances will need to be developed as hydrogen ready. Further to these two reports we also heard from the International Energy Agency (IEA) in June who stated that in order to realise hydrogen’s potential  and for it to make a significant contribution, it needs to be adopted in sectors where it is almost completely absent, such as heat, power and transport. Now this is where the story of hydrogen gets interesting and where we need a touch of a reality check about what all of these pathways, scenarios and solutions to decarbonisation mean.

Let’s look at the evidence, in the graph below produced by the IEA, we can see the challenge ahead.

Globally we are currently producing just shy of 75Mtons of hydrogen annually. It is currently all used in refining and ammonia production, with a very small amount classed as ‘other’, which includes electronics, food production and manufacturing as well as heat, power, transport. Helpfully the National Grid in their scenarios tell us that looking at heating alone in the U.K, in 2018 we used 805TWh, today we produce 0.7Mt of hydrogen in the UK, which is approximately 27TWh [i] >, somewhat short of the requirement and almost none of which is currently available for this use.

This may seem like a stark truth, but it is certainly not the end of the story. We can deliver this new world where a hydrogen economy is a reality and not simply the speculation of novels and demonstration projects, but delivers a decarbonised future that will not have our children taking to the streets in fear of their futures. However, we will have to make policy commitments, government and industry investments, build new infrastructure now and begin the process of saying yes this is our future.

Hydrogen offers us another positive, there are lots of ways to produce it. Mostly we hear about steam methane reforming using carbon capture and storage (CCS), for a start just using CCS would be new. Currently we do not use CCS and that means that the autothermal reformed CO₂ is released to atmosphere making the current production of hydrogen no better than using methane as a solution and less efficient. This means CCS infrastructure is critical to this future.

The next most commonly discussed hydrogen production method is electrolysis of brine or water; this is currently a fraction of hydrogen produced. It uses electricity to split water and will need a massive investment to grow the sector and improve the efficiency of electrolysers. The following are a list of other production techniques, some greener than others[ii]:

• Hydrogen as a by-product of chlorine, electrolysis of salty water, needs a lot of electricity, similar to iron or steel manufacture (maybe low carbon using nuclear power)
• Hydrogen produced at refineries through desulfurisation (not so green)
• Gasification of wastes, coverts organic matter to syngas (good use of wastes, requires CCS)
• Dark fermentation, anaerobic digestion in the absence of light producing hydrogen gas (greener)
• Thermochemical hydrogen production splitting water using heat from solar or nuclear power (green, low carbon)
• Hydrogen production by nuclear fission, hydrogen and oxygen gas formed by radiolytic dissociation of water (low carbon)

What these methods tell us is that like methane gas, there are many ways to produce this energy vector and we shouldn’t become too focused on one pathway. Specifically by locking into a natural gas pathway for autothermal/ steam reforming we will have to ensure we always have access to the natural gas feedstock, which in itself comes with GHG emissions associated with the extraction, storage and transportation.

The next 10 years are going to require a serious commitment from our big energy companies, our governments and energy end users to create an environment where a hydrogen economy can thrive and where real reductions in GHG emissions are made up and down stream of our heat, power and transport system.