Why Hydrogen?

Tommy Isaac introduces a series on the opportunities and challenges

THE cheap, abundant and seemingly limitless energy supply of the 20th Century driven by fossil fuel consumption led to unprecedented economic growth and improvements in quality of life. But much like financial debt, the long-term cost will ultimately be higher than the short-term gain. Society has reaped the short-term benefits of fossil fuel consumption and the environmental bailiffs are now at the door.

Hydrogen offers a unique cross-system opportunity for fundamental change in the energy landscape. This series of articles will provide an overview of the opportunities and challenges facing hydrogen development and deployment. The potential benefits that adoption of hydrogen would accrue to the climate cause and energy customers will be discussed, as well as the barriers which must be overcome to achieve such deployment. All technical assessments will be framed within the context of the UK energy markets (power, heating and transport) given the maturity of the UK energy markets as well as the legally-binding carbon emissions targets set by the UK Government.

The challenge

Decarbonising the global economy is the largest challenge humanity currently faces, as the existential crisis of climate change becomes ever more present and violent. The cultural revolution taking place which is redefining the relationship between humanity and our environment will come to shape the trajectory of social development over the course of the 21st Century. As societal attitudes adapt and change, the transition from fossil fuel driven economies to environmentally sustainable economic models will provide new opportunities and economic benefits for those who have the courage to act now and grasp the first-mover advantage.

Like every great challenge facing humanity, environmental sustainability seems insurmountable when viewed from the perspective of the status quo. However, there is no alternative – maintaining the status quo is to knowingly continue to build the structure of society out of materials borrowed from its own foundations whilst wishing for calm winds.

Decarbonisation options

There are three options by which the world can decarbonise the global economy and meet the Paris targets of maintaining average temperature rises below 1.5^oC relative to pre-industrial times, or to push beyond that reduction to the recent IPCC assessment of net zero emissions by 2050. The three options are: reduce energy demand; capture carbon dioxide following fossil fuel combustion; and reduce the carbon intensity of energy.

Within each of these options lies a spectrum of technological avenues to policy makers and the exact balance of vectors will be country specific, determined ultimately by ease of use and minimum cost to customers. Taking each of these options in turn will allow a pragmatic conclusion to be drawn on the relative significance of each option.

Option 1 involves technological development in the form of efficiency gains and cultural change in the form of reducing absolute demand. Both of these strategies are, and will remain, important contributors in reducing carbon emissions; however, scale is the issue here. Carbon reductions on the scale required to achieve an 80% reduction by 2050 relative to 1990 simply cannot be achieved using this option without previously unseen technological advances and currently unacceptable disruptive changes to consumer lifestyles.

Although wind and solar power have been transformative to date in decarbonising electricity, extending that logic to the other energy vectors of gas and oil (heating and transport) does not stack up when taking a system approach

If option 2 is to be the dominant technology vector, this world view would be contingent on connecting every household’s gas boiler flue, industrial flue stack, gas turbine and moving vehicle in the UK to CCS infrastructure. This is self-evidently not practical nor politically acceptable. Post-combustion CCS will likely play a role, especially where easily isolatable streams of significant carbon dioxide volumes are ready for capture, such as during the production of fertilisers. However, post-combustion CCS is unlikely to be a universal solution.

This leaves us with option 3 - reducing the carbon intensity of energy by replacing fossil fuel usage with low carbon sources. This strategy is the least disruptive option from the perspective of the consumer and is achievable with current technologies given the maturity of the necessary technologies in other industries other than energy supply. The primary barrier to fully realising the opportunity of this strategy has been a clear and cohesive national plan with the necessary regulatory mechanisms to allow private investment and market-driven solutions.

Option 3 has been the dominant strategy to date via the electricity market by replacing coal fire stations with gas, biomass, wind and solar. This strategy has achieved a 50% reduction in the carbon intensity of electricity from 2013 to 2017.¹

Why Hydrogen

Extending the current decarbonisation approach of electrification across all energy sectors would be, at a minimum, myopic and certainly unfeasible. Although wind and solar power have been transformative to date in decarbonising electricity, extending that logic to the other energy vectors of gas and oil (heating and transport) does not stack up when taking a system approach. As is shown in Figures 1 and 2, the UK’s electricity demand is the smallest of the three, annual transport demand is 1.4 times electricity, and heat is 2.7 times electricity. Therefore, to electrify these demands with intermittent electrical supply would be predicated on building generation,  transmission and distribution assets equating to four more grids along with industrial levels of battery deployment to transfer summer power to winter heat.

All considerations are then exacerbated when viewing the problem from the perspective of the current level of resilience required within the gas network which must cater for the 6 minute 1-in-20-year heating demand, and then factoring daily travel patterns regarding electric vehicle charging peaks.

Clearly, low carbon electricity has a natural economic ceiling to its deployment. The question therefore turns to alternative energy vectors to lower the carbon intensity of heating and transport in an economically and politically acceptable way. The two options for reducing the carbon intensity of energy supplies alongside electrification are: renewable hydrocarbon sources such as biomethane and liquid biofuels; and hydrogen.

Biomethane and liquid biofuels are important vectors within the energy landscape as they offer sources of fuel which promote a closed system of carbon. They are limited, however, to the availability of sustainable feedstocks. For example, biomethane based on domestic feedstocks could contribute 100 TWh/y, which represents around a third of domestic gas demand.² This is significant. However, other complementary sources will be required, given that total UK natural gas demand is up to around 1,000 TWh/y.³ Hydrogen is not feedstock limited as it can be produced from a variety of sources and can potentially unlock negative emissions. Therefore, it has the potential to play a very significant role as a vector to reduce the carbon intensity of energy.

Heat

Displacement of natural gas for the purposes of heating is the principal opportunity that hydrogen represents. Heating accounts for almost half of all emissions in the UK⁴, therefore tackling this source of carbon dioxide will be paramount in achieving the legally-binding reductions set by the UK government. Hydrogen deployment within the context of heat could take a variety of forms, from blending in the network, to full conversion of industrial users or even the wider network. The opportunity of hydrogen has been recognised by all gas distribution networks (GDNs) as demonstrated by the number of projects underway. The gas industry has a history of hydrogen, given that it was the single most abundant component in towns gas - the UK’s gas supply prior to the discovery of natural gas beneath the North Sea. It is through demonstration projects such as the HyDeploy project that the hydrogen-for-heat landscape is being carved, setting the technical and regulatory scene for wider adoption and deployment.

Power

Within the electricity market, hydrogen is a symbiotic vector alongside intermediate renewables supplies. Electricity production from hydrogen is a dispatchable generation source which provides mechanical inertia to the grid. The reduction in mechanical inertia of the electricity grid, due to replacement of thermal generation (alternating current) with renewable generation (direct current followed by an inverter), has resulted in increased challenges in maintaining grid frequency, as recognised by National Grid’s EFCC project. A low-carbon thermal generation source has a valuable role in stabilising the electricity grid if intermittent sources are to play the role they are expected to play within the future generation mix. Hydrogen-powered gas turbines or industrial fuel cells would provide the necessary mechanical inertia needed to maintain a stable electricity grid, whilst further reducing electrical energy carbon intensity.

Transport

Transport is a second-order decarbonisation problem – the technical solutions for electricity and gas will provide the infrastructural framework for transport decarbonisation. If electricity is to be the sole form of energy for transport then major investment in dispatchable generation, alongside smart technologies would be required to allow charging of vehicles when required. Hydrogen peaking plants are likely to provide a lower cost and more stabilising vector relative to the counterfactual of industrial batteries. Hydrogen can also be used directly for transport using fuel cells, delivering zero emissions at the point of use.

Building on the adoption of electric drive trains, a hydrogen fuel cell is functionally equivalent to a battery, with associated benefits of range and fill rate following development and deployment. The notion therefore holds that whichever decarbonisation strategy prevails within the transport market,  hydrogen is expected to play a key role.

Production

If hydrogen is to play a central role in the decarbonisation of our energy systems, major investment in production will be required. The importance of hydrogen production technologies has been recognised by the UK Government and has resulted in the £20m Hydrogen Supply Competition.

Production technologies will be covered in more detail within this series, however the most established and suitable processes for bulk production require converting methane to hydrogen and carbon dioxide via steam methane reformation (SMR), or autothermal reformation (ATR). Therefore, deployment of bulk production at the scale required would be contingent on the establishment of CCS infrastructure. Electrolysis with renewable electricity has a role but cannot economically supply bulk hydrogen at the scale required, as demonstrated by Figure 3. In the long run, hydrogen produced via solar-thermal hydrolysis and transported in shipping tankers could provide the ultimate environmentally sustainable model.

Methane conversion coupled with CCS provides a necessary foundational production process which would allow the required regulatory and commercial frameworks to be developed to enable wider deployment.

Deployment strategy

The challenges of hydrogen deployment extend across technological development, commercial models, regulatory support mechanisms and customer perceptions. None of these challenges are insurmountable when considered in isolation, however when aggregated and put within the context of the scale of decarbonisation required, the sum total could seem daunting. It is therefore incumbent to tread the path of least regrets. Projects which de-risk the route map of deployment, for example by removing the need to modify existing appliances and equipment, whilst still representing material carbon savings, should be favoured for early deployment. Adopting this rollout strategy would allow the necessary commercial frameworks and regulatory mechanisms to be established to facilitate deeper deployment whilst minimising the cost of early adoption to consumers.

Cost

Finally, with regards to cost, it would be intellectually dishonest to set expectations that decarbonisation of the economy will not come at a cost compared to the status quo. This is because at present, our energy systems do not properly internalise the cost of the damage caused by carbon emissions. The known reserves of the major oil and gas companies are more than enough to exceed the carbon dioxide requirements to breach the Paris limits. Therefore, decarbonisation is fundamentally a moral decision, not an economic inevitability.

It is the duty of policy makers and informed entities to promote the least-cost pathway, as this will ensure the economic burden does not prohibit the success of the cause. Hydrogen is a key element of that pathway. The deployment of hydrogen can be achieved with known technologies in a way that maximises the utilisation of existing assets, principally the gas network, whilst enabling deeper deployment of other low-carbon technologies.

Through the course of this article series the opportunity that hydrogen presents, as well as the challenges facing its deployment, will be presented, to inform debate and drive evidence-based conversations.

References

1. National Grid, Future Energy Scenarios Workbook, 2018

2. https://bit.ly/2TZb1CI

3. BEIS. Supply and consumption of natural gas and colliery methane (DUKES 4.2), July 2018

4. BEIS. Final UK greenhouse gas emissions national statistics: 1990-2016, March 2018

5. BEIS. Electricity fuel uses, generation and supply (DUKES 5.6), July 2018

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This is the first article in a series discussing the challenges and opportunities of the hydrogen economy, developed in partnership with IChemE's Clean Energy Special Interest Group. For more entries visit the series hub.