A vital element


The UK Government is committed to reducing our impact on the environment and transforming our energy system to make it cleaner and more affordable, through the Clean Growth Strategy and the 25 Year Environment Plan, as well as collaborating and supporting other countries to reduce their impacts.

Domestic policy commits the UK to achieving net-zero emissions by 2050; these targets are among the most ambitious globally and the next few years will see record investment in clean growth innovation. To meet these objectives, and for energy to become more affordable, clean and secure, a continued shift away from fossil fuels towards renewable energy sources is required, supported by carbon capture, utilization and storage (CCUS) and nuclear power.

Hydrogen will be a key component of any future net-zero carbon scenario for the UK. It has historically experienced cycles of interest within the UK and internationally, but up until now has largely been discounted due to the immaturity and relatively high cost of the technologies in question. This is changing. There is an ever-growing evidence base – of roadmaps, reports, projects and practical infrastructure implementations – demonstrating that hydrogen can play a critical role in the efforts to decarbonize the UK’s energy system.

There is also increasing awareness that while significant decarbonization is possible without hydrogen, it will be very difficult to get to net-zero without it as there are many sectors where hydrogen is likely to be the only zero-emission energy vector capable of replacing fossil fuels without significant increase in cost or loss of utility.

Driven in part by a significant reduction in the cost of offshore wind and partly by government incentives, there has been a huge decrease in CO2 emissions from the electricity sector in the last few years. It is now responsible for just 12 per cent of UK CO2 emissions, compared to 34 per cent in 1990. However, within the UK’s electricity grid system, there is a growing need for grid-scale storage technologies to mitigate the intermittency of renewables and enable the continued transition away from fossil fuels.

Batteries are well suited to grid balancing over short timescales but they are not designed to hold their charge for long periods of time. For longer term storage, hydrogen is a more realistic option and can be produced via electrolysis of water using electricity generated from renewable energy systems during times of high supply/low demand. It can be stored for use during periods of high demand or transferred to the gas grid for distribution and use in other applications.

Attractive option
Despite the progress within the electricity sector, there is still a long way to go in other sectors. Heating and transport are both still heavily dependent on oil and gas and make up the bulk of the other 88 per cent of UK CO2 emissions.

In the UK, 23 million homes are currently dependent on gas for heat, with most of the supply coming from non-renewable natural gas sources. The Committee on Climate Change has estimated that by 2050 around 60 per cent of heat demand in domestic, commercial and industrial applications could come from hydrogen. Hydrogen combusts similarly to the natural gas that is commonly used within homes today so it would not require a change in habits or any major changes to the existing heating system. Unlike natural gas however, hydrogen does not produce CO2 or other pollutants when combusted, only water, making it an attractive option to support decarbonization.

Hydrogen could either be blended with natural gas as a medium-term option or combusted directly. Transporting hydrogen via the gas grid would enable the UK to utilize existing gas infrastructure assets and could reduce the costs associated with electrification of the energy system.

As the UK’s National Metrology Institute, the National Physical Laboratory (NPL) is working with UK gas network operators to assess the feasibility of converting the existing natural gas grid to hydrogen, which would allow coupling of heating and transport applications. NPL is also carrying out cutting edge research to support improvements in performance, lifetime and cost of hydrogen fuel cells and electrolyzers to enable large scale adoption of these technologies.

One potential drawback of hydrogen is that fuel cell performance is sensitive to trace levels of contaminants that can be introduced during hydrogen production, storage and distribution. NPL is working with other European research institutes to quantify the impact of key contaminants on fuel cell stack performance under representative automotive conditions, including fuel recirculation. This important work is feeding into revision of international standards for hydrogen purity in automotive applications, de-risking the business case for investment in hydrogen infrastructure.

Vital role
Sulphur-based odorants used in natural gas are not suitable for use in fuel cells due to their significant poisoning effect. NPL is involved in a number of research programs to screen non-sulphur-based odorants for hydrogen, as well as investigating sources of contamination from the existing gas grid and their impact on fuel cell performance.

Within the transport sector, it is important that we overcome the electric battery versus hydrogen fuel cell battle. These technologies are highly complementary and shouldn’t be seen as competing. Neither technology is able to decarbonize this sector alone. Hydrogen is well suited to heavy duty applications, long distance transport and seasonal storage of energy due to its very low mass and the ability to be stored for longer periods of time.

However, due to their much higher efficiency in converting between chemical and electrical energy, batteries are the most suitable technology for light duty applications over short timescales, including passenger vehicles and short-term grid balancing. It is therefore important that hydrogen is not deployed in these areas unless there are good reasons for doing so, e.g. local availability or use of fleet vehicles. Deployment of batteries and hydrogen according to their respective strengths will minimize the risk of stranded assets in the future.

Like every technology, hydrogen does not have all the answers but it will play a vital role in decarbonization as its flexibility allows it to fill gaps in decarbonization of energy that other technologies cannot reach.

Dr Gareth Hinds is a leading voice on hydrogen technology in the UK and Science Area Leader in Electrochemistry at NPL. NPL is the UK’s National Metrology Institute, providing the measurement capability that underpins the UK’s prosperity and quality of life. Based in Teddington, south-west London, NPL employs over 600 scientists. NPL also has regional bases across the UK, including at the University of Surrey, the University of Strathclyde, the University of Cambridge and the University of Huddersfield’s 3M Buckley Innovation Centre.

For further information please visit: www.npl.co.uk