Comment: Deploying hydrogen as an alternative fuel for net zero

There are several approaches currently being investigated to decarbonise power, heating and transport in the UK to meet net zero targets. One of these, highlighted in the UK government’s 10-Point Plan for a Green Recovery and the 2020 Energy White Paper, is using hydrogen as an alternative fuel source for generating power, decarbonising heat by transitioning from natural gas, and for decarbonising part of the transport sector by creating new infrastructure to support vehicles powered by fuel cells, rather than combustion engines. Subsequently, detailed plans and targets were released within the government’s 2021 UK Hydrogen Strategy.

To achieve the ambitions outlined within the UK Hydrogen Strategy, innovation at pace and scale is required across the economy to support new and emerging industries and technologies and to support well established industries, with a transition from traditional business practices and procedures.

The government has ambitions to grow UK supply chains for “Green Technologies”, reducing the UK’s dependency on imported goods and services and leading to a further reduction of our environmental impact, simultaneously strengthening the economy by creating export opportunities in an emerging global market. Standards play a key role in support of this activity. They are used to optimise the development of products and services and can provide confidence to end-users and investors.  Furthermore, UK organisations need to be involved in the development of standards to ensure the interests of these companies are represented and protected in a global market.

Well-established industries, currently using natural gas as part of their production or operational processes, or transmitting, distributing, and storing natural gas throughout the country for heating, are investigating how to transition from natural gas to hydrogen safely, efficiently, and with minimal disruption to their businesses and customers.  Again, standards play a key role in support of this activity - providing confidence in infrastructure material suitability, and developing future methods for monitoring, reporting and controlling loss of containment.

The era for fuel cell vehicles, and how standards support their development and adoption.

There are various scenarios to consider when we talk about “vehicles”.  There are road, rail, aviation and maritime vehicles, to name a few.  The majority of these categories have subcategories also, each of which have unique characteristics and requirements. For example, focusing on aviation vehicles or planes, a vast amount of power is required for take-off but less power is needed when cruising. Therefore, industry experts have deduced that hybrid engines may be the most suitable way to decarbonise the aviation sector using hydrogen, focussing on specific flight types. For road vehicles, most UK drivers use their vehicles for short trips like commuting, which are more than achievable with a full or even partly charged electric vehicle battery. The occasional long-distance journey with a longer stop to recharge isn’t considered too disruptive in the grand scheme of things. However, heavy goods vehicles that are required to travel long distances with short stops to refuel need to be able to travel further on a single tank and, therefore, any fuel they transition too needs a high power density, with methods to refuel similar to those in use now.

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In the UK, there is a lot of ongoing work investigating which technology is most suited to which application and it’s becoming evident that the optimum scenario will be a combination of technologies rather than any individual one, for the aforementioned reasons.

Present day thinking suggests that hydrogen fuel cells have a role to play for HGVs, other heavy duty vehicle types and fleets; however, to support wide-scale roll-out and adoption of hydrogen fuel cell vehicles, refuelling infrastructure will be required across the UK.  This creates unique issues as hydrogen fuel cell vehicles face different challenges to those powered by internal combustion engines. The quality of hydrogen, and in particular the impurities that are present due to production methods and operational equipment, can have a serious impact on the health or lifecycle of the fuel cell. Therefore, quality assurance and quality compliance frameworks that utilise measurement standards are needed to underpin refuelling station infrastructure - to protect consumers. 

Laboratories like NPL are crucial players in specifying purity levels for fuel cell vehicles, providing an accredited hydrogen purity measurement service which enables hydrogen refuelling stations to comply with the international standard ISO 14687 Grade D. This specification provides amount fraction thresholds for 13 impurities at the ppb to ppm level. Together with international collaborators, we are making an important ongoing contribution to revision of this standard via automotive fuel cell stack testing, with the ultimate aim of minimising costs through reduction in unnecessary conservatism in purification requirements.

A novel device for concentrating the impurities in a sample of hydrogen before performing purity analysis has also been developed at the laboratory which allows much lower amount fractions to be measured using routine techniques, simplifying and speeding up purity analysis where the need for quality and efficiency is increasingly in demand at lower cost. In order to rapidly identify purity issues in hydrogen refuelling stations, we have been developing an online hydrogen quality sensor which allows operators to take swift remedial action.

These are just a few examples of activities which are vital to scale the roll-out of such technologies, to avoid premature ageing of fuel cells, or in the worse-case; catastrophic failures, which could stop the adoption of such technologies in its tracks.

Ben Rowton, strategic business manager at the National Physical Laboratory