The role of hydrogen in achieving Net Zero

TRL's submission to UK Parliament Science and Technology Committee on the Role of hydrogen in achieving Net Zero

Published on 08 February 2021

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The House of Commons Science and Technology Committee invited responses to an inquiry into the role of hydrogen in achieving Net Zero. TRL’s response, summarised here, is focussed around the role of hydrogen in achieving Net Zero in transportation.

We believe that Government’s plans are fundamentally flawed in two respects:

  1. The scale of low carbon hydrogen production suggested (5GW) is insufficient and will hardly cover the needs of road haulage alone.
  2. The funding allocated (£240m) is inadequate to cater for all hydrogen uses in industry, heating and transport.

To decarbonise the whole energy system in the UK needs more ambitious targets.

We recommend the creation of a National Centre for Hydrogen, coordinating research and development efforts with the likes of the H2FC Supergen and the UK National Hydrogen Transport Centre, as well as advising central government on hydrogen policy matters. The centre could also be used to stimulate opportunities for UK businesses operating in this sector.

Carbon capture storage (CCS)

We believe it is unfeasible to generate the amounts of hydrogen needed for transport by 2030-2040 without CCS. The main policy target that justifies the use of hydrogen is the reduction of greenhouse gas emissions. Low carbon hydrogen can be generated via a broad range of pathways - including SMR and coal gasification in combination with CCS. CCS is a necessary step until countries can generate enough low carbon hydrogen at scale for it to become low-cost hydrogen. This is unlikely to happen for a couple of decades, hence the dependence on CCS is fully justified, if we want to meet the decarbonisation objectives.

Hydrogen trials

TRL has been involved in Innovate UK’s “Low Emission Freight Trials”, monitoring and evaluating the performance of dual-fuel hydrogen-diesel internal combustion engine heavy goods vehicles. The outcome of the trial indicated that the technology needed further investment to move up to the next technology readiness level. The trials also highlighted the need to include the upstream supply chain when designing such trials, as availability of suitable fleets was as much an issue as availability of hydrogen.

A follow-on trial is planned for 2021 with potential for assessing heavy goods vehicles based on hydrogen fuel cells, solid oxide fuel cells, battery electric powertrains with hydrogen range extenders and dual-fuel biomethane-green hydrogen internal combustion engines. We recommend that this “Zero Emissions Road Freight Trial” should include hydrogen transport refrigeration units, as the transport of food represents ~4% of the GHG from transport. It is not realistic to power a heavy duty trucks with batteries and expect those to power frozen multi-temperature trailers (e.g. 10 kW ~ 4L diesel equivalent/hr). However, hydrogen can work.

TRL suggests that future trials should be planned in rail, shipping and aviation to also include refuelling systems for hydrogen, liquid organic hydrogen carriers, and ammonia supply chains.

In the transitional period of decarbonising transport, while we expect fuel cells to reach cost parity by 2030 (or sooner), it is our view that alternative hydrogen powertrains (e.g. dual fuel) can still play a useful role. These can help to build the skills and knowledge required, improve the maturity of the supply chain and to accelerate cost reductions as a result of the economies of scale.

In evaluating the performance of options, TRL recommends that a standard method of calculating carbon intensity factors for hydrogen energy pathways should be adopted. Using a “well-to-wheel basis” yields realistic emission factors for each transport mode, whereas using BEIS emission factors fails to recognise that the transport sector may have different hydrogen supply chains.

The commercial challenge associated with using hydrogen as a fuel

Low carbon hydrogen is still too expensive (via electrolysis) compared to fossil fuels (as the negative externalities are not internalised). To encourage the use of green hydrogen, TRL strongly proposes the development of a standard for guarantees of origin, and policy development for international trading.


We predict procuring significant levels of low carbon hydrogen for use in the UK will require the import of hydrogen from countries with much lower production costs (e.g. electrolytic H2 from the South of Spain, Saharan Africa or even Middle East). The impact of importing hydrogen is that UK port terminals will need to be converted from natural gas to hydrogen and hydrogen carriers, and the safety of salt caverns will have to be certified. We know that transport requires higher quality hydrogen than the one used on the gas network. It would be possible, but inefficient to purify all hydrogen. Therefore, we are certain that new infrastructure will be necessary to increase the purity and supply pressure of hydrogen for its use in transport. Research is urgently needed to evaluate the most efficient point in the supply chain for this purification process (centralised vs distributed treatment).

Prioritising hydrogen applications

It is a fact that catenary and battery electric powertrains are more energy efficient than the ones powered by hydrogen and fuel cells. However, due to the characteristics of the UK energy system, it is not possible to electrify heating, industry and transport simultaneously. With regards to transportation, TRL therefore recommends that hydrogen should be prioritised in those transport modes where batteries can impose a penalty on occupancy factors or payload (e.g. rail freight, long-distance passenger rail, aviation, long-haul heavy goods vehicles).


TRL also provided a simple SWOT analysis of hydrogen and fuel cells in transport compared to battery electrification.


  • Long range (even longer when hydrogen is liquified)
  • Fast refuelling time (even faster at higher pressure)
  • Lower impact on payloads (e.g. a battery electric freight locomotive can weigh 250t while a FC one weighs around 30t)
  • Contributes to provide energy flexibility (multiple zero carbon energy pathways and feedstocks avoids the electricity generation capacity constraint – SMR / gasification / electro-fuels)
  • Contributes to improve the resilience of the grid (hydrogen can be stored for long time and use for providing different services to the power sector – e.g. energy balancing, avoiding curtailment, etc.)
  • Contributes to improve the security of the energy system (multiple generation pathways to reduce geopolitical dependency on oil producing countries)
  • Similar user experience as conventional cars


  • Higher procurement costs than BEV, until 2030
  • Poorer refuelling infrastructure than incumbents and higher capital costs refuelling stations
  • Lower WTW energy efficiency than BEV
  • Storage of liquid hydrogen produces boiling-off (up to 1% leakages daily). Recovery is recommended when possible


  • With economies of scale, total costs of ownership potentially cheaper than the other powertrain technologies.
  • New guidelines allowing co-location HRS with conventional pumps will decrease capital costs
  • New catalysts could improve systems efficiency.
  • New storage vectors could result in higher volumetric energy densities
  • Possibility to improve instant torque
  • Potential to improve power density fuel cells
  • Role of different FC types such as SOFC in combination with biofuels (e.g. biomethane)
  • Decisive role to support the development of a UK green industrial strategy
  • Potential synergies with other energy systems (heating, industry and power sectors).
  • Soft transition pathway for oil companies to reduce reliance on fossil fuels
  • Inclusion of hydrogen as a renewable fuel of non-biological origin in the Renewable Transport Fuel Certificates
  • Possibility for a market for Guarantees of Origin for green hydrogen and an enables for vehicle-to-grid technologies


  • Breakthroughs from battery technology innovation could make FC technology obsolete (and vice-versa)
  • As other electric road vehicles, the taxation system needs to be adapted to cover for the lack of revenue for the exchequer
  • NIMBY attitudes towards HRS deployment and customers’ acceptance of hydrogen as a fuel for transportation (safety)
  • Lack of harmonisation of green hydrogen standards and potential misalignment between UK and EU
  • Production of hydrogen at large scale require fossil fuels and CCS in the short-term to yield low GHG emissions
  • Inefficient delivery and transformation systems (liquefaction, transportation)
  • Except electrolysis, most production pathways require complex filtration/purification systems
  • Production costs of green hydrogen are expensive
  • Lack of UK natural reserves of platinum and other critical materials (most platinum reserves are in South Africa)
  • Due to slow reaction time of FC, FCEV still require batteries (relatively small)
  • Need for worldwide harmonisation of quality, safety and engineering standards (e.g. nozzle shapes, etc.)
  • To power the transport sector we need CCS and imports



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