Trains fit for the future? Contents

4Alternative decarbonisation technologies

63.Network Rail’s TDNS recommended that hydrogen powered trains would be suitable for 6% (900 STK) of the unelectrified network, battery power for 3% (400 STK) and 15% (2,300 STK) for further analysis. In this Chapter we examine in more detail the scope for hydrogen and battery powered trains.


64.Hydrogen is an emerging technology being developed as a zero-carbon power source for use on the rail network, as well as the wider economy. In September 2020, the world’s first hydrogen passenger service train was introduced by Alstom in Austria, on four routes in Lower Austria, Vienna and Styria.86 Within the UK, Porterbrook and the University of Birmingham have developed the HydroFLEX train but it has not yet been introduced into passenger service. Our predecessor Committee visited Porterbrook to observe the HydroFLEX train in September 2019.

Advantages of hydrogen fuel

65.A key benefit of hydrogen fuel is that it is zero-emission at the point of use, given that hydrogen combines with oxygen to produce electricity, heat and water.87 It is quiet and, unlike electrification, it does not require extensive trackside infrastructure.88

66.The Government is keen to encourage the development of hydrogen as an energy source more generally. In November 2020 the Government published The Ten Point Plan for a Green Industrial Revolution89 which set out aspirations to cut emissions in different areas of the economy and secure long-term growth for the whole country. One of the ten points is to drive the growth of low carbon hydrogen, including an ambition to develop five gigawatts of low carbon hydrogen production capacity by 2030, the equivalent of a power station’s output.90 The Ten Point Plan also states that the Government will publish a Hydrogen Strategy in 2021. In September 2020, Julian Critchlow, Director General, Energy Transformation and Clean Growth, told the Environmental Audit Committee that hydrogen will have a big role in decarbonising Transport.91 He said the strategy will contain the “detailed and specific policy levers” required to make the UK “a world-leading hydrogen market.”92

Challenges of hydrogen fuel

67.There are limitations with hydrogen technology in its current state of development. Most notably, hydrogen is not capable of delivering the power required by freight and high-speed train services because of their high energy demand.93 Although hydrogen capability is expected to develop over the next 30 years, many witnesses considered it highly unlikely that the capacity would ever develop sufficiently to power freight and high-speed services.94 The RSSB told us:

Hydrogen has an energy density limitation, which means you cannot generate the power you need to move a freight train at the speeds required across a mixed-use network, or drive trains very fast. That will probably always be the case.95

68.Although hydrogen does not require extensive overhead wires like electrification, the use of hydrogen on the rail network would also require the development of its own supporting infrastructure and a supply chain which the UK does not currently have and would require significant levels of investment.96

69.The production of hydrogen has also been criticised for its environmental impact. Although hydrogen production is widespread, no low-carbon production methods are commonplace due to the high costs involved.97 Currently only 4% of the worlds’ hydrogen supply is produced “greenly” using the process of electrolysis; the rest is generated by heavy industry using coal or natural gas.98 Moreover, the production and use of green hydrogen consumes around three times more energy than conventional electric trains, because a greater amount of energy currently is required for the electrolysis and compression process.99 Hydrogen trains also require batteries to store residual energy and so suffer from some of the same drawbacks we cover in paragraphs 74 to 76 in respect of battery powered trains.100

70.Giving evidence, the Minister for Transport Decarbonisation said that “hydrogen [will play] a massive role in the decarbonisation of transport”.101 She said that the Government was currently working on the practical challenges of producing and commercialising green hydrogen.102

Battery power

71.Battery-powered trains are “electric multiple units and locomotives which carry batteries in order to provide traction power for in-service use.”103 Battery technology is already successfully being used on some parts of the rail network. For example, Vivarail have developed an operational battery train with a range of 60 or more miles between charges and the accompanying charging system.104 Hitachi Rail and Great Western Railway have announced that services between London Paddington and Penzance will be partly powered by battery—this will be the first long distance service in the UK to use battery power.105

Advantages of battery power

72.Similar to hydrogen trains, battery technology is zero emission at the point of use, it can travel on the network without a “contact system” (which eliminates the need for the overhead wires required by electrification) and it is quiet. Battery technology is also a natural complement to electrification—for instance, batteries can easily be incorporated on electric trains and they can charge from the existing electricity infrastructure.106 Batteries also have the added benefit that they can be used to reduce peak electricity load and can work during a power outage.107

Challenges of battery power

73.Similar to hydrogen, we were told that battery technology is not currently capable of delivering the required energy for freight and high-speed services. Angel Trains explained:

At this stage, battery-only trains are not a viable replacement for diesel or electric trains. Based on the current technology available, they would require batteries of 40 times the physical volume of the diesel to provide the same amount of energy.108

74.Batteries also have a significant “embodied carbon value”, meaning lots of carbon is emitted during their production. They are typically made with chemicals from minerals found in Asia, South America and Africa. The extraction of these minerals through mining is often very labour-intensive and requires significant amounts of heavy machinery. Poor working practices have also been reported in some mines, including low pay, long hours, and child labour.109 The minerals are then shipped to the manufacturer, where they are combined through a high energy process and are then shipped to suppliers.110

75.In addition, the disposal of batteries is a high energy process and recycling is complex.111 Current battery life typically ranges from five to 15 years whereas the lifetime of a train can be 30 to 40 years.112 This means that, over the lifetime of a train, the embodied carbon in producing and recycling the battery has to be accounted for several times over.

76.No domestic battery manufacturers are currently based in the UK.113 The UK’s withdrawal from the European Union may also have an impact—under the EU-UK Trade and Cooperation Agreement, rules of origin requirements mean that batteries will need to be sourced from the EU or UK from 2027 to benefit from tariff-free trade between the EU and UK.114

77.We questioned the Department about the potential use of battery-powered trains. The Minister for Transport Decarbonisation recognised the ethical concerns about the production of batteries in some other countries and explained that the Government aimed to develop a domestic battery industry:

The Government set up the Faraday Institution, which is funded with about £374 million. They are developing our own skill set in battery technology [ … ] We are committed to investing in the UK to have a supply of batteries that is ethical, renewable, and sustainable. We are working on sustainability and recycling technology for batteries. I am confident that this industry will develop very quickly. We want to have a “gigafactory” in the UK as well.115

78.We believe that battery and hydrogen technology should play an important part in decarbonising the rail network and should feature prominently in the Department’s long-term decarbonisation rail strategy. New technology should be embraced although we recognise that at present both battery and hydrogen have limitations in that neither can deliver the energy demands required for high-speed rail and freight services.

79.The Department must make the case within Government to ensure that hydrogen trains are fully incorporated within the forthcoming national Hydrogen Strategy. This will help ensure the roll out of this new technology is properly co-ordinated and supported by appropriate infrastructure.

80.In its response to this Report, the Department should provide more information on how it intends, working with other Government departments, to support the growth of a domestic battery industry to ensure this form of technology can be utilised on the railway.

Enabling flexibility for technological advances

81.Some witnesses highlighted the risks of Network Rail and others being too definite about the future power requirements of the rail network, given the likelihood of technological advances during the long implementation timeframe. Alstom told us:

The TDNS sets out to forecast, based on the technology base of today, the end state for the decarbonised UK rail network. Whilst we fully accept the risks of basing forecasts on assumed technological advances, we would be concerned that a strategy set today, based on technologies known today, extending to beyond 2050 risks stifling any further innovation. It could be a mistake to focus on the current limitations of alternative technologies, rather than their future horizons.116

82.Arriva Trains UK drew a comparison between the development of hydrogen and battery technology and the development of the offshore wind industry. It highlighted that, between 2010 and 2020, the offshore wind industry focused on the development of the supply chain, innovation, financing and skills development. By 2020, offshore wind was one of the lowest cost options for new power in the UK and cheaper than nuclear power. Arriva suggested that, through proper investment, battery and hydrogen technology could develop at the same pace.117

83.Other witnesses, however, were concerned that waiting for battery and hydrogen technology to develop until it was viable for wider use on the railway could hinder the challenge of fully decarbonising the rail network and meeting the 2050 net-zero target.118 While Network Rail was supportive of incorporating hydrogen and battery-powered trains onto the network, “it does [not] take away the need for electrification in the intervening period; otherwise, you are dependent, frankly, on speculation that somehow technology is bound to emerge when there is no pathway to that at this stage.”119 Riding Sunbeams said there is “an enormous amount of uncertainty around the future capability of hydrogen to deliver substantial emissions reductions.”120

84.Network Rail recognised that battery and hydrogen technology were rapidly developing and could have an impact on the economic and technological assumptions underpinning the TDNS, and thus potentially change the optimum balance of decarbonisation technologies.121 Network Rail’s proposed approach was to focus first on the so-called ‘no-regret’ electrification schemes on the more intensively used parts of the network (see paragraph 50). This could allow time for further developments in battery and hydrogen technology to potentially change the business case behind the balance of technologies and encourage greater utilisation of these alternative technologies. Network Rail proposed that the technological assumptions built into TDNS would be refreshed on a “five yearly basis to factor in any future changes in technology.”122 The RIA agreed that this was a sensible strategy:

If we are setting out a 30-year programme, and we crack on for the first 15 or 20 years electrifying the core bits of the network and rolling out low-carbon rolling stock, we will know a lot more about the technology when we are deciding about the last 10 years. I could entirely see that there would be more hydrogen and battery in the last 10 years displacing some electrification, but it is not going to displace electrification in its entirety.123

This view was also supported by other witnesses, including the Taskforce.124

85.On the other hand, the train manufacturer Alstom, which had developed hydrogen trains, asserted that reviewing the assumptions every five years was not frequent enough:

[We] recommend a route by route evaluation of the most suitable traction technology as has been made by the TDNS, but crucially it should be based on the development state and economics of technologies available at the time each route is to be addressed, not just as they are today.”125

86.We asked the Department how a long-term rail decarbonisation strategy would be flexible enough to adapt to new technological developments and innovations. The Minister for Rail was not specific but said he was keen to support a flexible approach by “opening up opportunities for companies”.126

87.Although the rail industry requires a long-term strategy for decarbonising the rail network, it is important that the strategy is sufficiently flexible to incorporate alternative technologies, such as hydrogen and battery, and other new technologies that might be developed. When and if it is demonstrated that clean, green and cost-effective alternatives to electrification can deliver the energy required by freight and high-speed passenger services, they should be introduced to decarbonise the rail network.

88.The long-term rail decarbonisation strategy must explain the process by which the development of alternative technologies will be reviewed and how such technologies can be incorporated into the network strategy, if they reach the necessary level of development.

87 Fuel Cell Basics, Fuel Cell & Hydrogen Energy Association

88 Angel Trains (TFF0028), Alstom UK (TFF0024), Rail Delivery Group (TFF0021), West Yorkshire Combined Authority (TFF0020)

90 Ibid. p10

91 Q39 [Leo Murray]

92 Environmental Audit Committee, Oral evidence: One-off session with the Secretary of State for BEIS, HC 755 Q40 [Julian Critchlow]

93 Q88 [Helen McAllister], Q105 [Andrew Kluth]

94 Q89 [Helen McAllister], Q106 [Andrew Kluth]

95 Q111 [Andrew Kluth]

96 Aldersgate Group (TFF0011), Alstom Transport UK Limited (TFF0024), Anglo American (TFF0025), Eversholt Rail Limited (TFF0014)

98 Committee on Climate Change, Hydrogen in a low-carbon economy, November 2018

99 Bombardier Transportation UK (TFF0033)

101 Q129 [Rachel Maclean]

102 Ibid.

106 Q11 [Leo Murray], Q14 [Leo Murray]

108 Angel Trains (TFF0028)

113 Yun Zhang et al. A SWOT Analysis of the UK EV Battery Supply Chain, November 2020

115 Q153 [Rachel Maclean]

116 Alstom Transport UK Limited [TFU0008]

117 Arriva UK Trains [TFF0030]

118 Q88 [Andrew Haines], Q89 [Helen McAllister], Q26 [Mary Grant]

119 Q110 [Andrew Haines]

120 Q10 [Leo Murray]

121 Q110 [Andrew Haines]

123 Q11 [David Clarke]

124 Q87 [Malcolm Brown]

125 Alstom Transport UK Limited [TFU0008]

126 Q152 [Chris Heaton-Harris]

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