Battery strategy goes flat: Net-zero target at risk Contents

Chapter 2: Applications of batteries and fuel cells


8.Batteries and fuel cells have long histories and play important roles in energy systems. Batteries were invented in their familiar form in 1800 by Italian physicist Alessandro Volta, and use chemicals to store energy that can be released as electrical energy.8 Fuel cells were invented in 1839 by Welsh physicist and judge William Grove, and use chemical reactions without combustion to produce electricity and heat.9 The technologies have advanced considerably and their use has increased in recent decades. Batteries have become ubiquitous in the era of portable electrical and electronic devices.10 Fuel cells were advanced in the 1950s–60s for powering NASA spacecraft and have since found a range of applications such as power generation in remote locations and combined heat and power (CHP) units in buildings.11

9.Batteries and fuel cells are now seen as key components for decarbonising the economy. This new imperative is directing their continued development. Batteries are increasingly being used in light road transport (cars and vans). Fuel cells and batteries may have applications in other transport modes including heavy road transport (trucks, buses and coaches), rail, shipping and aviation. In stationary, non-transport applications, batteries are being deployed at scales ranging from individual households to substantial grid installations, to provide energy storage and short-term balancing services.12 Fuel cells can serve a range of functions, partly because they can be designed to use different fuels. If power grids were linked with future hydrogen systems, then fuel cells would play an integral role by using stored hydrogen to help balance electricity supply and demand. Where high energy densities are required (for example in shipping or off-road transport), fuel cells could use ammonia, but there are challenges due to ammonia’s toxicity and the production of air pollution during combustion.13

UK energy supply and demand

10.In the evidence about batteries and fuel cells, there was frequent discussion of energy and power; these are introduced in box 1, along with the concept of ‘energy vectors’.

Box 1: Energy and power

Energy and power are closely related, but need to be distinguished. Energy is the total amount of work that can be done; power is how quickly that work can be done; that is, power is the ‘energy per unit time’. Energy is measured in units such as kilowatt-hours (kWh); power is measured in units such as kilowatts (kW).

For example, a battery might be able to store 50kWh of energy and its maximum power might be 25kW. This means that it could run at full power for two hours or at 10kW for five hours, and so on. For a battery (particularly in a vehicle) the stored energy is often the more important factor because it determines the range; but the power can matter for more applications such as providing immediate back-up for a power grid.

Fuel cells tend to be described in terms of power, because the energy is determined not by the fuel cell but by the fuel supply (which could be finite tank or an essentially unlimited supply from a gas grid). A fuel cell might have a power rating of 500kW but the amount of energy that it can generate depends on how long it operates. For example, if operating for 75% of time, it would produce 3.3 gigawatt-hours per year (GWh/yr).

Finally, energy can be spoken of as sources and ‘vectors’. Energy sources are self-explanatory, and include natural gas, nuclear and renewables. Energy vectors are the ‘media’ that transport energy, and include sources such as gas but also ‘intermediaries’ such as electricity and hydrogen.

11.In 2019, the UK used around 2,100 terawatt-hours (TWh) of energy14 (where ‘tera’ means ‘one billion billion’, or ‘one followed by 12 zeros’). This includes all of the different sources and uses of energy. The biggest contributions to energy supply were from oil (44%, used mostly for transport) and natural gas (29%, used for heating and electricity generation). Total electricity demand was around 300 terawatt-hours. This electricity was sourced mainly from natural gas (40%), renewables (37%) and nuclear (17%), and the use of electricity was split roughly into thirds between industry, homes and ‘other uses’.

12.Traditionally, each energy source and energy vector has been largely confined to particular sectors of the economy, albeit with some overlaps. Liquid fuels have been used for transport and some heating. Electricity has been used for appliances, some heating and in industry. Gas has been used for heating and industry, and in some power generation (a ‘one-way link’ to the electricity system).

13.These delineations are becoming increasingly blurred, creating added complications but new opportunities. Transport and heating increasingly use the electricity system, adding to demand but offering storage opportunities (for example, in vehicle batteries). Hydrogen could replace natural gas and other fuels, including in power generation (allowing a two-way link with the electricity system if the hydrogen has been produced by electrolysis).

14.Electricity demand in the UK is forecast to grow considerably. In figure 1, the actual generation mix in 2017 (which is roughly the same as demand) is compared to two illustrative scenarios for potential electricity demand in 2050. These scenarios by the Committee on Climate Change envisage at least a doubling of electricity demand due to transport, heating and hydrogen production, and a possible quadrupling of demand in the event of further electrification. These scenarios are considered further in the discussion about energy storage for electricity systems, along with the related deadline of 2035 for decarbonising the electricity generation mix.

Figure 1: Scenarios of future electricity demand and generation mix

Scenarios of future electricity demand and generation mix.

Source: Department for Business, Energy and Industrial Strategy, UK Energy Statistics, 2019 & Q4 2019 (26 March 2020): [accessed 7 July 2021]. And: Committee on Climate Change, Net Zero—Technical Report (2 May 2019): [accessed 7 July 2021]

15.Similarly, figure 2 presents a potential scenario of hydrogen demand in 2050, and how that might be supplied, again based on work by the Committee on Climate Change. This scenario envisages hydrogen demand of around 270 TWh per year by 2050, which is the same amount of energy as natural gas currently provides for electricity generation.15 The Government has an initial target of 5GW of hydrogen production by 2030; if this operated constantly, it would produce 44 TWh of hydrogen per year (around 16% of the scenario’s demand in 2050).

Figure 2: Potential hydrogen demand and production in 2050

Potential hydrogen demand and production in 2050.

Source: Committee on Climate Change, Net Zero—Technical Report (2 May 2019): [accessed 7 July 2021]

Transport applications

16.Transport accounted for around one third of the UK’s 522 MtCO2e of greenhouse gas emissions in 2019. Surface transport (that is, road and rail) accounted for around two-thirds of transport emissions (22% of the UK’s emissions).16 The UK’s share of emissions from international shipping and aviation contribute 3% and 7% of the UK total, respectively.17 There are currently no international agreements for including these emissions in national accounting, but in 2021 the UK Government committed to include the UK’s share in the sixth carbon budget (for 2033–37).18

17.Two decarbonisation options are considered relevant for transport: internal combustion engines (ICEs) using low-carbon fuels, such as synthetic fuels, biofuels, hydrogen or ammonia; and electric propulsion powered by a battery or by a fuel cell that operates on a fuel such as hydrogen, ammonia or an alcohol. Hybrid vehicles have both an internal combustion engine and an electric drivetrain. Batteries are used not only in battery electric vehicles (BEVs) and hybrids, but also on a smaller scale in fuel cell electric vehicles (FCEVs).

Road transport

18.The decarbonisation options for different types of road transport will depend on factors such as the purpose (passenger or freight) and the duty cycle (light or heavy). The duty cycle is the proportion of time spent operating, and correlates with vehicle weight, average distance travelled per trip and propulsion type. Roughly speaking, light vehicles include those up to a weight of 3.5 tonnes (minibuses and equivalent-sized vans), and heavy vehicles are everything above that weight.19

Light road vehicles

19.Light road transport (cars and vans) has seen the most progress of any transport sector to-date. BEVs accounted for 6.1% of sales of new cars in the UK in 2021, and 10.7% of sales from January to June 2021 (in addition to plug-in hybrids and non-plug-in hybrids).20 The Department for Transport’s Public Attitudes Tracker survey in relation to EVs found that 87% of car owners plan to replace their current vehicle (via purchase or a lease); of these, 30% plan to seek a hybrid and 9% an EV.21

20.This progress is largely due to the sector having a clear technology pathway. This has given the automotive industry the confidence to invest. Globally the industry has decided to focus on battery electric vehicles more so than on fuel cell electric vehicles. Ian Constance, the CEO of the Advanced Propulsion Centre, made the analogy of light-duty transport being “a two-horse race with battery electric winning but fuel cell still in the mix”.22 Witnesses believed that BEVs would dominate the market for low-carbon light road vehicles, in part due to reductions in the cost of lithium ion batteries. However, Ian Constance foresaw “fuel cell penetration into that sector [of] perhaps 5% or 10%” for “certain applications and users that need to travel long distances or haul relatively heavy loads”.23 Several hydrogen fuel cell cars and vans have been developed globally. Some models are available in the UK 24 and over 250 light FCEVs are running on UK roads.25

21.The clearer technology pathway for light road transport has given governments the confidence to set targets and apply regulatory pressure. In the UK, the Government has banned the sale of new petrol and diesel cars and vans from 2030,26 following a recommendation of the Committee on Climate Change.27 This will be followed by a ban on the sale of hybrid cars and vans from 2035, covering both plug-in hybrids and non-plug-in hybrids. However, because of the large variation in emissions of different hybrids models, sales of some hybrids could cease in 2030 based on the outcome of an upcoming Government consultation on distances travelled with zero tailpipe emissions (called ‘significant zero emission capability’ or the ‘significant distance’ measure).28

Buses and coaches

22.In the heavy-duty road passenger sector, the bus industry has growing confidence that batteries and fuel cells are good options for local buses, with recharging or refuelling provided at depots.29 Cities such as London might need buses with longer ranges, because limited space for parking means they cannot stop for long to charge. Similarly, the technological challenges are greater for long-distance coaches, due to their greater range and weight. The UK Government’s Ten Point Plan of 2020 committed to “invest £120 million next year to begin the introduction of at least 4,000 more British built zero emission buses”.30 The commitment to introduce at least 4,000 zero-emission buses was reiterated in 2021 in the first national bus strategy.31 The Government has consulted on the date for banning the sale of new diesel buses and a decision is pending.32

23.Currently the UK’s bus fleet consists of 2% zero-emission buses, 14% hybrids and 84% diesel vehicles.33 Electric buses are being deployed in large numbers in the UK, for example: there are over 400 in London;34 Coventry and Oxford are transitioning to fully electric fleets;35 and First Bus is installing 162 charging points at a Glasgow depot.36 There are almost 100 hydrogen buses in operation in Europe, including 10 in London and six in Aberdeen.37 Wrightbus and Ryse Hydrogen told us about the development of hydrogen buses, including the world’s first hydrogen electric double-decker bus. They discussed the fuelling infrastructure for bus depots, explaining that “10 MW of electrolysis provides a capacity of more than 4 tonnes hydrogen per day … sufficient to fuel … 200–250 buses”.38

Heavy road freight

24.The heavy-duty road freight sector has made only limited progress on decarbonisation, largely because it is not yet clear which technological solutions are most appropriate for meeting its more demanding requirements. In contrast with light duty vehicles, Ian Constance referred to heavy-duty road transport being in “a three-horse race with hydrogen fuel cells, battery electric with the potential perhaps for on-road charging, and then zero-carbon fuels”.39 Professor Nigel Brandon, Dean of the Faculty of Engineering at Imperial College London, said that for “larger vehicles, off-road vehicles … or long-distance trucks … hydrogen fuel cell electric is competing with synthetic fuel combustion … [and] with ammonia”.40 As noted earlier, ammonia’s toxicity would pose challenges, for example in the event of a fuel spillage.

25.The Government told us that trials that are under way to try to identify the best options for HGVs. In the Energy White Paper, the Government announced £20 million of investment in road freight trials in 2021 to “pioneer hydrogen and other zero emission truck technologies to support industry to develop cost-effective, zero emission HGVs in the UK.”41 The £23 million Hydrogen for Transport Programme “is funding the deployment of around 300 hydrogen vehicles, eight new refuelling stations and upgrades to five existing stations.” The £2 million FCEV Fleet Support Scheme is “supporting public and private sector fleets to become early adopters” of hydrogen technology.42

26.Companies are developing low-carbon propulsion systems for HGVs. In November 2020, the Volvo Group and Daimler Truck AG signed an agreement for a “joint venture to develop, produce and commercialize fuel-cell systems for use in heavy-duty trucks as the primary focus, as well as other applications.”43 Volta Trucks told us about its Volta Zero, “the world’s first purpose-built full-electric 16-tonne commercial vehicle designed specifically for inner-city logistics and freight distribution.” It explained that the vehicle can be “equipped with either a 150kWh or 225kWh battery … [for] an operating range of 90–125 miles”.44

27.The Committee on Climate Change has recommended a ban on the sale of new diesel HGVs by 2040.45 At the end of our inquiry, the Government published its Decarbonising Transport plan46 and opened a consultation on ending the sale of new diesel HGVs weighing up to 26 tonnes by 2035, and HGVs weighing over 26 tonnes by 2040.47

28.In order to make the transition to low-carbon technologies, the heavy road freight sector needs urgent clarity about which technological options are best-suited to its needs, and firm commitments that infrastructure will be deployed at scale. Clear deadlines from the Government, such as a finalised timetable for ending the sale of HGVs, would focus efforts as is happening in the light road sector.

29.We recommend that the Government promptly confirms the end of sales of new diesel HGVs from 2040 or earlier. This will provide a clear timeline for research and development of technologies (including batteries and fuel cells), manufacture of vehicles and deployment of infrastructure.


30.The rail sector accounts for 1.4% of transport emissions (0.5% of all UK emissions).48 Emissions per passenger-kilometre and tonne-kilometre for freight are already lower for rail than for other modes of transport. Rail will retain this advantage as decarbonisation continues, and the strategy for decarbonising transport relies on a degree of modal shift of freight and passengers onto rail.49

31.Freight and passenger trains can be powered by diesel or electric systems. It should be noted that electric trains (powered by overhead cables or live rails) are distinct from battery trains. The UK Government proposed in 2018 that diesel trains should be removed from the network by 2040.50 A report in 2019 by the Rail Industry Decarbonisation Taskforce detailed how this could be achieved.51

32.The Railway Industry Association told us that electrification of additional high-use routes is “the gold-standard of zero-carbon transport solutions”. Electric trains have proven performance, and their main advantage is their lighter weight because they do not carry fuel or batteries. Where electrification is uneconomical, trains would be powered by batteries or hydrogen fuel cells. This would include routes with limited usage and routes that are otherwise electrified but have sections where that is too expensive. Electrification will need to be extensive enough such that the remaining sections are manageable for batteries or fuel cells.52

33.The Railway Industry Association explained that batteries and fuel cells were unsuited to freight or higher-speed passenger trains, due to the size and weight of systems that would be needed to provide the necessary range.53 Helen Simpson, Projects Director at Porterbrook, said that batteries offer a range of 50–60 miles and hydrogen fuel cells several hundred miles but with the disadvantage of large hydrogen tanks.54 For particular applications, trains are being developed that use fuel cells,55 and trains that use both batteries and fuel cells.56

34.Battery trains are being used for some short routes57 and various applications are foreseen for small batteries: on routes where other options are uneconomical; on electric trains for ‘discontinuous electrification’ over short distances that are too costly to electrify; and in conjunction with rapid, wireless charging to allow trains to operate with smaller batteries.58 In addition, Helen Simpson observed that “there is a large and increasing market in the parcels and light logistics sector that could be adapted for other technologies such as hydrogen and batteries”.59

35.The UK’s rail electrification programme is falling behind schedule.60 We heard concerns that the UK’s strategy was not as clear some other countries’ and lacked long-term funding. One result is “a boom-and-bust cycle” for the supply chain, which is detrimental to the development of new technologies.61 More generally, we were told that the UK faces a practical impediment to modifying its railways and trains: namely, confined space compared with many other countries. The UK’s trains have a smaller loading gauge (width and height), such that it can be harder to fit the new technologies on board. The UK’s bridges and tunnels are commensurately lower, such that there is less space for overhead electrical cables. Developing these bespoke solutions for the UK adds to the cost.62

36.Electrification of the railway network (using cables and live rails) will have to be strategic and extensive, to allow greater use of electric trains and so that those sections left without electrification are within the capabilities of trains powered by batteries and fuel cells. Otherwise, sections may be left for which decarbonisation is more expensive or more challenging. This poses the risk that the necessary increases in freight and passenger rail may not occur, and indeed that some usage could shift to roads.

37.The Government must ensure that the railway electrification programme is accelerated in order that it reaches as far as is economically and technically feasible by 2040, when diesel trains will be phased out. The development of battery and fuel cell trains should be supported to serve those parts of the network that remain non-electrified.


38.The main requirement for shipping fuels is that they must have sufficient energy density. Weight and space are less constrained than in other modes of transport, but are still important considerations. As with any mode of transport, higher speeds incur disproportionately higher fuel consumption, and there can be particular pressure on shipping operators to increase speed in order to reduce the time taken on routes of days or weeks. Batteries can be used for small boats over shorter distances, for example harbour tugs, pleasure craft and oilrig supply vessels.63 For larger ships, the energy source must be dense enough to propel their large weight over long voyages without refuelling.64 The two main maritime fuels at present are diesel and fuel oil: diesel is used near to ports and other population centres because it is less polluting than fuel oil, which is generally used only out at sea.

39.However, fuel oil pollution is a problem in any location. Professor John Irvine of the University of St Andrews told us that this is a driver for adopting alternative fuels such as methanol or ammonia. He recommended using ammonia in a high-temperature fuel cell connected to an electric drivetrain, which would provide the required range (whereas hydrogen could not) and improve energy efficiency by 50% compared to an internal combustion engine. The downside, he noted, was the high cost of fuel cells, but this would be expected to fall as their market share grew.65 The impacts of nitrous oxide pollution produced by the combustion of ammonia would need to be assessed.

40.Early development programmes are under way. Dr Mark Selby told us that ammonia fuel cells for shipping are being developed by companies in South Korea and Europe.66 In March 2021 UK Research and Innovation and the Department for Transport, launched a “£20m funding opportunity … around maritime decarbonisation, for which both battery and fuel cell projects are sought.”67


41.Aviation has the most stringent technical requirements of all modes of transport. Fuels must have high energy densities in order to minimise their weight and volume (and to enable long distances in some cases), and must be handled with extreme caution to mitigate the risk of serious incidents in the air. UK Research and Innovation told us that research initiatives are under way through the Aerospace Technology Institute Programme, the Future of Flight Challenge and the new Jet Zero Council (a partnership between industry and government).68

42.Paul Stein, Chief Technology Officer at Rolls Royce, predicted that propulsion technologies in the aviation sector would diverge in future according to energy requirements. He said that long-distance flights by large aircraft (that is, flights of over 1,500km, which account for 75% of global aviation’s CO2 emissions) have such high energy demands that they will continue to need energy-dense liquid fuels.69 He suggested that medium-to-large planes on short-distance routes could use liquid hydrogen in fuel cells, having sufficient space and low enough energy requirements to cope with its lower energy density. We heard that Airbus has announced plans for a hydrogen fuel cell plane.70

43.We heard about a future generation of small, fixed-wing, vertical take-off aircraft powered by fuel cells or batteries. Paul Stein said that these would undertake short flights (including most internal UK flights) and operate as emergency vehicles.71 He said: “We can fly about 10 people about 200 kilometres with today’s technology. That will extend up to about 350 kilometres by the end of the decade as battery technology develops, and we are targeting 500 kilometres by 2040.”72 The Aerospace Technology Institute said that electric aircraft offered significant cost benefits: “a nine-seater aircraft flying a 160km flight required around $6 worth of electricity compared to a conventional combustion engine which would have used around $300–400 worth of fuel”.73

44.The aviation sector is very challenging to decarbonise, particularly its long-distance routes. However, battery and fuel cell technologies could offer solutions for shorter routes, and their application to electric vertical take-off and landing aircraft could allow aviation to play a more flexible role in national transport and emergency services.

Stationary applications

45.Batteries and fuel cells can play roles on power grids and other stationary energy systems. Batteries can provide short-term balancing services on electricity grids, and can store excess electricity generation for use at a later time. This is particularly relevant for intermittent renewable electricity sources, allowing energy produced at times when is not needed to be released when demand is higher or when the renewable output is too low. Fuel cells do not store energy but can be used to generate electricity using a stored chemical fuel such as hydrogen, which ideally will have been produced by electrolysis powered by low-carbon generation. Fuel cells can also produce heat for buildings and hot water. Each of these applications can be at different scales, from individual buildings to communities to supporting the wider energy system.

46.The electricity sector has had the most success in reducing greenhouse gas emissions thus far, out of the various sectors in the UK. However, further improvements could become incrementally harder. The commitment to reduce emissions by 78% by 203574 will require the electricity generation mix to be decarbonised by that time, ahead of sectors that are harder to decarbonise. The anticipated doubling (or more) of electricity demand by 2050 (see figure 1) will require a range of measures,75 as discussed below.

Energy storage for electricity systems

47.Storing energy decouples production and consumption; that is, it allows energy to be used at a different time to when it was produced. This is becoming increasingly important with the changes in the methods of supply and patterns of demand required by decarbonisation. The different scales and durations over which balancing must occur mean that there are opportunities for various storage technologies, including: pumped hydroelectric, hot water tanks, thermochemical systems, batteries, and low-carbon chemical fuels coupled with fuel cells or turbines.76 The energy that can be stored in a device at any one time depends upon its capacity, whereas the energy stored over the course of a year depends on how often the device is charged or discharged. Therefore, making thorough comparisons between batteries and other storage systems requires detailed assumptions about the operating regimes, and are not attempted in this report.

48.Scenarios of possible future demand for electricity are modelled by various organisations.77 Nick Winser, Chair of the Energy Systems Catapult, told us that UK electricity demand is currently 300 terawatt-hours per year (TWh/yr). He said that demand is expected to be at least twice that level by 2050 (partly driven by BEVs) but that it could be up to four times the current level depending on the extent to which heat pumps78 are deployed and smart systems are used to manage demand. He cautioned that these scenarios would raise “some very serious issues for the electricity system” and recommended getting “the absolute maximum out of the existing infrastructure, because building a system that is three or four times as big is enormously expensive and very time-consuming.”79

49.Increased electricity demand will require action on three fronts: more capacity to generate electricity; upgraded networks to distribute electricity; and smarter systems to balance supply and demand.80 We were told that the system will need low-carbon baseload generation capacity, such as nuclear, biomass, and fossil fuels with carbon capture and storage (CCS),81 and that interconnectors to other countries allow access to a wider range of power generation.82 However, witnesses agreed that most electricity generation will come from wind and solar power.83 These sources cannot be controlled and some of their output is lost when demand is low by comparison, and making use of the ‘excess energy’ is one of the rationales for storage.

50.Flexible operation of the electricity system offers alternative ways of balancing supply and demand with less need for new generation capacity and upgrades to networks. Flexibility includes shifting demand (for example through ‘smart tariffs’) and storing energy for use at later times. Witnesses explained that storage is needed over a range of timescales: intraday (seconds to hours), short-term (days and weeks) and seasonal (months). They warned that the scales can be very large and that providing this in future could be challenging. For example, Dr Keith MacLean, Managing Director of Providence Policy, noted that the gas grid currently provides 3–4TWh per day of storage in its pipes and tanks, which is almost as much gas as the UK uses for a cold winter’s day.84 This gives the system inherent flexibility to cover peaks in demand such as hot water in the morning and the varying need for electricity during the day. He said that energy storage requirements will remain at the scale of “terawatt hours per day, tens of terawatt hours per season, and over 100 terawatt hours across the year.”85

51.Professor Tim Green, Co-Director of the Energy Futures Laboratory at Imperial College London, explained that longer-term storage would have to be able to cover several successive days in winter with high demand and low wind speeds, and that these large scales necessitated a chemical fuel such as hydrogen (which has a high energy density when compressed). He calculated that a “a one-in-10-year winter” with particularly long incident of low wind speeds would equate to around 20–40 terawatt-hours of electricity, and that conversion inefficiencies translated that into around 60 terawatt-hours of hydrogen.86

52.Batteries are being used on the UK power grids to provide balancing services. That is, they are one of the technologies that provide short-term changes in flows to help maintain parameters such as voltage and frequency within the correct operational ranges. As such, batteries are sometimes spoken of in terms of their power as opposed to their energy. That said, as batteries are increasingly used for providing energy over longer periods of time, their energy capacity will also be important to grid operators. As an example, the Thurcroft battery site in South Yorkshire has a maximum power of 50 MW and a storage capacity of 75 MWh.87 This energy could supply around 7,500 homes for one day, or it could be released at maximum power for up to 1.5 hours.88 The UK’s largest planned battery installation will be at London Gateway, which will have a power of 320MW and a storage capacity of 640MWh.89 This energy could supply 64,000 homes for one day, or it could be released at maximum power for up to 2 hours.

53.Nick Winser estimated that the UK would need storage across all energy vectors with a total power rating of 200–500GW, of which batteries might need to provide 20–35% (that is, a lower limit of 40GW). In terms of scale, he noted that 50GW is the size of the current electricity system (that is, the typical power flow). In terms of deployment, he said that “we are a long way short of the amount of battery [storage] that would be on an optimised grid system.90 However, even those large numbers of batteries offer limited storage compared to chemical fuels. The energy stored at any one time would depend on the battery technology and the specific design. Using current types of batteries to provide 50GW of power would equate to stored energy in the range of 100–200GWh.91 Larger amounts energy storage could be achieved using alternative technologies such as flow batteries (which are discussed in chapter 3). As noted above, the energy stored over the course of a year would depend on how often the batteries were charged and discharged.

54.Battery storage would be needed at different scales, as Professor Green said: “There is a role for megawatt-scale batteries… but the kilowatt-scale domestic batteries provide an additional service, which is to take some of the stress off a local distribution network.”92 He said that two-hour batteries would be particularly useful for “balancing of short-term variations in load and wind speeds”.93 Professor Brandon said flow batteries might be considered for durations of 10–12 hours.94

55.We heard that other battery technologies might be needed: technologies such as sodium-ion batteries and flow batteries may offer advantages over lithium-ion, including lower cost, better safety and less reliance on materials that are rare and/or toxic (as discussed in chapter 3).95

56.In the context of batteries, there are interesting links between stationary storage and low-carbon transport. On the one hand, the impacts of charging EVs can be partially mitigated by adding batteries to homes or local power grids.96 These stationary batteries can be charged at times of lower demand and then EVs can be charged without the need for (any or as much) grid reinforcement.97 On the other hand, the batteries in EVs can be controlled such that they charge at optimal times and even feed energy into the grid if needed: so-called ‘vehicle-to-grid’ flows. National Grid’s Future Energy Scenarios 2020 estimated that in 2050 vehicle-to-grid technologies could offer up to 38GW of power to the grid.98 These two-way interactions offer greater flexibility for grid management but require the development of control algorithms to deal with large quantities of data and tariffs to incentivise consumer engagement.99

57.In order to decarbonise the electricity system by 2035 and to meet at least a doubling of demand by 2050, there need to be large upgrades to network capacity, smart controls need to be implemented, and a wide array of storage technologies must be deployed. Without batteries of different scales and potentially fuel cells drawing on stored hydrogen, increasing amounts of renewable energy will be wasted. Without smart operation and storage, the costs of grid expansion will be significantly higher. For larger grid-connected batteries, there is merit in developing alternatives such as sodium-ion and flow batteries. For smaller batteries in homes and businesses, there will need to be more sophisticated tariffs and control systems to optimise the benefits. To provide inter-seasonal storage, there may be a need for grid-scale fuel cells to be deployed as part of the UK’s wider hydrogen strategy.

58.The Government and Ofgem must ensure that electricity network regulations and incentives are aligned to bring about the necessary investment in networks, storage and smart systems. They must ensure that energy market rules facilitate more sophisticated services, including tariffs to enable demand shifting, extensive use of battery storage, and smooth interactions with hydrogen systems.

Fuel cells for power and heat

59.We heard about a number of applications for fuel cells, in homes and businesses, in local communities and at larger scales on energy networks. Fuel cells produce electricity but also heat, which can be harnessed to provide space heating and/or hot water. That is, they can operate as a combined heat and power (CHP) unit, with an overall efficiency of well over 90%.100 Heat accounts for over a third of UK carbon emissions. Decarbonising this sector will be crucial for reaching the Government’s net zero target.101

60.Micro-CHP units (which have power ratings of a few tens of kilowatts) can be used as a substitute for boilers in individual homes.102 Of the various CHP technologies that are available, fuel cell CHP units have higher efficiency and lower emissions.103 Fuel cell CHP units are not used widely in the UK. Japan has high uptake compared to most countries, with 45,000 purchased in 2019 and 350,000 installed overall to-date.104 Professor Kucernak from Imperial College London noted that “Some of them also operate in a grid independent mode, so they can operate for 72 hours without any electricity … in the event of a grid failure.”105 Because fuel cells could use a gaseous fuel delivered by existing gas infrastructure, Professor Brandon pointed out that a fuel cell could charge an electric vehicle without having to invest as much in the electricity network.106

61.Fuel cells could also be used for heating in non-domestic settings; for example, a construction site for National Grid’s Viking Link project was heated using fuel cells.107 Similarly, fuel cells can provide power for business premises. Professor Irvine told us that “applications are already quite well spread throughout the US”, for example providing uninterruptible electricity supplies for internet companies and data centres.108

62.Several witnesses advocated the use of larger fuel cells (for example, with power ratings of a few megawatts) at a local and community level. Professor Andrea Russell of the University of Southampton recommended using larger fuel cells for “making localised use of hydrogen that is produced.”109 Professor Irvine agreed, saying that fuel cells “can generate electricity at high efficiency in decentralised systems”.110 Professor Kucernak supported fuel cells as a way to “delocalise electricity production in the UK, give greater resilience and offset the requirements for reinforcement of the grid”, and to “distribute … hot water around the local houses in a local heating network.” He told us that a one-megawatt fuel cell system is “about the size of a 20-foot standard shipping container would power about 160 homes” and that the systems “are very quiet and do not produce any pollutants.”111 There are examples of local projects using renewable electricity to power electrolysis to produce hydrogen that can then fuel FCEVs or be stored and used to generate power and heat at a later time.112

63.The UK could make better use of fuel cells in conjunction with electrolysers in a range of stationary applications. Trials of local and community-scale systems could quickly be replicated, to increase the use of excess renewable electricity to produce hydrogen for transport, heating and power. The use of fuel cells in buildings connected to the gas grid would have merit if those buildings were supplied with ‘low-carbon’ hydrogen.

64.Fuel cells would be needed at larger scales if there was to be more widespread use of hydrogen. In addition to using hydrolysis to utilise excess electricity from renewables, hydrogen might in future be produced using high-temperature chemical cycles such as the ‘sulfur-iodine cycle’.113 The necessary temperature (around 1,000°C) could be achieved by concentrated solar-thermal collectors or advanced next-generation nuclear reactors (also called ‘Generation IV’ technology).114 Advanced reactors are being trialled in small-scale demonstration projects,115 and could be designed at different scales including as small modular reactors (with powers or around 300 megawatts) that could be deployed at the level of small cities.

65.A clear strategy is needed for large-scale hydrogen storage in order to make better use of excess renewable electricity (by producing hydrogen via electrolysis), and in the future to be coupled with hydrogen produced using advanced nuclear reactors.

Expectations and acceptance

66.If a technology is to make a contribution to decarbonisation, it must work in a technical sense and provide the required service in a way that meets user expectations and gains public acceptance. This is true of batteries and fuel cells, which are being used to replace familiar technologies and perform core tasks for daily life and work.

67.Comparisons may be made in factors such as: performance and reliability; convenience and ease-of-use; cost and payment models; safety; and environmental impacts. Those making these judgements depend on the context. For example, many individuals decide on which technologies to use in their homes (for heating and energy storage) and for their cars. The Department for Transport provided a list of research projects that seek to understand people’s views about electric vehicles.116 The Transport and Tech Tracker survey of attitudes and behaviours relevant to transport found that 88% of people think that BEVs offer advantages over internal combustion engines but the same proportion mentioned at least one disadvantage.117

68.However, some decisions about technologies are made not by individual users but by landlords for rented homes and workplaces, by utility companies for energy networks, and by transport operators for freight and passenger services. In all cases, there are elements of public acceptance by those who are not directly using the technology or services.


Charging infrastructure

69.We heard concerns over charging of electric vehicles, including the need for more rapid chargers in towns and on the strategic road network. According to the Transport and Tech Tracker survey, the most common group of concerns about EVs relate to charging (45%), including lack of charging points (22%), where or how to charge (10%) and the time taken to recharge (10%).118 The Committee on Climate Change wrote in a 2020 report that the UK currently has around 400,000 plug-in electric cars and vans and around 18,000 public charging points, and that a forecast fleet of 23.2 million EVs in 2032 would need 325,000 public charging points.119

70.Ian Constance spoke of the need for “the ubiquitous supply of energy and charging points”. He said that the “home charging regime is well under way”, but that more public chargers were needed in order to “give people the confidence that they can go out and use their cars”.120 The Government’s announcement in the Ten-Point Plan of £1.3 billion to accelerate the rollout of the charging infrastructure121 was “a good start”, but there “will be the need for a huge amount of chargers in rural locations, in city locations and on the strategic road network and in towns and cities.”122

71.One solution could be rapid wireless charging. Dr Jeffrey Chamberlain, CEO of Volta Energy Technologies, said that with “a ubiquitous fast charge network, you can make cars with smaller batteries so the cost can go down” and that this could soon be delivered by wireless charging.123

72.We heard about challenges to the deployment of chargers. Ian Constance observed: “One of the big issues is the fact that land costs in the UK are very high, and providing the land to put these chargers in will be very expensive.”124 Deployment of public chargers varies between local authorities125 (and between the nations of the UK). There are concerns that some areas lack the resources to develop a strategy and make use of available funds.126

73.Where extra power flows necessitate grid reinforcements, these are generally undertaken by the local Distribution Network Operator. Their work is funded via price controls set by Ofgem, which recently announced £300 million of funding to support 1,800 rapid chargers at motorway service areas and key trunk road locations (tripling the current network), and a further 1,750 charge points in towns and cities.127

74.There can be problems with operation of chargers. We heard that too many public chargers are out of commission, which is partly due to the expiration of maintenance contracts.128 There are concerns that companies’ different payment methods create complexity that can deter customers. Rachel Maclean MP, Parliamentary Under Secretary of State at the Department for Transport, told us that the Government has consulted on “consumer experience” and will “lay regulations [to] require all charge-point operators to have a simple, standard contactless payment mechanism.” She added: “it has to be just as easy for people to fill up their electric car as it is at the moment to fill up a diesel or petrol car.”129

75.In order to give individuals and companies the confidence to invest in electric vehicles, there needs to be faster deployment of infrastructure for charging, including rapid chargers in towns and on the strategic road network. Charging has to be accessible to all, with suitable options provided for those without dedicated parking spaces or driveways. In the longer-term, wireless charging could be important, and should be developed and evaluated for transport applications. The user experience has to be simplified, with standardisation of technology and payment methods.

76.The Government should ensure electric vehicle charging for all users, including by accelerating the expansion of the public charging network, to deliver around 325,000 charging points by around 2032, as recommended by the Committee on Climate Change. This will require supporting local authorities to develop and implement strategies for deployment and maintenance of public charging-points. Regulations to standardise charging and payments methods should be introduced at the earliest possible time. We ask the Government to confirm the legislative timings in its response to this report.

Hydrogen infrastructure

77.An advantage of fuel cell electric vehicles (FCEVs) is that, like conventional vehicles, they can be completely refuelled in a few minutes. In addition, users might appreciate the similarity and familiarity of refuelling infrastructure compared with conventional fuelling stations. However, the UK currently lacks sufficient hydrogen supply infrastructure. In 2019 there were only 15 hydrogen stations in the UK (compared to 8,500 petrol stations).130 The Committee on Climate Change estimates that the UK will need around 100 hydrogen stations by 2035 and 250 by 2040.131

78.Ian Constance said that “there is a need for a clear hydrogen strategy” without which “this kind of activity will stall”. He pointed out: “Some countries already have it, particularly in Asia. Japan has a very clear hydrogen strategy and understands where it is going. That enables a much clearer route to investing and putting in place the products that are required to go forward.”132

79.In order for companies to have greater confidence in hydrogen vehicles, there needs to be an expansion of the hydrogen fuelling network, particularly on the strategic road network to support road freight.


80.Users can be unsure whether a new technology will perform as well as (or in the same way as) the technology with which they have been familiar. For transport applications, performance includes range, acceleration, time to refuel and so on. In the Transport and Tech Tracker the second most common concern about EVs was the range provided by the batteries (36%).133 These concerns are higher amongst rural dwellers. These issues are primarily a matter of battery performance, which is discussed in chapter 3.134


81.New technologies generally start off more expensive than the incumbents, in terms of upfront costs and/or running costs such as fuel. For EVs, the Transport and Tech Tracker survey135 found that the third-most-cited benefit was cheaper running costs (24%), but the third most-cited concerns were various costs (22%), including the cost of purchasing a BEV (10%). Ian Constance said that innovation can “bring those costs down to something that will be broadly acceptable and accessible for everybody”.136 Professor Brandon noted that FCEV cars are more expensive than alternatives.137 He said that economies of scale will reduce costs, noting that hydrogen buses are “sort of boutique, and made in low volume, and are therefore expensive products.”138

82.In terms of energy costs, electricity for cars and vans is currently cheaper than petrol or diesel, whereas hydrogen is more expensive.139 The carbon intensity of electricity will continue to fall as the generation mix changes, whereas for hydrogen there is a trade off at present between cost and carbon-intensity. The Aerospace Technology Institute told us that ‘green hydrogen’ (produced by electrolysis) costs $3.00–7.50 per kg, compared with $0.90–3.20 per kg for ‘brown hydrogen’ (produced by steam methane reformation).140 Professor Irvine said that the aim is for hydrogen to cost $2 per kilogram,141 which is around £1.50 per kilogram and would be cheaper than petrol, diesel and electricity for cars on a per kilometre basis.142

83.Amer Gaffar, Director of the Manchester Fuel Cell Innovation Centre, told us that businesses focus on the total cost of ownership when making investment decisions. Relevant factors include “future electricity prices, clean air zones or the likelihood of taxation on electric vehicles or hydrogen fuel in the future.” He explained that these businesses “think that they can make an impact, especially with fuel cells in heavy goods vehicles”, but the “lack of hydrogen refuelling infrastructure is informing many decisions [by] multiple fleet operators”.143

84.At present, most batteries for stationary applications are lithium-ion. They benefit from the cost reductions seen in recent years due to economies of scale in the automotive sector. Additional savings are made by using ‘second life’ batteries, which have been removed from vehicles when they can charge to only around 80% capacity.144 Other battery chemistries could become cheaper once they achieve economies of scale. As well as the battery costs, we heard about taxation. Solar Energy UK said, “Since October 2019, residential solar and storage installations have been subject to complex VAT rules, in many cases increasing VAT from 5% to 20%.” They recommended that VAT should be zero for “solar and storage installations, including maintenance”.145


85.Users and the general public may have concerns about the safety of new technologies, including the risks posed by electrical and hydrogen systems. INFACTNI is an organisation representing people in Northern Ireland living close to very large Battery Energy Storage Systems facilities. They told us about risks posed by lithium-ion batteries: “Lithium-ion fires are notoriously difficult to extinguish … Often they are just left to burn out, as [dousing] them for several days with water causes toxic fire-water runoff which contaminates land and water ways. However, leaving them to burn out means that huge clouds of toxic gas are released into the air damaging human health and soil.” They cited fire departments in the UK and abroad whose concerns included lack of information about the contents of large battery installations and lack of clarity about how to treat battery fires at installations or in vehicles.146

86.Ian Constance said that EV battery fires that took several hours to extinguish were “down to early development issues” and “In general the automotive industry has a very strong safety track record”. He said that “a new approach will be required from the fire service and the first responders”; they “will need new equipment as well”. Similarly, he was concerned about vehicle maintenance workers who are not trained to work with high-voltage systems.147 The Faraday Institution is providing £1.52 million over 4 years for the SAFEBATT project that is seeking to understand the degradation and damage that can lead to fires and to “develop a consensus around the optimal method of fighting large [lithium-ion battery] fires”.148

87.Regarding hydrogen for FCEVs, Professor Marcus Newborough, Development Director at ITM Power, pointed out that the fire risk is small, in that “If you make [hydrogen] electrochemically and then use it electrochemically, there are no ignition sources in that chain.”149 Jo Godden, Managing Director for Fuel Cells at Johnson Matthey, told us that “The hydrogen tanks within the vehicle will vent safely if there was an accident, and that removes the stored energy on the vehicle, which is difficult to do with other fuels.” She added, “For public perception, the more used the public are to seeing hydrogen-fuelled buses on our roads, and using them regularly, as well as the battery electric vehicles and fuel cell powered commercial vehicles, trains and cars, the more it brings that confidence in the technology … [that it] is a safe design”.150

88.Helen Simpson told us about safety issues in the rail sector. For batteries, there was “monitoring and detection of battery temperatures at individual cell level”, and “packaging of batteries is different in rail from other sectors because we have these higher levels of safety integrity for rail.” On hydrogen, the first step was having tanks that are “tested … to a very high level of pressure”, and “release and venting is done in a controlled manner and only in an emergency”. She explained that “Once hydrogen is in the air, it dissipates very quickly indeed”, but there is a risk when it is contained in a small space such as a railway tunnel. Looking ahead to the first fleets of hydrogen passenger trains, she said there was the need to consider “the infrastructure and skills needed for refuelling trains with hydrogen. That is very different from what we do now.”151

89.Aviation has the most stringent safety requirements of all transport sectors. Electric planes pose challenges with their high currents and voltages, because air at high altitude has lower density and hence lower electrical resistance. Paul Stein said the industry is “having to come up with whole new regimes to manage safety”. The less dense air is a poorer thermal conductor; he highlighted the need for “thermal runaway containment” for batteries, which had to “go to another level over and above what can be tolerated on land and sea.” For hydrogen, he noted its “incredibly low flash point”, such that it is essential to avoid leaks and to ensure the “accident integrity” of storage tanks. His view was that most of the challenges were surmountable but “Liquid hydrogen is the one where the jury is still out.” Finally, he discussed non-physical safety, saying that electrical vertical take-off and landing aircraft would require advances in “digital flight control systems … collision avoidance algorithms … and air traffic management systems probably using artificial intelligence.”152

90.The Government should take steps to build public confidence in the safety of batteries and hydrogen technologies. The concerns of residents and drivers about the fire safety of batteries must be taken seriously. Action must be taken to mitigate the risks of existing battery installations, including more stringent safety standards. Regulations and incentives should be used to drive development of safer battery technologies in transport and stationary applications. Effective fire-fighting protocols need to be developed, with provision of training and equipment for fire fighters, other first responders and vehicle maintenance workers.

Environmental impacts

91.Batteries and fuel cells are being deployed to bring about environmental benefits, including reducing emissions of greenhouse gases and other air pollution. Batteries emit nothing during operation and hydrogen fuel cells emit only water153 (although other fuels such as ammonia do produce air pollutants). In the most recent Transport and Tech Tracker survey, the top benefits cited were environmental, such as reduced pollution (77%), and third on the list was being quieter than traditional vehicles (9%).154 However, negative environmental impacts could affect levels of public acceptance. For example, as noted above, there are concerns about battery fires putting toxic chemicals into the air and water courses.155 Chapter 4 considers unwanted impacts that can occur at different stages of the technologies’ life cycles, such as resource extraction and end-of-life.

8 Encyclopaedia Britannica, ‘Development of batteries’: [accessed 2 July 2021]

9 Encyclopaedia Britannica, ‘Development of fuel cells’: [accessed 2 July 2021]

10 Q 20 (Professor Paul Shearing)

11 Written evidence from Ceres Power (BAT0016)

12 Balancing services are those measures used by the electricity System Operator (National Grid in the case of the UK) to maintain key grid parameters within acceptable ranges, for example the voltage and frequency. These balancing actions have to be taken very rapidly, such that the power can be more important than the energy that is available. Over longer timescales, the total amount of available energy become important, in order to meet demand.

13 Ammonia is itself toxic, and some of its combustion products are harmful. Ammonia consists of nitrogen and hydrogen, and during combustion the nitrogen combines with oxygen to produce nitrogen oxide (NOx) gases, much the same as when nitrogen in the air reacts with oxygen in internal combustion engines. Of these gases, nitric oxide (NO) and nitrogen dioxide (NO2) contribute to urban air pollution and affect ozone in the troposphere; and nitrous oxide (N2O) is a potent greenhouse gas.

14 Department for Business, Energy and Industrial Strategy, UK Energy Statistics, 2019 & Q4 2019 (26 March 2020): [accessed 7 July 2021]

15 Department for Business, Energy and Industrial Strategy, UK Energy Statistics, 2019 & Q4 2019 (26 March 2020): [accessed 7 July 2021]. It should be noted that gas-powered electricity generation is up to around 60% efficient, so the amount of electrical energy generated is less than the chemical energy in the gas.

16 Committee on Climate Change, The Sixth Carbon Budget: The UK’s path to Net Zero (9 December 2020) pp 24 and 29: [accessed 2 July 2021]

17 Committee on Climate Change, The Sixth Carbon Budget: The UK’s path to Net Zero (9 December 2020) p 30: [accessed 2 July 2021]

18 HM Government, ‘UK enshrines new target in law to slash emissions by 78% by 2035’ (20 April 2021): [accessed 2 July 2021]

19 Q 99 (Ian Constance)

20 SMMT (Society of Motor Manufacturers and Traders), ‘SMMT Vehicle Data: Car Registrations’: [accessed 12 July 2021]

21 The results cited in the text are from the sixth edition of this survey, dated November 2020: Kantar and Department for Transport, Transport and Technology: Public Attitudes Tracker—Wave 6: Summary report (November 2020): [accessed 2 July 2021]. This survey has been conducted six times since 2018, and the full set of results is available here: Department for Transport, ‘Transport and transport technology: public attitudes tracker’ (28 January 2021): [accessed 2 July 2021]

22 Q 99 (Ian Constance)

23 Q 99 (Ian Constance)

24 FCEVs available in the UK include the Toyota Mirai and the Hyundai Nexo. See Toyota (GB) plc, ‘Hydrogen-powered Mirai’ (March 2017): [accessed 12 July 2021]. See also Hyundai Motor UK Ltd, ‘All-new Nexo’ (2018): [accessed 12 July 2021]

25 Written evidence from UK H2Mobility (BAT0022)

26 HM Government, Government takes historic step towards net-zero with end of sale of new petrol and diesel cars by 2030 (18 November 2020): [accessed 21 June 2021]

27 Committee on Climate Change, Reducing UK emissions: Progress Report to Parliament (25 June 2020) p 19: [accessed 21 June 2021]

28 In the Government’s response to its consultation on the phase-out of petrol and diesel cars and vans it said that “significant zero emission capability will be defined through consultation later this year.” See the Department for Transport and the Office for Zero Emission Vehicles, ‘Outcome and response to the ending the sale of new petrol, diesel and hybrid cars and vans’ (10 March 2021): [accessed 12 July 2021]

29 See, for example, Written evidence from Wrightbus and Ryse Hydrogen (BAT0039)

30 HM Government, The Ten Point Plan for a Green Industrial Revolution (November 2020) p 16: [accessed 21 June 2021]

31 The national bus strategy reiterated the commitment to introduce 4,000 zero-emission buses, and set out plans to support British bus manufacturing, but did not explicitly reiterate the commitment that the 4,000 buses would be British-built. Department for Transport, Bus Back Better: National Bus Strategy for England (2021) pp 13 and 73: [accessed 21 June 2021]

32 Department for Transport and the Office for Zero Emission Vehicles, ‘Ending the sale of new diesel buses’ (15 March 2021): [accessed 21 June 2021]

33 Department for Transport, Annual bus statistics: England 2019/20 (28 October 2020) p 11: [accessed 21 June 2021]

34 Transport for London, London’s buses now meet ULEZ emissions standards across the entire city (14 January 2021): [accessed 21 June 2021]

35 Department for Transport, ‘Coventry and Oxford set to be UK’s first all-electric bus cities’ (6 January 2021): [accessed 21 June 2021]

36 First Bus, ‘First Bus begin works on UK’s biggest electric vehicle charging station at flagship Glasgow depot’ (7 June 2021): [accessed 21 June 2021]

37 Fuel Cell Electric Buses, ‘Knowledge Base—map of deployments in Europe’ (2021): [accessed 21 June 2021]

38 Written evidence from Wrightbus and Ryse Hydrogen (BAT0039)

39 Q 99 (Ian Constance). On-road charging includes two potential options: pantographs to draw energy from overhead wires (as electric trains do), and wireless electromagnetic induction to draw energy from cables buried in the road.

40 Q 13 and Q 3 (Professor Nigel Brandon OBE)

41 Department for Business, Energy and Industrial Strategy, Energy White Paper: Powering our Net Zero Future, CP 337, December 2020, p 94: [accessed 5 July 2021]

42 Written evidence from HM Government (BAT0041)

43 Daimler AG, ‘Fuel-cell joint venture: Volvo Group and Daimler Truck AG sign binding agreement’ (2 November 2020): [accessed 21 June 2021]

44 Written evidence from Volta Trucks (BAT0003)

45 Q 77 (Rachel Maclean MP). See also Committee on Climate Change, The Sixth Carbon Budget: The UK’s path to Net Zero (9 December 2020) p 29: [accessed 2 July 2021]

46 Department for Transport, Decarbonising Transport: A Better, Greener Britain (July 2021): [accessed 14 July 2021]

47 Department for Transport, Consultation on when to phase out the sale of new, non-zero emission heavy goods vehicles (July 2021): [accessed 14 July 2021]

48 Written evidence from the Railway Industry Association (BAT0043)

49 Office of Rail and Road, Rail Emissions 2019–20 (5 November 2020) p 5:–20.pdf [accessed 21 June 2021] This report notes that: “Railways made up 1.4% of the UK’s transport CO2 emissions in 2018, but in comparison 10% of all passenger kilometres were made using rail. Rail emissions account for 0.5% of the UK’s total CO2 emissions.”

50 HM Government, ‘Let’s raise our ambitions for a cleaner, greener railway’ (22 February 2018): [accessed 21 June 2021]

52 Written evidence from the Railway Industry Association (BAT0043)

53 Written evidence from the Railway Industry Association (BAT0043)

54 Q 101 (Helen Simpson)

55 For example, the French rail manufacturer Alstom has used fuel cell technology developed by Cummins for its ‘Coradia iLint’ fuel cell powered train, which entered service in Lower Saxony in September 2018. See Alstom, ‘World premiere: Alstom’s hydrogen trains enter passenger service in Lower Saxony’ (16 September 2018): [accessed 23 June 2021]

56 For example, we were told about the HydroFLEX project that has retrofitted an existing Class 319 train with a hydrogen fuel cell and batteries. See written evidence from Porterbrook (BAT0042)

57 Battery trains are being trialled on a route in Denmark in 2021. See ‘Denmark to get battery-powered trains from next year’, The Local (29 November 2019): [accessed 23 June 2021]

58 Written evidence from the Railway Industry Association (BAT0043)

59 Q 103 (Helen Simpson)

60 Network Rail electrified 251km of lines in 2019–20, compared with the average of 450km per year needed to achieve the 13,000km that is estimates will be needed by 2050. See Railway Industry Association, ‘Railway industry urges Government to begin programme of rail electrification now, in order to meet Net Zero legal commitments’ (22 April 2021): [accessed 23 June 2021]

61 Q 99 (Helen Simpson)

62 Q 99 (Helen Simpson)

63 Ship Technology, ‘Electric ships: the world’s top five projects by battery capacity’, (25 August 2020): [accessed 23 June 2021]

64 Written evidence from Frazer-Nash Consultancy (BAT0030)

65 Q 35 (Professor John Irvine)

66 Q 93 (Dr Mark Selby)

67 Written evidence from UK Research and Innovation (BAT0045)

68 Written evidence from UK Research and Innovation (BAT0045)

69 Q 98 (Paul Stein). See also Q 46 (Professor John Irvine)

70 Q 44 (Professor Anthony Kucernak)

71 Q 98 (Paul Stein). See also Q 46 (Professor John Irvine)

72 Q 100 (Paul Stein)

73 Written evidence from the Aerospace Technology Institute (BAT0021)

74 HM Government, ‘UK enshrines new target in law to slash emissions by 78% by 2035’ (20 April 2021): [accessed 14 July 2021]

75 Q 105 (Dr Jane Dennett-Thorpe) and Q 105 (Professor Tim Green)

76 See, for example, Q 106 (Dr Keith MacLean) and Q 106 (Nick Winser CBE)

77 See, for example, National Grid ESO, ‘Welcome to the ESO Future Energy Scenarios’ (2021): [accessed 23 June 2021]

78 Heat pumps are a technology for heating buildings, and most versions are powered by electricity. They are essentially the opposite of a fridge. Heat pumps are highly efficient, exploiting thermodynamical principles to provide more energy as heat than they consume as electricity. However, even with this efficiency, heat pumps would shift significant energy demand from the gas networks to the electricity networks.

79 Q 105 (Nick Winser CBE)

80 See, for example, Q 110 (Dr Jane Dennett-Thorpe)

81 Q 105 (Nick Winser CBE) and Q 105 (Professor Tim Green)

82 Q 107 (Professor Tim Green)

83 Q 105 (Nick Winser CBE) and Q 105 (Professor Tim Green).

84 Watson et al., ‘Decarbonising domestic heating: What is the peak GB demand?’, Energy Policy, vol. 126 (2019) pp 533–544: [accessed 23 June 2021]

85 Q 106 (Dr Keith MacLean OBE)

86 Q 106 (Professor Tim Green)

87 Flexitricity, ‘UK’s largest battery set to help keep the nation’s lights on’ (November 2020): [accessed 14 July 2021]

88 Average daily household electricity consumption is around 8–10kWh (where heating is not provided by electricity). The upper level of 10kWh is used in these examples for simplicity.

89 Intergen, ‘InterGen gains consent to build one of the world’s largest battery projects in Essex’ (30 November 2020): [accessed 14 July 2021]

90 Q 106 (Nick Winser CBE)

91 This assumption is based on data for typical battery installations such as those cited above with an ‘energy-to-power ratio’ of around 2 MWh-to-MW, and others such as a 250MW/1,000MWh project by AGL in Australia with a ratio of 4 MWh-to-MW. National Grid’s Future Energy Scenarios assume a ratio of around 2 MWh-to-MW. See Energy Storage News, ‘UK’s largest battery storage project at 640MWh gets go ahead from government’ (30 November 2020): [accessed 14 July 2021]. See also National Grid ESO, Future Energy Scenarios (July 2020) p 112, Figure SV.45: [accessed 14 July 2021]

92 Q 115 (Professor Tim Green)

93 Q 106 (Professor Tim Green)

94 Q 14 (Professor Nigel Brandon OBE) Flow batteries are discussed in chapter 3. In summary, they can store more energy than conventional battery designs by using tanks containing additional electrolyte.

95 Q 22 (Dr jerry Barker) and Q 31 (Professor Paul Shearing)

96 Written evidence from Solar Energy UK (BAT0017)

97 For example, the Evalu8 project trialled the use of batteries to address grid constraints at service stations. The batteries were charged overnight when demand was low, and then used to charge EVs. See the European Commission, ‘Exploiting the business potential of electric vehicles’ (10 December 2014): [accessed 23 June 2021]

98 National Grid ESO, Future Energy Scenarios (July 2020) p 6: [accessed 23 June 2021]

99 Q 107 (Professor Tim Green) and Written evidence from Johnson Matthey (BAT0011)

100 Written evidence from Ceres Power (BAT0016)

101 Department for Business, Energy and Industrial Strategy, Clean Growth—Transforming Heating (December 2018): [accessed 24 June 2021]

102 See for example, PACE, ‘Fuel Cell micro-Cogeneration’: [accessed 24 June 2021]

103 Staffell et al., ‘The role of hydrogen and fuel cells in the global energy system’, Energy & Environmental Science, Issue 2 (2019) pp 463–491: [accessed 24 June 2021]

104 Q 14 (Professor Nigel Brandon OBE) and Q 34 (Professor Anthony Kucernak)

105 Q 34 (Professor Anthony Kucernak)

106 Q 14 (Professor Nigel Brandon)

107 National Grid, ‘World’s first hydrogen heated construction site’ (7 September 2020): [accessed 24 June 2021]

108 Q 42 (Professor John Irvine) and Q 43 (Professor John Irvine)

109 Q 35 (Professor Andrea Russell)

110 Q 35 (Professor John Irvine)

111 Q 42 (Professor Anthony Kucernak)

112 There are several hydrogen projects in Orkney, including BIG HIT, Surf’n’Turf, HyDIME, HyFlyer. Each has its own website, but for a general overview, see, ‘Hydrogen’ (2021): [accessed 24 June 2021]

113 The International Union of Pure and Applied Chemistry (IUPAC) has decided that only the spelling ‘sulfur’ should be used, replacing the spelling ‘sulphur’ in the UK.

114 International Atomic Energy Agency, Hydrogen Production Using Nuclear Energy (2013): [accessed 12 July 2021]

115 HM Government, The Ten Point Plan for a Green Industrial Revolution (November 2020) p 12: [accessed 21 June 2021]

116 Supplementary written evidence from the Department for Transport (BAT0049)

117 Kantar and Department for Transport, Transport and Technology: Public Attitudes Tracker—Wave 6: Summary report (November 2020): [accessed 2 July 2021]

118 Kantar and Department for Transport, Transport and Technology: Public Attitudes Tracker—Wave 6: Summary report (November 2020): [accessed 2 July 2021]

119 Committee on Climate Change, Briefing document: The UK’s transition to electric vehicles (2020) p 2: [accessed 12 July 2021]

120 QQ 99–100 (Ian Constance)

121 HM Government, The Ten Point Plan for a Green Industrial Revolution (November 2020) p 17: [accessed 21 June 2021]. See also Q 165 (Rachel Maclean MP)

122 Q 100 (Ian Constance)

123 Q 150 (Dr Jeffrey Chamberlain)

124 Q 100 (Ian Constance)

125 Q 165 (Rachel Maclean MP)

126 See, for example, Energy Saving Trust, Procuring electric vehicle charging infrastructure as a local authority (September 2019) p 14: [accessed 25 June 2021]

127 Ofgem, ‘Ofgem delivers £300 million down payment to rewire Britain’ (24 May 2021): [accessed 25 June 2021]

128 Q 163 (Dr Bob Moran)

129 Q 165 (Rachel Maclean MP)

130 Staffell et al., ‘The role of hydrogen and fuel cells in the global energy system’, Energy & Environmental Science, Issue 2 (2019) pp 463–491: [accessed 2 July 2021]

131 Committee on Climate Change, The Sixth Carbon Budget: The UK’s path to Net Zero (9 December 2020) p 99: [accessed 2 July 2021]

132 Q 103 (Ian Constance)

133 Kantar and Department for Transport, Transport and Technology: Public Attitudes Tracker—Wave 6: Summary report (November 2020): [accessed 2 July 2021]

134 Range is also affected by driving style (acceleration, speed and braking), so there is scope for improvements from behaviour change.

135 Kantar and Department for Transport, Transport and Technology: Public Attitudes Tracker—Wave 6: Summary report (November 2020): [accessed 2 July 2021]

136 Q 99 (Ian Constance)

137 Q 10 (Professor Nigel Brandon OBE)

138 Q 10 (Professor Nigel Brandon OBE)

139 Typical fuel consumption for a new conventional car is 5.7 litres per 100 km (petrol) and 5.1 litres per 100 km (diesel); at fuel costs of around £1.30 per litre, these equate to about £7.40 and £6.60 per 100km, respectively. Typical hydrogen consumption is approximately 1 kg per 100 km, with each kilo of hydrogen currently costing £10–15, and is hence about twice the price of petrol or diesel. A BEV would typically require approximately £3 of charge to cover the same distance, which is about half the price of petrol or diesel. See RAC Foundation, ‘Environment’ (2021): [accessed 12 July 2021]. See also House of Commons Library, ‘Electric vehicles and infrastructure’, Library Note, CBP-7480, 23 June 2021, p 14

140 Written evidence from the Aerospace Technology Institute (BAT0021)

141 Q 36 (Professor John Irvine)

142 Using the same data as in the previous example, but reducing the cost of hydrogen from £10–15 per kg to £1.50 per kg, gives a cost of about £1.40 per 100km, which is lower than the current values for petrol, diesel and electricity.

143 Q 12 (Amer Gaffar)

144 Written evidence from Johnson Matthey (BAT0011)

145 Written evidence from Solar Energy UK (BAT0017)

146 Written evidence from INFACTNI (BAT0001)

147 Q 104 (Ian Constance)

148 The Faraday Institution, ‘SAFEBATT—The Science of Battery Safety’ (2021): [accessed 23 June 2021]

149 Q 95 (Professor Marcus Newborough)

150 Q 95 (Jo Godden)

151 Q 104 (Helen Simpson)

152 Q 104 (Paul Stein)

153 Q 33 (Professor John Irvine):

154 Kantar and Department for Transport, Transport and Technology: Public Attitudes Tracker—Wave 6: Summary report (November 2020): [accessed 2 July 2021]

155 Written evidence from INFACTNI (BAT0001)

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