Great Planet

This is part 7 of a seven part series which explores some of the issues around zero carbon vehicles and which future technologies might be best for HGVs to avoid carbon emissions. The seven parts are:

1. Understanding the Typical Power Requirements of an HGV
2. Basic Designs of Diesel, Battery and Fuel Cell Powertrains
3. Comparing Diesel, Battery and Fuel Cell Powertrains
4. Assessing Future Manufacturing Costs of Diesel, Battery and Fuel Cell Powertrains for HGVs
5. Costs of Hydrogen Fuel / Building A Hydrogen & Electric Charging Infrastructure
6. Commercial Viability of Operating A Battery or Fuel Cell Powertrain HGV
7. Summary, A Look at Developments Which May Help Achievement of Zero Carbon In-use HGVs (this post).

Part 7: Summary, A Look at Developments Which May Help Achievement of Zero Carbon In-use HGVs

Part 7 provides a summary of fuel cell and battery electric HGV feasibility for the first generation of vehicles, along with a look at how Generation 2 of zero carbon trucks could be developed further.

7.1 Summary Assessment of Fuel Cell and Battery Electric HGV Feasibility

From the findings in Parts-16, both hydrogen fuel cell and battery electric HGVs could deliver the technical and commercial performance to be competitive with diesel trucks by 2025. The challenges identified at the start of this series have, in the main, potential solutions in place:

Power output: Delivering the appropriate power output (circa 500-750kW) is achievable with currently available technology.

Driving range & refuelling time: Delivering the desired driving range (800-1,600km) using upwards of 60kg of hydrogen or a 1,131 kWh battery is achievable. Developments in fuel dispenser flow rates (above 120kg/hour) are needed to close the gap with diesel refuelling rates. This technology should start to be introduced during 2020/2021. Rapid recharging of larger batteries presents a key challenge. In the short term, suitable applications would involve vehicles being charged overnight at their operating depot.

Durability: Life in running hours of over 25,000 hours has been demonstrated by fuel cell bus operations with future maintenance costs potentially in line with diesel HGVs.

Weight impact: Fuel cell HGV powertrains have the potential for lighter weight than diesel, although choices on storage battery capacity may offset this. Challenges exist for weights on large capacity vehicles although compromises on driving range can compensate for this.

Volume impact: Bulkier hydrogen storage systems will create demand for up to 3m³ of extra truck volume, but design solutions have been identified.

Fuel cell HGV manufacturing costs: By 2025, the price premium over diesel powertrains for a hydrogen FC powertrain HGV could be as little as 40% and around 100% for a Battery Electric HGV.

Fuel costs: Hydrogen refuelling costs of $4.23/kg are potentially achievable which, using electrolysis and renewable electricity, would lead to zero GHG emissions. Battery electric HGVs would have lower fuel costs.

Hydrogen refuelling/Electric Charging infrastructure: Policy makers have demonstrated a willingness to provide funding to encourage the building of refuelling networks. Building charging facilities for electric vehicles at HGV operating centres would be a first step for most truck operators.

Commercial viability: Subject to achieving fuel economy levels of 7.5kg/100km, FC HGV annual operating costs for operators can be competitive with diesel vehicles. Whilst the solutions are credible, they are yet to be fully demonstrated. From a technology perspective, FC HGVs could best be described as at an engineering prototype stage or Technology Readiness Level 6 (TRL 6), as evidenced by the operation of the Toyota Project Portal demonstrator truck (DOE 2011). Figure 25 shows the subsequent steps that need to be taken before the technology is ready for full commercial operation (TRL 9). The launch of the Nikola pre-production truck in April 2019 signalled a move to TRL 7. Although Nikola may argue this is TRL 8, the trucks will not be produced using the final manufacturing processes. Battery electric HGVs could also be competitive by 2025.

Figure 25: Technology Readiness Levels

Level	Description	Detail
TRL9	Full commercial operation	Actual system operated over the full range of expected mission conditions.
TRL8	Pre-production	Actual system completed and qualified through test and demonstration
TRL7	Demonstration system	Full-scale prototype system demonstrated in relevant environment
TRL6	Engineering Prototype	Engineering-scale models or prototypes are tested in a relevant environment.

With technology not proven for full commercial readiness there are potential risks that progress will not be as rapid as anticipated or proposed solutions do not deliver promised performance. Conversely, there are ongoing developments in short-haul BEV freight vehicles, such as the Tesla Semi and the Mercedes-Benz Electric Truck, which could drive more rapid powertrain development and increased manufacturing volumes for components such as electric motors (Electrek 2018, Daimler 2018).

Of the technical/commercial issues covered in this review, the poor fuel economy of the Toyota demonstrator truck (12.5kg hydrogen/100km) and the lack of availability of hydrogen refuelling at cost close to $4.23/kg (£3.20/kg) raise concerns. This is because fuel economy combined with the cost of hydrogen fuel could be critical to commercial success for FC HGVs, particularly with the likelihood that the purchase price of FC trucks will be at a premium to diesel HGVs until well beyond 2025.

Policy makers appear to be placing a strong emphasis on agreeing international vehicle and refuelling safety regulations, which should give market re-assurance that hydrogen FCEV are safe in operation. In the US (mainly California), Japan and Europe there is encouragement for the development of a hydrogen fuelling infrastructure which is mainly targeted around cars and buses. The UK policy approach of encouraging the building of local clusters of hydrogen refuelling stations will also require greater emphasis on hydrogen fuel prices, to break out of the hydrogen fuel challenge described in Part 5. Consideration needs to be given to higher volume fuel dispensers to cope with heavier truck refuelling weights of circa 60-80kg of hydrogen rather than just those for cars (5kg) and buses (20-40kg).

Policy makers generally, including the UK, have chosen not to apply a fuel duty to hydrogen fuel for transportation, which should encourage earlier adoption of the technology. A key challenge will come if fuel duty revenues from diesel vehicles decline rapidly. Policy makers will have to balance recovering lost revenue, by potentially introducing a hydrogen fuel duty, against the wider benefits of decarbonising the transport sector and reducing health harming NOx emissions.

In the US the Department of Energy, along with CARB, are encouraging specific truck demonstrator projects but this is not currently being repeated elsewhere. The UK can be described as an interested spectator rather than an active encourager of hydrogen fuel cell technology for trucks. Despite the UK’s Committee on Climate Change suggesting that 40% of HGV’s will need to be hydrogen powered by 2050 there are little signs of any active policies to achieve this or any investment in FC truck research; something that will need to be rapidly addressed if the UK wants a mainstream role in FC technology. Some funding (£1.3 million) has been given to ULEMCo to explore the use of hydrogen as a dual-fuel in a modified internal combustion engine, but this is a tiny fraction of the investment required (Commercial Fleet 2017, ULEMCo 2018).

7.2 Future Work on Fuel Cell HGVs: Generation 2.0

This article has highlighted the significant challenges to achieving a first generation of hydrogen powered and battery powered zero-emission trucks. This section takes a brief look at where a future generation of fuel cell HGVs could potentially improve on Generation 1.0.

Fuel Economy Improvements from Battery Dominant Designs
With fuel usage a major contributor to truck operator annual operating costs, any improvements in fuel economy will improve the commercial viability of FC HGVs. There is evidence that battery dominant designs, such as the Nikola One, can offer better fuel economy than the fuel cell dominant Toyota demonstrator. With battery storage and effective power management, a fuel cell can run at optimum efficiency for longer rather than adjusting rapidly to changes in power demand, improving fuel economy. As the cost of fuel cell stacks falls further, the economics of larger fuel stacks running at lower and more fuel-efficient power outputs can be explored as originally proposed by Barbir & Gómez (1997).

Ammonia rather than Hydrogen?
The projected manufacturing cost in 2025 of the Nikola One 60kg hydrogen storage tanks is $45,800, 160% higher than the $17,400 cost of the fuel cell system itself. There are potential technical developments on the conversion of ammonia to hydrogen which may allow significant reductions in manufacturing cost, weight and volume of storage systems by switching from 700 bar hydrogen gas to 10 bar pressure ammonia liquid (Zamfirescu 2009, Afif 2016, Phys 2018, CSIRO 2018). A switch in fuel type to ammonia may also help reduce the 30-40 minutes of refuelling times for dispensing larger volumes of compressed hydrogen, althugh it looks likely that by 2021 Heavy Duty hydrogen refuelling technology will be available. A sufficiently compact reforming unit, capable of decomposing the ammonia to hydrogen at the right rate, would need to be added to the truck systems. However, there is scope to fund this by replacing expensive hydrogen gas storage tanks. As a less bulky fuel than hydrogen, ammonia is already being considered to safely transport renewably generated hydrogen by ship from Australia to access markets in Asia (ABC News 2018). The logical extension is to use ammonia in the vehicles themselves.

Fuel Economy Improvements from Solid Oxide Fuel Cells
Battery dominant designs allow alternatives to PEMFC to be considered, if they deliver better fuel economy at stable output levels. Solid Oxide Fuel Cells have the potential to be 5-10% more efficient but were historically discounted for transport applications due to their poor dynamic response to power and their slow start-up from cold as they operate at temperatures of 800-1,000°C. Bossel (2012) has demonstrated a small-scale SOFC which reaches operating temperature in under 5 minutes. Using 240kWh of battery storage, a truck could be powered from the battery alone for upwards of fifteen minutes even with high power demand. If the start-up time for a 240kW output SOFC could be improved to under 15 minutes, then there appears potential for use in HGVs, particularly as an HGV driver can spend 10-15 minutes on daily walkaround checks of a vehicle (DVSA 2013).

There are signs that SOFC technology could be used for transport applications with news that UK-based Ceres Power, in partnership with Nissan, have been awarded research funding to develop its SteelCell SOFC for electric vehicle applications. SteelCell is a 5kW modular stack which can be scaled up to at least 200kW and has increased power density, reduced start-up times and vibration tolerance to address automotive applications. The research project will build a compact and robust demonstration SOFC stack to be deployed with a Nissan fuel cell module. There are no details on efficiency or potential stack cost, but Ceres claimed “the fuel cell stack could be mass produced at a competitive price due to its low-cost steel and ceramic parts” with applications including cars, light commercial and heavy commercial vehicles (Ceres 2018a, 2018b). The Ceres fuel cell could work with natural gas and bio-fuels as well as hydrogen, meaning that it is not dependent on having a widespread hydrogen fuel infrastructure. Ceres have indicated that efficiency exceeds 60% at 50-90% of rated power (EFCF 2018).

Whilst no assessment of the Ceres claims is possible at this stage, it does suggest that a new generation of SOFC could be suitable for transport applications as an alternative to PEMFC, given competitive manufacturing costs. No published data is available on SOFC manufacturing costs for transport applications but a 10% improvement in fuel economy from a truck achieving 7.5kg/100km could deliver annual fuel savings to truck operators of circa $4,224 (£3,200), creating scope for SOFC to be competitive with PEMFC even with higher stack costs. The use of ammonia fuel may also be possible in a SOFC without a separate reformer, due to the high temperature stack.

Use of Fuel Cell Technology for Heavier/More Power Intensive Applications
Both hydrogen FC and BEV technologies offer the potential for zero carbon and pollutant emissions for cars, buses and trucks carrying lighter loads for shorter journeys. Assessing which technology is most likely in the future to dominate these lower power applications is outside the scope of this research. However, there is evidence that fuel cells offer benefits over BEV technology in applications requiring higher power output for longer durations, such as powering a long-haul 40-tonne truck. By increasing the number or size of fuel cell stacks, the power output can be scaled up, providing the potential to power larger vehicles which are unlikely to be suitable for BEV technology. This includes heavy construction vehicles and extends to other applications currently using powerful diesel engines, such as trains and shipping. Early signs that this is being considered are:

• JCB, one of the world’s top three manufacturers of construction equipment, took a 9.1% stake in ITM Power (2015) a hydrogen energy specialist/ fuel station operator.
• Alstrom (2018) announced the approval of 14 hydrogen fuel cell trains to come into service in Lower Saxony at the end of 2021. These are two-car diesel multiple units with a 314kW fuel cell with 94kg of hydrogen for each train car (Railvolution 2018).
• CARB in California announced grant funding in 2018 for a project to demonstrate a hydrogen fuel cell-powered ferry providing passenger service between the Ports of San Francisco, Oakland, Redwood City and Martinez (CARB 2018).

For heavy construction applications, such as excavators, power outputs similar to trucks would be needed (210kW for a JCB 33 tonne tracked excavator). Train power output requirements vary from circa 314kW for a train car up to 4,500kW for a high-power locomotive. Ship power requirements vary hugely in size from 2,500kW for a 5,000 tonne ship up to 44,000kW for a 560,000 tonne ultra large crude carrier (MAN 2007). Despite the huge step up in power for trains and ships, the modular nature of fuel cells means the technology could potentially be applied. 

7.3 Conclusion

Based on current expectations of progress, hydrogen fuel cell and battery powered HGVs could be technically and commercially competitive with diesel powered trucks of 31-44 tonne GVW within 10 years and potentially by 2025. Achieving this would deliver reduced carbon and pollutant emissions from HGVs as well as improving air quality and reducing vehicle noise concerns in urban environments. The use of renewable electricity to produce hydrogen by electrolysis could deliver zero well-to wheel emissions. Major challenges to be overcome include: reducing fuel cell stack and hydrogen storage tank costs by producing greater volumes; significantly reducing the forecourt pump price of hydrogen fuel; improving the fuel economy of fuel cell HGVs. Using historic replacement rates, 93% of the UK diesel HGV fleet (31-44 tonne) could be replaced over a 20-year period. If this was combined with policy incentives to replace the remaining diesel vehicles, then 2050 GHG emissions would reduce by circa 6.6 MtCO₂e and NOx emissions by 17,000 tonnes.

However, UK policy makers are currently playing little part in the development of first generation fuel cell trucks, with key technology being developed and trialled by companies in the USA, Japan and Scandinavia primarily supported by the US Department of Energy and individual businesses. The UK is gradually building a hydrogen fuel infrastructure, but this does not currently accommodate refuelling speeds required to satisfy the needs of commercial truck operators. From a policy perspective this leaves the UK as an interested spectator, relying on the developments of others and acting as a follower if fuel cell truck technology is a success. The result is that achievement of the UK’s Committee on Climate Change 2050 targets to reduce carbon emissions from Heavy Goods Vehicles by 80% relative to 1990 levels is possible but not controllable by the UK.

Limitations of this article
This research involved a wide-ranging review of a rapidly developing technology area where commercial interests often limit access to detailed published information. To produce an overview assessment, assumptions were made in several areas based on indications and statements rather than published papers. In particular, claimed fuel economy figures are plausible rather than certain and future fuel cell truck mark-ups and selling prices will depend on the choice of route to market by manufacturers (direct or via a truck dealer). As commercial hydrogen FCEV trucks appear on the market, more accurate technical information should become available.  

Recommendations for UK Policy
The speed of hydrogen fuel dispensing for trucks needs to be addressed. UK policy makers also have the opportunity to look beyond a first-generation fuel cell truck, to encourage research on the potential use of more fuel-efficient Solid Oxide FCs rather than existing Proton Exchange Membrane FCs. Combining this with the use of ammonia as a fuel could address the high cost of hydrogen storage tanks for trucks and extend the use of fuel cell technology to larger transportation such as trains and ships, giving the UK a future stake in the development of a new generation of fuel cell technology.

References

ABC News (2018). News report: Hydrogen fuel breakthrough in Queensland could fire up massive new export market [online]. Available at http://www.abc.net.au/news/2018-08-08/hydrogen-fuel-breakthrough-csiro-game-changer-export-potential/10082514 [Accessed 4 February 2020]

Afif (2016). Ammonia-fed fuel cells: a comprehensive review. ScienceDirect. Renewable and Sustainable Energy Reviews 60 (2016) 822–835

Alstrom (2018). Alstrom news release: Coradia iLint hydrogen train receives approval for commercial operation in German railway networks [online]. Available at https://www.alstom.com/press-releases-news/2018/7/coradia-ilint-hydrogen-train-receives-approval-for-commercial-operation-in-german-railway-networks [Accessed 4 February 2020 ]

Barbir & Gómez (1997). Efficiency and economics of proton exchange membrane (PEM) fuel cells. ScienceDirect. International Journal of Hydrogen Energy, vol. 22, no. 10, pp. 1027-1037

Bossel (2012). Rapid startup SOFC modules. Science Direct Energy Procedia 28 (2012) Pages 48–56

CARB (2018). California Air Resources Board news release: CARB awards $20 million in Cap-and-Trade funding to zero-emission technology demonstrations in freight, farm and passenger transportation [online]. Available at https://ww2.arb.ca.gov/news/carb-awards-20-million-cap-and-trade-funding-zero-emission-technology-demonstrations-freight [Accessed 4 February 2020 ]

Ceres (2018a). Ceres Power News release: Ceres Power unveils latest SteelCell advances at Fuel Cell Expo [online]. Available at http://www.cerespower.com/news/latest-news/ceres-power-unveils-latest-steelcell-advances-at-fuel-cell-expo/  [Accessed 4 February 2020]

Ceres (2018b). Ceres Power News release: Ceres wins £7m UK funding to support electric vehicle application with Nissan [online]. Available at http://www.cerespower.com/news/latest-news/ceres-wins-7m-uk-funding-to-support-electric-vehicle-application-with-nissan/ [Accessed 4 February 2020]

Commercial Fleet (2017). News article: ULEMCo awarded £1.3m Government funding for hydrogen fuel vehicles trial [online]. Available at https://www.commercialfleet.org/news/latest-news/2017/02/02/ulemco-awarded-government-funding-for-hydrogen-fuel-lorries-trial [Accessed 4 February 2020]

CSIRO (2018). Website news release: CSIRO tech accelerates hydrogen vehicle future [online]. Available at https://www.csiro.au/en/News/News-releases/2018/CSIRO-tech-accelerates-hydrogen-vehicle-future [Accessed 4 February 2020]

Daimler (2018). Daimler Website: The Mercedes-Benz Electric Truck. Connectivity meets eMobility [online]. Available at https://media.daimler.com/marsMediaSite/en/instance/ko/Daimler-Trucks-sets-up-global-E-Mobility-Group-and-presents-two-new-electric-trucks-for-the-US-market.xhtml?oid=40507299 [Accessed 4 February 2020]

DOE (2011). US Department of Energy: Technology Readiness Assessment Guide DOE G 413.3-4A [online]. Available at https://www.directives.doe.gov/directives-documents/400-series/0413.3-EGuide-04a/@@images/file [Accessed 4 February 2020]

DVSA (2013). Driver and Vehicle Standards Agency: HGV driver’s daily walkaround check [online]. Available at https://www.gov.uk/government/publications/heavy-good-vehicle-drivers-daily-walkaround-check [Accessed 4 February 2020]

EFCF (2018). Proceedings from the 13th European SOFC & SOE Forum 2018: Chapter 07 – Session A15: Cell and Stack Design & Characterisation [online]. Available at https://pdfs.semanticscholar.org/bac2/62a73cbdfa4916bb0ad70a056e332d8f42e6.pdf?_ga=2.222805019.1838995132.1580817884-1760909611.1580817884 [Accessed 20 August 2018]

Electrek (2018). News article: Elon Musk is ‘optimistic’ about beating Tesla Semi specs that competitors already don’t believe possible [online]. Available at https://electrek.co/2018/02/24/elon-musk-tesla-semi-specs-beat/ [Accessed 4 February 2020]

ITM Power (2015). News release: £4.9M STRATEGIC INVESTMENT BY JCB IN ITM POWER [online]. Available at https://ir.q4europe.com/Tools/newsArticleHTML.aspx?solutionID=3512&customerKey=itmpower&storyID=13573419&language=en [Accessed 27 August 2018]

MAN (2007). Man website: Propulsion Trends in Tankers [online]. Available at https://marine.mandieselturbo.com/docs/librariesprovider6/technical-papers/propulsion-trends-in-tankers.pdf?sfvrsn=20 [Accessed 4 February 2020]

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ULEMCo (2018). ULEMCo to Demonstrate First Zero Emission Combustion Engine Truck [online]. Available at http://ulemco.com/?p=2638 [Accessed 4 February 2020]

Zamfirescu & Dincer (2009).  Ammonia as a green fuel and hydrogen source for vehicular applications. ScienceDirect. Fuel Processing Technology, vol. 90, no. 5, pp. 729-737

This is part 6 of a seven part series which explores some of the issues around zero carbon vehicles and which future technologies might be best for HGVs to avoid carbon emissions. The seven parts are:

1. Understanding the Typical Power Requirements of an HGV
2. Basic Designs of Diesel, Battery and Fuel Cell Powertrains
3. Comparing Diesel, Battery and Fuel Cell Powertrains
4. Assessing Future Manufacturing Costs of Diesel, Battery and Fuel Cell Powertrains for HGVs
5. Costs of Hydrogen Fuel / Building A Hydrogen & Electric Charging Infrastructure
6. Commercial Viability of Operating A Battery or Fuel Cell Powertrain HGV (this post)
7. Summary, A Look at Developments Which May Help Achievement of Zero Carbon In-use HGVs.

Part 6: Commercial Viability of Operating A Battery or Fuel Cell Powertrain HGV

In Part 6, real world fuel economy figures from diesel truck operators are compared against estimated fuel economy for proposed fuel cell and battery HGVs, in terms of kg hydrogen per 100 km and for BEVs kWh per 100km. These are then compared with a truck operator’s capital and operating costs to examine overall annual costs.

6.1 Fuel Economy of Diesel HGV Powertrains

UK operational data on 38-44 tonne diesel trucks shows fuel economy of 7.6–8.5 mpg (US gallon 6.3-7.1 mpg) which equates to hydrogen usage of 9.9-11.1 kg/100 km (at hydrogen LHV). There is no indication of the average freight weight carried but US data shows that efficient truck operators run circa 20% empty and some cargos would be volume limited rather than weight limited, which would improve fuel economy compared to an always fully loaded vehicle (RHA 2018, FHA 2007).  

6.2 Fuel Economy of Hydrogen Fuel Cell HGV Powertrains

In the absence of published data with comparative drive cycles, performance claims regarding two hydrogen fuel cell HGV demonstrators from manufacturers Toyota and Nikola have been examined along with data from Ballard, a fuel cell manufacturer.

Toyota Project Portal Demonstrator & Fuel Fuel Economy

Toyota’s ‘Project Portal’ class 8 demonstrator truck, based on a Kenworth T680 “Glider” (a truck supplied without a powertrain) was announced in October 2017 (Kenworth 2018). It produces 500 kW for “short bursts” with 228 kW fuel cell output (two Toyota Mirai 114 kW fuel cell stacks) with 12 kWh of battery storage. It uses a fuel cell dominant design with 40 kg of hydrogen stored in four 10 kg tanks at 700 bar with a range of 320/km making fuel economy 12.5 kg/100 km (Toyota 2017, Trucks 2017a). The Toyota demonstrator operates in an area around the US port of Los Angeles. Driver feedback is that the truck causes less fatigue, is smooth to drive and quiet: “This is the first vehicle I’ve ever driven that I can hear the suspension when I drive down the road.” (Freightwaves 2018)

Given the short-haul nature of the Toyota demonstrator, likely to operate at urban rather than motorway speeds, the 500kW peak output is in line with expectations from the UK Short-haul HGV specification (468kW) modelled in Part 1.6. Fuel cell power output at 228kW is towards the top end of that expected by modelling. As the Toyota demonstrator uses two standard Toyota Mirai car fuel cells this may just be the consequence of component standardisation. Toyota have yet to produce any detailed comments on design choices or performance.

The 12 kWh of battery storage requires a battery power to energy ratio of circa 23 W/Wh to produce at least 272 kW for a short period of time. This is a surprisingly high ratio compared to the more common power to energy ratio of 5-10 W/Wh (Sakti 2014). Battery storage would be exhausted in under 3 minutes of peak power output, confirming the “short burst” nature of the peak power.

The Toyota Project Portal truck achieves 12.5 kg/100 km, based on 40kg of hydrogen storage with a reported range of circa 320 km. A Beta version of this truck has been announced, with an extended range achieved by additional hydrogen storage rather than any claim of improved fuel cell system economy (Autoblog 2018, Toyota 2018b).

Initial comparison between the Toyota truck (12.5 kg/100km) and typical UK diesel efficiency (9.9-11.1 kg/100km) is not favourable. However, Toyota have yet to provide detailed drive cycle data or weight of loads carried so specific reasons for poor fuel economy relative to diesel trucks are hard to identify. One possible avenue for future consideration may be the impact on fuel cell stack efficiency of delivering the much wider range of power outputs required for a fuel cell dominant 40-tonne truck using stacks originally designed for the much lighter weight Toyota Mirai car.

Ballard Modelling

Ballard (2018a) model a drayage truck not dissimilar to the Toyota Project portal with economy of 8.3 kg/100 km. This appears to be a battery dominant design, which permits the fuel cell to be turned off at low power requirements, unlike the Toyota, which may explain the better efficiency. It is modelled at overall 36,000 kg truck weight (rather than 40,000 kg) although this is not an unreasonable assumption given that the truck will not always be carrying a full load.

A collaboration between suppliers and the Swiss Co-op also reports a 34-tonne prototype truck with fuel efficiency of 7.5-8 kg of hydrogen/100 km based on a 100 kW Powercell manufactured fuel cell and 120 kWh of battery storage with peak power of 250 kW. The vehicle stores 34.5 kg of hydrogen at 350 bar. The fuel cell system efficiency is quoted at 52% and is a fuel cell dominant design. There are no specific details on any battery SOC changes for this fuel efficiency or typical journey cycles (H2 Energy 2018, Coop Mineraloel 2018).

Nikola One Projected Fuel Economy

Nikola Motor plan to launch the Nikola One Class 8 truck in the US in 2021. The specification is still somewhat fluid with different figures being mentioned in press articles and tweets from Nikola. The truck was believed to deliver peak power of 746kW with a 240kW fuel cell system (2 x 120kW stacks) with 60-80kg of hydrogen and 240-360 kWh of batteries powering a set of four electric motors delivering circa 735-746kW. Pre-production test models were launched in April 2019. No data is available on the pressure of the stored hydrogen (Tu 2016, Nikola Motor 2018).

It is believed to be a battery dominant design with a range of 800-1,600 km, intended for use as a long-haul trans-continental truck. The Nikola One is likely to see a wider range of extreme conditions than the Toyota, so a higher peak output and a slightly higher fuel cell output with more hydrogen storage is not unexpected. Fuel economy can be calculated at between 5-7.5 kg/100 km assuming the battery State of Charge (SOC) is the same at the start and end of the journey.

The Nikola One is estimated to achieve somewhere between 5-7.5 kg/100 km. A caveat is that Nicola claim an 800-1,600 km range without distinguishing between 60 kg and 80 kg hydrogen tank options, making an accurate assessment impossible (achieving 800 km on 60 kg of hydrogen delivers an economy of 7.5 kg/100 km, whilst driving 1600 km on 80 kg delivers 5 kg/100 km). Both fuel economy figures will be used to calculate truck annual operating costs, primarily to show the potential financial impact that improvements in fuel cell fuel economy can have. Until road testing data on Nikola One pre-production prototypes is published, these figures can only be considered as indicative. At 7.5 kg/100 km the fuel economy is still favourable, compared to a diesel powertrain. In the calculations it is assumed the battery state of charge is the same at the start and end of the journey. The Nikola One was originally anticipated to be offered with 240 & 360 kWh storage battery options but this may change as greater experience with the pre-production vehicles is built. for the purposes of calculations the 240 kWh battery storage option is assumed.

Fuel Cell Powertrain Fuel Economy Summary

The data above has provided some contrary indications on fuel economy. The Toyota Project Portal fuel economy (12.5 kg of hydrogen/100 km) is well below that of real world diesel truck data whereas the Nikola One fuel economy claims provide both a highly optimistic picture (5 kg/100 km) and a more cautious one (7.5 kg/100 km). The Nikola, Ballard and Swiss Coop figures are in line with academic studies that indicate hydrogen fuel cell powertrains have the potential to be more efficient than diesel in terms of Tank to Wheels (TTW) energy (Helmers & Marx 2012). The magnitude of the difference between the Toyota and Nikola estimates is hard to explain. There could be differences in the use of regenerative braking (there is no information on whether the Toyota truck uses it) and different assumptions on profiles of journey cycles and average weights carried. However, the Toyota’s poor performance against diesel powertrains, which do not use regenerative braking and are based on real world measures, creates a significant question over whether Toyota’s fuel cell dominant design approach is best suited to the high-power demands of HGVs. Limited evidence suggests that the battery-dominant design as proposed for the Nikola One may be better suited to heavy freight applications, especially as the greater battery storage capacity allows fuel cell power output to be more stable, creating opportunities to control fuel cell output at an optimum level of efficiency.

6.3 Fuel Economy of Battery Electric Vehicle (BEV) HGV Powertrains

As with the hydrogen fuel cell powertrain, the fuel economy of a BEV HGV is based on claims from manufacturers with demonstrators. The Tesla Semi is the most publicised of these. Announced in 2017, currently availability is indicated for summer 2020 with a “limited run” although demonstrators have been running for some time (CNBC 2019). Basic news/rumour is that 600kWh and 1,000kWh versions will be available with the latter offering a 640km range. This equates to fuel economy of 1.6 kWh/km (2.5 kWh/mile), although no drive cycle data is available and the Tesla website claims that energy consumption is less than 1.25 kWh / Km (2 kWh/mile) (Tesmanian 2020). For the basis of this article the 1.25 kWh /km figure will be accepted as an aspiration for 2025 production versions. An electricity price of £0.15/kWh is assumed for recharging cost, although this could vary significantly depending on the charging location.

6.4 Annual Operating Costs

RHA (2018) in the UK and ATRI (2017) in the US provide good overviews of costs faced by diesel powertrain truck operators, acquired through surveys. UK data is shown in Figure 22 which assumes annual mileage of 136,850 km (85,000 miles) per year for a 44 tonne 3-axle tractor unit & 3-axle trailer. US data is broadly in line on comparable measures. A number of costs, such as driver-based costs and repair and maintenance, are arguably similar for both diesel and fuel cell trucks.

Figure 22: UK Truck Operator – Annual Costs for Diesel Powertrain

Cost	£	£/mile	% costs
Vehicle Excise Duty	1,200	0.014	1.0%
Insurance	3,435	0.040	2.9%
Depreciation – tractor	14,580	0.172	12.2%
Depreciation – trailer	2,044	0.024	1.7%
Fuel	45,339	0.533	37.9%
Tyres – tractor	1,527	0.018	1.3%
Tyres – trailer	1,562	0.018	1.3%
Maintenance – tractor	8,729	0.103	7.3%
Maintenance – trailer	4,901	0.058	4.1%
Driver costs	36,354	0.428	30.4%
TOTAL	119,671	1.408	100.0%

For operating cost comparison purposes, annual truck depreciation and fuel costs have been combined in Figure 23 and then cost differences from diesel presented in Figure 24. Assumed fuel economy is 12.5kg hydrogen /100km for the 500kW Fuel Cell and both 5kg/100km and 7.5kg/100km have been calculated for the 750kW Fuel Cell. 125 kWh / 100km has been calculated for the Battery Electric Vehicle (BEV) truck.

Figure 23: UK Truck Operator – Annual Costs for Truck Depreciation and Fuel

Powertrain	1,000 units current price with H2 price £10/kg	10,000 units post 2020 price with H2 price £6.50/kg	50,000 units post 2025 price with H2 price £3.20/kg
Diesel – HGV	£59,919	£59,919	£59,919
Fuel Cell – 12kWh battery, 40kg hydrogen, 500kW power Fuel Efficiency: 12.5kg/100 km	£202,426	£133,489	£74,389
Fuel Cell – 240kWh battery, 60kg hydrogen, 750kW power Fuel Efficiency: 7.5kg/100km	£149,98	£97,141	£60,287
Fuel Cell – 240kWh battery, 60kg hydrogen, 750kW power Fuel Efficiency: 5kg/100km	£115,981	£74,701	£49,407
BEV – 1,131kWh battery, 750kW power Fuel Efficiency: 125kWh/100km	£82,356	£59,725	£55,901

Figure 24: UK Truck Operator – Differences in Annual Costs for Depreciation and Fuel

Powertrain	1,000 units current price with H2 price £10/kg	10,000 units post 2020 price with H2 price £6.50/kg	50,000 units post 2025 price with H2 price £3.20/kg
Diesel – HGV	–	–	–
Fuel Cell – 12kWh battery, 40kg hydrogen, 500kW power Fuel Efficiency: 12.5kg/100 km	£142,507	£73,570	£14,470
Fuel Cell – 240kWh battery, 60kg hydrogen, 750kW power Fuel Efficiency: 7.5kg/100km	£90,062	£37,222	£368
Fuel Cell – 240kWh battery, 60kg hydrogen, 750kW power Fuel Efficiency: 5kg/100km	£56,062	£14,782	-£10,512
BEV – 1,131kWh battery, 750kW power Fuel Efficiency: 125kWh/100km	£22,427	-£194	-£4,018

Shading meaning: white – competitive, red – uncompetitive, green – offers commercial savings

Figure 24 shows that by 2025 the 750kW Fuel Cell and the 750kW BEV could be competitive with diesel trucks on annual operating costs at a fuel economy of 7.5kg/100km and 125kWh/100km. At an “optimistic” fuel economy of 5kg/100km, the 750kW Fuel Cell would offer savings of circa £10,500 (9% of all operating costs). The 500kW truck would be uncompetitive at a fuel economy of 12.5kg/100km, with depreciation and fuel costs circa 25% higher than the diesel equivalent. The poor fuel economy makes it a weaker commercial proposition for truck operators , despite its lower capital costs. No allowance has been made for any additional labour costs from the slower “refuelling” of BEVs or the use of operator owned renewable electricity generation (wind or solar) to reduce recharge costs.

Truck Operating Cost Summary

By 2025 FC HGV trucks and BEVs could be commercially competitive with diesel equivalents, subject to achieving anticipated manufacturing volumes, technical developments, hydrogen fuel prices and electricity recharging costs. This assumes no significant introduction of charges for carbon or pollutant emissions for diesel vehicles or changes to fuel duty on hydrogen fuel or electricity for transport applications. As capital costs for FC and BEV HGVs are still likely to be higher than diesel in 2025, the key to competitiveness will be a combination of vehicle fuel economy and hydrogen/electricity fuel costs. Banning the use of diesel HGVs in towns and cities will also change the balance.

Part 7 provides a summary on the prospects of hydrogen fuel cell and battery electric HGVs and looks at developments which may help the achievement of zero carbon In-use HGVs.

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