Planes, trains & automobiles (and trucks, anchorships, buses and… forklifts)
image credit: Solaris New Hydrogen Bus, 350km on 1 charge
- Jan 22, 2020 12:18 pm GMT
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As cities, regions and countries legislate for clean air and low carbon emissions, the transport market is ripe with opportunity for innovation, disruption and transformation.
About 96% of transport energy is derived from fossil hydrocarbons. Of the rest, most is biofuel (not without its controversies). Only about 1% of transport is electric; and not all using low-carbon electricity.
While bio and other ‘clean’ fuels continue development, much focus has shifted towards electrification.
Here most argument centres around the electricity generated aboard and used to propel electric vehicles (EVs). Will it come from energy stored in a battery or, via fuelcell conversion, energy stored as hydrogen? Will EVs be battery (BEVs) or fuel-cell (FCEVs)?
Planes, trains & automobiles (and trucks, ships, buses and… forklifts)
Ask a member of the public about hydrogen and they may have heard about hydrogen cars. They’ll likely never have seen one on the road though, nor encountered a hydrogen filling station.
Ask them about battery electric cars and they may well have seen one glide past. They will likely have seen charging points too, even if they still exhibit symptoms of ‘range anxiety’. If they are Norwegian and bought a new car in 2019, it was probably a BEV. Few can escape increased advertising from car firms committed to launching new battery-based models.
In the first nine months of 2019, Hyundai and Toyota (who dominate sales of hydrogen cars) sold about 6,000 between them, worldwide. For comparison, the UK alone sold more than four times as many pure BEVs in the same period. On a worldwide basis, the multiple was around one hundred and fifty times.
In the short-term, continued battery cost reduction and performance improvement, more vehicle choice and huge and growing investments in capacity across the supply chain - from raw materials to manufacturing to recycling - mean BEVs will dominate this segment.
Walk before you run
In order to identify useful lessons for hydrogen’s way forward, including transport segments where it might better compete, it’s instructive to highlight reasons for the success of BEVs so far.
The cost of lithium-ion batteries has dropped 85% in the past ten years, along learning curves that fall as production scalerises. That scale wasn’t driven initially by EVs but by demand from an entirely separate battery application: consumer electronics. Both fuel cell and hydrogen production costs need to follow similar learning curves to become competitive; so both need to concentrate on applications that can quickly build scale.
That means fighting battles in segments where it can compete. Some may not be in transport at all: cost reductions gained through industrial hydrogen, for example, can benefit applications in transport.
Refilling & infrastructure
BEVs have limited ranges, though growing as battery technology improves and larger batteries become affordable. Range might be a deal-breaker for some car purchasers. But for many it simply isn’t the problem some FCEV advocates claim; particularly when offset against factors including lower purchase and running costs and at-home charging convenience.
One side of the range equation is how often and how far people drive. Mostly this is infrequently and not far: well within the range of even small BEVs.
On the other side is how easily they can ‘refill’. The vast majority of BEV charging happens at home. It happens slowly, over hours, because the car is sitting there anyway. It involves no more infrastructure than plugging into the existing electricity supply. Increasingly, the ‘charging infrastructure’ for BEVs will appear anywhere where grid connections and motionless cars coexist: supermarkets, car parks, workplaces, cinemas...
So BEV owners look bemused when told that filling up in five minutes with hydrogen would be more convenient: they rarely even have to visit a filling station; and hydrogen would cost more anyway.
Of course for longer journeys, BEVs require fast charging stations. Tesla recognised this from the start and invested in their own supercharger network. Other charging networks exist, are growing and are getting faster. For most the biggest business challenge is that they are very under utilised; because few customers need them.
As BEV numbers grow, yes, the grid will need reinforcing. Yes, solutions will need to be found for those without off-street parking. But these are growth problems. They will be addressed incrementally, as the market scales beyond ‘early adopters’.
For hydrogen, the immediate challenges are barriers to entry, not barriers to growth. So applications which maximise the value of fast refills and minimise the need for new hydrogen distribution and filling infrastructure are key.
One segment, already serviced by more than 25,000 FCEVs in the US alone, is forklift trucks.
Whereas the average American spends less than 400 hours per year behind the wheel of their car, a forklift on single-shift operation can rack up over 2000 hours per year; even more if used over multiple shifts in 24/7 businesses.
Time spent charging is time being unproductive, so fast energy refills matter. Battery swapping is an option, but close-at-hand battery rooms for large fleets can eat up more space in a facility than a hydrogen fuelling point. That leaves less room for valuable stock. Only one hydrogen fuelling point is needed, perhaps linked to onsite electrolysis. There’s no need to wait for the ubiquitous roll-out of hydrogen infrastructure.
Perhaps hydrogen cars too will find their niche. This could be in segments where intensive usage requirements and higher refill opportunity costs exist. Or, further into the future, where technologies transform the way transport markets operate.
Imagine a future where car ownership dwindles because people prefer ‘mobility-as-a-service’ provided by fleets of cars, including autonomous ones. Like forklifts, being stationary means a fleet car is not generating revenue. Downtime is costly and constant ultra-fast charging could shorten battery lives. Hydrogen infrastructure costs can be minimised by siting and financing based on incremental market growth and learned analysis of routing patterns and trends.
In the short-term though, hydrogen will struggle to compete head-on with BEVs for the same customers. It needs to target market and customer segments where batteries can’t offer practical or economic solutions.
Heavy does it
Clean hydrogen means either ‘blue’ production (conventional means combined with carbon capture) or ‘green’ (electrolysis, using renewable electricity). Both may coexist. Though either source leads to local air quality and noise benefits compared to internal-combustion transport, green hydrogen is the climate purists’ choice: criticisms of blue hydrogen are that it perpetuates fossil hydrocarbon extraction and cannot capture 100% of the carbon released.
However there is an efficiency problem for green hydrogen when competing with battery transport. For each kWh of renewable electricity generated, losses from ‘generator-to-wheel’ in a BEV (grid, battery, AC/DC conversions, motors and so on) are low: perhaps 25-30%. For a green hydrogen-fuelled FCEV, losses during electrolysis (electricity to hydrogen) and then in the fuel cell (back to electricity), mean ‘generator-to-wheel’ losses are much higher. Even with electrolysis onsite, so no transport losses, at least 65-70% of the original renewable electricity is wasted.
In short, putting electricity in and out of a battery is a lot more energy efficient than turning it into hydrogen and then back to electricity again.
This obviously has an economic impact. All other things being equal, it needs a lot more valuable renewable electricity to power an FCEV than a BEV. So, for hydrogen to make competitive sense, all other things must not be equal.
Which brings us to the issue of weight.
Batteries are heavy. Hydrogen isn’t, but strong tanks to contain it at high pressure are, as is the fuel cell. For small vehicles, both BEVs and FCEVs are similarly obese: for example a Toyota Mirai is over 1,800kg and a Tesla Model S over 1,900kg.
But when it comes to increasing the amount of energy stored onboard a vehicle, BEVs and FCEVs differ in how vehicle weight scales.
Storing more energy in a BEV means adding more batteries. If you need to move something very large for a long distance, needing lots of energy, that means a lot more weight. More weight for the battery means more weight in the supporting vehicle structure too.
Storing more energy in an FCEV means adding more hydrogen – which is light. Of course higher volume storage tanks weigh more than smaller ones, but this doesn’t scale in direct proportion to the energy stored, in the way that batteries do.
As the energy storage capacity of a system gets bigger, the higher energy density of hydrogen beats battery storage – in terms of both system weight and size requirements.
This matters for transport applications involving big vehicles which have to carry this stored energy over long distances with them: heavy trucks, buses, trains, ships and aircraft.
The heaviest trucks require about 8 tonnes of batteries for a range exceeding 500 km. The weight of an equivalent hydrogen system is about 1.5 tonnes. More weight in the drivetrain means less cargo capacity. With more energy storage, refilling time differences become more acute too.Reduced cargo capacity and longer filling times are both opportunity costs, potentially creating economic disadvantage.
Batteries also weigh the same whether full or empty, whereas a hydrogen system’s weight decreases as fuel is used. Hydrogen is light, so this is a minor consideration in most cases, but there could be examples (long-haul flight, for example) where this provides another important ‘total journey’ advantage in future.
So when do the opportunity costs and other practical barriers of increased battery weight, volume and charging times, outweigh their ‘generator-to-wheel’ energy efficiency advantage?
This is a key question for the relative competitiveness of FCEVs and BEVs in various transport segments.
There’s no simple answer of course!
This is a shifting playing field. Battery energy densities are improving and costs reducing. But electrolysis and fuel cell efficiencies are improving too - and their costs coming down.
Competition and coexistence
Customers for heavy vehicles are businesses, not consumers. They are less swayed by ‘sticker’ costs, technology wars, colours of hydrogen and energy efficiencies, than by suitability for a given task and by total costs of ownership:fuel, maintenance, reliability and asset lifetimes.
Both start-ups like Nikola and established heavyweights like Hyundai are signing ‘all-in’ deals with customers for hydrogen trucks, which include the cost of fuel. Nikola, like Tesla with its supercharger network, recognise the need to develop infrastructure of strategically located hydrogen filling stations, if they are to persuade long-distance trucking companies that fuel will be accessible.
Some trucks run on stable routes and schedules. The same is true of buses too. In such cases, if hydrogen is available at the start and end, and range sufficient to get between the two, widespread hydrogen infrastructure is not an issue. These are the kinds of situations in which hydrogen transport could first succeed.
Nevertheless, Nikola (amongst others) also recognise that hydrogen is not the best solution for all their target customers’ needs. They intend to offer battery-trucks and hybrids too.
Similarly in shipping, Norwegian company Norled claims theirs will be the first hydrogen-powered car ferry when it starts operating in 2021. Having launched the world’s first battery-powered car ferry back in 2015, it’s another example of choosing the technology which best fits its needs. Similar to transit and urban buses, many passenger ferries suit batteries because they go short distances, stop regularly and don't need to go fast. For Norled, choosing hydrogen for its newest ferry allows increases in both range and speed: a different solution to a different requirement.
In trains, a similar segmentation is likely to emerge, based on range and speed requirements. Battery trains and associated charging systems already exist, on low-speed lines with ranges up to 100km. But companies such as Alstom are amongst those looking at more ambitious plans; refitting existing stock to achieve ranges up to 1,000km and speeds of 140km/h, utilising hydrogen.
Not surprisingly aviation is the least developed segment in terms of electrification.
Eviation, an Israeli firm, made headlines at last year’s Paris airshow with the launch of its prototype battery plane; aiming to carry nine passengers up to 1,000km by 2022. In the hydrogen space, in the same timeframe, ZeroAvia aim to carry up to twenty passengers over a range of around 800km.
Electrifying the largest-capacity intercontinental flights is a long way off though - it may never happen. Hydrogen may instead be used in the production of synthesized liquid jet fuel replacements (‘synfuels’). Companies such as the Dutch start-up SkyNRG are working on such technology, though costs are currently prohibitive.
However aviation is also an example of a sector with attractions to hydrogen beyond the aircraft.
Airports provide a range of carbon-intensive transport applications: buses, luggage tractors, forklifts and various other service vehicle fleets. Any investment in centralised hydrogen fuelling capability can be repaid through multiple uses. Stationary fuel cell applications can be interesting too: from baseline electricity and heat provision to back-up or remote power capabilities.
Plenty to play for, but stay focused
If anyone states with absolute certainty that hydrogen will never compete with batteries in transport, treat them with extreme caution. So too those who claim that batteries are only a temporary bridge to a glorious hydrogen-dominated future.
Battery-powered transport is off and running, across multiple sectors. Its capabilities are only improving. It isn’t going away. Hydrogen is playing catch-up.
But transport is a diverse sector and each segment in turn has a diverse set of users and usage requirements.
It’s unrealistic to think one propulsion solution fits them all. Simple, single-factor energy efficiency, energy density or other analyses don’t provide firm conclusions. Ultimately customers want something to fit their particular needs and make decisions based on multiple factors.
The short-term imperative for hydrogen proponents is not to be distracted by grand dreams or long-term barriers to growth, but to focus on customers for whom hydrogen works best in the short-term and where barriers to entry can be minimised.
References & further reading
1. FCEV sales by Hyundai and Toyota: https://www.greencarreports.com/news/1126247_hyundai-on-track-to-become-world-s-top-seller-of-hydrogen-powered-cars
3. Two articles with a variety of information on hydrogen trucks, including progress from Nikola and Hyundai: https://www.commercialmotor.com/news/buying-advice/closer-look-hydrogen-fuelled-trucks & https://www.trucks.com/2019/11/12/hyundai-nikola-toyota-build-hydrogen-highway/
4. Nikola working on battery electric trucks too, in this case in partnership with Iveco: https://www.ttnews.com/articles/iveco-nikola-begin-work-battery-electric-truck
5. An article on recent hydrogen train announcements, including Alstom’s retrofitting for long-distance and high-speed using fuel cells: http://www.fchea.org/in-transition/2019/9/23/hydrogen-powered-train-blog-update
6. An example of a 100km-range battery train from Vivarail: https://www.railtech.com/rolling-stock/2019/03/20/battery-trains-a-good-alternative-to-diesel-trains-or-electrification-of-railway-lines/?gdpr=accept
7. The world’s first hydrogen-powered car ferry (due in 2021): https://www.energylivenews.com/2019/07/02/worlds-first-hydrogen-car-ferry-to-hit-the-water-in-2021
8. The Scottish Islands are evaluating hydrogen ferries: https://www.cruiseandferry.net/articles/scotland-explores-feasibility-of-hydrogen-powered-ferries
9. ZeroAvia, with UK government support, working in hydrogen planes: https://www.energy-reporters.com/storage/uk-govt-funds-hydrogen-plane-project/ & more details here: https://www.fastcompany.com/90388931/this-plane-can-fly-500-miles-powered-entirely-by-hydrogen
10. Eviation’s battery electric plane: https://www.bbc.co.uk/news/business-48630656
11. Other applications of hydrogen in aviation: https://www.airport-technology.com/features/where-could-hydrogen-be-used-in-aviation/
12. SkyNRG and synthetic aviation fuels: https://www.bbc.co.uk/news/business-49725741