What is a hydrogen internal combustion engine, and can it be a real alternative to battery EVS?

In a world faced with more uncertainty than ever, the only well-documented certainty is that fossil fuels will soon be ditched in favour of alternative energy sources for mobility applications worldwide. Most automakers have already climbed aboard the promising electric mobility vessel, and are working to transition from internal combustion engine (ICE) vehicles to ones powered by lithium-ion batteries. However, not every player wants to head down that route, and some prominent names are evaluating other forms of power sources for future vehicles, including using hydrogen as a fuel in an ICE vehicle.

Haven’t hydrogen-powered vehicles been around for years?

Yes, the world has seen a variety of hydrogen-based fuel-cell electric vehicles (FCEV) – both in concept and production forms – over the last few decades. However, despite several attempts, no carmaker has been able to push FCEVs into the mainstream spotlight, and as such, they continue to be a rarity. At this time, the only FCEVs in production are the Hyundai Nexo crossover and the Toyota Mirai, with Honda recently having pulled the plug on the Clarity FCEV. Both the Hyundai and the Toyota use hydrogen to power the fuel cell, which turns the energy into electricity via a chemical reaction and powers an electric motor to propel the vehicle.

But it’s a complex process, and the application is expensive. Now, Toyota is proposing a more direct (and nearly as clean) solution in the form of an internal combustion engine that runs on hydrogen.

What’s different about a hydrogen combustion engine? Does it bring any benefits?

With an FCEV, there’s a lot to account for – the vehicle carries hydrogen tanks, the fuel cell as well as the electric motor or motors (depending on the vehicle configuration), all married into one cohesive unit. It also uses platinum, a rare ingredient that’s also quite expensive, for the oxygen reduction reaction in the fuel cell.

A hydrogen ICE, like the name suggests, simplifies the hardware, as it is essentially the good old combustion engine converted to run on H2. Existing engines can be adapted by changing certain components – such as the fuel delivery system and spark plugs – to use hydrogen instead of petrol or diesel, which means carmakers have a proven, time-tested base to build on and refine to further suit hydrogen applications, without making heavy investments on electric powertrains.

The primary purpose of using hydrogen would be to turn a car into an ultra-low emissions vehicle. With the combustion of hydrogen, the vehicle would mostly emit water vapour only. The reason why it isn’t a zero-emissions application is because a minute amount of carbon dioxide (CO2) is also emitted because of the burning of engine oil, and the combustion process in a H2 ICE leads to the emission of nitrogen oxides (NOx). While these emissions are significantly lower than a petrol/diesel vehicle’s, FCEVs better H2 ICEs on this front, as they are true zero-emissions vehicles.

What has Toyota done to push development of the hydrogen combustion engine?

Earlier this year, Toyota converted the 1.6-litre, three-cylinder turbo-petrol engine from the Toyota GR Yaris hatchback to use compressed hydrogen, and plonked it into a Corolla hatchback racer.

Motorsport, said Toyota, would be the best place to give the hydrogen combustion engine a shot at life, as learnings from the track would expedite the development process and help realise mass adoption of the powertrain at a much quicker pace. The Japanese auto giant tossed the hydrogen-fuelled Corolla into its toughest test right away, entering it into the Super Tec 24-hour endurance race at the Fuji Speedway, in May.

Toyota plonked the GR Yaris’ 1.6-litre, three-cylinder turbo-petrol modified to run on hydrogen, into the Corolla race car and entered it into the 24-hour endurance race at the Fuji Speedway. Image: Toyota

Admirably, the Corolla – driven by former F1 racer Kamui Kobayashi and Toyota Motor Corporation chief Akio Toyoda, among others – managed to finish the race in one piece. That said, it was off the pace – over 24 hours, the Corolla H2 could only log in 358 laps of the Fuji Speedway, which was almost half that of other conventionally-powered vehicles on the circuit. The Corolla – which logged a lowly average speed of 68 kph – also made more refuelling stops (35 in total) compared to the average of 20 for other participants, and each fuel stop also took longer (around six to seven minutes), meaning it had to stop for fuel roughly every 42 minutes, and of the 24 hours, spent close to four hours receiving refills.

In more promising showings, the Corolla H2 has since raced at the five-hour-long Super Taikyu endurance races at Autopolis and Suzuka, with Toyota claiming the hydrogen race car is now as powerful as the petrol-powered racer (which wasn’t the case previously), with acceleration boosted by 10 percent and fuel flow rate increased to slash the refuelling time to just two minutes. Performance is said to have improved in a big way, and enthusiasts will love the fact that it sounds more or less like a conventional race car, which is a refreshing change from the super-quick but dead-silent EVs. All this, while largely emitting water vapour.

Sounds great – but there has to be a catch, surely?

The reason why the Corolla H2 had to make as many refuelling stops as it did during the 24-hour endurance run was because of the reduced efficiency of hydrogen fuel as compared to petrol. Stored in high-pressure tanks in gaseous form, hydrogen – which isn’t as dense as petrol – suffers from volumetric inefficiency and requires higher amounts of storage and combustion capacity than conventional liquid fuels. The Corolla’s rear seats were thrown out to make space for the hydrogen tanks, which were stacked to the roof, completely blocking the view through the rear windscreen. With a road-going vehicle, the required storage for hydrogen tanks that would give a vehicle an acceptable travel range would eat into masses of interior space, rendering the vehicle largely impractical.

Rearward visibility in the Corolla race car was zero due to the rear seating area being occupied entirely by large hydrogen storage tanks, without which the car simply wouldn’t have the required range. Image: Toyota

Compared to conventionally-powered ICEs, hydrogen ICEs only offer between 20–25 percent efficiency, power output varies basis the energy density of the hydrogen/air mixture and hydrogen ICEs are also prone to knocking, which can negatively impact engine durability as well as fuel efficiency. However, the last issue can be overcome with the help of an exhaust gas recirculation system.

Then there’s the cleanliness of hydrogen fuel itself. At present, the process of creating hydrogen mainly involves the use of fossil fuels, which contributes greatly to CO2 emissions. This is a counter-productive solution, and the ideal and cleanest alternative, green hydrogen (produced by harnessing renewable resources), is significantly more expensive, costing anywhere between $3.5 to $6 per kg. Any significant drop in the price of green hydrogen is unlikely to happen before the end of this decade. Until that happens, running a hydrogen vehicle – on any other form of hydrogen – may actually be worse for the environment than running a fossil fuel vehicle.

And then there’s the hydrogen fuel infrastructure itself. While charging stations for battery electric vehicles are being set up almost every day across the world, there are only a handful of hydrogen fuel stations in major countries, meaning movement in a hydrogen vehicle is hugely restricted. The cost of setting up a hydrogen station – which is said to range between $2 million to $3.2 million depending on the type of station – is prohibitively high in most markets, and with hardly any hydrogen vehicles on sale, investing in one doesn’t make much business sense at this point.

To further complicate matters, while filling up a hydrogen vehicle only takes a few minutes, there would still be a wait involved at a station – a wait of as much as 20 minutes, as there needs to be sufficient pressure in the storage tank to be able to supply hydrogen to the car’s tank, which otherwise can’t be filled up fully. In case of mass adoption, queues at stations would be serpentine and not every driver would have the time to spare.

Even Hyundai’s recently revealed Vision FK hydrogen FCEV prototype can only do 0-100 kph in less than four seconds, which is notably slower than most high-performance EVs today, and the company itself admits the packaging of this prototype is

Safety also remains an area of concern for hydrogen storage facilities. High-intensity explosions at hydrogen refuelling and storage facilities in Norway and South Korea in the past have raised questions about how safe hydrogen – which is highly flammable – would be for mass uptake, and also led to resident groups opposing the establishment of new hydrogen refuelling stations and production facilities in their vicinities.

Lastly, hydrogen vehicles have been left far, far behind by BEVs on almost every front. Range anxiety is fast becoming a term of the past thanks to BEVs with larger, more efficient battery packs, and electric vehicles will always pip hydrogen vehicles when it comes to performance. Charging times continue to drop every year, and quick and constant evolutions in battery technology will almost certainly lead to batteries only needing as much time to charge fully as needed to fill up an ICE vehicle’s fuel tank.

Is India making progress on the green hydrogen production front?

The pursuit of green hydrogen is gaining pace in India. State-owned GAIL India Ltd has recently announced it will set up a 10 MW green hydrogen facility – the country’s largest such plant – over the next 12-14 months. Reliance Industries chief Mukesh Ambani has said the company, as part of its clean energy business, is striving to bring down the cost of green hydrogen down to as little as $1 per kg by the end of this decade.

The Indian government has already outlined safety standards for the production of green hydrogen, and Union Minister Nitin Gadkari has, on multiple occasions, advocated the uses of hydrogen as an automotive and industrial fuel, the adoption of which would help cut the country’s fuel import bill substantially.

Will hydrogen engines find application anywhere – or even become a feasible concept?

There does exist a use case for hydrogen combustion engines – specifically on the commercial vehicle side. Vehicles that have significantly higher uptimes than private use vehicles – such as heavy-duty trucks, buses and heavy machinery – are a perfect fit for hydrogen ICEs, as they need to operate for a set number of hours (and cannot afford to stop for long durations to charge their batteries), have fixed journey points and would struggle with the added weight of extremely large battery packs. Within a controlled environment and with a small number of hydrogen refuelling stations, such vehicles can easily make the switch to H2, and a number of manufacturers – including heavy machinery specialist JCB – are on their way to adopting a hydrogen ICE for their commercial vehicles.

A case could also potentially be made for hydrogen in motorsport. Races are conducted within a controlled environment where hydrogen fuel could be made available as needed, costs wouldn’t be as big an issue and viewers would be excited to hear the sound of combustion engines again, unlike in the pure-electric Formula E race series, deemed dull because of a lack of sound from the race cars.

Toyota and Hyundai are the two main carmakers who continue to press forward with their idea of a hydrogen-powered society, but some fundamental, game-changing technological breakthroughs would be needed for the hydrogen combustion engine to hit the big time, and even if those do occur in the coming years, BEVs will likely already have moved the game beyond the reach of H2.

Source: First Post

Tags: Alternative Fuels, Hydrgen fuel, Hydrogrn combustion, Toyota

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