HYDROGEN - YOUR Electric is the future of transport
Emissions from transport, causing environmental issues such climate change and poor urban air quality, are on the rise. And this brings a demand for zero emission technologies.
But the solution for taxi and private hire vehicles may not necessarily be battery electric. Hydrogen is the most abundant element in the universe and can be used in a fuel cell to produce electricity to power vehicles.
Fuel cell electric vehicles (FCEVs) use compressed hydrogen gas and oxygen from the air in a reaction that generates electric power for the motor and emits water from the tailpipe - no greenhouse gas emissions.
There are now several FCEVs on the market, the first and one of the most popular is the Toyota Mirai (‘Mirai’ meaning ‘Future’ in Japanese).
The four-seater Mirai has a fuel tank capable of holding 5 kg of hydrogen, which is equivalent to around 500 km on the road; its top speed is 179 km/h and it can accelerate 0-100 km/h in 9.6 seconds.
It’s the vehicle of choice for a five-year pan-European project called ZEFER (Zero Emission Fleet vehicles for European Rollout, funded by Europe’s Clean Hydrogen Part- nership), which is researching the potential application of hydrogen in high-mileage fleets, such as taxis and private hire vehicles.
The project has deployed 170 Toyota Mirais across London (50 for Green Tomato Cars), Paris (60 for Hype) and Copen- hagen (60 for DRIVR) for private hire and taxi operations, with an additional ten Mirais for London Metropolitan Police.
As passengers are increasingly eco-conscious, and major cities commit to Clean Air or Low Emission Zones, zero emission vehicles are in demand.
Range anxiety and recharge times are potential barriers to adopting battery EVs, and sales of plug-in hybrid vehicles will soon be banned alongside petrol and diesel. With similar refuelling times and processes to conventional vehicles, hydrogen, could fill that gap.
Hydrogen also has a high mass-based energy density compared to other fuels: approximately three times more than diesel and 120 times more than EV batteries, which means larger increases in range bring only a small increase in mass (and heavier batteries need more energy to move).
Peter Joseph, one of the first Mirai drivers at Green Tomato Cars, is a fan of the vehicle’s credentials. “We all have to do our bit for the environment and the Mirai is at the forefront of that technology,” he said.
“The car is lovely to drive, like you’re almost floating on air as you take off as it’s so smooth and quiet. It’s really com- fortable and ticks all the boxes for me and my passengers.
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“I’ve had no problems at all with safety and I’ve always felt safe driving the car. When I first started, especially in the first six months, I had customers who knew that hydrogen was flammable and were keen to know the safety levels of the car.
“Part of my induction involved someone from Toyota talking us though their research into hydrogen and protect- ing the tanks to make sure everything runs above board so I’m able to reassure any passenger concerns.”
Since the first 25 Mirais were deployed to Green Tomato Cars in April 2018, over 7 million kilometres have been driven as part of the ZEFER project, using 72,000 kg of hydrogen - the largest dataset of its kind in Europe.
An additional 25 Mirais were added in October 2019, and according to the latest project data, the Mirais used by Green Tomato Cars averaged 180 km and 14 journeys per day, and 31 km/h.
The average annual distance driven by each FCEV taxi is 48,000 km; this compares to the fleet’s petrol/diesel and plug-in hybrid vehicles, which average 39,000 km/year.
Over the course of all these kilometres, and the inevitable collisions that occur, there have been no dangerous incidents involving the release of hydrogen or problems with the fuel cell system, and concerns have eased over the years.
One thing drivers have noted is the seasonal variations in fuel efficiency between summer and winter months. Generally, temperature has a negative correlation with vehicle energy consumption (i.e., fuel efficiency is lower in winter) due to factors including: reduced battery and mechanical efficiency, greater use of cabin heating during the winter and increased wind resistance.
Data from the ZEFER vehicles in London shows that fuel economy can be as low as 89 km/kg in Jan-19, compared to 119 km/kg at its highest in Sep-20; the average across the year is 105 km/kg.
Of course, fuel, and refuelling, is an important factor in transport operation, costs and emissions.
The zero emission credentials of FCEVs are reliant on hydrogen produced from renewable sources. Traditionally, hydrogen has been extracted using fossil fuels in a process called steam methane reforming (SMR), although this is not necessarily the case for hydrogen used in transport applica- tions.
Electrolysed hydrogen, a process of using electricity to split water molecules into hydrogen and oxygen, (referred to as ‘green hydrogen’ when using renewable energy), offers a true net zero solution that can integrate wind and solar sources of energy. This integration allows hydrogen to work alongside battery electric, to utilise excess electricity for hydrogen production and fill the gaps during intermittent production.
MAY 2022
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