Hydrogen fuel cell cars have three times emissions of battery EVs - UQ study | The Driven
Toyota Mirai hydrogen fuel cell
A Toyota Mirai hydrogen fuel cell vehicle. Supplied.

A major new study from researchers at The University of Queensland warns that hydrogen fuel cell vehicles will likely have three times the emissions of battery electric vehicles, if using the main grid, and won’t make much environmental sense until the Australian grid is largely decarbonised.

The findings by the researchers, published last week and presented at the Australian Electric Vehicle Association’s annual conference on Friday, are an important reality check for consumers considering their next options on vehicles, partiuclarly if that choice is based on environmental concerns.

Research fellow and co-author Jake Whitehead says the reasons for the significantly higher emissions from hydrogen fuel cell vehicles (often abbreviated as FCEV, or FCV, or HEV) is because of the amount of energy required to create the hydrogen that powers the cells.

“Whilst some reductions are expected over the coming years, the universal laws of thermodynamics dictate that a minimum of 39 kWh of electricity is required to split 9 litres of water into 1 kg of hydrogen gas in a 100 per cent efficient electrolyser,” says the researchers, which include Robin Smit and Simon Washington.
“In addition, clean water must be supplied, requiring more energy. The hydrogen gas must then be compressed for use in transport, given its low energy density and standard atmospheric pressure, requiring another 15-20 kWh of electricity in total per kilogram of hydrogen gas, and then be distributed for use.
“One kilogram of hydrogen gas is expected to drive a FCV approximately 100 kilometres (under US EPA test conditions).
“This translates to an input of 80-100 kWh of electricity per 100 km travelled (after accounting to electrolyser inefficiencies and energy losses), compared to less than 30 kWh for BEVs (after accounting for electricity transmission losses).

Based on Australia’s average emissions for the main grid of 750g of Co2= per kWh (and it does vary from state to state),  it means a battery electric vehicle (BEV) is likely to achieve a 40 per cent reduction in emissions over an internal combustion engine vehicle (ICEV) – down from 355 grams of CO2/Km to 113 grams of CO2/km.

However, a hydrogen fuel cell vehicle powered from main the main grid is likely to produce three times more emissions than a battery electric vehicle – 647gCO2/kM, resulting in an 80 per cent increase in emissions over the petrol and diesel fleet we have now.

“H2 supply chain efficiencies may improve over time but even under the most optimistic scenario H2 FCVs will require 2.5-3 times the energy of EVs.”

And that means, according to the research by Whitehead and Co, that until Australia reaches a largely decarbonised grid, of nearly 100 per cent renewables, then hydrogen fuel cell vehicles will not deliver much in the way of emissions savings.

“Emission reductions from fuel cell vehicles are possible, but only …. when a switch has been made to renewable energy,” they say. “BEVs are the safest and most robust option of rapidly moving to a zero emission transport system.”

When the grid is decarbonised, hydrogen fuel cells cars will deliver emissions of 17gCo2 per km, while battery electric vehicles will deliver around 6gCO2 per km.

Of course, this does not mean that the electrolysers, like EV charging stations, can’t be fuelled by renewable energy. Most EV owners have their own solar supply on their rooftops, and most public charging infrastructure is claimed to be charged by renewables.

Hydrogen electrolysers could also put in similar arrangements, and facilities such as 1.25MW electrolyser in the ACT are based on the assumption that it will be powered by renewables – the ACT seeks to source the equivalent of all its electricity needs from renewables by 2020.

However, the UQ study notes that on the basis of 14 million passenger and light commercial vehicles in Australia, having a car fleet that is 100 per cent battery electric will require about 37TWh of electricity per year, or about 15 per cent of the country’s generation.

Having a fleet made up 100 per cent of fuel cell vehicles will require about 157 TWh of electricity per annum, or  63 per cent of Australia’s annual generation.

Hydrogen cars are starting to pop up more frequently in Australia, such as trials with local councils as part of a push to the development of a “hydrogen” economy, and exports of hydrogen fuels to Asian economies.

Again, the UQ study underlines, this will only make environmental sense if they are powered by solar or wind. The latest IEA report highlights that “green hydrogen” has a long way to catch up on fossil fuel power hydrogen on costs, although Siemens says this could happen within 5 years.

Hydrogen cars, however, have another major hurdle to overcome – and that is cost. According to the UQ study, the most common hydrogen car, the Toyota Mirai, has an upfront cost of more than twice most of its petrol, hybrid and full electric peers, and also a higher operating cost.





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