Why hydrogen vs battery debate doesn’t need a winner: Understanding the emissions from ‘zero-emission vehicles’

Emission reduction by switching to electric vehicles is largely dependent on the energy source

By Shubham Srivastava
Published: Monday 19 December 2022
Hydrogen vs battery debate doesn’t need a winner: Understanding the emissions from ‘zero-emission vehicles’
Photo: iStock Photo: iStock

This is the first of a two-part series on battery-operated and hydrogen powered electric vehicles. Read the second part here

Governments across the world have set time-bound targets to phase out internal combustion engines (ICE) that run on fossil fuels and increase the percentage of zero-emission vehicles (ZEV) in their vehicle mix. 

The goals are in line with the energy transition and emission reduction commitments made by the countries under the Paris Agreement and, more recently, at the 26th Conference of the Parties (COP26) to the United Nations Framework Convention on Climate Change to restrict global warming to 1.5 degrees Celsius above pre-industrial levels. 

At COP26, India promised to derive half of its power requirements from renewable sources and subsequently bring down the carbon intensity of its economy to under 45 per cent by 2030. 

India has also signed a declaration during the UN summit to switch to 100 per cent zero-emission cars and vans by 2030-40.

Read more: Time for green hydrogen in India is now, says RK Singh; invites private players to invest

ZEVs are vehicles that do not emit any exhaust gases during operation. But the definition does not take into account emissions during the life-cycle of the vehicle or generation of its fuel.

Researchers have been debating over which of the two technologies — battery electric vehicles (BEV) and fuel-cell electric vehicle (FCEV)— is better on the basis of ‘well-to-wheel’ efficiency, mileage, refueling process or even driving experience.

Hydrogen and batteries are storage systems used to produce electricity to power the motor and propel the vehicle. BEVs run on electricity produced via chemical reactions between a lithium cathode and an anode. FCEVs use electricity generated by the reaction of hydrogen with atmospheric oxygen. 

The jury is also out on which one will stand the test of time. And for good reason. There does not need to be a winner as both these technologies have different use cases.

There is also scepticism among the stakeholders in the electric vehicle sector about the emissions caused to produce the energy to run these vehicles. Electricity and hydrogen generation emit greenhouse gases, but the lifecycle emissions are lower compared to vehicles running on traditional fuels.

Murky yet ‘cleaner’

The one point that critics have been trying to hammer home is that both the BEV and FCEV ecosystems rely on dirty energy sources dependent on fossil-fuels, nullifying the environmental benefits derived from using these vehicles. 

For this reason, environmentalists and researchers have drawn flak for advocating ZEVs as a solution to reduce the carbon footprint of the transport sector.

The electricity used to charge BEVs come from the grid and the hydrogen in FCEVs is largely produced using natural gas. 

India’s installed fossil fuel-based energy generation capacity was 57.9 per cent as of September 2022, while renewables make up for 29 per cent only, the country’s Union Ministry of Power estimated. The power sector in India is still largely coal-dependent, forming 50 per cent of the energy mix.

Over 90 per cent of the hydrogen used in the country is produced by ‘steam methane reforming’ (SMR), in which natural gas is made to react with very hot steam. The process releases large amounts of carbon dioxide. 

If SMR is used to produce hydrogen without capturing the CO2, it is called grey hydrogen. If CO2 is captured, it is called blue hydrogen. The carbon is captured either permanently or for industrial use. Hydrogen produced through electrolysis of water using renewable electricity emits zero CO2 and is called green hydrogen.

SMR is preferred because it is cheaper and more efficient, given the current demand for hydrogen globally.

Read more: Germany’s emissions-free trains: Is hydrogen fuel really a better alternative for transport?

But these technologies are still cleaner than ICE vehicles: Studies have revealed that even in their current state of being powered by fossil fuel-based energy systems, both BEVs and FCEVs produce much lower life-cycle emissions compared to petrol, diesel or CNG vehicles.

In 2021, the International Council on Clean Transportation, a US-based non-profit, estimated the life-cycle emissions of passenger cars with ICE, BEV and FCEV cars in four regions of the world, including India. The study assumed that the cars will be used for 15 years, with a lifetime mileage of 165,000 kilometres (for sedans) or an annual mileage of 11,000 kms. The mileage was assumed to decrease 3 per cent every year.

Life-cycle GHG emissions of sedan segment ICEs, BEVs and FCEVs registered in India in 2021

Source: International Council on Clean Transportation

In India, lifetime emissions of BEVs were estimated to be 19-49 per cent lower than petrol vehicles, depending on the extent of policy support. The upper limit (49 per cent reduction) was estimated for a scenario in which the Paris Agreement targets are met. 

With a solely renewable energy-based grid, BEVs were found to emit 83 per cent less greenhouse gases compared to petrol vehicles, the report showed. 

FCEVs that use grey hydrogen released 16 per cent less emissions than gasoline ICEs, according to the study. But the ‘20-year global warming potential’ of methane released as fugitive leakage during grey hydrogen production reduced the overall emission difference to just 6 per cent. 

Blue hydrogen FCEVs emitted 48 per cent lower than petrol ICEs, the researchers found. With green hydrogen, the emissions went down by 68 per cent. 

Read more: Role of hydrogen as a clean fuel for sustainable mobility

For petrol vehicles, lifecycle emissions include those during vehicle manufacture, fuel production and fuel consumption. For electric vehicles, emissions during vehicle manufacture, electricity / hydrogen production and battery / hydrogen tank production are calculated.

The biggest component of the lifecycle emissions of gasoline vehicles is that from fuel consumption. For electric vehicles, however, it is that from electricity / hydrogen production.

The quantum of emissions reduced by switching to electric vehicles, therefore, depends heavily on the extent to which clean energy sources are used to produce electricity or hydrogen.

Read more: 

Betting on green hydrogen to fulfil energy needs ‘risky’, finds study

Hydrogen costs to fall over 95% by 2050, predicts report

Blue-sky thinking: Net-zero aviation is more than a flight of fantasy

Net Zero by 2050 possible, but clean energy investments need to outweigh fossils fast: Report

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