Governments are increasingly incentivizing automakers to produce non-petrol vehicles. However, it remains unclear if these vehicles will produce lower emissions than traditional cars.
Jason M. Luk and colleagues from the University of Toronto, Canada, explore the potential implications of the US's corporate average fuel economy standards, which require petrol vehicles' fuel economy to improve while exempting non-petrol cars. They model the emissions of cars that run on either natural gas or electricity with various levels of fuel economy, and compare these to petrol cars that meet the 2025 target.
They find that vehicles using supposedly low-carbon fuels may sometimes produce higher 'well to wheel' emissions than future petrol vehicles. This could be because battery electric vehicles become heavier as battery size increases to improve driving range, or compressed natural gas vehicles become less efficient, as fuel efficiency technologies are avoided to reduce price.
The research shows replacing petrol-driven cars alone is insufficient to guarantee lower emissions from transport; the design of the alternative-fuelled vehicles also makes a big difference.
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Hope, M. Driving emissions reductions. Nature Clim Change 6, 541 (2016). https://doi.org/10.1038/nclimate3048
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DOI: https://doi.org/10.1038/nclimate3048
