Professor Hannah Daly:

I thank the committee for the opportunity to provide evidence and discuss this topic. I am a professor in sustainable energy at the school of engineering and the Science Foundation Ireland MaREI centre at University College Cork. I research options across the Irish energy system to deliver rapid decarbonisation. Even with the enactment of the far-reaching targets outlined in the climate action plan, the transport sector is set to significantly overshoot its allocated sectoral emissions ceiling. Carrying forward this overshoot to subsequent carbon budget periods would require increasingly infeasible decarbonisation trajectories after 2030, so mitigation measures must be enhanced and accelerated.

Carbon budgets are essentially fossil fuel budgets. While it is important to set targets for clean energy measures in the future, such as electric vehicles, EVs, public transport and biofuels, it is cumulative fossil fuel use that ultimately matters for climate change and for our legislated carbon budgets. Even though decarbonisation measures are starting to be deployed, fossil fuel use in transport is not falling and greenhouse gases are rising. We are running just to stand still. To illustrate, for example, the blending of biofuels in transport fuels is growing but petrol and diesel volumes have also grown so far this year, and are nearly back to pre-pandemic levels. The sale of full battery electric vehicles grew by 60% so far this year relative to the same period last year, and EVs now represent 18% of new car sales, which is a positive trend. However, despite this, the sale of fossil fuelled cars is also growing, in fact, by more than EVs. Meanwhile, even though public transport usage is growing, total car traffic volumes are as high as ever. According to the most recent census, nearly four times more children and students travel to school, childcare and college by car compared to 1986. Rates of walking, cycling and public transport use have fallen significantly since then. Car dependency is extremely high, and is a leading driver of greenhouse gas emissions in transport.

What we are here to discuss today is the type of cars being sold. That is another important driver of greenhouse gases. Cars are getting bigger and heavier, which is offsetting efficiency gains from technology improvements. The average mass of new passenger car vehicles sold in Ireland increased by 25% in the past two decades. Cars are now 300 kg heavier than they were in 2001. The mass of individual car models is growing but sales are also shifting towards larger and heavier vehicle types, such as sports utility vehicles, SUVs. That trend is not being caused by vehicle electrification. Larger cars require more energy and emit more CO2 because of a few factors. The greater mass requires more energy to move. The size and shape cause less favourable aerodynamics; these cars create more drag. Greater material requirement creates larger embodied carbon emissions at the manufacturing stage. Efficiency improvements in new passenger cars have stalled since 2014, partially because of this trend.

We did some analysis in UCC and we estimate that had vehicle mass remained as it was two decades ago, without the increase of 300 kg, the average CO2 intensity of new passenger cars would be 10% lower than it currently is, all else being equal. Over the lifetime of a car driving 300,000 km, this amounts to an extra 1,500 l of fuel. This aggravates cost-of-living expenses, energy import dependence and greenhouse gas emissions. That extra weight causes an additional 3.5 tonnes of CO2 emissions from a typical vehicle, and an additional carbon taxation burden on drivers. There is a compelling argument to include weight and vehicle footprint in the calculation of vehicle registration tax, VRT, for both fossil fuelled and electric cars. We undertook analysis which found that introducing a policy measure to cut the CO2 intensity of new vehicles from 2024 would reduce the cumulative emissions from the transport sector by 5.5 million tonnes of CO2 in the period to 2035, which would contribute substantially to addressing the projected overshoot of the legislated sectoral emissions ceilings.

While greater greenhouse gas savings can be achieved from addressing the weight of fossil fuelled cars, the increasing weight in EVs is also of concern.

Currently, Irish vehicle taxation does not distinguish between EVs on the basis of efficiency, weight or size, which is a missed opportunity. Heavier EVs are less efficient, consume more electricity and put additional strain on power generation and renewable electricity deployment as we decarbonise the power sector. A continued trend towards heavier EVs could create additional electricity demand equivalent to the electricity generated by 200 MW of onshore wind capacity, more than all the capacity added in 2022.

Speed is crucial for accruing carbon savings. Enacting a policy to reduce the weight of new cars and effecting that improvement in efficiency in 2024 has 28 times more impact on our carbon budgets over that period than implementing that policy in 2030. It is also fairer and more effective to apply taxation at the point of initial sale, rather than over a car’s use and lifetime. The new car market from now determines the second-hand car market in the next two decades and there is no policy signal to shift consumers to smaller or lighter cars. There are additional grounds for modifying car taxation to include weight and vehicle footprint on the grounds of public safety, given the additional hazards for vulnerable road users, as we promote walking and cycling, as well as the space larger cars take in urban areas, and their greater noise and air pollution.

There is a real urgency to expand the range of mitigation measures in the transport sector. The increased size and weight of passenger cars has various negative implications for fuel consumption and public health, which could be addressed through taxation.