Transport Decarbonisation is an Energy Problem
EV uptake poses both a challenge and an opportunity for future energy systems
Transport is currently the second-largest carbon-emitting sector in the world. In the UK, it has been the sector with the highest emissions since 2016, overtaking energy supply as we have moved to using renewable technologies. Understandably, reducing transport emissions is one of the priorities of our clients in the City Modelling Lab and the reason we have developed the Pandia tool.
Ultimately, transport emissions are an energy emissions problem; the fuels burned to drive our vehicles contribute to most of their climate change impact.
In a previous blog, we made the point that replacing our existing vehicle fleet with electric vehicles won’t save us. Here, I will reinforce that point by looking through an energy lens.
TL;DR: electrifying the vehicle fleet will put too much pressure on renewable energy supply, so must be implemented with parallel efforts to both reduce the number of trips people need to take by car, and shift the charging patterns of those who own and use EVs.
Electrifying all transport will hinder the transition to net-zero emissions electricity
Let’s assume that the current vehicle fleet is fully electrified. That is, all car, bus, LGV, and HGV trips remain the same, but they consume electricity, not fossil fuels. This would lead to around 230 TWh annual electricity demand from transport in the UK, increasing by 77% the approximately 300 TWh of electricity we consume today to power lighting and appliances in our homes, and cooling systems in commercial buildings.
This moves the goalposts on decarbonising the supply of electricity. Not only do we need to replace existing supply from coal and natural gas with renewable energy, such as wind and solar power, but we need to almost double that capacity again! It took more than 55 years for UK electricity demand to increase by 77% to today’s levels, and we might see it increase by the same amount again by 2050, less than 30 years away.
Arguably, this is an extreme example — surely, we will reduce our electricity demand in buildings and transport due to the increased efficiency of the technologies we use?
That is likely to help: the UK’s annual electricity demand peaked in 2005 before dropping about 13% by 2014.
Still, population increase and changes in demographics might counteract these benefits in the long term, or even lead to increased demand. For instance, all UK government traffic scenarios up to and beyond 2050 see more traffic on the road than today. On top of that, transport is not the only sector on track for mass electrification; heating demand is shifting from gas boilers to heat pumps, which could add another 150–200 TWh annual electricity demand (stay tuned for more on heating in future posts!).
The scale of electrification will ultimately surpass any efficiency improvements. To avoid putting our net-zero ambitions at risk, we must reduce the number of trips that people need to take by car.
Electric vehicles could exacerbate the mismatch between renewable supply and electricity demand
When we rely on wind and solar energy for our electricity, we have less control over when electricity is available to meet demand. If left to their own devices, charging patterns from electric vehicle owners are expected to follow a very similar pattern to electricity demand today — peaking in the morning and the evening. This is not the best time for renewable energy supply, which would peak in the middle of the day for solar and is highly variable for wind.
To match supply and demand, we need “flexibility mechanisms”, which come in many forms. We could:
- Install even more renewable energy than needed for the annual average to meet these peak demands, switching off the technologies when they are overproducing (known as “curtailment”).
- Rely more on international electricity markets to smooth out renewable energy by mixing supply from regions that are thousands of kilometres apart.
- Store the energy in periods of over-supply for use in periods of under-supply using water reservoirs, batteries, or even hydrogen.
- Include a sizeable amount of potential supply from technologies whose output we can control, such as from power plants operating on biofuel or whose emissions are captured and stored underground, out of harm’s way.
- Incentivise or even control when people consume energy, known as demand-side management.
Each mechanism has its advantages, and we’ll likely see a mix of them in play. Given the sheer scale of possible electricity demand from electric vehicles, demand-side management could be one of the best ways to balance demand. In work I did before joining the lab, I found that an EV fleet that charges when it is best for the grid would mitigate the need for large-scale storage solutions, biofuel use, and renewable energy curtailment in Europe.
Although the potential is there, there is still too much uncertainty to raise hopes that it can save us. We currently know so little about the extent to which electric vehicle charging patterns could be influenced, and the means by which it could be done. How effective might smart pricing strategies be? Would careful siting during charging infrastructure roll-out be enough? Would we be expected to plug in all the time with no clear idea of when our car will be charged?
The City Modelling Lab is well-placed to try and address these kinds of questions. With our agent-based modelling approach, we can analyse the effect of infrastructure choices and policy interventions on individuals. By aggregating those effects, we can build electricity demand from a future vehicle fleet from the bottom up, a vital piece in the puzzle for energy system planning.
Conclusion
The pressure that electrifying transport will have on renewable energy deployment is too high to allow us to make as many car journeys in 2050 as we do today — this is yet another reason to pursue increasing mode shares of active travel and public transport. Yet, some electric vehicle charging demand in future is no bad thing; if we can understand how to influence charging demand patterns in favour of the energy system, electric vehicles could become the key mechanism to balance the variable renewable energy supply-demand mismatch.
The challenges we face — and opportunities we can seize — in navigating the complex, interconnected systems in which we live are the focus of my work in the lab. I’m excited to share more over the coming months!
