Blog written by Dr. Ian Philips
_{Formatted and edited by Dr. Theresa Nelson}

I recently presented to researchers interested in issues relating to the uptake of Electric Vehicles (EVs) and the electricity supply Grid. These researchers from Leeds ITS and the Karlsruhe Institute of Technology (KIT) were primarily interested in electric-cars, but I started by pointing out that, technically speaking, e-bikes and e-cargo bikes are also EVs.

Colleagues within my own research group and others at Leeds argue strongly that to reduce transport emissions and meet carbon targets more broadly then we need to take energy demand reduction seriously¹. My colleagues explain (see Where next for transport and carbon budgets? and Rearranging Elephants on the Titanic) that we will not cut enough carbon if we just switch to electric cars (e-cars.) We have to reduce our demand for car travel, too. Further, a practical yet serious concern in the uptake of electric cars is that the transition from combustion engine to e-cars could place a great strain on the Electricity Grid.

Below is one of the three e-cargo bikes used during our ELEVATE Project trials, the Raleigh Stride. This specific e-cargo bike has a 500Wh battery, whereas the e-car batteries in the UK tend to be 50-100kWh, depending on the make and model. Let’s take a 75kWh e-car battery as an example.

Both the typical e-car and the e-cargo bike must be plugged into the grid, but the e-car batteries need roughly 150 more times more energy to charge them. On top of this, the e-cars must shift one to two tonnes of car whereas the e-cargo bike only weights about 35 kg… E-cargo bike batteries are moving smaller but more electrically efficient vehicles. 

Focusing more on charging, when we plug our e-car and e-cargo bike batteries in we again see the demand reduction potential of e-cargo bikes, a typical at-home wall charger for an e-car is 7.2 to 7.4kW, which means they require 21 times more power than an e-cargo bike or e-bike when charging.

So it’s possible that e-bikes will have a lower impact on the grid. But it can be taken much further than this (using a generic and simplified example).

Let’s say I have 2 combustion-engine cars and decide to replace them with two e-cars. For each e-car, the charger is 32 amps… that could mean 2* 32 amps = 64 amps.

The consumer unit in my house says 80 amps max… It’s after work, both e-cars are on to charge, and I decide to put on the oven for a Yorkshire pudding… If I put the electric oven on to do so (40 amps on average)… I’d be tripping fuses…

Now keep in mind this — two cars plugged in charging at the same time as you’re trying to cook your evening meal at peak electricity usage time— is the worst-case-scenario for domestic electricity grid thinking. What I’m providing here is meant to be a rough, simple, and illustrative example of electric grid issues. There are economists working on the pricing of electricity and pricing of cars. There is research looking into “smart charging,” e.g., making chargers come on at certain times to lessen the impact on the electricity grid. Further, there are engineers working on widgets, cables, and switch boxes to minimize this problem and make it much smaller of an issue. I am also NOT saying to keep your diesel car. We want and need to electrify our car fleet and reduce energy usage sooner rather than later (including reducing the number of cars we own); but, let’s carry on with our simplified, generic example…

What if, I instead, replaced my two combustion cars with one e-car and one e-cargo bike. Lets do the maths. E-car (32 amps) + E-bike (1.5 amps) + Electric oven (40 amps average)= 73.5 amps . This gives us a much more fuse-box friendly combination.

If we take a look at electricity substations -Bear with me I know it sounds like beyond trainspotting levels of nerdery here… but it’s important! – these might in some places serve what we might call affluent and less affluent homes. Many households have multiple cars, and many of these multi-car households are car reliant – living in rural areas with no public transport, and some households have “forced car ownership;²” – in other words the car(s) are a big expense, but without the cars, it would prevent those in the household from functioning… but the car(s) is still needed to get to jobs , get children to school, etcetera. If affluent earlier adopters, who can afford the electric transition faster, take the substation capacity – poorer, later adopters might not be able to get an e-car charger if the local substation is at capacity. This would create vulnerability³.

Now, back to e-micromobility, if e-bikes are a part of the transport mix then e-micromobility could alleviate our exposure to vulnerabilities and inequalities like this in our future.

For some people in some places, e-bikes e-cargo bikes and other forms of e-micromobility might be part of the solution, not just for helping the electricity grid, but for a just transition.

1. There is concern from these same colleagues that the CCC are placing too much emphasis on technology and not demand reduction, see for example “Technology in First Class, Demand Measures in the Rear View Mirror?” ↩︎
2. Also see Vulnerability to motor fuel price increases: Socio-spatial patterns in England ↩︎
3. More about the idea of transport vulnerability: https://doi.org/10.1016/j.jtrangeo.2019.05.009 ↩︎