Comparing efficiency of electric vehicles to petrol/diesel ones

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

17 April 2022

The natural question following up from last week’s article is: how do electric vehicles (EVs) compare with petrol/diesel ones in terms of cost of energy? The bus manufacturer, BasiGo has an interesting offer: you buy the 25-seater bus for Sh5 million and then you pay them Sh20 per kilometre to cover the cost of the battery – recharging, servicing and maintenance (including replacement when needed).

This is like buying a regular diesel-powered bus for Sh5 million and then paying the Sh20/km to meet the cost of fuel! The question then is whether this money would be enough to fuel the bus. The consumption rate depends on the model of vehicle and size of engine. However, one of the popular buses in Nairobi is the Isuzu NPR. This is actually a lorry fitted with a bus body! (There are very few real buses in Kenya – perhaps less than 10 per cent).

I checked the real-world data posted by owners of Isuzu NPR on the Internet (www.fuelly.com) and found that it consumes about 4.25km/L. This is an average taken from 48 vehicles running for 680,000 cumulatively.

Working backwards, 4.25km/L comes to about 0.235L/km. Therefore, at the current price of Sh115 per litre of diesel, this vehicle will need fuel worth about Sh27 per km. This is about 35 per cent higher than the cost of the electric bus. So, Sh20 per km looks like a pretty good deal.

However, BasiGo is a 25-seater, the Sh20/km works down to 80 cents per seat. The Isuzu NPR is usually a 33-seater and its fuel cost of Sh27/km comes to 82 cents per seat. In other words, the two buses have the same running energy cost per passenger. It is therefore best to wait and hear what the operators will say after a few months.

What about personal EVs: are they better than their petrol cousins? The website www.ev-database.org has data on nearly all electric vehicles in the market. The electricity consumption varies from 0.104kWh/km to 0.295kWh/km. The average is about 0.2kWh/km. (Of course, the quantity electricity is NOT measured in litres!).

The price of electricity in Kenya is currently about Sh21 per kWh; so, energy cost of an electric vehicle would be between Sh2.20/km and Sh6.20/km. The average is Sh4.20/km How does that compare with a petroleum fuel powered vehicle?

At the current price of Sh134.70 per litre of petrol in Nairobi, you will get 0.031L (that is, 31ml) of petrol for Sh4.20 – the average consumption for EVs. Working backwards, 0.031L/km comes to about 32km/L of petrol. I don’t know any car that reaches that level of fuel economy!