I won’t make myself popular by saying this, but I’m pretty sure I will witness, in my lifetime, the death of diesel engine.
That does rather depend on whether the Grim Reaper spares me for another decade or so, but despite all the advances in emissions control for diesels (and bus and coach engines are, beyond doubt, very clean) two spectres hover over them.
The first is the problem of fossil fuels. While it’s possible to run compression-ignition engines on vegetable oils, several studies have pointed out that, to do so, our farmland would have to be turned over to fuel cultivation; with the global population growing exponentially, that space is needed to grow food.
These days, I refuse point blank to discuss fossil fuels with climate change deniers. Whether or not you think man-made carbon dioxide is the culprit, the fact remains that CO2 is increasing in the air we breathe at a rate far faster than any global, cyclic change. If cutting transport emissions will help, we need to do it.
The second reason it may be time to ditch diesel – and petrol, for that matter – is an economic one. There are upwards of 1,500 moving parts in a four-cylinder IC engine. Potentially, using hub motors, an electric vehicle drive needs a dozen. Potentially, electric vehicle drives require no maintenance (and don’t require a gearbox or retarder unit, for example), and don’t need gallons of lubricating oil or AdBlue.
Even paying full whack for electricity, it’s a lot cheaper per mile than derv. You don’t need tankers to distribute the fuel. There are just so many ‘plus’ points that it’s hard to see the negatives… until someone mentions batteries.
Batteries are, it must be said, a Work in Progress. Lithium’s a scarce resource and, in batteries, can be tricky and uneconomic to recycle. That said, partly-spent vehicle batteries may well find a second life as static batteries for recharging stations, and in that role, could be useful to ‘bank’ solar energy during daylight, when most vehicles are in use.
Great minds are at work in battery technology, and their energy density is increasing very quickly, as are methods of charge control. The gains are making this technology very attractive for investors. In a very short time, we will be seeing batteries and charging systems which make sound sense.
When that happens, the economic argument for electric buses will be won. And it is the economic argument which will see wholesale adoption of electric buses, not political dogma.