Are clear skies a sign that we'll soon retire the combustion engine?

Clear skies seen over cities like Beijing and Seoul after industrial activity was scaled back and vehicles were taken off the roads during the COVID-19 lockdown demonstrated just how dirty fossil fuel technology can be.

But those skies give us a preview of what we might see if there were permanent reductions in fossil fuel combustion — including perhaps the retirement of the internal combustion engine in ground transportation.

Improvements in vehicle combustion engines

The internal combustion engine we're familiar with in cars and trucks today was a product of the 19th century. In 1876, Nicholas Otto introduced the Otto four-cycle internal combustion engine, the ancestor of most automobile gasoline engines today. In 1892 Rudolf Diesel developed another type  — the compression ignition engine — which of course was developed into the diesel engine that powers some cars, many trucks and commercial vehicles. 

These systems had huge advantages over steam technology because they could be much more compact. They could do away with the separate water boiler to generate pressure to drive pistons and use the expansion of the fuel itself. They also used new liquid or gaseous fuels that were frequently more convenient than the coal or wood used for traditional steam engines.

These new engines were less bulky, cleaner, quieter and more efficient than older steam technology and were widely accepted by industry to provide power in factories. 

Later, these stationary industrial engines were miniaturized and adapted for transportation. 

Of course there was a price to pay for this in the form of vehicle related smog. For much of the 20th century, vehicles produced noxious fumes and soot which made air quality in cities a huge problem. Unburnt hydrocarbons, and nitrogen oxides, which can in turn produce ground-level ozone, made air in cities unhealthy, leading to respiratory distress and, of course, unsightly yellow haze.  

This is quite aside from the vast amount of carbon dioxide they produced that is affecting the Earth's climate.

Today's vehicle engines are much cleaner thanks to catalytic converters and other technological improvements, and they get much better fuel mileage than the gas guzzlers of the past. But they're still not very efficient compared to an electric motor.

Combustion engines are complicated, with thousands of high-tolerance, fast-moving parts. That they work so well is a testament to the incredible engineering developments over a century that allow cars to turn thousands of explosions a minute into forward momentum. 

A small gas-powered car running at a constant speed on flat ground is about 20 per cent efficient, though that number can be higher or lower depending on the size and shape of the vehicle, the engine size and driving conditions. That means that of all the energy stored in gasoline, only 20 per cent of it is driving the car. Most of the rest of the energy is lost as waste heat.

On the other hand, electric motors are much more efficient and produce much less waste heat. According to the U.S. Department of Energy, "[electric vehicles] convert about 59 per cent to 62 per cent of the electric energy from the grid to power at the wheels."

Here's another way to think about it. Suppose you go for a fill-up and put $50 into your tank. Only $10 of what you spend will actually go to moving the car. The rest is just heating the atmosphere.

Cleaner electric cars not without pitfalls

Electric cars have been slow to take off, but there's little doubt that's changing. In some parts of the world, the internal combustion engine is already losing popularity. Norway set a goal that all new cars should be fossil-free by 2025. The Netherlands and Iceland have set similar standards for 2030. The government of India is providing incentives for a rapid production of electric vehicles to deal with its air pollution issues. 

The cost of electric cars is coming down as more manufacturers switch over, and battery technology is improving to provide more range, making it easier for consumers to choose electric the next time they go for a new vehicle. 

Before and after video shows the impact of the coronavirus lockdown on air quality in various cities around the world

5 years ago

Duration 1:10

An unintended consequence of the coronavirus lockdown has been a noticeable improvement in air quality. Here's a look before and after the lockdown began in various cities around the world.

Of course, there will be other issues to arise if all cars on the road become electric, such as where all that electricity will come from. Clearly fossil fuel generated electricity would be somewhat counterproductive, though there would still be efficiency gains.

Ideally, for maximum climate benefit, it will be from solar, wind, geothermal, tidal — perhaps solar power satellites — or all of the above.

Of course, all energy production comes with environmental costs, whether it be land flooded by dams, or wildlife deaths at wind turbines. There is also the cost of manufacturing batteries using limited resources like lithium and scarce rare earth metals. 

So research into cheaper, lightweight batteries, large-scale energy storage and perhaps alternative ways to extract energy from oil without contaminating the atmosphere could all be vital parts of our transition into a truly green economy. Green technology is already one of the fastest growing sectors of the economy, with tremendous potential for growth as current products improve their performance and new products come online.

Of course there will be challenges, but the clear skies over cities during the pandemic are an opportunity to ponder the next technological revolution.

Perhaps there will come a time in the not-too-distant future when internal combustion vehicles will sit alongside steam locomotives in museums as a reminder of a time when these noisy, smoky vehicles rumbled along our rails and roadways.