Electric vehicles matter. Here’s why
The transport world is in an unusual period of transition. For the first time in over a century, the main way we carry energy to run our transport vehicles is changing. This change is slow but it’s gaining momentum.
In the early 20th century most of our transport received energy in the form of grass and hay. Horses were supplanted by cars, trucks and other motorised transport in a few short years. Now we are seeing a small but growing transition to vehicles using electricity as their energy carrier.
What do I mean by carry energy? All modes of transport we use rely on a source of energy to ultimately produce mechanical energy to drive their wheels, force high velocity gas from their jets, or drive their propellors.
The original sources of this energy have, for the past 100 years or so, primarily come from deposits of crude oil and natural gas in the ground. Even today, over two-thirds of the total energy used by transport come from these two sources. Where did the energy in these sources come from? Primordial sunlight energy was captured by photosynthesis in ancient plants. These plants were buried in the earth and slow natural processes broke them down into coal, crude oil and natural gas. It is this concentrated form of ancient sunlight that we now use to power our transport fleets.
These energy sources are typically unusable in their natural state. They can contain pollution-forming sulphur. They are mixed with water, which is bad for transport engines of all kinds. Crude oil is highly viscous and does not atomise well in fuel injectors, making it a poor choice for internal combustion engines. And natural gas often contains lots of carbon dioxide (CO2) which provides no heat when you try to combust it.
To make these fuels usable, we use processing plants to convert them to refined fuel products — natural gas, liquefied petroleum gas (a mix of propane and butane), petrol (gasoline), distillate (diesel fuel), kerosene (mostly used for jet fuel), and fuel oil for shipping. These refined fuels are chemically stable, contain much less pollution-forming chemicals, and are easily combusted in our vehicle engines to provide mechanical energy.
These refined fuels are energy carriers — they provide a convenient way for us to carry energy from their original crude oil or gas energy sources to our vehicles for final conversion into mechanical energy for our use. They are not sources of energy. This distinction matters, as you’ll see shortly.
The oil- and gas-derived energy carriers have served us very well. They have enabled the development of aircraft, private cars, trucks, and smaller water craft. They can be transported by pipelines, trains and trucks across countries or by ship around the world. They are convenient to use and usually affordable.
The downsides of oil- and gas-based energy carriers are well known. Using them makes pollution at the point of use — generating smog in our cities which negatively affects the health of people, especially the young and the elderly.
The energy sources (oil and gas deposits) are often remote from the people who want to use the energy carriers. This means some countries must pay other countries continuously for access to their transport fuel energy sources.
Energy source remoteness adds to transport costs for transport fuel and contributes to energy security concerns. 30% of maritime-traded petroleum is transported through narrow shipping channels in the Straight of Hormuz between Iran and Oman. This is a politically-unstable part of the world. In the event of conflict or blockades of this one narrow stretch of water, a significant amount of oil trade could be interrupted, causing significant spikes in the prices of transport fuels.
Using hydrocarbon fuels like petrol, diesel or natural gas also limits our options for the energy sources our transport ultimately uses. We do not have a feasible way to produce these energy carriers from any other source of energy than crude oil, coal or gas in the ground.
Switching to electricity as an energy carrier can change all that. We can produce electricity from almost any energy source we can think of. Wind, solar, hydro, coal, oil, gas, nuclear, geothermal — any of these can generate electricity which can be used for our cars. This helps address the security of supply issue that dogs oil-based energy carriers. Even countries not endowed with gas or oil can still make electricity from other sources.
Electricity also offers the potential for more energy efficiency. A conventional fuel-powered vehicle uses a heat engine to convert chemical energy in the energy carrier (petrol, diesel etc.) into mechanical energy to drive vehicle. Heat engines are naturally limited in how much of the chemical energy it is possible to convert to mechanical energy — this limit is described by something called the Carnot efficiency. As a result much of the fuel’s energy is wasted as heat. We can use this heat a bit, mainly to heat the cabin of the vehicle. But most of the heat is simply thrown away via hot exhaust gases or via the vehicles radiator or cooling system.
Power stations are often heat engines too — those that burn fuels like coal or gas are constrained by the Carnot efficiency limit. However, unlike a vehicle, a stationary power station has the option to put the waste heat to good use. If located in a building or near an industrial plant, the waste heat can be used for other purposes, avoiding the need to burn so much fuel for heating at those other places. And some power stations are not heat engines at all — wind or hydro power stations simply turn one form of mechanical energy, such as moving air or water pressure, into another — and thus are not limited so much.
By using this ability to get more value out of the energy sources we use, electricity lets us move our vehicles around using less of our energy source than is required using traditional or gas based fuels.
Electric vehicles have had, until recently, two key disadvantages that have kept them off the roads in any significant numbers.
Disadvantage One: they are expensive, primarily because of the difficulty of storing electricity in moving vehicles. Most of our electrical appliances are connected to the power grid directly, and thus don’t need to store electricity. The electric vehicles mostly used at present are electric trains and trams — which run on fixed rails and along fixed power lines. For vehicles like cars or trucks, we need to be able to move anywhere. The precludes fixed power lines.
So we need to find another way to store electricity in vehicles. We can do this directly with batteries. Alternatively, we can use electricity to generate a chemical fuel like hydrogen, and then convert hydrogen back to electricity in the vehicle using a fuel cell. Until recently both options were very expensive and impractical. Batteries could not hold much electricity per kilogram of weight, which meant big heavy batteries were needed to give even a modest range for the vehicle. Fuel cells require storage of hydrogen, which takes up lots of space and requires a high pressure storage tank. Batteries and fuel cells were both very expensive.
Even mass-produced electric vehicles from Tesla are still much more expensive to buy than comparable non-electric vehicles from other car makers. Tesla has dealt with this problem by “disruption from above”. It has built expensive luxury and performance vehicles of very high quality to compete at the high-price end of the vehicle market, where margins are highest. It is using the experience of building these high-end vehicles to help develop better electric vehicle systems that will be more affordable at lower price points.
But now, finally, batteries are beginning to overcome their cost disadvantage. The move towards larger levels of mass production is reducing the costs of batteries. Improvements in battery science and engineering are reducing their costs further.
Disadvantage Two: electric vehicles have had a limited range. Even modern electric vehicles like the Tesla Model S are limited in how far they can travel on a full charge of electricity, compared to a typical petrol or diesel vehicle with a full tank of fuel. And when the charge has depleted, it takes a long time to charge the batteries compared to the short time to refuel a petrol or diesel car.
The range disadvantage is becoming less of an issue as battery technology improves, allowing cars to store more electricity with less weight of batteries than before. Fast charging technology, much of it derived from mobile phone charging technology, has also improved the slow charging problem. The range concern is less of an issue for daily commutes to the workplace, where there is an opportunity to charge the car during the day and overnight between uses.
In time, however, with the improvements in the costs of batteries, reductions in battery weight, and steady reductions in the price of electric vehicles, it is easy to see how more and more vehicles on our roads can transition to electric over the next ten years or so. Many vehicles makers are following Tesla’s lead and developing electric vehicles of their own, which will further accelerate this trend.
Electric vehicles do have some advantages which will encourage their adoption once the price and range barriers are overcome. They have fewer moving parts and so have lower servicing costs and fewer mechanical parts to go wrong. For example, electric vehicles do not require a complex multi-speed gearbox like a fuel-based car, as electric motors can spin to any speed the vehicle needs. They produce much less waste heat than a conventional vehicle, removing the need for heavy and large cooling systems.
Electric vehicles are quieter, leading to lower noise in our cities, though potentially this may present higher risks to pedestrians crossing our roads. This makes for a more pleasant and quieter ride, and more pleasant life in our cities.
Electric vehicles also open up the packaging of the batteries and drivetrain. Instead of requiring a large space for an engine, gearbox and fuel tank, batteries can be oriented in almost any place in the car. The Tesla approach is to put the batteries in a wide and flat package under the floor of the car. The electric motors can be built into the wheels or into hubs leading to the wheels. This opens up a lot of extra luggage space, as well as the potential for new more radical designs for vehicles to improve safety, aerodynamics and performance.
Why does all this matter? Some of the implications will be profound. Around two-thirds of global crude oil production is used to make fuels for land vehicles (petrol and diesel, mainly). If demand for these fuels starts to fall, it will force a dramatic downward pressure on oil prices, with geopolitical and economic impacts across the world.
More countries will be able to become more self sufficient in their transport energy for the first time. This includes island nations that import most or all of their transport fuels. Electric vehicles will enable domestic electricity production (e.g. from wind, solar, hydro, as well as non-renewable sources like coal or natural gas) which will allow vehicles to run independent of supplies of crude oil.
Air pollution will fall significantly, especially in cities. By moving the energy sources (and their air emissions, if they burn fossil fuels) to power stations outside the cities, the air quality of cities will improve dramatically as electric vehicles take over. Central power stations also have much better capability to control emissions of air pollutants than millions of individual cars.
Individual consumers will be able to generate at least some of their own transport energy from home-based solar power units. It’s unlikely most consumers will produce enough solar-based electricity to meet all their vehicle energy needs, so some supplementation from grid power will still be needed. Still, it will liberate drivers from centralised oil companies for the first time.
The electricity grids will begin to operate quite differently. In most parts of the world, electricity demand falls to a low ebb late at night as people switch off appliances and go to sleep. In an electric vehicle world, this will be the time when cars will be charged. So significant new electricity demand will arise at night, requiring significant changes in how grids and their associated power stations operate.
Governments will need to find new sources of revenue. At present many nations receive large revenue streams from taxes on fossil fuels. As fossil fuel demand falls, this revenue will need to be made up elsewhere. If governments start taxing grid-based electricity supplies in response, this may encourage more people to invest in their own solar generation to harvest and use their own power.
This is a exciting time for energy geeks like me but it does present some significant challenges for governments, economies and businesses. The transition to more electric vehicles could happen much faster than people expect. I hope our political and business communities are getting ready.
David T. Kearns PhD is a Melbourne, Australia-based engineering and sustainability consultant with a background in process/chemical engineering. He established environmental and engineering consulting business Sustainable Services in 2015, offering technical and environmental services across a range of energy and resource industries. He is a lecturer in Sustainable Processing at Monash University and an occasional lecturer at the University of Melbourne.
Originally published at Sustainable Services.
