Electric vehicles are changing more than the cars we drive.
They are also changing how we think about electricity.
Instead of filling a tank with petrol or diesel, an electric vehicle can be charged at home, at work or at a public charging station. That creates an important connection between transport and the electricity system.
As electricity generation becomes cleaner, electric vehicles have the potential to become cleaner too.
But the relationship between electric vehicles and renewable energy is more complicated than simply plugging a car into a solar panel.
How Does an Electric Vehicle Work?
A fully electric vehicle, often called a battery electric vehicle or BEV, uses electricity stored in a large rechargeable battery.
That electricity powers an electric motor that drives the wheels.
There is no conventional petrol or diesel engine, fuel tank or exhaust pipe.
When the battery becomes depleted, the vehicle is connected to an electricity supply and recharged.
Plug-in hybrid vehicles work differently. They contain both a rechargeable battery and a combustion engine, allowing them to drive some distance using electricity before using fuel when required.
For clean-energy purposes, fully electric vehicles are particularly interesting because the energy used for driving can increasingly come from renewable electricity.
Where Does the Electricity Come From?
An electric vehicle itself doesn’t determine whether the electricity charging it is renewable.
That depends on the electricity supply.
An EV charged from a grid dominated by fossil fuels will indirectly be associated with more emissions from electricity generation than the same vehicle charged from a grid containing large amounts of renewable or other low-emission electricity.
As electricity systems add more solar, wind, hydropower and other low-carbon generation, the electricity used by EVs can become cleaner without anything about the vehicle itself needing to change.
This creates an unusual advantage.
A petrol car doesn’t gradually become cleaner because the electricity grid changes.
An electric car can.
Charging an EV With Rooftop Solar
For households with both an electric vehicle and rooftop solar, there is another possibility: charging the car using electricity generated at home.
During sunny periods, rooftop panels may produce more electricity than the household is using.
Rather than exporting all that excess electricity to the grid, some of it can be directed into the vehicle’s battery.
How much solar charging is possible depends on the size of the solar system, the vehicle, how far it is driven and whether the car is actually at home when the panels are producing electricity.
Someone who drives to work every morning and returns after sunset may have less opportunity for direct solar charging than someone whose car remains at home during the day.
Smart chargers can help by adjusting charging to periods when solar production is available.
Electric Cars Are Also Large Batteries on Wheels
The battery inside an electric vehicle can store a substantial amount of energy.
Most of the time, that energy has one job: powering the car.
But engineers are increasingly exploring ways for EV batteries to interact more intelligently with homes and electricity grids.
One example is vehicle-to-home technology, often shortened to V2H.
A compatible vehicle and charging system can potentially supply electricity from the car’s battery back to the home.
That could allow the vehicle to help power household appliances during certain periods or, where systems are designed for it, provide backup electricity during an outage.
What Is Vehicle-to-Grid?
Vehicle-to-grid, or V2G, takes the idea one step further.
Instead of electricity only flowing from the grid into the vehicle, a compatible EV can potentially return electricity to the wider electricity network.
Imagine millions of electric cars connected to chargers.
Some are charging. Others are parked with batteries containing more energy than their owners currently need.
With suitable technology, electricity pricing and grid management, a portion of that stored energy could potentially help support the electricity system during periods of high demand.
The vehicles could then recharge later when electricity is plentiful.
This doesn’t mean every EV will become a miniature power station.
Vehicle compatibility, battery management, charging infrastructure, electricity-market rules and consumer participation all affect whether V2G is practical.
But it demonstrates how EVs could become part of the energy system rather than simply another source of electricity demand.
Can Millions of EVs Overload the Grid?
Electric vehicles will increase electricity demand.
If large numbers of vehicles all begin charging at the same time — particularly during an existing evening demand peak — that can place additional pressure on local electricity networks.
But charging doesn’t have to be uncontrolled.
Many cars spend most of their lives parked. They may only need a few hours of charging to replace the energy used during the day’s driving.
Smart charging can move some of that demand to periods when electricity is more readily available or cheaper.
For example, vehicles might charge overnight when general demand is lower, or during the middle of the day in regions with abundant solar generation.
The challenge isn’t simply supplying more electricity.
It is increasingly about supplying and using electricity at sensible times.
Are Electric Vehicles Really Cleaner?
Electric vehicles have no exhaust emissions while driving, but that doesn’t mean they have no environmental impact.
Manufacturing a vehicle requires energy and raw materials.
EV batteries require minerals that must be mined, processed and transported. Battery manufacturing can also create significant emissions before the vehicle has travelled its first kilometre.
The electricity used for charging matters as well.
For these reasons, a fair comparison between electric and conventional vehicles needs to consider the vehicle’s full life cycle rather than only what comes from the exhaust pipe.
The environmental advantage of an EV generally improves when it is charged using cleaner electricity.
Battery production is also an area where recycling, improved manufacturing and responsible mineral sourcing will become increasingly important as electric transport expands.
What Happens to EV Batteries When They Wear Out?
An EV battery doesn’t suddenly become useless when it can no longer provide the driving range expected from a vehicle.
Some batteries may be suitable for a second life in less demanding applications, including stationary energy storage.
Eventually, batteries need to be recycled.
Recycling can recover valuable materials and reduce the need for some newly mined resources.
The battery recycling industry is still developing, and systems differ considerably between countries.
As millions more electric vehicles eventually reach the end of their lives, effective battery collection and recycling will become an increasingly important part of the clean-energy transition.
EVs Aren’t the Only Answer to Cleaner Transport
Electric cars can reduce the dependence of road transport on oil, particularly as electricity generation becomes cleaner.
But replacing every petrol car with an electric car doesn’t solve every transport problem.
Cars still require roads, parking spaces, tyres, raw materials and energy.
Walking, cycling and public transport can move people using far less energy and infrastructure in many situations.
Electric buses, delivery vehicles, vans and other commercial fleets can also play an important role.
The clean transport transition is therefore bigger than the electric car.
EVs are one part of a broader change in how people and goods move.
Renewable Energy and EVs Can Grow Together
Electric vehicles and renewable energy solve different problems, but they can complement each other remarkably well.
Renewable electricity can reduce the emissions associated with charging electric vehicles.
Smart EV charging can shift electricity consumption towards times when renewable power is abundant.
Rooftop solar can provide some households with their own source of vehicle energy.
And technologies such as vehicle-to-home and vehicle-to-grid could eventually allow parked cars to provide useful energy storage.
None of this happens automatically.
Electricity grids need investment. Charging infrastructure needs to expand. Batteries need responsible supply chains and recycling systems. Consumers need charging options that fit their lives.
But something fundamental is already changing.
For more than a century, road transport has depended heavily on liquid fossil fuels.
Electric vehicles create the possibility of powering much of that transport with electricity — and increasingly, that electricity can come from the sun, wind, water and other cleaner sources.
The car of the future may therefore be more than a way to get from one place to another.
It may become another connected part of the clean-energy system.
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