The Truth About Electric Vehicles: Energy Efficiency – Combustion Engine Vehicles versus Electric Vehicles

I wanted to provide some more answers to the myths about electric vehicles. Last week, I discussed their environmental and public health impacts; this week, I will discuss their energy efficiency.

Please don't think that I'm an expert at all of this; I care about passing on the correct information to help counter the current negative media spin, and I have done my research to provide this.

Energy Efficiency – Combustion Engine Vehicles versus Electric Vehicles

Combustion Engine Vehicles

Internal combustion engine vehicles (ICE) have inherent inefficiencies due to their design and operation, such as the heat generated by burning the fuel used to power them. Only about 20% to 30% of the energy stored in the fuel is converted into actual mechanical power that drives the wheels. The rest of the energy is lost primarily as heat.

When the vehicle's fuel is burned, not all of it is converted into power due to incomplete combustion. This leads to exhaust fumes, which are also not used as energy.

When an ICE vehicle is idling or switched on and not moving, it still burns fuel, a significant source of energy inefficiency (this also creates air pollution from exhaust fumes), particularly in busy urban areas where people sit in traffic and stop frequently.

Electric Vehicles

The electric motors in an EV convert over 60% of the electrical energy directly into mechanical power to drive the wheels. This high efficiency is because electric motors involve less mechanical complexity and have fewer moving parts than an ICE vehicle.

Electric motors operate using electromagnetic force to generate motion. Unlike the combustion process in an ICE vehicle, which relies on burning fuel, the electromagnetic process is clean and efficient. The direct conversion of electrical energy into mechanical energy occurs without the intermediate step of heat generation, which happens with combustion engines.

Since no combustion is involved, electric motors do not generate significant heat from burning fuel. The absence of combustion means that almost all electrical energy can be used for vehicle propulsion rather than overcoming thermal inefficiencies.

Electric motors typically have fewer moving parts than ICE vehicles that use pistons, crankshafts, and valves. This means there is significantly less friction within the motor, which in turn means less friction and less heat generated during its operation.

Although electric motors and their associated components, such as batteries, generate some heat, EVs are equipped with advanced thermal management systems. These systems are designed to maintain optimal operating temperatures, reduce heat loss, and improve efficiency.

In some advanced EV designs, the heat generated by the motor and battery during operation is not just dissipated wastefully. Instead, it can be used through heat pump systems to heat the vehicles, thereby beneficially utilising what little heat is produced.

EVs can achieve much higher overall energy efficiency by converting a more significant proportion of electrical energy directly into motion with minimal heat loss. This translates into better performance and range from the same amount of input energy compared to ICE vehicles.

Since electric motors use energy more efficiently, the cost of driving an EV per mile is lower compared to driving an ICE vehicle. This is particularly noticeable, especially when comparing the electricity cost of an EV overnight home tariff to filling up with petrol or diesel. The overall price does increase if using public charging, as there is a 20% VAT levied on these charging costs, compared to 5% on home charging. (I will also discuss this in a later newsletter.)

An EV also uses energy recapture in the form of regenerative braking. This process converts kinetic energy into electrical energy, which is then stored in the battery and used for driving the vehicle. This capability further enhances the overall energy efficiency of EVs.

Using "regen" in an EV means you can use the accelerator to manage speed more efficiently than in a combustion engine vehicle. There is less need to use the main foot brake, so we call this "one-pedal driving," which is a joy to experience when you get used to it.

Electric vehicles with minimal heat loss contribute significantly to mitigating climate change by optimising their energy use and reducing the need for energy produced from fossil fuel sources.

This enhanced efficiency reduces individual vehicle emissions and supports the overall decarbonisation requirements in the UK.

To conclude this newsletter, I completely understand why people are concerned about the move to an EV; I was, too, before I moved to one. It's like stepping into the unknown, mainly as everyone has been so used to driving a combustion engine car for a long time.

But when it comes down to it, it's just a car. It has the same four wheels, steering wheel, body, windscreen, etc; it's just powered differently.

I loved my petrol VW Golf, but I knew how it was polluting and adding to my carbon footprint. My husband and I both recognised that we needed to make a change.

Thinking about it and doing your research is the first step; taking the leap and doing what we need to do to reduce our carbon emissions and the overall air pollution in our towns and cities is the second.

Thanks for reading

Liz