What is the technology?
Battery electric vehicles (BEVs) use electric motors and motor controllers instead of internal combustion engines (ICEs) for propulsion. They derive all power from battery packs and thus have no internal combustion engine, fuel cell, or fuel tank.
BEVs use a battery pack that is charged up to store electric energy. The energy is released in the normal day to day running of the vehicle, heating, lights, wipers etc and also when the accelerator pedal is pressed.
The power from the battery energises an electric motor, supplying the necessary torque to rotate the wheels and give the vehicle propulsion.
There are two types of electric flow - alternating current (AC) and direct current (DC). Motors powered by DC can be found in an electric vehicle, but only as small, mini motors used to power things like the windshield wipers and electric windows, but not to power the vehicle itself. For the traction of an electric vehicle, an AC motor is required.
BEVs typically have 90% fewer moving parts than an ICE vehicle. The common components include:
- Electric engine/motor - provides power to rotate the wheels.
- Inverter - converts the electric current in the form of Direct Current (DC) into Alternating Current (AC).
- Drivetrain - BEVs have a transmission which sends power from the motor to the wheels.
- Battery - stores the electricity required to run a BEV. The higher the kW of the battery, the longer the range.
How is it produced?
Electric vehicles rely on regular charging from the local electricity network – in the UK this is known as the National Grid. Electricity is generated from a mixture of different sources, including fossil fuels such as coal, gas, and oil, along with renewable sources such as wind, solar and hydro, however, the mix is still dominated by fossil fuels with renewables having someway to go before they overtake fossil fuels.
For a full breakdown of the UK’s energy sources, see the UK Energy in Brief 2022 report
Environmental considerations
With no tailpipe to worry about, tailpipe emissions are zero on BEVS – no carbon, no poisonous gases. However, as alluded to above, the UK still relies heavily on electricity produced from fossil fuels but renewable energy sources are growing year on year and the UK currently generates around a quarter of its electricity from renewables.
Generating renewable electricity is the easy part though - storing it and balancing supply and demand through the grid is where the difficulty lies. The target date for 100% renewable electricity in the UK is 2035; whenever this point is reached in practice will be the day BEVs are, theoretically at least, zero emission vehicles.
All that said, even at today’s renewables levels, electric trucks still generate far less lifecycle CO2 than fossil fuelled vehicles, partly down to the increased energy efficiency of electric motors (around 90%) compared to diesel engines (around 40%). This is true even when the emissions from production and disposal are included in the calculation.
Fuel cost
Even in the current volatile energy market, the energy required to power an electric truck costs much less than that of a diesel truck. This is down to increased driveline efficiency combined with the lower cost of electricity compared to diesel. Electricity does not include fuel duty like diesel, although it includes VAT at 20% (which is unclaimable).
The fuel duty revenue, currently collected from fossil fuels, will decline over time as transport shifts to renewable energy. Road user charging is likely to be introduced to make up for these losses in the longer term, however these will apply to diesel vehicles too.
This reduced ‘fuelling’ cost can sometimes offset the additional capital cost of the vehicle, although this very much depends on the operation.
Vehicle cost
Today, electric trucks cost around three times more than diesel trucks, however, they are not three times more expensive to produce from a materials or labour perspective. Part of the increased cost is due to the battery and motor technology which is not built in-house like a diesel engine would be, and part is due to lower volumes and less economies of scale.
There will also be a premium from suppliers who want to amortise their development costs quicker in the early adopter market. Prices should soften over the long term but will unlikely always carry a heavy premium.
The total cost of ownership (TCO), which considers purchase cost, fuel cost, maintenance cost and depreciation, needs to work to drive mass adoption of electric vehicles. However, the fundamental that TCO comparisons can overlook is the increased capital cost that comes on day one.
Infrastructure
Depot based A/C charging overnight will be the most economical way to charge an electric truck, unfortunately it will be hard to only depot charge as the vehicle’s range will unlikely be high enough for a day’s work. On-the-road D/C charging will therefore be necessary for most operations. D/C chargers are much faster than A/C charges, but they are more expensive to buy and more expensive to install.
Megawatt chargers and vehicles capable of taking this current will be required and these are just beginning to be announced with standards and compatibility also emerging. Megawatt charging capability will be fundamental to minimise disruptions to the ways of working we are familiar with today. The chargers and vehicles however are only half the story; electrical capacity to the site in question to power the number of chargers simultaneously will almost certainly need to be upgraded, and safety procedures and equipment will also be required to manage the heat, the high current and the surprising size of the cables required to deliver this large volume of power so quickly.
Availability
Looking at the range of electric trucks offered by manufacturers today, we have 4x2 and 6x2 distribution rigids and 2 axle distribution artics, but many models and options are still limited. Some models such as 8x4s will likely only be available in the tridem format due to battery size making the more traditional configuration with twin steer axles at the front impossible.
Over time, more and more models will become available, however, the most common vehicle in the UK today, the 6x2 (midlift or twin-steer), poses a big problem for designers as the chassis space for batteries is extremely limited, especially where discharge equipment is also required such as a wet kit. The UK 6x2 artic will likely only be possible with some breakthrough in battery technology or as an extremely limited range model.
Range
Today, BEVs have a range typically around 30% of that of an equivalent diesel vehicle. The range will improve over time as battery technology develops and will also be mitigated to a degree with a dense network of megawatt chargers.
It is unlikely that vehicles capable of tramping multi days on a single fill will ever be possible with batteries as the main sources of energy. It may be necessary for some transport operations to reconsider their locations, and may require others to build new RDCs or depots to match the service levels we have today.
Payload
For vehicles operating at weights below 44 tonnes, a dispensation allowing increased weights is applicable to compensate for the additional weight of the vehicle to some degree, however for 44 tonners no such dispensation is possible as the limit is based on road strength so is unlikely to be changed.
With BEVs, empty vehicles weigh as much as full vehicles as the fuel is not consumed during the journey in the same way as diesel is. Perhaps the 44 tonne on 6 axles UK specific legislation will need to be reviewed at some stage, but for now reduced payload seems to be an inevitability. This will impact bulk hauliers and may have an impact on downstream processes that have grown up around current vehicle capabilities. Payload reduction, especially at 44 tonnes is something we are going to have to accept for BEVs.
Summary
It’s clear that there is still some way to go before BEVs are practical and affordable for anyone but the biggest or most profitable of operations today and it is also clear to see that sectors outside of distribution will take longer and likely suffer more compromises.
Certain sectors like heavy haulage (STGO), mobile plant and operations in remote locations require significant further development in battery technology if they are ever to work, or they will need some kind of exemption to continue to use liquid fuels.
As with any future ambition, there are still some unknowns in our path. For example, we don’t yet know if battery development will plateau and the current progress towards smaller, lighter and higher capacities will hit diminishing returns before a practical 6x2 artic is possible.
Running an electric truck or two in a fleet today is possible but with some compromises. Running even a small fleet is very much more complex and expensive and likely not possible until some of the above obstacles are overcome.
The continued development of electric motors and batteries also helps to make other solutions like hydrogen fuel cells or catenary a more viable possibility.
