The past decade has been one of rapid growth in the uptake of electric vehicles (EVs) for transportation, with Europe becoming the largest market for electric cars for the first time in 2020. However, we’re still only at the start of our transition to cleaner, greener mobility with industries like construction still relying on diesel-powered vehicles. Here Steve Hughes, managing director at e-mobility power component specialist REO UK, explains how the electrification of construction trucks can reduce the industry’s environmental burden.
A report by the Global Alliance for Buildings and Construction estimates that 39 per cent of process-related carbon dioxide emissions can be attributed to the buildings and construction sector. While there is little research on how much of the global greenhouse gas (GHG) emissions can be attributed to non-road mobile machinery for construction, the sector itself could use up to 36 per cent of global final energy usage.
Electrification of excavation vehicles could go some way to reduce this environmental burden. However, construction relies on fleets of heavy-duty vehicles that can weigh more than 30,000 kilograms with added attachments. All this weight, combined with long working days and large building sites, adds to the challenge of electrification.
Diesel is still the popular fuel choice for construction workers because it packs approximately 27 times more energy per full tank compared to batteries and, therefore, can work all day without having to refill. If EVs are to compete in this sector, the vehicle components need to be efficient to extend the battery runtime for as long as possible.
Optimising battery life with braking resistors
When a driver applies the brakes on an excavator, heat is one of the main excess energies produced and lost. Regenerative braking involves recovering this energy and feeding it back into other vehicle processes, minimising losses and reducing the amount of required battery power. Braking resistors with good heat dissipation are needed to make sure excess energy is used productively and doesn’t overload the system. The braking resistors by REO UK, for example, use water-cooling for increased heat dissipation, allowing more energy to be reclaimed into alternative processes.
Because of the increased torque needed, braking resistors for heavy-duty construction vehicles must be able to manage a higher wattage than those used for normal EVs. They must also be small because heavier vehicles are harder to manoeuvre and, in many cases, less energy efficient. Some big construction vehicle manufacturers are currently trialling cable powered EVs, to eliminate the need for a battery and save on weight. However, these EVs would require better infrastructure and could be limited to small driving ranges.
Protecting EVs with better infrastructure
If a construction project manager has several building sites spread across a vast geographical area, a vehicle may have to leave its base for several days or weeks to complete a project. Therefore, if the infrastructure isn’t in place to accommodate EV charging, contractors can’t be expected to remain productive.
Improving the infrastructure will involve installing more charging points on building sites, fitted with harmonic filters. One of the challenges of increased EV charging is the threat of harmonic currents, which occur when AC power system voltages are converted to DC voltages. REO’s harmonic filter prevent harmonic currents from damaging the grid and overheating the capacitors and transformers in the vehicle. They operate by administering a counteracting frequency, which removes signal distortions and increases the reliability of the charging point, as well as the network stability.
To build a more sustainable future for construction, EVs will play an important role. To accelerate the switch, EV manufacturers need choose vehicle components that will prolong battery lifespans and protect the integrity of the charging infrastructure.
