In December 2023, RenewableUK published figures on battery storage capacity in the UK. It said the total is 3.5 GW, with 3.8 GW under construction. A further 24.5 GW has been consented, 27.4 GW has been submitted to the planning system and 25.7 GW is at an early stage of development but yet to be submitted.

One type of battery storage that is not considered in RenewableUK’s figures is the growing battery resource in the electric vehicles that represent a growing proportion of the UK’s transport sector. Electric cars are already being deployed in the balancing market, via aggregators such as Flexitricity, which is able to interrupt charging at customers’ homes to boost the power available to the system operator. Now companies with larger storage capacities to play with have an eye on the revenue streams available from using batteries to support the grid.

In southeast London Veolia is trialling a vehicle-to-grid (V2G) technology that will enable its waste collection trucks to power UK homes by feeding back stored energy from their batteries to the grid.

The project involves a fleet of 40 electric refuse trucks that collect waste and deposit it at the SELCHP combined heat and power plant. The trucks are charged in the adjacent depot, where the vehicles are parked from around 1pm to 6am, when not on collection rounds. Veolia has been trialling the use of V2G technology with two of the vehicles since April 2023.

Each truck battery holds six times the energy stored an average car. They depart the depot at around 6 am with a full charge and – except on extremely cold days – they return with the batteries at a 50-70% charge level. With the fleet parked for up to 18 hours, the vehicles can vary charging to help make instant adjustments to maintain local electricity supply parameters (frequency and voltage). They may also charge at times when power prices are low – typically the early afternoon or overnight – and export the power back to the grid at peak energy consumption times – typically 5-7 pm – when prices are high.

The vehicles batteries are 300 kWh, with 270 kWh of usable battery capacity, so discharging at a 100 kW rate from a full battery provides two hours of discharge to support the grid.

The first phase of the V2G trial performed by Veolia has been successfully completed, enabling two specially designed bi-directional vehicles to charge and discharge. Veolia now plans to expand the trial and test it out on the streets, using 40 Westminster council collection vehicles to pilot the innovation.

While they are parked, the trucks are performing the same function as stand-alone batteries, as they can recharge from the electrical grid, feed back stored energy from their batteries to the grid, contribute to grid stability by regulating frequency and voltage and even store excess energy for later use.

The fleet’s battery usage will eventually be managed to optimise battery health, the carbon intensity of grid supplies used to charge the batteries, revenue from frequency response services to the grid and power arbitrage.

Veolia said the first two trucks had been active participants in the electricity balancing market since April 2023. It said previous V2G trials had not opened up the market because each had used a different charging standard, but this trial uses common combined charging standard (CCS) technology.

Veolia said it plans to electrify all of its 1800 UK refuse collection vehicles by 2040, which will enable the company to provide around 200 MW of flexible power capacity to the grid.

In addition, Veolia will maximise the use of local energy from its waste-to-energy plants to power its vehicles. So chargers at the Landmann Way depot will be powered by low-carbon electricity bought under a power purchase agreement with the adjacent SELCHP plant and delivered via a 2.5 MW private wire. The company says the direct connection will enable the link to be provided more quickly than new connections to the local distribution network.

For the project, Veolia partnered with electric vehicle charger manufacturer Turbo Power Systems, vehicle repower experts Magnetic Systems Technology (Magtec) and EV charge point management software provider Fuuse, with support from technology provider, Advantics.

The V2G trial was demonstrated at a Veolia “energy day” where chief executive Estelle Brachlianoff stressed that there was 400 GW of “untapped energy potential” in energy efficiency across Europe that could be accessed by measures such as using waste heat. She said: “We need to innovate… and transform our traditional approaches to take advantage of untapped sources. This requires a change of mindset and a collective willingness to rethink the way we produce, distribute and consume energy. The success of the V2G demonstration illustrates this perfectly. By enabling electric vehicles to become active players in the power grid, we are harnessing their potential to balance energy supply and demand, reduce carbon emissions and promote renewable energy.”

Author: Janet Wood

This article first appeared in Modern Power Systems magazine.