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18 August 2017

Enel and Nissan claim V2G storage trial success, plan expansion

Italian utility Enel is looking to turn the tables by using EVs as storage assets rather than potential blackout liabilities. Utilities are already bracing themselves for costly upgrades to their network infrastructure and generation capacity, as more electric vehicles come to market, but Enel is looking at using stationary cars as mobile battery storage for the grid.

The growth in the number of proof of concept projects in the V2G area is impressive, and demonstrates a momentum towards a world where every EV could potentially act as a grid asset and generate income for their owner. Earlier this year, Riot covered a V2G project involving Hitachi and Moixa on an island off the coast of the UK. The US military has also been using EVs in partnership with Kisensum to access California Independent Systems Operator (CAISO) frequency response contracts – using 42 Nissan Leafs.

As automakers sell more electric vehicles (EVs), a utility will have to deal with a significant increase in demand on its network at peak times, when commuters return home to recharge their cars – while at the same integrating more renewable generation capacity, as its costs come down.

Last August, Nissan began a project with Enel to test the potential of a vehicle-to-grid (V2G) system. The project saw 10 Nissan e-NV200 vans hooked up to Danish utility Fresriksberg Forsyning’s network infrastructure, over a two-way communication grid connection – allowing the car to draw energy from the grid but also to send energy back on to the grid if necessary. The combined total capacity of the vans was 10kW.

Over the course of the year, each vehicle earned $1,530 from the utility by allowing it to exploit the vehicle’s spare battery capacity. The project appears to have been successful and will provide a model for V2G testing on a larger scale in the future.

A utility can justify paying to use an EV’s spare battery capacity, because of the impact changes in demand and supply have on a utilities network – as long as the cost of the payments is lower than potential outages or the capex of installing the storage itself. More renewable sources of energy generation, such as wind, are making the network’s alternating current (AC) frequency more difficult to manage – and failure to manage AC frequency can result in outages.

A utility needs to keep AC frequency within a tight tolerance band across its network, to ensure that generating assets are synchronized. If demand is greater than generation supply, the frequency falls, while if generation is greater than demand, the frequency rises. When the AC frequency of the grid changes within a far enough distance of the original band, an asset still generating energy at the original AC frequency can no longer deliver power on to the grid – potentially causing huge outages.

Critically for this project, there are four ancillary balancing markets, where utilities can purchase energy storage capacity to regulate the AC frequency of their network. It is through these market that the vans are registered as a storage asset and a utility can pay to use their spare capacity – offloading excess electricity when needed, or drawing from batteries if there is a shortfall.

The number of EVs globally is set to increase at a faster pace than was previously anticipated, as automakers like Volvo announce that it will no longer produce solely petrol driven vehicles. The increase in the number of EVs on the roads presents a large opportunity for utilities to exploit all this extra battery capacity in balancing the grid – if they can sign the right deals.

Denmark has long been a leader in renewable wind generation and has years of experiencing integrating the renewable into the energy network. Balancing the network has involved developing systems of highly accurate weather forecasting. Denmark uses more wind power to meet electricity demand than any other country. In 2015, wind power counted for 42.1% of all electricity consumption. The Danish government has a national target for energy consumption by wind to reach 50% by 2020.