Vehicle to Grid trials are underway globally but questions remain as to the economic viability of rolling out the technology on a commercial basis.
As the cost of electric vehicle ownership comes down and the infrastructure is put in place, effective power management will become critical to the overall stability and effectiveness of the power system. Numerous car manufacturers have committed to ending non-EV car production within a decade, with many more set to follow this trend. National Grid predicts up to 11 million EVs on UK roads by 2030, and as many as 36 million by 2040 in its most recent Future Energy Scenarios report. A recent report by campaign group Transport and Environment ‘Electric Surge: Carmakers’ electric car plans across Europe 2019-2025’ shows where the future electric cars and batteries will be produced in Europe, predicting that the number of models of predominantly battery electric (BEV), plug-in hybrid (PHEV) and also some fuel cell vehicles (FCEV) is set to soar from 60 at the end of 2018 to 176 by 2020, 214 by 2021 and 333 by 2025. And worldwide passenger EV sales will rise from 2 million in 2018 to 28 million in 2030 and 56 million by 2040, according to Bloomberg New Energy Finance.
Vehicle to Grid charging (V2G) will make it possible for EV owners to sell electricity back to the grid, which in turn will help manage national energy supply and demand. Essentially the EV fleet could become like a system of distributed batteries, discharging excess electricity to the grid at times when there is peak demand on energy networks, and recharging when energy demand and prices are low. This goes beyond unidirectional V1G charging, which can provide ancillary services to the grid by adjusting charging times to absorb excess renewable generation during the day, for example.
Adaptive charging will introduce scheduling to accommodate charging of multiple EVs. For example, California Institute of Technology Caltech has developed the Adaptive Charging Network (ACN) to help researchers develop adaptive charging algorithms. It uses over 80 EV charging ports in a garage on the Caltech campus with the system currently charging an average of 65 EVs a day. The ACN provides a useful data set for researchers with each item of data consisting of a single charging session, accessible via application programming interfaces (APIs) such as JSON, REST or Python. Also available is a data-driven, open-source simulator providing a modular, extensible architecture which captures the complexity of real-world charging systems.
The economic value of V2G will go beyond one-way smart charging, but much will depend on customer behaviour and location. Smart and V2G charging could generate significant revenues by providing frequency response or balancing services to a network operator if in a congestion management zone.
There are as many as 50 V2G projects globally according to a report commissioned by Innovate UK, of which 25 are in Europe, 18 in North America, and 7 in Asia, with Renault, Nissan and Mitsubishi taking center stage in this arena.
The report concludes that V2G has been technically demonstrated but the challenge now is identifying a viable commercial model. Hardware cost and power losses are a major obstacle to the development of V2G charging, and two-way charging may accelerate battery degradation leading to very high replacement costs, although
“It is technically quite proven and now at a point we need to seriously evaluate if there is a business case. Through the UK trials, our members involved in the projects begin to see that the cost of aggregation – total costs including power conditioner, IT costs, communication costs and operation management costs – are quite high,” says Tomoko Blech, representative of the EV charging manufacturers’ group CHAdeMO Association Europe.
Nissan is leading the way with regard to real world application trials in the UK, with one project in collaboration with OVO Energy providing V2G services for domestic customers, and well on its way to its target of installing 1,000 domestic V2G chargers at customers’ homes. This service is open to users of Nissan Leaf EVs (2013 onwards) but other EV manufacturers are following close behind with Honda set to make all new EV models ready to have AC bi-directional charging capabilities in the future and Mitsubishi adopting similar plans.
Francisco Carranza, Managing Director of Nissan Energy in Europe, tells Engerati: “The environmental and economic arguments for V2G technology are very clear, not only in terms of balancing the grid but also in generating income for electric vehicle owners. We already have a number of EV drivers in Europe who have been using their vehicles to earn money from selling electricity to the grid at peak times. For those combining electric vehicles, solar energy, battery storage and V2G, the case becomes even more compelling.”
Transpower is conducting a number of V2G trials until September 2021 including a project to convert a 30-bus garage to V2G, a trial involving 1,000 V2G fleet vehicles, a domestic customer V2G trial involving customers in specific areas, public charging networks working with a local authority and a charge point provider targeted at the 60-70% of Londoners that have no access to off-street charging.
In a trial led by EDF, the ‘V2GO’ scheme is a large-scale demonstration of V2G charging in Oxford using 100 electric fleet vehicles (cars and vans) including several delivery and taxi companies. Octopus Electric Vehicles and Wallbox have a V2G partnership using a bespoke aggregation platform developed by Open Energi and working alongside UK Power Networks to integrate domestic V2G into their flexibility services. This step forward in technology has been achieved by using a silicon carbide inverter to switch power from DC (used by electric cars) to AC (used in homes and by the grid) at a rate much faster than previously possible.
With an Innovate UK vehicle-to-grid competition last year awarding £30m funding for projects spanning 2,700 vehicles, many more V2G applications could emerge in the UK in the near future. But industry groups recently warned the government that policy changes, such as the decision to increase VAT on home batteries from 5% to 20% from October, could hold back growth in the sector.
Honda and Nuvve are trialling V2G at the University of California San Diego in a project called Invent, using multiple vehicle types and chargers. The project is testing the value of providing services to the grid such as demand charge management and frequency regulation using Nuvve’s platform GIVeTM, which will be connected to multiple EVs using unidirectional and bidirectional charging stations for comparison.
Also in California, ZEV School Buses is a V2G electric school bus initiative running eight Bluebird electric school buses deployed at the Rialto Unified School District providing ancillary services and energy management services. Using V2G it can generate cash flows substantial enough to allow ZEV school buses to operate without subsidies.
Grid Motion, a privately funded scheme in France are running a large-scale demonstration of V1G and V2G technologies with V2G charging installed in fleet locations using 15 Peugeot iOn or Citroën C-ZERO vehicles with Enel bidirectional charging stations. V1G chargers are installed at consumers’ homes utilizing 50 Peugeot iOn, Partner Electric, Citroën C-ZERO or Berlingo EVs.
In the Netherlands, We Drive Solar is a car sharing hub operating 70 Renault EVs that utilize V2G AC bi-directional charging to ensure 100% clean energy for charging. A number of public bi-directional charging points have been installed in Utrecht and the network continues to expand.
Efforts to harmonise emerging standards defining the communication between the charging plug and the EV are underway, such as the Open Charge Point Protocol (OCPP) for communications and compatible sockets for bi-directional charging. Currently the market leader Nissan adopts the CHAdeMO style protocol and socket while the Combined Charging System is also widely used, but is not expected to enable bidirectional charging until 2025. China has its own standard, as does Tesla.
In the future network operators will need to adapt interconnection standards and processes and design DSO services with V2G in mind. The price of hardware for bi-directional charging will likely come down as deployment ramps up but V2G projects will need to determine where they can add value that exceeds the considerable costs. The potential benefits both for grid balancing and customer value mean that it will probably not be long before commercial applications are announced.