EV batteries get new life through vehicle-to-grid integration

Utilities are piloting the use of electric vehicle (EV) batteries to facilitate a host of ancillary grid services.
Published: Tue 18 Oct 2016

The fact that authorities in California have instated a minimum quota on the number of electric vehicles sold or leased by car manufacturers should provide an indication of how this market has progressed over the last few years. The government in Quebec, Canada, plans to follow suit after statistics have shown that the number of owners of electric cars has doubled every year over the past four years.

The global market for electric vehicles has expanded tremendously, boosted by governmental incentives in the form of subsidies; and the development of more efficient and less costly batteries is increasing the trend towards sustainable developments. The low operating cost of electric vehicles is further fuelling the demand.

The benefits of electric vehicles are manifold. In addition to the most obvious benefits of electric vehicle (EV) use – a diminished carbon footprint and less air pollution – electric car batteries have been found to improve electricity grid stability and can offset the ownership cost of electric vehicles.

New life

The National Renewable Energy Laboratory (NREL) has conducted a study on the viability of reusing discarded electric vehicle batteries, and found that they still have roughly 70% of their original capacity at the end of their “usable” life in a vehicle.

Second life electric car batteries are being piloted as an effective means toward enabling the addition of solar and wind farms without impacting grid stability.

In California, Pacific Gas and Electric Company (PG&E) and automaker BMW teamed up last year to test the ability of electric vehicle batteries to provide valuable services to the electric grid. BMW was tasked with managing a minimum of 100kW of electric demand on PG&E’s system.

In an interview with Metering & Smart Energy International, Jana Corey, director of electrification and alternative fuels at PG&E, said: “PG&E has a few different objectives for the programme, which includes evaluating how managing customer-owned EVs can benefit demand response and testing how utilities can leverage second life batteries to support the grid during demand response events.

“The utility’s third objective is to determine how automakers are able to provide managed grid services and develop incentives to help grow the market for EVs.”

This pilot is the first that PG&E is running that specifically leverages a combination of managed charging and used EV batteries. The programme is helping PG&E assess how EVs can support the grid. When PG&E calls a demand response event, BMW helps PG&E manage power demand on its grid in one of three ways, through: energy storage, smart charging, or a combination of both.

BMW created a large energy storage unit at the BMW Group Technology Office in Mountain View, California, using eight lithium-ion batteries from old BMW MINI E EVs. Like other storage systems, these second life batteries can absorb electrical energy when demand is low, and export it back to the grid on request when demand soars. BMW is thus able to export up to 100kW to the energy grid from this energy storage unit.

“Smart charging”

BMW will also help PG&E manage power demand on its grid through smart charging. As part of the pilot, BMW enlisted 100 BMW i3 EV customers based in the San Francisco Bay Area to take part in the BMW i ChargeForward programme. If PG&E needs to curb customer demand, it will send BMW an alert over the Internet, indicating how much load to cut and for how long. BMW will then signal the telemetry equipment in each participating vehicle, telling it to halt its charging for the duration of the event. PG&E will pay BMW for these services, as it does other demand response participants. However, BMW will pass on all of these payments to participating customers, thereby lowering the overall cost of owning the BMW i3 EV. Customers participating in the programme receive an upfront incentive to enrol and an ongoing incentive based on their performance in reducing load. Each customer in the programme will be able to track the value of the ongoing incentive as well as opt in/out for each event via a phone app throughout the 18-month pilot.

The third way BMW will help PG&E manage power demand on its grid is a combination of exporting energy from the second life battery system and delaying charge for customers’ EVs.

Early results prove that BMW has met the obligation to deliver 100kW in nearly every event, with a combination of managed charging and battery storage from second life EV batteries. BMW has also performed in both day-ahead events with a 24-hour notification as well as real-time events with as little as 4 minutes notice.

When asked if the pilot has proved successful in the integration of renewable energy into the utility’s network, Cory said: “The focus of this pilot is on shifting EV load to reduce peak demand when there is strain on the energy grid, which will be critical to alleviating the sharp ramping periods created as we increase the amount of renewable energy onto the system. The pilot is also helping us better understand charging behaviour, such as when and where people charge.

“Through focus groups and surveys, we are also learning what is needed for EV charging throughout the day when there is excess generation from renewable resources. While this is a pilot programme, the 100kW of electric demand is a good gauge as we model how we can manage load on vehicles, backed by second life batteries.”

 Corey said that interest in the pilot “exceeded expectations.” Over 500 PG&E customers applied for the 100 available spots. Additionally, 92% of pilot participants surveyed have indicated they are highly satisfied with the pilot, and 86% would likely recommend the programme to family and friends.

Enel and Nissan V2G pilot

Further afield, integrated energy company Enel and Japanese car manufacturer Nissan signed a similar agreement in December 2015. The two firms partnered to develop an energy management solution that uses a Vehicle-to-Grid (V2G) recharging device which allows car owners as well as energy users to operate as individual “energy hubs” – able to draw, store and return electricity to the grid, and thus providing grid balancing services.

Ernesto Ciorra, head of innovation and sustainability at Enel, tells Metering & Smart Energy International that two proof of concept projects have been launched in Denmark (January 2016) and in the UK (May 2016). The aim of these pilots is to test and eventually implement the solution at commercial scale. Ciorra said the technology is already fully developed and tested. The sustainability and profitability of the business model that lies behind the initiative is now being assessed.

“[We are] offering the unique V2G units for the charging infrastructure and its support to enhance the V2G management platform developed by the US startup Nuvve. Besides providing our extensive know-how in energy management and energy trading, we are also working hard to define a sustainable business model that allows all the parties to be profitable in their own domains,” he says.

“We want to bring mobility into modernity and combat climate change by reducing CO2 emissions through the most innovative solutions in both the energy and automotive industries.”

Ciorra adds: “We will enable customers to connect and recharge electric cars when energy cost is at its lowest while using the electricity stored in their car batteries at any time, releasing the rest back into the network, with a reasonable economic return. In this way, Enel can become the ‘AirBnb’ of EVs.”

By the end of 2016, 44 Nissan LEAF electric vehicles and 44 Enel V2G charging units (10kW each) will be leveraged, acting as “distributed resources” to provide primary regulation grid services to the Danish TSO in Denmark. The aggregated power of the 44 chargers is 440kW, equivalent to a small hydropower plant with the potential not just to inject, but also to consume, energy. So far, Enel has provided 4 V2G charging units to DTU (Danmarks Tekniske Universitet) and 10 units to Frederiskberg Forsyning, the first customers that will benefit from this new technology.

Under the UK pilot, 100 V2G units will be installed and connected at locations agreed by private and fleet owners of Nissan LEAF and the e-NV200 electric van by the end of the year.

V2G charging infrastructure

Enel’s 10kW two-way V2G charger is also compatible with small renewable energy generation plants and is the only bidirectional charger in the world tested and approved by CHAdeMO Association.

Ciorra explained that through the V2G system (platform + recharging station), owners of electric vehicles can charge their car’s battery during off-peak times, when energy is cheaper, and discharge it during peak times, when energy is expensive, thus cutting running costs. He says that the utility’s charging infrastructure allows the V2G platform to offer demand response services aggregating capacity provided by EVs.

Nissan chairman for Europe, Paul Wilcox, via emailed statement, said: “A Nissan electric vehicle is connected to the grid through a dedicated V2G charging unit that is bidirectional meaning that it has the ability to charge the vehicle and take energy from the vehicle’s battery.

“The V2G charger essentially works as an interface to control the operation of charge and discharge and it is connected remotely through a modem to the platform operated by an agent that acts as an aggregator.

“The aggregator collates all of the information about the vehicles connected to the V2G chargers and works directly with the grid system so that energy from the vehicle's battery can be provided to the grid upon demand, taking into account the needs of the vehicle owner via a dedicated app.”

The pilot project in the UK is the first ever vehicle-to-grid project carried out in the country. The project has been designed to afford Nissan electric vehicle owners the ability to plug their vehicles into the V2G system, providing the National Grid with increased flexibility, power and balancing services, as well as changing energy management in the UK.

Ciorra concludes by saying: “Not only will Nissan electric vehicle owners be able to play an active role in grid stability, but it will change how energy is supplied to the grid: once scaled up, the V2G technology can become a game-changer for owners of EVs in the UK as they become fully-fledged and active participants in the UK energy sector.

This article appeared in Metering & Smart Energy International Issue 3, 2016.

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