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The battery-powered home: Charging where it matters

Freddie Holmes investigates potential uses for EV batteries once they reach the end of their usefulness to the vehicle itself

In July 2015, the National Renewable Energy Laboratory (NREL) conducted a study on the viability of reusing discarded electric vehicle (EV) batteries, and found that they still retain approximately 70% of their original capacity at the end of their ‘usable’ life in a vehicle.

Mercedes-Benz energy storage tablet
Mercedes-Benz energy storages are also suitable for private use to buffer surplus power virtually free of any losses

How then, should these discarded batteries be used after being stripped of their automotive duties? Domestic power provision seems an obvious application, and is one that is being explored with growing enthusiasm by OEMs in collaboration with battery manufacturers.

The number of EVs hitting roads around the world is increasing. Latest figures from the International Energy Agency (IEA) show that global sales of battery electric vehicles (BEVs) increased year-over-year by 53% in 2014. As such, there is a large and growing market of batteries fitted in early EVs making their way beyond ‘useful’ life for powering the cars for which they were intended, and an opportunity has arisen to utilise those batteries.

There are a number of reasons why domestic power provision is an attractive prospect, and solar power is already widely used by many homes for the same reasons. Batteries with remaining life could be used to offset peak power demand, and ensure continuous and reliable power in developing countries. In addition, there is the potential for businesses and homes to reduce their reliance on the grid, and perhaps completely disconnect altogether and become self-sufficient.
A number of OEMs are approaching the idea of domestic power provision – admittedly with caution at first, but several plans are taking shape.

Produce and reuse

GM took initial steps in 2010 by partnering with Swiss supplier ABB to collaborate on battery research for EVs. This had progressed by November 2012 to the production of a prototype power storage unit that utilised repackaged batteries from the Chevrolet Volt EV.

Chevrolet Volt batteries data centre
Five ‘used’ Chevrolet Volt batteries work with an adjacent solar array and two wind turbines to help supply power to the administrative offices at GM’s new Enterprise Data Center

Five Volt batteries that were past their ‘useful life’ were integrated into a modular unit capable of providing two hours of electricity needed by the equivalent of three to five average US homes. Pablo Valencia, Senior Manager of Battery Lifecycle Management at GM observes that “in many cases, when an EV battery has reached the end of its life in an automotive application, only 30% or less of its life has been used. This leaves a tremendous amount of life that can be applied to other applications like powering a structure before the battery is recycled.”

As for whether these domestic charging stations could utilise new Volt batteries as a way to provide EV owners with a reliable and convenient charging solution, Valencia told Megatrends: “There’s definitely a potential for us to use secondary use Volt batteries in home energy storage, but we have nothing to announce today. There are minimal modifications that you need to make to the batteries when they are used in a secondary use application. For one, you have to reconfigure the modules so they can be packed more efficiently, and we also make slight modifications to the battery management system itself to manage the energy flow in any new application.”

A quick Internet search would suggest that the partnership may have lost momentum, but Valencia advised that GM is still actively working with ABB on the implementation of secondary use systems on the grid, adding: “We are not focused on using new batteries for home power solutions.”

The current focus of the project is on extending the “useful life” of battery systems after they have reached the end of their useful life in the vehicle, he explained. “We think this strategy is more beneficial in terms of overall economics when you consider that a battery could be deployed in a secondary use application for more than ten years beyond the vehicle, depending on use.”

As it stands, five used Volt batteries are helping to keep the lights on at GM’s new Enterprise Data Center at its Milford Proving Ground facility in Michigan.

ABB is also involved with Shenzhen BYD Daimler New Technology (BDNT), the Chinese joint venture (JV) between Daimler and BYD. In 2013, the Chinese government introduced a fast charging standard – GB/T 20234 – to encourage technical innovation and stimulate market acceptance of EVs. This standard aimed to provide Chinese consumers the opportunities to conveniently charge their vehicles at home and in public.

In February last year, ABB began providing home wall-mounted fast chargers for BDNT’s battery electric Denza model. Arno Röhringer, Chief Operating Officer of BDNT, heralds the ability to install these chargers efficiently as “equally important” as the efficiency of the battery technology itself.

In October 2009, Nissan and Sumitomo Corporation announced plans for a JV, titled 4R, to ‘reuse, resell, refabricate and recycle’ lithium-ion batteries previously used in EVs. At the time, Nissan noted expectations of the demand for second-life batteries to reach the equivalent of 50,000 EVs per year by 2020.

More than five years down the line in June 2015, 4R Energy teamed up with Green Charge Networks to develop and distribute second-life lithium-ion batteries from Nissan’s Leaf EV for stationary commercial energy storage. “A lithium-ion battery from a Nissan Leaf still holds a great deal of value as energy storage, even after it is removed from the vehicle,” says Brad Smith, Director of Nissan’s 4R Energy business in the US.

The first unit will be installed at a Nissan facility later in 2015, where multiple Leaf batteries will offset peak electricity demand. The system can also be paired with solar power for renewable energy.

Private energy storage

Mercedes-Benz energy storageDaimler’s next venture into domestic charging came through its subsidiary Deutsche Accumotive. Established in 2009, the company develops, produces and markets highly complex drive batteries for hybrids and EVs for Daimler’s Mercedes-Benz and smart brands.

In June 2015, Deutsche Accumotive began the provision of private energy storage units. These (Mercedes-Benz branded) lithium-ion battery units can incorporate up to eight 2.5kWh battery modules for a capacity of up to 20kWh.

Unsurprisingly, Tesla – one of the pioneering companies to go purely electric with all its vehicles – had already taken a similar step with the announcement of Powerwall in May 2015.

The shake up

Powerwall is a stationary battery to provide power to homes and businesses in a step to shake up the “entire energy infrastructure of the world”, according to Chief Executive Elon Musk. In an industry that produces increasingly complex vehicles, Powerwall appears to be a relatively simple idea: take the batteries that are already in production for the Tesla Model S, and prepare them for domestic use.

“This is going to be a great solution for people in remote parts of the world, where there are no electricity wires, or where electricity is extremely intermittent or extremely expensive. You can take the Tesla Powerwall and it can scale globally,” Musk told press at a conference in May 2015.

Unlike Daimler and ABB’s offerings, Powerwall will use solar energy to provide environmentally-friendly power. It will come in two forms – a 7kWh unit for US$3,000 and a 10kWh unit for US$3,500 – both of which will use the same batteries that Tesla produces for its EVs.

“The fact that it is wall mounted is very important,” commented Musk at its launch. “It is flat against the wall, it has all of the integrated safety systems and converters, and it addresses all of the needs. If you are thinking about buying a battery, it gives you peace of mind,” he explained. “You don’t need to worry about being out of power.”

Here comes the sun…

The Powerwall can also be stacked. Up to nine can be combined, “so if you’ve got a pretty big thing going on, you can have up to 90kwh,” he added.

As for the rationale behind the development of the Powerwall, Musk stated: “How energy is delivered across the earth today is pretty bad…in fact, it sucks.”
The solution, he says, is fairly obvious: the sun. “We have this handy fusion reactor in the sky; you don’t have to do anything, it just works. It shows up every day and produces ridiculous amounts of power.” He told press that contrary to popular belief, “very little land is needed to completely get the US off of fossil fuels.” Elaborating, Musk explained that the area needed to power the entire globe with photovoltaic panels would be less than 1% of the total land mass of the US, and most of that could be deployed on existing rooftops and buildings.

Tesla Model S powerwall

For much larger buildings that require greater levels of power, a Powerpack is available, and can be designed to scale infinitely. With 160 million Powerpacks, the entire US can transition to solar power, and with 900 million, the world. To transition all transport and all electricity generation and heating globally, approximately two billion power packs would be required. “Is that a crazy number? It is not. The number of vehicles put on the road every year is two billion, so this is within the power of humanity to do. We’ve done it before,” he concluded.

Telsa is a pioneering company, as it has proven by hedging its bets entirely on EVs when there was no real demand. As such, only time can tell whether this was a sound investment, but the company is beginning to face stronger competition from global OEM giants, hinting that the company is on the right track. Does this suggest then, that just as the Model S arguably sparked a renaissance in EV demand, new competitors will arise and begin a domestic charging battle?

This article appeared in the Q3 2015 issue of Automotive Megatrends Magazine. Follow this link to download the full issue.

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