What are we going to do with all these batteries?
With an increase of electric cars on the street we have to start thinking about their end of life. The first component to weaken is the Li-Ion battery. Its environmental impact can be measured by the critical materials used. Based on the defined criticality screening procedure the Research Centre for Energy Economics identified cobalt, lithium, nickel and graphite as critical raw materials in lithium ion traction batteries. (Anika Regett, 2017) A material is critical if it ranks high on all of the following criteria (Anika Regett, 2017),
it plays a key role in the future energy system
and leads to a relevant increase in demand of raw materials,
whose recyclability and substitutability are limited
and which either go along with a supply or an environmental risk.
By using the concept of the Substitutable Nominal Capacity by Kim et al. (D. Kim, 2015), which is derived from battery ageing models, it is shown that an extension of a traction battery’s life time can lead to a reduction of critical resource consumption (D. Notter, 2010).
The battery capacity decreases with time and usage. If it reaches 80% of its starting capacity, it is seen as ineffective to use any longer in an electric vehicle (S. Fischhaber, 2016). The time it takes until the battery reaches this point varies depending on usage.
After about 8 years, the batteries capacity is lowered to 80% compared to its starting capacity. These Li-Ion batteries are still powerful and recycling should be considered the last resort. Instead the second life applications of a Home Storage System or a Primary Control Reserve should be considered (D. Notter, 2010). The Primary Control Reserve proved to be more efficient in reducing critical materials, due to a longer second life time of the battery (D. Notter, 2010).
This potential has been recognised by several companies in the automotive industry. BMW, Daimler and Renault have invested into research and pilot projects looking into possibilities to reuse these batteries. BMW in cooperation with Vattenfall built an energy storage in Hamburg, using batteries from electric vehicles. It stabilizes the grid while also being used as an energy backup for quick charging stations (BMW, 2014).
In this video it is shown, how the old batteries are used as an energy storage to provide enough energy for a fast charging station without straining the grid.
In the US BMW started a project called BMW i ChargeForward (America, 2015). This 18-month pilot study aims to better understand the relationship between home EV charging and the energy grid. Electric vehicle owners offer their car’s battery to be used as energy storage to smoothen the grid. To ensure that driver needs are consistently met while achieving desired grid-load reductions, BMW i ChargeForward pairs intelligent management of vehicle charging with a stationary battery storage system, comprised of used MINI E vehicle batteries (America, 2015).
Renault teamed up with Connected Energy to launch E-Store in the UK (Renault, 2016). It uses electric vehicle batteries at the end of their useable in-vehicle life in order to by provide energy storage that prevents power grid overload and balances supply and demand. It also can store energy generated from on-site renewable generation resources such as solar panels and wind turbines, and then release it as it’s needed at a later time. The system also allows the batteries to be charged via low-cost off-peak electricity tariffs, enabling users to reduce their energy costs. Instead of charging vehicles via a high-capacity supply directly from the grid, E-STOR allows multiple batteries to be charged at a slower rate over a period of time, ready to release their energy and charge a car when an EV driver needs it (Renault, 2016).
These projects and others, like Everest energy storage (Beasley, 2015) or Greencharge (Greencharge, 2017) in cooperation with Nissan, prove the viability of a Second-Life-Application of a battery as an energy storage to prevent power grid overloads.
The batteries can be part of the energy storage system until their capacity dropped down to 70% of its starting capacity, which is considered as its final end of life criterion (D. Notter, 2010).
This reuse of a battery can reduce the environmental impact of the battery production. A study by Anika Regett6 calculated a GHG-saving-potential of 34 -106 kg CO2e per kWh of a lithium-ion battery used in Primary Control Reserve.
A second application of a product can therefore safe resources, energy and add an economic value, which could decrease the price of the first purchase indirectly. If I would were to buy an electric car for £20 000, but I know I can sell the battery afterwards for £5000 to an energy storage company, the actual money I am paying overall are £ £150000.
References
America, B. o. N., 2015. content.bmwusa.com. [Online] Available at: http://content.bmwusa.com/bmwi_pge/index.html [Accessed 20 01 2017].
Anika Regett, S. F., 2017. Reduction of Critical Resource Consumption through Second Life Applications of Lithium Ion Traction Batteries. s.l.:Research Centre for Energy Economics.
Beasley, P., 2015. www.futuretransportsystems.co.uk. [Online] Available at: http://www.futuretransportsystems.co.uk/projects/everest-energy-storage/ [Accessed 20 01 2017].
BMW, 2014. www.press.bmwgroup.com. [Online] Available at: https://www.press.bmwgroup.com/deutschland/article/detail/T0193200DE/bmw-i-batterien-werden-als-„second-life-batteries“-flexible-speicher-fuer-erneuerbare-energien-und-sichern-die-stabilitaet-des-stromnetzes?language=de [Accessed 20 01 2017].
D. Kim, A. G. C. M. D. H., 2015. Quantifizierung des Umweltnutzens von gebrauchten Batterien aus Elektrofahrzeugen als gebäudeintegrierte 2nd-Life-Stromspeichersysteme. Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Volume Bauphysik 37.
D. Notter, M. R. W., 2010. Contribution of li-ion batteries to the environmental impact of electric vehicles. s.l.:Technology and society laboratory, Swiss federal laboratories for materials science and technology (empa).
Greencharge, 2017. www.greencharge.net. [Online] Available at: http://www.greencharge.net/business-government/ev/ [Accessed 20 01 2017].
Renault, 2016. media.renault.com. [Online] Available at: http://media.renault.com/global/en-gb/renault/Media/PressRelease.aspx?mediaid=75381 [Accessed 20 01 2017].
S. Fischhaber, A. R. S. S. H. H., 2016. Second-Life-Konzepte für Lithium-Ionen-Batterien aus Elektrofahrzeugen - Analyse von Nachnutzungsanwendungen, ökonomischen und ökologischen Potenzialen. Begleit- und Wirkungsforschung Schaufenster Elektromobilität (BuW), Volume Ergebnispapier Nr. 18.
