In the world of batteries, what does “end of life” really mean? According to the industry, end of life is defined as that point in time when a battery has lost 20% of its original energy storage capacity or 25% of its peak power capacity. This implies that an EV battery, with an initial range of 100 miles per charge, will reach its end of life when, years later, it only delivers 80 miles per charge.
That time is likely to be reached only after the battery has carried an electric car about 200,000 miles or 2,000 cycles. But that’s not really the end for an EV battery -- it’s just the beginning of a second life that not many people know about.
What options exist for a battery in its second life? The first and most well-known option is recycling. While recycling is a great option to break down and reuse nearly all of the components and chemicals in the battery, there’s an even better option: use the remaining 80% of storage capacity to work in a different application.
Depending on the quality of the battery, which can be determined statistically through the management of the batteries on our network, there are a number of applications where these batteries can add enormous value.
The highest quality second life batteries can continue to be used in electric cars: in cities or on islands where driving ranges are lower, for customers who prefer lower-range batteries at a discount, or in vehicles that would not support newer battery configurations.
High-to-medium quality batteries can be used as stationary energy storage in grid applications, either repacked into larger installations (at the megawatt level) or simply used as they are. One example of this is frequency regulation -- using energy storage to maintain the proper frequency of the power grid by balancing second-to-second energy supply and demand.
Another example is energy arbitrage, in which end-users or grid service operators buy energy during the low-rate period, store the energy in batteries, and then sell the energy back during the high-rate period. Yet another use is generation smoothing for renewable energy. For instance, the off-peak energy generated bysolararrays and wind installations can be stored in batteries until they are needed and are able to fetch a higher price.
Additionally, EV battery packs can be tapped for community energy storage, where a standard 24kWh pack is installed in houses or businesses to reduce local power consumption.
The lower quality batteries can be used in low-intensity applications. One such cluster of “low intensity” applications is to meet energy demand for people in developing countries who live in areas without an electric grid connection. The power requirements for such uses are relatively low -- less than 5 kilowatts for cooking and small-plot irrigation and an order of magnitude less for lighting, cell phones and radios. Although seemingly small in scale, these few kilowatt-hours of energy are immensely valuable to these regions. For example, lighting can extend the day’s productivity and enable home education, cell phones can increase access to markets and banking, and automatic irrigation can greatly increase yields and efficiency on a small-plot farm. In these cases, battery modules (smaller components of the larger pack) can be used to provide a light, easily-transportable energy solution.
Although the second life battery market is in the exploratory/pilot phases, we are already seeing some promising applications in the works. For example, a joint venture between EnerDel and Itochu is deploying second life batteries as stationary energy storage in a Tokyo apartment complex. The batteries will be used for residential load-leveling, storage of energy during off-peak times for use during peak hours, as well as back-up power. Another Enerdel-Itochu application is using second life batteries in a photovoltaic solar power system that delivers energy to gas stations in Japan for powering electric cars. DTE Energy has deployed a pilot exploring the use of second life batteries as community energy storage, an approach to stabilizing the grid by placing small amounts of storage closer to the customer.
Electric utilities like Southern California Edison and DTE Energy are using huge battery packs built by A123Systems (up to 2 MWh, the equivalent of about 80 electric car batteries integrated into a shipping container) to store energy at large wind power and solar power sites. A123 and Altairnano have both provided batteries to AES for frequency regulation. While these applications currently use brand new batteries, second life batteries will represent an even higher profit potential when they reach the marketplace.
As the first company to manage large inventories of electric car batteries, Better Place will be the first to bring them to the second life market in a coordinated fashion, with complete, verified usage histories and quality diagnostics attached. Furthermore, our networked solution enables constant monitoring and early issue detection, and our pooled battery resource enables regular service and maintenance without fear of inconveniencing our customers.
Encouraging a healthy second life for our batteries is a good idea for many reasons: it lowers the effective cost of batteries by introducing a realizable residual value, and it maximizes the use we can derive from a fixed resource. We have the opportunity to lower the cost of integrating renewable energy into our electric grid through low-cost energy storage, so a battery can contribute to the reduction of greenhouse gas emissions by electrifying transportation in its first life and enabling renewable energy in its second life. Perhaps most inspiring is the opportunity to help the world’s disadvantaged populations. If we deploy second life batteries in developing countries, we can share a superior technology with these emerging markets, improving quality of life and helping to stimulate education and the economy, allowing others to reap the benefits of the electric car.
Michal Vakrat Wolkin, PhD is the Global Head of Battery Technologies, Automotive Alliances at Better Place.
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