Second-life energy storage systems from old laptop batteries

With its second-life battery research, start-up company Nunam is advocating for an environmentally friendly power supply in rural India in particular. It is a multi-layer project that demonstrates how energy storage can be designed to be CO₂-neutral, for example.

08/25/2020 Reading Time: 5 min

The Nunam vision – second-life energy storage systems for the future

German-Indian start-up company “Nunam” (Sanskrit for “future”) has commited itself to give used lithium-ion battery cells such as those from electronic scrap sources a second life, thereby demonstrating that it is possible to not only reduce waste, but also lower the costs for energy storage and make it CO₂-neutral at the same time.

Nunam, a non-profit start-up company, obtains large quantities of used lithium-ion batteries from sources including discarded laptop batteries from electronic scrap dealers. The dealers obtain these batteries from private households, public institutions, and companies.

Nunam takes the used batteries and creates a new product: the stationary Nunam energy storage system. It can supply low-power loads such as smartphones, fans, or lamps with power. For example, a five-year-old laptop can serve as a light source for Indian fruit and vegetable sellers on a market and provide people in rural India with power sources.

Laptop batteries with a residual capacity of roughly 65 %

And these energy storage boxes benefit from a great deal of residual power. Initial experiences from the project have shown that the batteries often still have a residual capacity of roughly 65 %. Using Nunam energy storage systems can thus counteract the waste created by electronics that are simply thrown away day after day in a targeted way.

The idea of these “second-life energy storage systems” is multi-layered: It is a concept that satisfies the various “rules” (Rs) for sustainable life and a future worth living. The project directly addresses all four Rs – reduce, reuse, recycle and rethink – in addition to the topic of enablement.

Aside from reducing waste (REUSE) and replacing the purchase of new energy storage systems with the secondary use of old ones, the project also pursues the following sustainable goals:

This new technical solution reduces CO₂ emissions (REDUCE). The system is CO₂-friendly, as the production and disposal of conventional lead-acid batteries as well as new lithium-ion batteries create carbon dioxide and additional electronic scrap. The batteries used here have already been produced, and their use is continued for as long as possible as part of their “second life,” which means that fewer new batteries have to be produced.

There is a further positive aspect: Many regions in India experience power outages every day and, depending on the situation, make do with kerosene lamps, lead-acid batteries, and diesel generators (for larger users). Some have no backup system for power outages at all due to economic reasons.

In many cases, the use of affordable battery storage systems that are charged with environmentally friendly solar power can offer a better solution as compared to what was previously possible.

For example, the Nunam energy storage system can supply power to households that have little or no access to electricity, while also saving CO₂ emissions and minimizing electronic scrap effectively thanks to the positive environmental effect.

The long-term goal of the Nunam team is to offer the Nunam energy storage system for half the price of conventional energy storage systems.

To this end, the technology that regulates the use and interconnection of the used batteries in the background is optimized continuously. The Nunam energy storage systems are equipped with all sorts of technology features across Hardware and Software, including a SIM card that connects them to the Internet. This allows data, including the power capacity and geographical position, to be read out in real time.

This aspect is of fundamental importance in order to be able to get a transparent overview of the system and gain insights for the further development. It also schedules and initiates the recycling process, which takes place after the full residual capacity has been used. The documentation and location via the app ensures that the batteries that are discarded for good can be returned to Nunam. They can then be directed to functioning and effective recycling loops, thereby saving additional resources.

Positive influence on the environment and society

What’s special about this project is the social aspect. The low-cost provision of storage systems for solar energy in developing countries such as India provides the people who live there with easy access to clean electricity. Millions of people in India live without reliable access to electricity and can benefit from solutions like this. (RETHINK & ENABLE).

At the end of the project, the results, data, and findings from the project will be made available to anyone interested in an open source portal. This will ensure that the greatest possible number of interested persons can benefit from these findings and put them to further use.

Three questions on the project start for Prodip Chatterjee

What exactly does your pilot project with the street vendors in India look like?
Prodip Chatterjee:
The aim of our pilot project is to use our second-life batteries across different target groups that benefit greatly from them. We are starting with fruit and vegetable vendors who use our battery systems to light up their pushcart after sunset so that they can continue to sell their products. They can also charge their phones at the same time. As a next step, we are planning to use our batteries in households in rural Indian villages.

The batteries are about the size of a car battery and weigh two kilograms. The technology and interfaces are the same as those of conventional stationary batteries: There is a connection for charging the prototypes (e.g. with solar energy) and outlets for discharging them.

From where do you get the batteries?
Prodip Chatterjee: The lithium-ion batteries are delivered to us by local electronic waste dealers from Bengaluru and other cities. We extract the cells from the old laptop battery packs and test them. The average residual capacity is around 65 percent. It’s crazy to think about how much potential is just thrown into the trash

On the topic of the circular economy: At some point, the batteries really are empty. How do you get the batteries back so that they don’t end up in the trash after all?
Prodip Chatterjee:
I still see this as a major challenge that we intend to tackle with various elements and test with this project: All prototypes are initially connected to the Internet 24/7 via an integrated SIM card. This provides us with various data points in real time and tells us where it is and in what condition it is in (with the users’ consent, of course!).

In addition, each battery cell has its own ID with a QR code, which we call the “Nunam ID.” The Nunam ID contains information on the battery cell and from whom we received it originally. We have developed a smartphone app and an online dashboard for tracking purposes. This way, the usage data allows us to predict for how long the battery can be used and when it will really reach the end of its life and have to be returned to us. This feature enables us to contact the users proactively and ensure that these devices are returned to us at no cost so that we can then hand them over to a certified lithium-ion recycling process. Continuous contact with the customer will be crucial for ensuring that the battery does not end up in the trash again.

Renewable energy storage of the future? Battery recycling for India

Renewable energy storage of the future? Battery recycling for India

Read the full interview with Prodip Chatterjee here.

To the interview