Around 35% of Bulgaria's electricity comes from fossil fuels, so it may not seem like a leader in the green energy transition. But Bulgaria has one surprising strength: batteries for renewable energy. Bulgaria went from virtually zero battery storage in 2023 to a current capacity of 14 gigawatt-hours (GWh), transforming the country not only into a regional, but also a global leader in the sector – for comparison, the EU as a whole has 77.3 GWh battery capacity.
Such large storage allows Bulgaria to save its renewable electricity (mostly solar) for later use when the sun stops shining. It also helps with balancing out the grid, which can get overwhelmed during peak production hours.
Storing its excess electricity has allowed Bulgaria to keep power prices down, even during the periods when they normally climb – like for example when you come back home after your workday.
Bulgaria also sells its production surplus to its neighbours (like Greece and Romania), which creates additional revenue. The trade works particularly well in summer, when the abundance of sun pushes renewable electricity prices down. This means Bulgarians pay less for electricity, which encourages companies to invest in the country.
Another driver of Bulgaria's growing success is the more than €600 million in EU funding which has also helped attract private investment. This has allowed Bulgaria to aim for large-scale battery projects like in Stara Zagora. This influx of money meant a gold rush for many companies, resulting in a battery storage systems boom.
What about the rest of Europe?
The European battery industry as a whole has yet to reach a competitive scale to catch up with global leaders from China, South Korea, and Japan. However, the European Commission is boosting investment, and development is gaining speed. In June, the Commission promised €1.5 billion in funds for battery manufacturers to ramp up production in Europe.
Europe is also trying to secure lithium – an essential component in batteries. But there's a catch: Europe has very little lithium on its territory, and the few local deposits face fierce opposition from communities concerned about the environmental and health impacts of new mining projects.
That means only one thing: Europe needs to do its absolute best to reuse and recycle the lithium batteries it already has. And that's exactly where the system is stuck for now.
Reuse, repurpose, recycle
Take an average EV. At the end of its 15 year lifespan, its battery typically retains 70-80% of its original capacity. It'd be a massive waste to just get rid of it. These batteries can be recycled, which means the lithium in them is recovered to make new batteries. But there's still another important step in between.
Before batteries get dismantled for recycling, they can still have a successful second life as stationary energy storage – similar to the one that is now powering Bulgaria.
An old EV battery gets tested, and if its “health” is confirmed, it gets connected with several other old batteries to create a new, bigger battery system.
REBATTEX, a platform designed to improve the European second-life EV battery market, told TEC that about 180 GWh of battery capacity (equivalent to the annual output of four large gigafactories) could be made available thanks to old and accident-damaged EV batteries by 2035.
Globally, an estimated 50 million EV batteries will “retire” by 2050. Reusing just half of them for energy storage would create the capacity of 12,000 GWh and reduce the need for new critical mineral mining by 28%.
To make that happen, the second-hand battery market needs to get moving first. This can't happen without clear regulations, greater transparency around the battery trade and the batteries' origin, alongside unified standards for battery diagnostics – measures that are still lacking across Europe.