Walter Mérida Associate Dean, Research and Industry, Faculty of Applied Science, University of British Colombia Martin Siegert Professor of Geosciences, Deputy Vice-Chancellor (Cornwall), University of Exeter Electric vehicles (EVs) reached a global fleet of nearly 58 million in 2024,51 and they are just one example of a rapidly expanding range of devices and technologies equipped with rechargeable batteries. As battery technology continues to improve, stored energy is emerging as a potential asset for powering homes, buildings and even urban and remote power grids. Bi-directional charging allows electricity to move both into and out of batteries, enabling stored energy to be redirected based on use needs.52 Ongoing innovations in these technologies could support a cleaner, more flexible energy system, supporting the drive towards net-zero greenhouse gas emissions and easing pressure on planetary boundaries related to climate change, biogeochemical flows and “novel entities” such as air pollution and environmental toxicity. To permit two-way energy flow, bi-directional charging relies on advanced inverters to convert electricity between direct current stored in batteries and alternating current transmitted through power grids. Traditional inverters are limited by heat loss, size and conversion inefficiencies, but next-gen devices – often built with wide bandgap semiconductors such as silicon carbide – can handle higher temperatures, improve conversion efficiency and regulate power flows more precisely.53 Bi-directional charging technologies are currently being piloted across a range of real-world settings. In the US, electric school buses equipped with vehicle-to-grid (V2G) systems are supplying stored energy back to the grid during periods of high demand.54 Residential programmes, such as the University of California, San Diego’s INVENT pilot with Nuvve and the Austin SHINES project in Texas with Pecan Street, have tested home-based bi- directional charging installations. These pilots have allowed personal EVs to supply electricity for local energy management, such as campus microgrids and peak demand response in homes.55,56 In Australia, a bi-directional-capable electric vehicle was used to power critical medical equipment during a blackout in 2024, demonstrating how the technology can support emergency response in real-world conditions.57 In Canada, bi-directional charging has been coupled with smart grid technology, renewable energy sources and hydrogen production.58 If similar integration can be scaled up elsewhere, broad environmental, economic and societal benefits could result. Decreased urban emissions and air pollution from efficient load balancing and reduced reliance on fossil-fuelled backup generators support climate change and novel entities boundaries.59 However, if battery charging occurs when fossil fuels dominate the grid mix or if batteries are cycled inefficiently, emissions may rise rather than fall – undermining environmental benefits. Expansion of bi-directional charging could transform energy service industries and open new roles in battery health analytics, power systems coordination and decentralized energy management – particularly in regions vulnerable to blackouts or extreme weather. As adoption grows, a key challenge will be managing battery wear from frequent charging/ discharging cycles – but well-designed systems could expand access to backup power, reduce energy costs through local energy sharing and support the efficient redistribution of renewable energy to exactly where it is needed. Well-designed systems could expand access to backup power, reduce energy costs through local energy sharing and support the efficient redistribution of renewable energy. 10 Emerging Technology Solutions for Planetary Health 23

10 Emerging Technology Solutions for Planetary Health 2025