Where Will Tomorrow's Electricity Wait?

Solar panels can produce plenty of electricity at lunchtime, when many homes are empty. Later, people return, cook dinner, and turn on lights as the sun goes down. Over the next 10–30 years, storing energy could become a more familiar part of daily life. But what can we reasonably expect?

Some answers already exist. Batteries store energy through chemical changes and release it as electricity when needed. Large battery systems already help electricity networks balance supply and demand. Another method uses electricity to pump water uphill. The water then flows down through turbines, machines that use moving water to help produce electricity. Neither method creates extra energy, and some energy is lost in the process.

The International Energy Agency expects batteries to play a growing role as wind and solar power increase. This view is based on models of future energy systems, not a promise about what will happen. In the coming decades, storage could allow more daytime solar energy to be used in the evening. Some homes and businesses already use their own batteries this way, while larger systems can support the wider electricity network.

However, storing energy for a few hours is different from keeping it for several cloudy days with little wind. Researchers and companies are developing other methods, including different battery designs and systems that store energy as heat. These methods serve different purposes. Stored heat, for example, can be used directly in factories without being changed back into electricity.

It remains uncertain which combination will become most common. Cost, available materials, local geography, and the length of time energy must be stored all matter. A successful test does not automatically mean a system will be cheap to use on a large scale.

Tomorrow's energy storage will probably not be one amazing box. A more realistic possibility is a collection of tools, each suited to a different need.