No alternative energy sources offer the flexibility of petroleum. But we can’t rely on this energy source forever, says materials scientist William Chueh from Stanford University.

The biggest challenge with alternative energy sources is how to make this energy available when and where we need it. With solar, for example, we’re reliant on the sunshine to give us our power, but the Sun doesn’t always shine.

The problem is how to store it. Between batteries and fuel, fuel is more convenient. It can be moved in pipelines or containers and unlike batteries, doesn’t have to be packaged – which adds extra weight.

Batteries are still the only viable short-term solution. And this is Chueh’s challenge: making storing solar as efficient as possible.

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