ENERGY GROWS ON TREES:

About eight years ago, a major paper producer in Finland realised the world was changing. The rise of digital media, a fall in office printing and the dwindling popularity of sending things by post - among other factors - meant that paper had embarked on a steady decline.

Stora Enso, in Finland, describes itself as "one of the largest private forest owners in the world". As such, it has a lot of trees, which it uses to make wood products, paper and packaging, for example. Now it wants to make batteries as well - electric vehicle batteries that charge up in as little as eight minutes.

The company hired engineers to look into the possibility of using lignin, a polymer found in trees. Around 30% of a tree is lignin, depending on the species - the rest is largely cellulose.

"Lignin is the glue in the trees that kind of glues the cellulose fibres together and also makes the trees very stiff," explains Lauri Lehtonen, product manager for Stora Enso's lignin-based battery solutions.

Lignin, a polymer, contains carbon. And carbon makes a great material for a vital component in batteries called the anode. The lithium ion battery in your phone almost certainly has a graphite anode - graphite is a form of carbon with a layered structure.

Stora Enso's engineers decided that they could extract lignin from the waste pulp already being produced at some of their facilities and process that lignin to make a carbon material for battery anodes. The firm is partnering with Swedish company Northvolt and plans to manufacture batteries as early as 2025.

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