About a fifth of the world’s greenhouse gas emissions stem from transportation—and around 72% of those come from road vehicles. Crucially, the focus for reducing those road-based emissions has been electrifying vehicles, such as America’s most popular auto, the Ford F-150, whose Lightning version launched April 26. Often overlooked are the roads themselves, which are ripe for change.

“There hasn’t been much innovation in the road space since the Roman ages,” says Haakon Brunell, founder and CEO of Carbon Crusher, on today’s episode of the World Changing Ideas podcast. The Norwegian company repairs roads using a carbon-negative method, vital when the age-old process is highly carbon intensive; according to studies, constructing a lane-mile of road releases between 1,400 and 2,300 tons of CO2, even before any maintenance or reconstruction. That’s in part because road materials are bound together using bitumen, a sticky, blackish substance that’s a byproduct of crude oil.

Carbon Crusher builds new roads as well as fixes old and damaged ones, and it does so using lignin, an organic polymer found in trees that becomes a waste byproduct of paper production (and which is often then burned, generating more emissions). This “green carbon binder,” as the company calls it, contains carbon from its natural life, and continues to sequester carbon in the roads.

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