To increase decrease CO2 a lot of plans are made to cover city buildings with roof gardens. One problem however is that those gardens tend to be quite heavy. Especially when you are building in a country like Japan where the ground isn't that steady, that's a problem. That's why the Japanese company Suntory invented new a new kind of soil, mixed with 50% plastic. To make it lighter, but I guess it must also be a really good way to store waste.
Is it still trash when it doesn't look like trash?
suntory.com | Related: Green Roofs for Living