Last week, Ryan and I watched a marvellous mobile machine that turned chunks of ripped up concrete into gravel. We assumed it would then be used for hardcore – the bottom layer of roads and paving – and it’s a nifty way of locally recycling a material that might otherwise go to landfill. But it’s also an example of downcycling, turning a waste product into a new material, but one of lower quality than the original. Recycling office paper into toilet paper is a good (hypothetical, I don’t know if it happens) example of downcycling.