Marmalade

Seville is using the gas from fermenting left-over oranges to provide electricity for powering its water plant (https://www.theguardian.com/environment/2021/feb/23/how-seville-is-turning-leftover-oranges-into-electricity). This is a useful thing to do, so long as 'greenhouse gas' emissions are controlled. It's certainly better than placing the organic material in landfill.