It is the fate of all living things to eventually die and rot away. Before I get too existential let me be clear: I’m talking about compost.
Humans have composted for centuries but the earliest of early adopters probably never dreamt of the ways it could be used.
Compost can be made from anything that was once alive. That doesn’t mean that all compost is created equal; different grades have different standards, with the highest quality stuff used on agricultural land. Makes sense. I don’t like the thought of human biosolids from the water treatment plant being spread over my tomatoes, thank you very much. A lot of the municipal compost produced in Canada is used in its own operations—in parks, as erosion control or in the landscaping around municipal buildings—or sold to landscape companies and individuals.
Compost or biosolids are the precursors of biogas, which is just a fancy term for the methane—a greenhouse gas with 23 times the GWP of CO2—that is produced during decomposition. Lots of places all over the world capture methane from landfills and use it to generate electricity, power vehicles or produce heat.
Linköping, a city of about 100,000 in Sweden uses biogas to power its transit vehicles. The gas is produced from, among other things, local slaughterhouse waste.
The BKW biogas plant in Fürstenwalde, Germany produces electricity, heat, compost and liquid fertilizer from residential, restaurant and grocery store waste.
The waste is first separated and shredded then pumped into anaerobic (without air) digesters where it goes about its business decomposing. Inside the airless vats, microorganisms go to work eliminating pathogens and odours.