I know from shop talk among previous colleagues that waste incinerators often need natural gas to sustain firing. AFAIK this is mostly because mixed household wastes have a high moisture content, making them a bad fuel. However, I found no data on this. For some reason, the incineration industry does not advertise this fact. The only tidbit I found was on a site advertising natural gas, of all things. I want to understand this issue more.
Obviously not all waste fractions are equally interesting as fuel. Light plastics and some packaging are close to brown coal in caloric content and usually pretty dry, organic waste is also okayish from a caloric point of view but has a high moisture content while some other trash basically does not burn. Paper would make a good fuel but makes better pulp. So when asking about whether natural gas or other fuel is used for co-firing, we need to know what waste fractions are in fact incinerated or the answer is meaningless.
Is it actually true that many/most incinerators for unsorted household waste use additional fuel for co-firing?
What sorting steps are neccessary to arrive at a waste stream (Starting from household waste) that can be burnt without additional fuel?
With the latter question, I want to be able to look at the input waste streams into an inceration plant and be able to make an educated guess wether it uses additional fuels or not. I don't see natural gas used purely for thermal exhaust aftertreatment as co firing for this question.