a few years back, we did some work on biomass using energy systems model. Project details can be found under https://www.psi.ch/en/eem/projects/chp-plant-swarm
I would not recommend to look studies using LEAP as this is an integrated energy planning model where biogas maybe would be seen in a very simplified way: investment, O&M cost, fuel price if any.., capacity factor, dispatch order...That is OK for planning models, but to really understand what happens with biogas plants and its process I would recommend other tools.
There are some tools wich have more details for biogas. For example, in Retscreen there is a module for biogas and for landfill biogas.