Otherwise, the main tax item is going to be the yearly licensing fees that projects need to pay to get the right to harvest the resource.

Are these taxes production-related?

eg Enercon PartnerKonzept interests me, of course.

Yield-oriented cost structure
The costs for the ENERCON PartnerKonzept contract are based on the annual wind turbine output. The customer pays a minimum fee depending on the respective wind turbine type and a yield-oriented surcharge. This means that the customer pays more in good wind years with good yield and less in bad wind years with less output thus stabilising annual wind turbine profit.