Commercial scale wind turbines typically have a life expectancy of 20-25 years. When a turbine reaches the end of its useful life it can be retrofitted or removed altogether.
The state of Illinois requires companies developing a wind farm to sign an Agricultural Impact Mitigation Agreement (AIMA) with the Illinois Department of Agriculture and file it with the host county. The purpose of the AIMA is to set out how decommissioning will be determined, conducted, and paid for when and if a project becomes inoperable. In all cases the company is required to provide long-term financial assurance to pay for decommissioning should it ever by required, accessible to either the county or individual landowners. This ensures the cost does not fall to the landowner or taxpayers.