Consider the scenario of a large, incumbent, monopoly electric power generation and transmission utility. The utility has made substantial investments over the years, and carries debt. The cost of electricity in the marketplace includes payments on this debt.
As technology improves, the cost of generating electricity falls. A new entrant to the marketplace, unencumbered by the debt, can build a modern plant and generate electricity at a lower cost than the incumbent. Logical customers leave the incumbent utility for the new entrant, reducing the utility's revenue, and spreading the debt payments across the fewer remaining customers.
This is often caused by overly long depreciation schedules for large capital investments by utilities. The depreciation schedules were set presuming an ongoing monopoly.
Solutions to the Stranded Costs problem include assigning a portion of the incumbent utility's debt to the new entrant as a condition of entry, or charging all customers in the market area a Stranded Cost Recovery Fee. In some cases, a government may assume a portion of an incumbent utility's debt and assign it to the public debt, thus freeing the utility to compete against new entrants unhindered.