Capacity is a structure used in some electricity markets to pay generation assets to be available to meet peak electricity demand. Most commonly used in northeast and mid-Atlantic electricity markets, capacity pays for some of the fixed costs of building and maintaining power plants. These costs are passed on to consumers based on their annual peak usage. The Texas Performance Credit Mechanism has been called "Texas' version of a capacity market" by some observers. The big difference is that costs are not directly allocated to consumers, but are instead incorporated in the overall cost of electricity.