Furthermore, the capital grants for wind power plants provided under the latter act of 2005 can explain partly the permanent growth in w'ind electricity capacity since then. The PTC was created along with ITC and provides an inflation-adjusted tax credit of USD 15 /MWh (inflation-adjusted) for electricity genherated from qualifying renewable energy projects, in particular, wind. Indeed, the most rapid growth did not happen until after 1999. While the PTC could have played a key role in the business case for new renewable power plants, there were intermittent interruptions of the PTC - which occurred when Congress delayed in reauthorising the Act.