Since 1991 the Itaipu scheme on the border river has been operating with 18 units each, and in September 2006 the 19th unit went into commercial operation. With the inauguration of the 20th unit by President Luiz Inacio Lula da Silva of Brazil, and President Nicanor Duarte Frutos of Paraguay, the project has achieved the planned capacity envisaged when the project was conceived decades ago.
In 2006, Itaipu produced almost 92,700GWh, and over the last five years produced an average of 90,000GWh. With 20 units in place, the plant should be able to average 95,000GWh.
Until the recent work to install the last two units, the plant generally operated with 16 out of 18 units. It is expected that the scheme will typically operate in future with 18 units running.
Each turbine is a vertical-axis Francis unit with nominal capacity of 715MW. The design head is 118.4m and flow rate is 645m3/sec to give rotation speed of 90.9/92.3 rpm for 50Hz/60Hz synchronisation with generators.
