How is the steam used to produce electricity?

A 300 grams of water takes about 90 seconds to boil in a 2 kW kettle, so that is 2000 watts x 90 seconds which is 180,000 Joules of energy.

But to convert that water completely into steam requires an extra 300x550x4.2 Joules, which is nearly 700,000 Joules.

So converting it to steam takes 4-5 times as much energy as boiling it. That is why it takes a while for a kettle to boil dry.