High Performance High Pressure (HP-HP) turbines achieve high levels of efficiency. This is due to the blade and seal design. The HP-HP turbine consists of two rows of blades with seals attached - the inner blades are fixed, whilst the outer blades rotate. The seals force the steam through the blades preventing any from escaping

In traditional High Pressure turbines the inlet (or first stage) consists of one impulse stage and thirteen reaction stages. The HP-HP turbine gas only has reaction stages, half of the pressure drops over the moving blades. This means that the force on the rotor is a combination of changing direction of steam flow and changing velocity of steam.

We have installed HP-HP turbines at Ratcliffe because maintaining the steam load reduces the amount of coal burnt making the electricity generation process more efficient. The increased efficiency means that less steam will be required to produce the same amount of electricity. The pump will not need to send as much water into the boiler so less coal will be needed to heat it. This also produces a decrease in the amount of ash and emissions produced.