The National Grid Electricity System Operator, in its report “Road to Carbon Zero” (so to speak, at the side of which road, NG ESO has parked up to greenwash its reliance on natural gas for back-up power), it says on page 21, and I quote
GE Power Conversion say of their rotating stabiliser products –
So what I have say about this is that ideally, for maximum energy efficiency, you’d prefer it if you could safely align the rotational axis of the rotating stabiliser to be parallel with the axis on which the Earth spins – and the direction of that axis is most easily found from any place in the Northern Hemisphere to be in the direction of the Pole Star, Polaris.
That’s the only rotational axis which doesn’t change direction as the Earth spins on its axis every day. Point the rotating stabiliser axis in any other direction and it has to be twisted to change its direction by the ground as the Earth rotates and those twisting torques increase the frictional forces on the bearing and that uses up energy and wears the bearings out faster.
The pole star, Polaris, is the star you can use to find the direction north, but we wouldn’t want to point the axis of the rotating stabiliser towards the compass north, horizontally.
Oh no. We’d want to, if we could, point the axis of the rotating stabiliser directly at the Pole Star itself – which isn’t to be found at the horizontal north, but more like rotated upwards from the north compass direction by an angle equivalent to your latitude.
The latitude angle at Keith is 57.5 degrees, so ideally we’d like to be able to adjust the axis of the rotating stabilisers at Keith to point in the direction of the Pole Star. So something like this.
But the GE rotating stabilisers being installed by Statkraft and contractors Knights Brown at Keith don’t have a fully adjustable rotating axis.
For now, GE offers rotating stabilisers with only 2 options for the axis to be either horizontal or vertical.
Vertical is always the same direction from any one place – there’s no way to adjust a vertical axis rotating stabiliser at all – and the Pole Star is only vertical when you are at the North Pole and Keith isn’t at the North Pole, so the vertical axis rotating stabiliser is not ideal.
A horizontal axis rotating stabiliser can be adjusted to any horizontal compass direction but the Pole Star is only horizontally north from the Equator and Keith isn’t on the Equator, so the horizontal axis version is not ideal either.
There’s no point I don’t think in trying to retrofit a tilting mechanism onto either an original horizontal or vertical axis version because the bearings for the horizontal and vertical axis versions will not be designed to work properly unless the axis is in the designed-for orientation, be that horizontal or vertical. So a retrofit tilt is not going to work for long before the bearings break or wear out, sadly.
So I am afraid that Keith isn’t going to be able to get its first 2 rotating stabilisers pointed at the Pole Star, sadly. It’s just not practical unless the rotating stabiliser is designed from day one to have a fully adjustable axis and has specially designed bearings that can cope well with the weight acting in any direction on the bearings.
What’s required is for GE to go back to the design stage and design a new version of their rotating stabiliser product which has specially designed bearings which can work at any axis orientation so that the rotating stabiliser can be safely mounted in an adjustable rig that allows the rotating stabiliser axis to be adjusted to point in any direction, so that it can be pointed at the Pole Star from any place on Earth.
You can’t see the North Pole Star from the Southern Hemisphere but in that case you would need to point the rotating stabiliser axis at the South Celestial pole and finding that direction in the night sky is another matter.
Hopefully, if there is a demand, GE Power Conversion and their competitors will offer rotating stabiliser products which can be installed so its axis of rotation aligns with the rotating axis of the Earth so that we can minimise the ground to rotating stabiliser torque forces and minimise the additional friction on the bearings so as to maximise energy efficiency and bearing service intervals.
So not this time sadly 🙁 but hopefully when the next rotating stabiliser for the grid is installed it will have been designed to have that very special ability to be pointed at the Pole Star.🤞
UPDATE
Statkraft’s project in Keith starts delivering a Greener Grid for Christmas
Grid Services: Innovative solutions to stabilise the power grid
Putting Idle Turbine Generators to Work
HORIZONTAL AXIS
The following video shows that they opted for GE’s horizontal axis rotating stabliser.
Scottish Scientist 