Worn out drill bits
Three sizes - 24", 18" and 12", drill bits are triple headed and spun by 'mud-power'.
These are worn out (see blunt teeth on drill heads) - they do about 100m through Granite to get to this state. The 5km and 2.4km holes are dug, so now it is just a process of hooking up the pumps and turbines to get the first 3MW geothermal electricity generating station in the UK up and running.
The extra shows the drilling rig, which is being dismantled to go off to its next job elsewhere in Europe.
United Downs Deep Geothermal Project