(As sent to BBC 12.11.09, except , for readability,I have paragraphed it - Alan)
COMMENT ON RADIO "FARMING TODAY "
(Emailed to BBC 12.11.09 by Alan Shaw DEng(Hon) BSc CEng MIET
Thank you for these interesting programmes. It is quite obvious that the wayleave rentals per wind turbine are an offer that few farmers can resist accepting. Also the developers, who retain the ownership of the wind turbine , obtain huge profits from the electricity they sell to the National Grid. Neither farmer nor developer can lose. Thus support for the government's windfarm promotion policy is assured.
Unfortunately wind turbine output is entirely dependent on wind speed , unpredictable, variable and strongest in the far north and west of Scotland while the UK main demand for electricity is below a line between the Humber and the Bristol Channel. Thus huge costs are incurred in building new overhead and underground transmission lines and in reinforcing relevant existing lines to convey outlying wind power to demand centres.
But UK total demand for electricity in the whole UK system must be balanced exactly by generation at every second of the day. A shortfall causes system frequency , normally maintained at 50 cycles per second , to fall, slowing down electric motors nationally. Excess generation causes frequency to rise causing motor overspeed.
Beyond a certain point either eventuality can destabilise the grid causing wind turbines and power stations to trip out, An extreme case can cause national black out. In a transient situation National Grid can presently prevent total blackout by use of low-frequency relays temporarily cutting out major consumer circuits such as water pumping stations, and, in last resort, national voltage reductions.
But we are heading into an unprecedented situation in which, due to lack of government generation planning, this could be a daily occurrence over many years. Because of total dependence on wind, every wind turbine must be "backed up" by construction of dedicated fully controllable fossil fuelled turbine of nearly equivalent capacity whose capital cost must be added to that of the wind turbine . As this will only be called upon subject to lack of wind, this expensive plant operates variably instead of at its designed economic full load steady state condition.
All the above makes windpower the most uneconomic form of energy generation. Its uncontrollability prevents it from generating contractually in either base load or load following roles.It is therefore connected to either the Supergrid or distribution networks as uncontrolled "negative demand".
National demand presenting for balancing by responsive thermal and hydro generation is net of this "negative demand". A windpower component more than about 8 per cent of national maximum demand is a potential system destabilizer as has been found on the European continent.
UK ministers and their civil service advisors do not appear to comprehend the nature of these basic technical problems and are continuing blindly to promote windpower on land and sea. Experienced chartered engineers are appalled at both the danger to electricity security and the enormous increases to the cost of electricity to consumers which are already appearing and will become astronomical. We face an unprecedented and protracted electrical crisis.
Dr Alan Shaw