Why are Power Grids so Large?

Why are power systems so large and interconnected?

Generally larger provides better economies of scale and can provide better reliability.


Say each town had its own power station - if that power station had a fault the town would be blacked out. The only way to avoid that would be for the town to build an extra power station as a spare - so you'd need as many spare power stations as main ones - very costly. If ten towns clubbed together and interconnected their grids they need only build one extra power station instead of ten for the same effect - much cheaper. In fact if there was a bit of spare capacity on the main power stations they could probably get away without building a specific spare at all - cheaper still. Keep scaling up and the cost savings continue (if at a diminishing rate).


There can be similar benefits for load sharing - if the territory covered is large enough that maximum load doesn't occur simultaneously across the grid - e.g. max demand the south is probably summer to cope with air conditioning, but in the north it's probably winter for heating - then one centrally located power station might be able to satisfy the peaks for both.


The same reasoning applies on much smaller scales too - e.g. a domestic 32A socket circuit can serve a much larger floor area than two 16A circuits - especially if you think you might have to supply up to three 10A loads that might be randomly located by users.


   - Andy.

Why are power systems so large and interconnected?

Generally larger provides better economies of scale and can provide better reliability.


Say each town had its own power station - if that power station had a fault the town would be blacked out. The only way to avoid that would be for the town to build an extra power station as a spare - so you'd need as many spare power stations as main ones - very costly. If ten towns clubbed together and interconnected their grids they need only build one extra power station instead of ten for the same effect - much cheaper. In fact if there was a bit of spare capacity on the main power stations they could probably get away without building a specific spare at all - cheaper still. Keep scaling up and the cost savings continue (if at a diminishing rate).


There can be similar benefits for load sharing - if the territory covered is large enough that maximum load doesn't occur simultaneously across the grid - e.g. max demand the south is probably summer to cope with air conditioning, but in the north it's probably winter for heating - then one centrally located power station might be able to satisfy the peaks for both.


The same reasoning applies on much smaller scales too - e.g. a domestic 32A socket circuit can serve a much larger floor area than two 16A circuits - especially if you think you might have to supply up to three 10A loads that might be randomly located by users.


   - Andy.