Sunday, 4 February 2018

Power Stations to Close

New Single Electricity Market rules now in force will see capacity payments cut by 30%.  In some cases, the power stations may not receive any capacity payment at all.

The inevitable consequence of this is the closure of older power stations and less dispatchable plant available to keep the lights on. Dispatchable plant is plant that can be switched on quickly when required. Renewables like Wind energy are not dispatchable because their output is uncontrollable. Ireland (All Island) currently has about 10,000MW of dispatchable plant and about 4,000MW of wind energy. About 1,000MW of capacity will not qualify for capacity payments. This leaves around 9,000MW of dispatchable plant remaining.

Dispatchable plant MW
Remaining dispatchable9,046
Max demand (2010)6,878
Capacity margin2,168
Minimum new data centres1,136
Capacity margin after data centres1,032
Reserve Generation500
Capacity Margin Net Surplus532

When everything is accounted for, including periods of high demand such as occurred in winter 2010 and planned data centres, there is a capacity margin of 1,032MW. Reserve generation is required incase a power station trips out. Currently this is about 500MW. This leaves a net capacity margin of 532MW.

This is quite tight but what happens if Viridian shut down not one but both of their gas power stations in Dublin (they have notified the Regulator that they will close both).  

This would leave a capacity margin of just 132MW. It would be lunacy to allow this to happen as blackouts would be inevitable in a harsh winter.  Dublin would be at most risk where there is a requirement for two large power stations to be on load at all times (three if the UK interconnector is out). 

While it would reduce costs, a blackout would come at a greater cost. 

And what of Northern Ireland ?  Where is the surplus power to come from to export to the North through the North South Interconnector ? The new auction will result in the closure of power stations in the North (Kilroot and part of Ballylumford). Northern Ireland is already at risk of power shortages.

But don't worry the Energy Regulator knows what they are doing I hear you thinking ? Well, I will just leave this here : 

Look for Tuesday 30th January "Electricity Supply".

The interviewer asks the Regulator how much power do the Viridian power stations supply in percentage terms ? It's worrying that the Regulator had not checked this very important statistic. She replies that they are 800MW capacity so out of 9,000MW, it would be a bit less than 10%. But the 9,000MW is not demand, it's total capacity (capacity must be higher than demand). She also never mentioned the little problem of a minimum requirement for power stations in Dublin. Again, something I thought she should know. 

1) SEMO Auction Results -

2) Eirgrid Constraints in Dublin Region -

3) Planned Data Centres -

4) Maximum demand all time -


  1. Note how Ireland's regulator accepts her role is only to monitor energy prices. She has no role to compel.!rii=b9%5F20709930%5F48%5F13%2D01%2D2015%5F her degree is in commerse, not engineering.

  2. Note also that these are the 4th and 6th most efficient units in the country. The newer plant is the youngest in Dublin (Excluding the incinerator) by about 5 years.

    1. I wonder could Paddy elaborate on his post a little? Does he mean that newer plants are more efficient or that more efficient plants are being closed down.