The Eirgrid Generation Adequacy Report 2008 to 2014 was published recently.
The report states that Ireland is facing a tight electricity supply situation:
“The most significant factor influencing this is the poor availability of the generation portfolio. Improved availability performance would greatly reduce the risk to security of supply. However if availability continues at the current low levels, then the system is facing immediate deficits.”
We are moving to less diversity of supply as all new generation capacity planned in the near future is either (Russian) gas or wind generated power.
The report recognises the benefits of moving demand to off-peak hours. “Shifting 1% of annual consumption from peak to off-peak hours would remove the requirement for approximately 135 MW.”
With regard to wind power generation (WPG) the report states. “There is also considerable investor interest in wind powered generation, however, due to its inherent characteristics, it offers limited generation adequacy benefits. Furthermore if WPG is installed at a linear rate of 270 MW per annum there would be just over 1,700 MW installed by the end of 2010. This should be sufficient to enable 18.0% of the electricity requirement to be provided from renewable sources and would mean that the Government’s target of 15% by 2010 is exceeded.”
The problem with wind energy is, of course, that it’s only available when the wind blows. That means that it has very little effect on supply adequacy.
Furthermore the contribution of WPG towards generation adequacy (i.e. Capacity Credit of WPG) has not keep pace with the growth in installed capacity or energy supplied. In fact, while installed WPG capacity has increased by 40% per annum over the last 5 years, in the same period the capacity credit (as a percentage of installed WPG capacity) has fallen from 35 to 24 %, see Figure 4-7. As outlined in Section 2.3(b), this is due to the inherent inability of WPG to behave as a number of fully independent power plants. All WPG in Ireland tends to act more or less in unison as wind speeds rise and fall across the country. The probability that all WPG will cease generation for a period of time (as a result of wind conditions) limits its ability to ensure continuity of supply and thus its benefit from a generation adequacy perspective.
EirGrid recognise the benefits of moving demand to off peak times. They do not acknowledge in the report that energy demand management (EDM) can improve WPG adequacy if the EDM is operated based on actual current wind energy production rather than on tine based tariffs. In particular the possibility of stimulating demand at times of excess wind energy could reduce or eliminate the need for wind farm curtailment.