In 2014, the capacity factor for wind was 27%. In both 2016 and 2017, the capacity factor remained at 27% despite the higher wind penetrations allowed.
An analysis of wind speeds shows that wind speeds were fairly similar for those years, with 2015 being somewhat higher. I took a sample of six weather stations from around Ireland, the average wind speeds I obtained neatly fitted with the capacity factors for wind.
As can be seen from the last part of the table above, we went from allowing 50% wind into the grid to 60% and by the end of last year 65%. As wind had more access to the grid, we should have seen a higher capacity factor for wind.
This seems to suggest that we have already reached saturation point for wind energy. I would be interested to hear what people think. I have already written about market cannibalisation and diseconomies of scale. Here is strong evidence that supports that argument. Most of the best sites for onshore wind have been used up. The turbine layout at some sites is too dense and newer larger wind turbine models have failed to deliver any significant additional output. And after all, the wind resource itself is limited, particularly in Midland regions.
Sources
Eirgrid Constraint Report 2017
http://www.eirgridgroup.com/site-files/library/EirGrid/Annual-Renewable-Constraint-and-Curtailment-Report-2017-V1.pdf
Wind speeds from Met Eireann website (in knots)
https://www.met.ie/climate/available-data/historical-data
2014
|
2015
|
2016
|
2017
| |
Cavan
|
6.3
|
6.8
|
5.9
|
6.3
|
Kerry
|
9.5
|
10.3
|
9.1
|
9.3
|
Donegal
|
14.4
|
15.3
|
14.3
|
15.1
|
Cork
|
12.2
|
13.1
|
11.8
|
12
|
Tipperary
|
8.3
|
8.8
|
7.9
|
8.2
|
Carlow
|
7.3
|
8.2
|
7
|
7.3
|
All stations record wind speeds at 10m above ground level.
Note that total wind output did increase in 2017 by about 18% by adding an extra 530mw of wind capacity, an increase of about 20% on the previous years installed wind capacity. The capacity factor measures the actual output in relation to potential output if the entire wind turbine fleet had been operating at full output for the entire year. So theoretically if wind speeds increase so should the capacity factor. Or if wind speeds stay the same and the maximum level of wind permitted into the grid increases, then capacity factor should also increase.
The report states that Irish renewable energy is predominantly sourced from wind, and that the overall contribution from hydroelectric, solar photovoltaic, biomass and waste are so small as to be ignored. So the whole national conversation (i.e. policy) is 100% about wind. The contributory factors for dispatch-down of wind are the amount of wind generation installed and the capacity factor of the wind generation.
ReplyDeleteIt also clarifies that "dispatch-down" of wind energy refers to the amount of wind energy that is available but cannot be produced because of power system limitations, known as curtailments or constraints.
Curtailment refers to the dispatch-down of wind for system-wide reasons which include system stability requirements operating reserve and voltage control requirements. These are the focus of the DS3 "System Services" gold rush that is currently taking place under the guise of so-called "battery storage units" (see http://irishenergyblog.blogspot.com/2018/04/battery-storage-project-doesnt-live-up.html).
Constraint of wind occurs when there is more wind generation than the localised carrying capacity of the network or during maintenance. These are the capital works that either add further interconnectors or boost the current carrying capacity of existing infrastructure that is carried out under the control of EirGrid .
For the Irish Republic the breakdown of wind dispatch-down volumes in 2016 between curtailments and constraints was 72% and 28% respectively. This shows that grid destabilisation issues currently have an impact that is three times greater than any shortcomings in localised grid current carrying capacity.
Grid destabilisation arises from the shutdown of large, high mechanical inertia fossil-fuelled alternators with wind turbines that have a negligible mechanical inertia. In the case of the former, the control system counters an instantaneous high load (fault condition) by increased rotor excitation to maintain the output voltage, and the kinetic energy inherent in the heavy rotating rotor is instantly converted to supplying the high current draw (at the price of slowing down - the rate of frequency reduction).
It is an unfortunate characteristic of wind turbines that the need to manufacture the lightest possible alternator that can be mounted 90 metres or more above ground level means that it has little or no inertia. If the wind drops suddenly, the turbine will typically halt within a few revolutions, and any amount of sophisticated electronic circuitry simply cannot maintain either the power or the frequency.
The consequence of reduced spinning reserve is reduced inertia, a higher probability of RoCoF trips, and blackouts on the national grid. The DS3 programme is all about how to create "synthetic inertia" to substitute for that which we have turned off so that the inertia-free wind generation does not need to be curtailed.
The preferred solution from DS3 and the CRU is the supply of "system services". These are essentially large batteries connected to fast turn-on electronics that purchase electricity when the wholesale rate is low, and sell it back at a hugely inflated price for a very short time (turn-on <0.5s turn-off within 90s) to compensate for the lack of system inertia due to the lack of spinning reserve (see http://irishenergyblog.blogspot.com/2018/04/battery-storage-project-doesnt-live-up.html?showComment=1525027512401#c5971243742203383660).
This is a seriously lucrative wheeze - in Australia the AEMO (equivalent of Irish CRU) reports that for system services from the Tesla Big Battery the price settled above AU$5,000/MWh for nine trading intervals during three days of price volatility in South Australia on18/19 Jan and 7 Feb 2018). That beats REFIT at €66.85/MWh hands down. (See https://reneweconomy.com.au/inside-the-tesla-big-battery-how-it-made-money-and-cut-prices-15167/).
When Rabbitte took charge of what they call energy policy he asserted that we need to add 250 megawatts per annum to meet the target At 250 meg add per year wind penetration would stall at less than 20%. Which it did at .1% increased wind penetration per annum it would take 200 years. Now they are adding over 500 megawatts a year, double Rabbitts assertion of capacity requirement, and still cannot meet the target. The reasons for this are output losses, from wind energy availability losses of from 7 watts per metered squared to 1 watt per meter squared, due to wind farm density, output loss, up to 50% every 6 years, due to mechanical decline as wind turbines age, Building wind farms like building 150 meter high statues of Mickey Mouse creating output losses of 40% .Due to wind wake.I surmised that eventually Eirgrid should discover thats Rabbits assertion would be inadequate and the would significantly raise the capacity they thought would be needed and would significantly increase it. Which they did. But increasing wind penetration on the grid also allows increasingly turbulent generation on to the grid. Which will eventually crash the grid. Wind turbines mostly cutout at 90 kilometres per hour wind speeds. Running wind turbines in storms with wind speeds gusting to 150 kilometres per hour is dangerous . As you will have massive capacity and output drop offs. Which would make life interesting for Eirgrids balancing team. As they run out of suitable sites the capacity add will decrease leading large drop in output. Because of wind turbine mechanical break up and density issues. Sensible person would pack the whole crazy wind farm policy up and so something use full with their lives. Like building a new coal plant.
ReplyDeleteAnother potential problem for Eirgrid is the fact that most of these wind farms are loss making.In Denmark when the wholesale price drops to an unacceptable level up to 400 megawatts of capacity is shut down in an effort to drive the wholesale price back up . To a level to which losses are handleable.
ReplyDeleteWe wish to thank you once more for the stunning ideas you gave Jesse when preparing her own post-graduate research and, most
ReplyDeleteimportantly, with regard to providing all of the ideas within a blog post.
Provided that we had known of your web-site
a year ago, we would have been kept from the unnecessary measures we were
having to take. Thanks to you.