Eirgrid Increase Spinning Reserves - Irish Energy Blog Vindicated

To maintain a stable grid, Eirgrid have always ensured that there is enough "spinning reserve" (or back up generation) running or available to provide power at short notice in the event that a power station trips (i.e. suddenly has an outage) or there is a sudden change in demand. 

For many years, the minimum for this reserve requirement was set at 440MW, made up of four different types of reserve with different reaction times, of 110MW each. The quickest can deliver in less than five seconds, the slowest in less than five minutes, with the latter capable of lasting much longer than the former. The remaining reserves can react within 15 and 90 seconds. 

The two fastest reacting reserves are called Primary and Secondary Operating Reserve and are provided by units already running on the system that can change their output quickly to deal with unexpected events. The two slower reacting reserves are called Tertiary Operating Reserves and are provided by units both already on the system and that can start quickly at short notice. For additional security, there are also replacement reserves that can start from 20 minutes to four hours and are provided by fast acting offline generators such as open gas cycle turbines (basically jet engines).

The question then arises - if wind energy is inherently variable, just as demand is, or unpredictable just as a generator outage is, what impact does it have on reserve requirements in the event that it unexpectedly rises or falls ? In otherwords, does it contribute to an increase in unexpected events that can't be forecast by the grid operators ? If the answer is yes, then more reserves will be required, likely in the form of fast acting fossil fuel generators (and with a consequence increase in emissions.) Consider that the single largest generator that can fail in the system at any one time is about 500MW compared to combined wind energy capacity of 3,000MW which if acting in unison (as it usually does) is six times the size.

In 2014, the SEAI issued their  "Quantifying Ireland's Fuel and CO2 Savings from Renewables" report based on the contribution from wind energy during 2012. 

This is what they concluded in relation to the potential impact of wind generation on reserve requirements :

Future planned increases in wind capacity will influence the reserve requirements, particularly tertiary reserve requirements. The All-Island grid study showed that additional reserve requirement in hypothetical 2020 scenarios is related to the amount of wind installed but that the largest contributing factor remains the loss of the largest conventional unit. Wind power does not necessarily require larger amounts of primary and secondary reserve, when the characteristics of the wind are taken into account in the calculation of reserve requirements. The relative electrical isolation of the All-Island system means that the reserve levels consider the need for a high degree of generator flexibility, while additional rules ensure a sufficient number of units remain online to ensure frequency and voltage stability. Reserves allow the electricity system to respond to unexpected events but the ability of the system to incorporate variability and uncertainty due to renewable electricity generation is primarily determined by system flexibility. 

At present, renewable electricity generation on the All-Island system does not influence the quantity of reserve required.

In essence, the SEAI are claiming there will be little impact on reserves from wind power but with caveats thrown in about it impacting mainly tertiary reserve and careful use of words like "at present" which would indicate that future levels of wind energy are not being examined in their report anyway. 

In the same year, I wrote an article for this blog challenging the SEAI's report and in particular their omission of the impact of wind energy on reserves. I argued that higher levels of wind energy would indeed lead to an increase in reserves and based my argument on research done by both Danish and UCD researchers (in 2007 and 2005) : 

There should be enough spinning reserves to cover an outage of the largest unit in combination with a fast decrease of the current wind power production. However, the capacity of the largest online unit changes dynamically. (Doherty and O’Malley 2005) further demonstrate the dependency of the demand for TR1 [Reserve Type 1] from the installed wind power capacity. 

"Generally, the demand for replacement reserves increases with increasing wind power capacity installed. 

The occurrence of high demands for replacement reserves is mainly driven by a high number of simultaneous forced outages that happen simultaneously to relatively high wind power or load forecast errors. The value of these peaks tends to increase with increasing wind power capacity installed."  - Wind Variability Management Studies (P.Meibom et al)"

My article has now been vindicated four years later as a recent Eirgrid document shows that they have increased the minimum levels of spinning reserve required for the Irish grid.

Previous Operating Reserve Requirements

New Operating Reserve Requirements, Summer 2018

This means the minimum reserve now is 540MW (135 * 4), up 100MW, with at least half of that coming from units already running on the system. The reason for this increase is due to DS3 System Services Contracts. DS3 services, as explained before on this blog, are services required by conventional and other generators to facilitate high levels of wind energy. 

From the onset, the integration of wind generation presented a range of challenges previously unseen in the power sector. Through collaboration with the Regulatory Authorities and the wider electricity industry, DS3 has developed a number of innovative and progressive solutions. 

The cost of which may well become significant :

This means that some types of service providers could be available and eligible for payments for every hour of the year assuming they are not forced out or scheduled out for maintenance, even if the service is not required from those providers for all of these hours. The scale of overall payments will therefore increasingly depend on the portfolio of service providers and the expected availability of individual service providers.

2014 Irish Energy Blog article : http://irishenergyblog.blogspot.com/2014/12/seais-quantifying-savings-from.html

Battery Storage Project Doesn't Live Up to Hype

A new 200MW battery storage project in Co. Offaly has been hyped up in the media as a project that will "boost use of renewable energy and reduce dependence on fossil fuel-fired power plants."

From the Independent :

BESS (Battery Energy Storage Solutions) involves the storage of power from the grid which is then resupplied on demand. It will allow renewable energy generated at night to be stored, which would otherwise have to be curtailed due to a lack of demand.

The power can then be released back into the grid, avoiding the use of conventional oil or gas-fired power stations to generate electricity.

The 200MW proposed by Lumcloon could provide power for the equivalent of 170,000 homes.

In reality, the storage facility will not generate any electricity. It will not provide power for any home nor will it reduce dependence on fossil fuel power stations. In fact, it will increase dependence on fossil fuels during periods of low wind. 

According to the planning application, the main purpose of the storage unit is to provide a quick injection of power to restore balance to the grid when there is a fall in system frequency. A fall in system frequency could occur when there is too much wind generation in the system and not enough conventional. According to the Lumcloon Energy website, the facility will need to respond within 5 seconds.

The storage unit is an appliance, like a washing machine, in that it will be a consumer of electricity. It could be called on at any time to inject power, so it will need to be fully charged at all times. So while it will be able to charge at night when there is surplus wind energy, it will also need to charge during periods of low wind thereby increasing dependence on fossil fuel. Therefore, it will be useful during periods of high wind, but a drain on the grid when there is no wind.  

Ireland's only pumped storage facility, Turlough Hill, is also a net consumer of electricity. It has a fixed regime, where it stores electricity at night when it is cheap to do so and exports electricity during the day when prices are higher. Lumcloon is similar but different. Turlough Hill trades in the single market like any other generator. Lumcloon, on the other hand will be paid for providing "system services".

These services must be provided to the grid when requested by the grid operator at short notice , unlike electricity which is bid into the market in a competitive pricing system in advance. They are high quality sophisticated high voltage and frequency services.

A grid run on low levels of renewable energy and supplied mostly by conventional generation plant [i.e coal , gas, hydro, nuclear etc] , does not need to provide such services as they are embedded in the product conventional generators provide.

The storage unit will not sell electricity back to the system ( and receive a price for this product the same as an hydro or wind plant would ) , instead it will receive special remuneration set by the regulator and this remuneration is an additional cost to the system and will have to be recovered from the consumer. 

So the net result from this project will be additional costs to the consumer and it will have little impact (or even none) on the reduction of fossil fuels. A long way from the hype in the media.

Storms Linked to Power Station Trips

Eirgrid published this list of power station trips from the past few months:




I couldnt help but notice that most of these dates coincided with storms or very windy conditions:

5th october - Cyclone Xavier
12th october - Hurricane Ophelia
16th october - Hurricane Ophelia
21st october - Storm Brian
27th November - gale force winds
24th December - record wind penetration on the grid
3rd January - Storm Eleanor
17th January - Storm Fionn

It appears that as very high amounts of wind generation is allowed into the grid, the frequency can drop to a dangerously low level.

One of our key tasks is to maintain balance between electricity supply and electricity demand. Electrical frequency is the measure of balance between supply and demand. When supply and demand are balanced, the electrical frequency is at 50 Hz. We must maintain this balance on the system all day, every day. The normal operational frequency range is 49.8 Hz to 50.2 Hz [Eirgrid].

You can see from the above diagram that the frequency has dropped below 49.8Hz on a few occasions over this period.  As a result, the power station tripped and went offline. This then results in the frequency falling even further. At this stage, cutting demand is one of the few options open to the grid operator. This may explain some of the blackouts on these days.

Technical Problems with High Levels of Wind on Christmas Eve

New Report Describes Total Decarbonisation Dream as Wishful Thinking

On Christmas Eve, wind was providing just over 60% of electricity demand. This is new territory for the Irish grid (or indeed any grid). Eirgrid began trials of allowing a maximum of 65% for wind energy (wind penetration) in November. Wind generation was also exceeding the wind forecast. 

Jolly good I hear you say. However, it can be troublesome balancing this level of wind as other plant are forced to run below their optimum efficiency. The additional unforeseen wind also creates more problems as scheduled plant are constrained off.  Variances in the frequency are a good indicator of just how much trouble these high wind conditions can cause. A stable frequency is required for a stable grid and a certain amount of conventional plant is required to maintain the frequency within a tiny range. 

As the wind level rises, the frequency falls below 50Hz. At around 15:40, some of the wind energy is shut off and the frequency returns again to 50 Hz.


These technical problems have been highlighted in a new report on the German electricity grid (Hidden Consequences of Intermittent Electricity Production).

Another important difficulty caused by intermittency is the increased vulnerability of the electricity grid to instabilities. This is particularly visible in countries that are not so well interconnected like Ireland. An example of a threatening oscillation occurring at a 400MW power generator (24/4/2014 between 21:40:40 and 21:41:00) is shown in Fig. 3 (adapted from M.Zarifakis et al.,  “Models for the transient stability of conventional power generations stations connected to low inertia systems”, Eur. Phys. J. Plus 132, No.6, 289 (2017), op. cit.).

Grid stability is now a major issue around Europe :

Further, if one keeps the current Alternative Current grid technology, a certain minimum amount (~ 20-25%) of “rotating mass” has to be present to guarantee stability.  If this cannot be sufficiently provided using biomass, and if fossil and nuclear based power stations are not allowed, problems will arise. Instabilities caused by large contributions of intermittent power e.g. from wind or solar PV pose a major threat to the stability of the electrical network of a country and to the safe operation of conventional generator systems, as exemplified in Ireland. If no economical solution can be found for such difficulties, conventional backup power based on fossil fuels or nuclear power will necessarily have to remain part of the electricity system.

Their conclusion is in agreement with the work carried out on this blog :

A last point is the economic feasibility of such a system. Germany, with currently an installed capacity of about 90GW in solar PV and wind, has one of the largest renewable systems installed in the world. The cost (including feed-in tariffs, subsidies, extra costs because of court cases due to unfulfilled promises etc…) is estimated between 250 and 300 billion Euros, integrated over the last 10 years. The CO2 reduction on world scale realized by this system is less than 1‰. As discussed above, a 100% iRES without backup or storage systems makes not much economical sense and will lead to a doubling or tripling of the total costs, compared to the conventional system in use now. It is to be expected that not many countries are able to pay for such a costly and inefficient system. The question can thus be raised if the current EU plans for the electricity sector are bound to fail? 

Finally, the electricity sector is only a minor part of the problem. If one wants to completely decarbonise our economy then one should also include other private and economic sectors. Given already the challenge of a 100% renewable electricity system and the complexity of replacing the present primary energy supply based mainly on chemical energy by renewables, this total decarbonisation looks to be wishful thinking, at least at the present stage of technology. Would it not be more useful to invest in research and development of conventional and new energy systems rather than blindly investing in an existing “green” technology which seems bound to miss its goal? The other question is whether decarbonisation should be our primary concern. Is this really the best investment for a better future for mankind, as discussed in B.Lomborg, “Cool It”?A critical assessment of the EU plans is also voiced in countries outside the EU, in particular the United States under the presidency of Obama. Does transforming the present primary electricity supply (based presently mainly on fossil and nuclear sources) into a 100 % intermittent Renewable Energy System, as imposed by the EU, need to be the challenge and moral quest of the 21stcentury? This will for sure affect our society and standard of living if current EU plans are not corrected for the problems that are emerging from the grand renewable experiment in Germany of the recent years.

The full report can be found here : 
http://revue-arguments.com/articles/index.php?id=76