Monday, 13 April 2015

The evidence that Ireland cannot become Denmark

And why Curtailment of Wind Power will become substantial by 2020

We currently have over 2,000MW of wind. Theoretically, we are at the stage where it should be easy to export some of our excess wind energy, which we can't use, to the UK as curtailment levels are still relatively small (in 2013 we curtailed about 3.5% of our wind) and should not pose problems to the UK system which is 11 times greater than ours. When we reach really high levels of wind, we will want to export a lot more surplus wind energy to our neighbours.

When you extract the data from Eirgrid's website (See here) for the year 2014, electricity exports to the UK amounted to just 6.5% of what we imported.  So for every 1MW of electricity that we import, we export just 0.065 of a MW. So what is going on ?

Days like the 23rd February 2015, give us a clue because large levels of wind penetration occurred. Figure 1 shows wind output which remained unusually high throughout the day - between 1,500MW and 1,969MW which is a record for Ireland (A similar analysis was done for 30th March here).

Figure 1: Wind Generation 23/02/15 - output was very high throughout the day

The shortfalls between the blue line and red line gives an indication of the level of wind 
curtailment that occurred.  Demand was about 4,000MW, so if we take 1,700MW of wind 
and 500MW of imported power that gives  us total non-synchronous generation of 2,200 - 
over half of demand. This means Eirgrid had to curtail approx 200MW of wind to keep 
within the 50% non-sync limit. 

So the logical thing to do would be to instead of curtailing this wind, export it through the interconnector 
to the UK. Figure 2 shows that we were actually importing electricity about 70% of the time, and 
close to the maximum permitted by the interconnector which is around 500MW. 

If we assume that average demand was around 4,000MW, then this meant that just circa 1,500MW of 
wind could be accepted by the grid (4,000*50% less 500 for the interconnector) at any one time because
we were importing electricity. 

Figure 2: EW Interconnector Flows 23/02/15 - we were importing close to 500MW of electricity from UK from 8am till 10pm

So the fact is that we are not able to export wind energy except at night. This means that a large proportion of our wind cannot be exported and the situation is exacerbated by the fact that high wind speeds tend to occur during daylight hours (as wind is a function of heat).

 When we get to higher levels of wind at 4,000MW or more, we will be at a stage where wind will sometimes exceed even the daily demand.   Taking into account all the constraints in the system - baseload plant that must be running, 50% limit on wind and interconnection etc - this means substantial amounts of wind will have to be curtailed (i.e wind farms will be shutdown) unless it can be exported - currently this is not the case for around two thirds of each day on average and we have no reason to believe this will change in the future.

This presents a problem for the Irish renewable experts because Denmark is often held up as an example of what Ireland can do. But Denmark has 6GW of interconnectors and can export wind at any time to Sweden and Norway. These countries have a lot of hydro which can be switched on and off at the flick of a switch to facilitate the intermittency of Danish wind. This then, perhaps, gives us a clue as to what is going on in the UK.

The UK has only around 900MW of hydro which is kept running as baseload power regardless of what wind is doing.  Figure 3 shows an example of a day with large levels of wind penetration in the UK system. Like Ireland, it is CCGT (gas plant) which is ramped down to accommodate the wind. The CCGT fleet in figure 3 has very low output which means they are running very inefficiently, like a car running in 1st gear. The UK do not want our wind at this time because, frankly, they do not have space for it. Nuclear must be kept running at baseload level and cannot be ramped down. There is a little more freedom with a coal plant but they too are designed mainly for baseload. An interconnector to France won't alleviate the situation as 80% of their electricity is powered by nuclear which cant be ramped down either.

And I might add that windy days in UK tend to occur at the same time as windy days in Ireland (see previous articles on this blog).

Figure 3: The UK system on a windy day

It will become all too clear in the coming years as to how this situation pans out but the phrase "badly thought out" springs to mind. Denmark, we are not, and can never be.

What this means is that it will be very difficult for us to achieve our renewable targets. The only way the UK will take our wind is if we compensate them for their CCGT running more inefficiently. This might sound like a mad idea (and yes it is) but the regulations already facilitate for such an arrangement - see here, its called negative pricing.

What this means for consumers is higher bills - either more payments to shutdown wind farms or payments to compensate the UK grid to take our wind (negative pricing).

By the looks of it, most likely Ireland will overtake Denmark in one aspect - as the country with the most expensive electricity in Europe by 2020.


  1. Paul O'Reilly14 April 2015 at 19:12

    Two years ago two major wind energy companies, Element Power and Mainstream Renewable Power, proposed plans to build up to 8GW of wind farms in the Irish Midlands. The system was to be separate from the Irish grid, instead exporting the output through new cables to Wales, to be known as the Energy Bridge. The UK were to get "raw wind generated electricity". Pat Rabbitte signed a memorandum of understanding on behalf of the Irish people with the British government. The European Investment Bank and several state sponsored lenders, including the National Pension Reserve fund, were in favour of investing their citizens money. No assessment was to be done and some Irish people wrote to the British Energy Department an assessment be performed before commitment. The British side withdrew ending the whole plan for now.

    In light of the revelations above, as an engineer, it raises a few question about what would have happened had the plan gone ahead.

    1) How would these turbines get their house power which must be regular grid electricity? Who would pay them their capacity payments which are essential for financial survival? If the British are expected to provide Ireland with power 70% of the time now, why would they accept Irish wind energy at the same time? Why not install the 8 GW of wind farms in the UK to begin with? With a capacity factor in the Irish Midlands of about 21%, and many calm days, they would have to make enough money when the wind blows to carry them over when it does not. So why would the British pay an exorbitant price for that? What would have happened if the British demanded proper grid quality electricity from Ireland? Would the Irish be expected to provide the base load and fast acting gas back up? Who would pay for all this? If Labour/SNP get elected in Britain this plan could be resurrected. The most likely event is that when built, it would be discovered that it must be connected to the Irish grid system, effectively adding 8 GW of wind to our existing 10GW bringing the total to 18 GW.

  2. There is only 2 forms of renewable energy which can stand alone without any other plant: River Hydro and Geothermal. Both need rare climatatic and topographical conditions. Norway and Sweden have the topography and the rain for Hydro, while Iceland has the volconic conditions. River Hydo is instantly dispatchable and sychronous. It is also forecastable by simply looking over the dam wall, there is plenty of time to start up thermal plant if the water is running low. If a country like Norway had a large capacity of wind under the control of one National generator, then it would appear that the hydro could provide a perfect balance to wind and the two combined would save thermal plant. For some reason, neither Norway nor Sweden installed much wind and this left a niche for Denmark to fill. The reality is it does not work, Denmark are giving their wind energy away at times, charging their consumers the highest electricity prices in the world and buring as much coal as before. They are huge exporters of oil, as is Norway. Ireland cannot repeat Denmark's experience, no other neighbour has the conditions for hydro. I concur with Paul above, I have always claimed wind generated electircity has little or no commercial value. The dream of wind proponants is to get it sold off to anyone who will take it using publically funded cabling. Fews are buying, confirming my opinion. Wind has little or no value. When the British decided to abandon the export gig, they did no bother to ring Pat Rabbitt. He ended up ringing a girl in an office at the Energy Department who broke the bad news ot him.

  3. If on the 23rd the wind is holding pretty steady (as per the graph), and the interconnector is pretty steady too, then why is the curtailment so erratic?
    Also, why is interconnector being prioritised over wind (priority dispatch)?

    And on a curious note; why do you have a .de domain?

    1. Some of it is due to the erratic nature of wind resulting in variance from forecast, some of it is due to keeping SNSP under the 50% limit. The sharp vertical jolts are due to curtailment of wind. You can see a large spike with the tip touching 2000MW. They could allow this much in at this time because peak demand occurred at 6pm.

      I dont know why the interconnector is being prioritised over wind but it could be long term commitments made by Eirgrid. They seem to have a preference for the i/c because the electricity is cheaper.

      I didnt know I had a .de domain, it looks like .ie domain to me ? - perhaps you can explain more ?

  4. Priority dispatch is subject to limitations, constrainment is included in the contract. The interconnector is firm and if we were to refuse it on the 30th March, (or days when the wind is strong) the British side might dispense with the whole idea and there would be no power to import when the wind speed is low. Remember on the British side, plant must be maintained and staffed to run it and if sales become intermittent fixed costs won't be covered and variable costs will only be covered when selling. Remember the difference in generation: 1) Dispatchable, firm and synchronous if kept running hot continuously. 2) dispatchable, firm and non synchronous, Imported D/C current and 3) Non dispatchable, non firm and non synchronous, = wind. Any combination of 2 and 3 must be kept below 50% of demand. --- On a point of information, EU renewable targets are quantified by the amount used by the final consumer i.e homes, businesses and public use. Irish average demand is (say) 3.5 GW therefore our present 2 GW of wind should have taken us over the line (2/3.5 X 100 ) = 57 %. There is no adjustment anywhere for the capacity factor for wind in the target. I would have thought the first part of the target setting process would be to decide on forecast factors for wind and make it a multiplier. viz: Say it was decided the factor for Ireland was 30%, then the calculation would be 2/3.5X100 x .3 = 17.14%. So a 40% wind capacity would need an installed capacity 2GW / 17.14 X40 = 4.66 GW of wind. I am reading reports of very low wind capacity factors world wide. I carried out a measuring exercise at Kingscourt for 2008 and 2009 and came up with a factor of only 24.1%., Professor Gordon Hughes of Edinburgh University found a 24% factor for Britain, Fr Collins Park in Dublin was reported to have a factor of 17%, while the attached report from Germany is giving theirs @ 14.5%. Eirgrid give a factor of 34.7% for 2004 while Met Eireann 1971 - 2001 wind speed record suggests a factor of 24%. So it is very strange. Low factors will break a wind company financially because, most of their income is variable. Investors in existing wind farms would need to check its factor very carefully.