Wind turbines in Denmark
Intermittence and hydraulics
Focus on the Danish case
Jean Pierre Riou
English translation Bernard Durand
Avertissement : cette série d'articles en anglais reprend des articles du Mont Champot en français afin d'étayer une publication ultérieure.
Cet avertissement explicatif sera rapidement supprimé.
Why the development of intermittency in France will impose additional load monitoring on its nuclear reactors, which deteriorates their profitability and compromises their safety, without participating in the decommissioning of any of them.
Costa Rica, Uruguay, Quebec and Norway generate more than half of their electricity from hydro power. A good part of this energy, stored in dams, allows them all the fantasies of production with intermittent means such as solar or wind.
But the problems raised by the Sivens dam project painfully remind us that this model is not universally applicable.
However there is no other mean of storing massively electricity than using hydraulic reservoirs. This is the reason why countries not having such an asset cannot reduce the installed power of their dispatchable power plants by a single MW in return for the development of intermittent resources, whatever their power.
This power of intermittent sources is likely to fall to less than 1% of its installed power when the wind drops, as this March 12, 2018 in Denmark.
"High pressure potatoes" can, however, fall on an entire week in Europe, while regularity of electricity supply to the network is essential. This explains why Germany has still not reduced its controllable fleet by 1 MW in return for 100,000intermittent MW. Similar is the case of Spain. The French are mistaking if they believe that the closure of 3 GW of coal is due to any reason other than the economy in electricity consumption due to the commissioning of the Georges Besse 2 plant for the manufacturing of nuclear fuel.
The Danish case
The case of Denmark requires special attention since it has succeeded in 25 years in reducing its fleet of coal-fired powerplants by 2 GW, from 10,214 MW in 1995 to 8,141 MW in 2015, in parallel with the development of 5 GW of intermittent wind power. And that, without having hydraulic reserves allowing to cushion the vagaries of the wind production. The table below details this development
This evolution of the Danish electricity fleet can only be understood within the Nordic network with which it is closely connected, mainly with Sweden and Norway which supply it with almost all of its imports, and with Germany to which it exports its surpluses, as shown in the graph below which illustrates the development of its cross-border trade since 1990.
The red line drawn on this graph shows the evolution of the trend of these exchanges. Denmark was a net exporter in 1995. The exports/imports balance gradually decreased, until it became negative from 2011, and represented up to 17% of Danish consumption in 2015.
Nordic and Baltic hydraulics
The Nordic electricity network, which connects Sweden, Denmark Norway, and further on, Finland, Estonia, Latvia and Lithuania is characterized by a considerable hydroelectricity input, with the exception of Denmark and Estonia. Hydraulic power provided, in fact, 96.3% of Norwegian electricity consumption in 2016 and half that of Sweden, Finland, Latvia and Lithuania. These countries are largely using this facility to open or close their floodgates to regulate the network, as shown by the sudden variations in Lithuanian hydraulic production, below.
All Denmark’s eggs in its neighbors' hydraulic / nuclear basket
Nuclear energy also characterizes the electricity mix in Finland, where nuclear / hydro power accounted for 83.4% of electricity production in 2016 (excluding cogeneration), and in Sweden for 80.3% of production (87% of consumption).
It is in fact the Swedish and Norwegian hydraulic reserves which allow Denmark to have power when the wind drops. And assure him a possible outlet for its excess of wind production, because these neighbors have no more difficulty opening floodgates for export than closing them to absorb surpluses. Imports by Denmark are all the more important as its wind turbines produce less, and it becomes an exporter when the power of its wind farm exceeds, roughly speaking, 2800 MW. This is shown in the graph below, which also illustrates the strict correlation between the amount of wind power produced by Denmark and the amount of power it exports, or is forced to import.
Source AIE, Danemark 2017
Such behavior with such accommodating neighbors more than makes up for its lack of hydraulic storage capacity, and avoids having to subsidize emergency thermal power plants when wind is lacking, as Germany does.
The hinge 2005 2015
Between 1995 and 2005, 2.5 GW wind turbines were added to the Danish electricity park almost without reducing the thermal park (minus 0.3 GW). This increase in installed capacity was, however, accompanied by a decrease in exports, due to an increase in consumption over the same period, as we can see in the graph below.
The horizontal red line highlights the similarity of consumption between that of 1995 and that of 2015, which frame this study, and without which any comparison would be biased.
It is the period 2005 2015 which is significant, since it was then that Denmark made most of the reduction in its thermal fleet. But also, from a net exporter, it has become an importer of 17% of its electricity needs, while its consumption fell regularly, from 34.2 TWh in 2005, to 31.7 TWh in 2015.
Its electrical system gives Denmark the most expensive electricity in Europe for households, with 0.3088 € / kWh in 2016, while its Nordic and Baltic neighbors benefit from a kWh 2 times cheaper: 0.12 € in Estonia, € 0.16 in Latvia, € 0.12 in Lithuania, € 0.15 in Finland, € 0.18 in Sweden and € 0.15 in Norway.
But at least the wind industry, with 25,000 jobs in Denmark, represented 8.5% of total exports, while the internal wind market represented less than 1% of activity in this small country in 2011, before China took over the market.
The other point of view
These figures were indicated in the letter sent by the industrial sector to the Minister of the Environment at the time, to remind him that the place of Denmark as European leader in this industry attracted the eyes of the whole continent on Denmark's wind energy regulations, and that plans to take into account the nuisance caused by their low-frequency noise risked being copied by other countries.
And that it would cause considerable damage to the Danish economy if the regulations concerning the protection of local residents were to be tightened.
This is roughly the content of this edifying letter, a sworn translation of which was published in a Finnish report (p 73/74 via Waybackmachine).
This letter is dated to the time when Professor H. Møller, undisputed acoustics specialist in Denmark, fought for wind turbines very low frequencies and infrasounds to be measured in homes and not just calculated. It was the time when he was sacked from the University of Aalborg where he professed. At which time this University spoke, on its own site, of the mafia practices of this dismissal on economic pretext, and the press also denounced these practices and paid him a vibrant tribute.