Denmark gets 20% of its energy from wind power, and plans to get to 50% by 2025. So it is frequently debunked by the opponents of wind power (the extractive energy industry) as “having to export most” of its wind power across its borders.
Others claim the export figure is as little as 0.1%, but perhaps the question itself misses the point. Normally having a commodity that you are in a position to sell is seen as a good thing.
All renewable energy sources can work together balancing each other, and the more options there are to balance output within the widest possible geographic region, the better.
The Denmark/Sweden/Germany/Norway/Finland market boasts significant (variable) hydro power, and on the other hand, district heating systems that can store surpluses.
So an exhaustively detailed paper presented today by Andrew Smith of London Analytics looked at hourly power data from 2000-2010, hourly price data from 2006-2010, and minute-by-minute data from the last twelve months, has some useful insights, on integrating 50% wind by 2025.
It concludes that Denmark is able to use its high-capacity inter-connectors at the border to smooth variations in wind generation at the minute by minute level. But, even more, it balances variations in demand in neighboring countries, due to fluctuating hydro power in neighboring countries.
Wind generally works best when farms are spread a larger geographic area, both for the variation in wind speeds, which get evened out over larger areas with variation in weather conditions, and in demand which also evens out by crossing time zones so that the people who use electricity are waking up and going to sleep at different times.
To export (and import), Western Denmark has an AC connector to Germany that can export at 1500MW and import at 950MW, 740MW of DC connectors to Sweden, and 1040MW of DC connectors to Norway. Eastern Denmark has a 1900MW AC connector to the Swedish grid, and a 600MW DC connector with Germany.
Denmark is only 16,621 square miles, half the size of Maine, and serves electricity to a home population of just 5.5 million. But one neighbor alone, Germany, has a population of 81 million, so enabling exports of electricity makes sense from a market point of view.
The study found that higher prices across the border was more of a determinant for exports than lack of demand at home, with high prices were driven by variations in regional weather conditions such as the dry years reducing hydro power in Norway and Sweden.
In order to integrate 50% onto the Danish grid, the report recommended integrating all the distributed players in the market, on both the supply and demand side, to meet future balancing needs.
One such source of balancing is the country’s extensive heat storage capacity in the Danish district heating systems. Previous energy researchers had found that “As a rough estimate between 20 and 30 GWh energy can be stored as useful heat.”
30 GWh of heat storage in a grid with up to 5 GW of wind capacity installed, would provide the needed sink for peaks of wind energy generation, by itself.
Denmark is frequently held up as a case study of a grid successfully integrating wind penetration of 20%, and so as it ramps up to 50%, so it has lessons for the US.
But fears about exporting electricity across borders is hardly one of them.
Image: Jónína Guðrún Óskarsdóttir
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