|21 November 2011|
Denmark's Smart Grid Intentions
Doubtful if the risk of power failures has been properly addressed
The Danish Ministry for Climate, Energy and Building has realized that a further increase of wind power in Denmark will put an additional strain on the electricity grids, eventually far beyond their load limits. The answer to this new challenge is called Smart Grid.
The ministry has presented its Smart Grid intentions in a report: "Main Report - The Smart Grid Network's recommendations".
Denmark will develop domestic balancing resources
In the Smart Grid concept new types of electricity consumption such as electric vehicles and flexible heating systems are expected to contribute to the utilization of surplus electricity during windy periods. It will be a special challenge to serve this additional electricity consumption without a corresponding reinforcement of the grids. Advanced automation of the grids and new market arrangements are supposed to replace or reduce grid reinforcements.
So far the growing need for balancing services due to Danish wind power has been covered mainly by foreign resources. Excellent opportunities have been provided by strong interconnections. Reinforcements of primary grids and interconnections will improve Denmark's access to international balancing services.
However, the neighbouring countries also have ambitious plans for wind power development and an increased competition for limited Norwegian balancing resources must be anticipated. Therefore I welcome the intentions of developing local flexibility in Denmark.
The 9 recommendations
There is no argument against the directions of the recommendations. They express intentions, but they do not indicate methods or quantities. Nobody knows the possible magnitude of consumer contributions to the balancing of wind power.
A joint international research effort
Therefore joint international projects such as the EcoGrid.eu project with field tests at the island of Bornholm can be useful contributions in the development process.
Growing risk of power failures
Smart Grids are supposed to be self-healing, but new self-healing arrangements seem to be missing in the recommendations.
The main report and its underlying "issue papers" do recognise the changing need for short term operational reserves (STOR) and the growing risk of power failures. The report recommends a careful monitoring of the need for reserves. The purpose is to prevent serious power failures.
However, power failures can never be excluded, and Smart Grid facilities for black start seem to be forgotten. The blackout in East Denmark in 2003 demonstrated insufficient black start capabilities except at Bornholm.
Serious power failures cannot be avoided, but it will be possible to obtain more acceptable restoration times than in 2003 with appropriate Smart Grid measures. A cell-structure of the grid and the ability to perform a separate black start within each cell has been outlined in the past.
Super Grid or Smart Grid?
This may be a possible solution in the very long term. In the short term new interconnections to Norway and the Netherlands together with the outlined offshore grids in the North Sea and the Baltic Sea will probably give Denmark the best possible access to purchase balancing services in the international electricity markets.
Balancing services from district heating
Denmark has a unique balancing capacity in the combined heat and power (CHP) systems. The flexibility of the CHP systems is due to the fact that most CHP systems include a large hot water tank. Surplus electricity can be converted into hot water by heat pumps or electrical heaters. During periods of suitable demand for electricity and hence profitable market prices, CHP plants can supply heat while recharging the hot water store.
Several CHP systems are already participating actively in the electricity spot market and in the market for regulating power. The potential can easily be quantified and mobilised when needed.
A robust Danish strategy
The future mixture of measures cannot be optimised in advance due to uncertainties. The planning must be currently adjusted in a moving planning process. Balancing services from the district heating systems can be mobilised at any time in accordance with demand. Flexible end-user demand will require a research and development period and considerable investments. Research activities should be maintained in order to keep this option open for implementation when needed.
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