Sector coupling

There is an enormous potential for renewable energy on Danish soil and in Danish waters. In Danish waters alone, offshore wind farms can be established which can produce approx. three times as much electricity as the volume needed by a fully electrified Danish society.

In addition to a full electrification of Danish energy consumption, the enormous potential makes it possible to convert power from renewable energy sources into gas, hydrogen and RE fuels – also called Power to X, or the third phase of sector coupling.

Denmark's huge RE-potentials can be utilized to electrifications and to indirect electrification via power to X for sectors that cannot run on electricity.

Three development phases 

Sector coupling in Denmark can be described in three development phases, which do not succeed, but supplement, each other, gradually creating better opportunities for green energy consumption throughout Danish society.

The first phase was the establishment of district heating and decentral CHP plants, which is something which most Danes take for granted. In the first wave, surplus heat from electricity production is utilised, and gas generators can alternately generate electricity and heating for distribution in large residential areas. In Denmark, there is well-established sector coupling between electricity, heating and gas (as well as waste incineration).

The second phase is direct electrification, which is currently being implemented. Individual heat pumps replace oil-fired boilers in houses outside the district heating areas, and largeelectricity-driven heat pumps are gradually established in the district heating sector. In a near future, electric vehicles and electrification of railway services will constitute yet another sector coupling between electricity and transport. The increasing biogas production from, in particular, residual products in the agricultural sector is also part of the second phase of the sector coupling. The direct electrification phase is vital to the green transition right now, and must be strengthened.

The third phase is still only being implemented on a small scale. It is called Power to X and can be characterised as indirect electrification. With Power to X, electrolysis is used to convert electricity from renewable energy production to hydrogen, which can be processed further into green gas or chemically based high-value products such as RE fuels for lorries, aeroplanes and ships.

Together with the heavy increase in Danish biogas production, completely new types of interaction between the electricity and gas systems may thus make significant contributions to reducing greenhouse gases from otherwise difficult sectors such as agriculture and very heavy goods transport.

Energinet is currently developing the gas system for future gas consumption which will be reduced from the current level and which will also be based on green gas. This work is an important element in sector coupling.

Opportunities

Power to X is a river delta which connects RE resources with the ambitious climate targets. If we imagine figuratively that Danish RE resources are a river of abundant wind power volumes which must be lead to provide different types of end consumption, then Power to X is a river delta with many branches. A river delta in which each single branch of the delta leads valuable green energy to an end consumption which was previously fossil-fuel dependent, but which is now becoming climate neutral.

If we stay with this image, four of the river delta branches can be described as follows:

• Carbon from biogas production can be used, together with hydrogen produced from excess wind turbine power, as green fuel in, for example, lorries and aeroplanes, or the hydrogen can be used to produce ammonia, which can become a climate-neutral fuel in ocean-going sea transport.

• Hydrogen or upgraded biogas can be used for that part of the industry’s process heating which currently requires more than 200 degrees of heat and which is therefore technically impossible or far too costly to electrify.

• The gas system and, not least, the gas storage facilities will be able to store electricity which has been converted into hydrogen or gas, thus solving the important and much-discussed challenge of storing enough energy for when the sun is not shining, and the wind is not blowing.

• The success of producing renewable energy at highly competitive prices also means that RE producers and their investors will have an increasing need to hedge the risk of their investment with other elements than the expected electricity price. Production of high-value products such as jet fuel out of surplus wind energy may be part of the answer for investors and thus increase the chances of continued high investor interest in offshore wind farms.

These four ‘river delta’ branches alone make it clear that the third wave of sector coupling, Power to X, has an enormous potential for meeting many difficult challenges in the green transition, all at once so to speak.