Sector coupling is a term that is increasingly heard in connection with the decarbonisation of energy systems. The decarbonising of electricity production will require more and more renewable energy from wind and solar generation. The need increases when electrification couples the renewable energy with demand from heating, industry and transportation. Wind and solar alone cannot secure an adequate electricity supply for all this demand because of their weather dependency. Wind and solar generation also need balancing, which is effectively provided by flexible power plants, energy storage, and also by flexible electricity demand in the future.
Sector coupling refers to the close integration of major energy-consumers, such as the heating, transportation, and industrial sectors, with the power producing sector. The main drivers for sector coupling are cheap renewable electricity, along with the development of new technologies that extend the feasibility of electrical power applications. Typical examples would be passenger vehicles, heat pumps and the production of hydrogen and other carbon-neutral fuels.
While electricity is already used to some extent by these sectors, energy is still mostly supplied from fossil fuels, gasoline-fuelled cars being an obvious example. The aim of sector coupling is to increasingly shift the energy source away from fossil fuels to clean electricity, and to decarbonise energy end-user sectors through electrification. In coupled energy systems, the sectors will have greater synergistic interaction, while the emphasis will be on utilising renewable energy.
The key is clean electricity, which can be generated from renewable sources, such as wind and solar, or by nuclear generation. The use of clean renewable electricity will decarbonise both the power sector and the entire energy supply.
On the energy demand side, sector coupling impacts energy consuming sectors in the following ways:
It will mean a huge increase in electricity demand and consequently, a need for more clean electricity generation. In a fully decarbonised energy system, electricity consumption could be more than three times what it is today. It will also mean that by installing vast amounts of wind and solar generating capacity, flexibility will be required to balance the fluctuating supply.
Sector coupling provides a means to increase overall system flexibility. It will enable energy systems to access more options for storage and demand response, which can then be controlled for balancing the supply of renewables.
Electrification means that balancing renewables can be built in to the design. For example, Power-to-X processes can be coupled with storage solutions, thereby allowing periods of high levels of generation from renewables to be fully utilised with energy going into storage. Similarly, wind and solar generation can be used to charge heat storage for heating, and electric cars participating in smart charging programmes.
It seems unlikely that the grid can handle all this generation, which is why Power-to-X processes could be located alongside generating plants. They could directly consume the electricity to produce, for example, clean fuels, which in turn would have their own distribution channels.
Thermal power plants will need to adapt to this new environment, meaning that their running hours will be reduced and that they will need to be capable of operating with clean fuels. Even though they will no longer be dispatched on a daily basis, they will be important for ensuring the security of supply. In a sector coupled system, electricity supply and demand will still need to be in balance, and should there be insufficient renewable generation, thermal plants will need to compensate for the shortfall.