By coupling the electricity, heating and transportation sectors and utilizing energy storage, excess energy that would otherwise go to waste, can be repurposed and flexibility can be generated in the energy system.
Sector-coupling plays a significant role in the decarbonization of energy systems. Taking a holistic energy system approach is necessary rather than dealing with the various sectors separately as stand-alone units.
The transition from fossil fuels to renewable energy sources is accelerating within the power part of the energy sector, while other energy-consuming parts of the energy sector such as industrial steam or heating as well as transportation are still predominantly depending on fossil fuels. Electrifying the remaining sectors and making electricity the default energy form can solve several of the current challenges related to power generation from renewable sources.
An integrated energy system based on renewable electricity
Wind and solar are fluctuating energy sources and are not always available when energy is needed. By interconnecting sectors, excess electricity generated during peak periods can be stored and repurposed within e.g., the industrial steam and heating, district heating and cooling as well as transportation sectors, thereby stabilizing the energy system. This conversion is referred to as Power-to-X (PTX).
The excess electricity from wind turbines, PV plants, or CSP plants can be used to heat molten salt as Power-to-Salt (PTXSALT). This can be used to balance the intermittent electricity production and via a steam turbine create on-demand and thereby stable power production for the grid or for green fuel production. Either through Power-to-Salt plants or directly from power production, the excess energy can be converted into green hydrogen (PTXH2) via electrolysis or carbon-neutral fuels such as green methanol or green ammonia. The hydrogen and carbon-neutral fuels can be used to power the mobility sector (e.g., trucks, cars, airplanes, ships etc.) as well as for various other applications and industries. The excess heat from green hydrogen, green methanol or green ammonia production can furthermore be used for district heating.
Heat pumps and Pit Thermal Energy Storage (PTES) systems are likewise important sector coupling technologies.