Power-to-X and sector coupling

In the energy system of the future, electricity will increasingly be generated from renewable energy sources. Power-to-X can be used to produce other energy sources and other products from electricity. These synthetically generated energy sources and products can be used in processes that previously relied on fossil fuels. 

Examples of power-to-X include:

• Power-to-gas: Power-to-gas technology produces energy gases from renewable electricity through electrolysis (splitting water into hydrogen and oxygen).
• Power-to-heat: With this technology, electricity from renewable energy sources is used to provide heat (e.g. via heat pumps). This coupling of the electricity and heat sectors can save fossil fuels and emissions in the heat sector. 

One example of the use of synthetic gases in the heat sector is combined heat and power (CHP). This is an established technology for sector coupling that is successfully used to provide heat and electricity. So far, this process has primarily used fossil fuels, which leads to greenhouse gas emissions. Technically however, it is also possible to operate using green hydrogen or synfuels, which can be produced with the help of renewable energy. 

In addition to converting electricity into heat, the following power-to-X technologies are widely used:

• Power-to-mobility: The mobility and electricity sectors can be connected in different ways. For example, battery or plug-in hybrid vehicles require electricity that can be generated from renewable energy. Additionally, fuel cell vehicles are powered by hydrogen and combustion vehicles by synfuels (power-to-fuel). These fuels can be produced using renewable energy.
• Power-to-chemicals: Electricity can be used to produce chemical energy sources or chemical feedstocks, such as ammonia. 

Renewable energy is subject to short-term and seasonal fluctuations. Power-to-X installations can respond to this and use electrical energy flexibly according to supply. This is because the installations can be slowed down (when the renewable energy feed is lower) or sped up (when the renewable energy feed is higher). This system flexibility is also known as demand-side management. 

Power-to-X products can also act as short-term storage (e.g. heat from power-to-heat) or long-term storage (e.g. gas from power-to-gas).