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Insight & Opinion

Power-to-X: Where to put surplus energy from renewable energies?

March 05,2019
Where to put surplus energy from renewable energies?   The expansion of renewable energies creates new requirements for the power supply. Weather-dependent regenerative energies such as wind and sun are subject to strong fluctuations that lead to temporary over- and undersupply of the electrical power demand. In case of oversupply wind turbines and solar panels are being shut down, instead of further producing energy. With the increasing share of renewable energies, the amount of potential surplus electricity will increase significantly and the question of actually using this electricity is becoming more important. Innovative storage technologies are needed to resolve the temporal imbalance between energy generation and demand and thus the success of the energy revolution.   In the future, this will be accomplished by including Power-to-Gas systems into the ecosystem for power generation and distribution. The term ‘Power-to-Gas’ refers to the conversion of electrical energy (electricity) into chemical energy (gas) by means of water electrolysis. The hydrogen gas produced in the first step can be used both energetically (for example as a fuel) and as a material (for example in industry). The sector coupling with mobility and the chemical industry creates economically attractive options and the possibility to realize significant CO2 reductions in these areas.   The hydrogen produced via electrolysis can also be further processed into methane and integrated into existing infrastructures or alternatively stored and used in various areas of application afterwards.   In an additional conversion step, it is also possible to produce synthetic, liquid fuels (so-called e-fuels). The entire conversion process is then called Power-to-Liquid. These e-fuels can fuel conventional internal combustion engines and thus do not require any adjustment of the consumer. Petrol stations and the infrastructure for transporting liquid fuels would continue to function as usual, but would be CO2-neutral, since carbon dioxide from the atmosphere or from CO2 emitting processes is used for their synthetic production.   According to experts, with the Power-to-Gas/ Liquid technologies the storage problem has already been solved, at least from a technical perspective, and represents a key technology for the energy revolution. So why are there no commercial Power-to-Gas/ Liquid plants apart from pilot projects?   In our study, we look closely at the technologies and opportunities of the Power-to-Gas/ Liquid value chain in the energy system and answer key questions related to the industries both providing and consuming energy today and in future.

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