Power-to-X (P2X)
The aim of sustainable P2X value chains is to produce CO2-neutral material energy sources, synthetic fuels and CO2-negative basic chemicals efficiently and flexibly over time using renewably generated electricity. These can be used in the lead markets of energy, heat, chemicals, and transport & traffic to replace climate-damaging fossil-based energy sources. Material P2X products thus make a significant contribution to reducing greenhouse gas emissions and thus help to achieve the goals of the energy turnaround, the agreement to phase out coal-fired power generation, and the international climate agreements. P2X thus provides a key technology for sector coupling, as well as for establishing a carbon circular economy. This opens up a large economic potential in the production of "green" recyclables, with new business areas emerging in particular for industrial CO2 point sources as a renewable raw material in a sustainable P2X value chain. With regard to industrial transformation processes in the context of the energy turnaround and the phase-out of lignite-based power generation, P2X can be seen as a central technology option for structural change and the development towards a sustainable post-mining landscape.
A core challenge in the field of P2X technology is currently the development of electrochemical processes and process technologies that are scalable and cost-efficient. In addition, the materials and components used must have long operating lifetimes.
Power-to-X refers to various energy and material conversion technologies, where "X" can denote gaseous (power-to-gas) or liquid (power-to-liquids) energy carriers and valuable materials, such as fuels (power-to-fuels) or basic chemicals (power-to-chemicals) (see Figure P2X-1). The starting point of sustainable P2X value chains is always renewably generated electricity from wind, photovoltaic or biogas plants, (waste) water and regenerative gaseous carbon sources, such as CO2 from industrial point sources, as well as nitrogen from the air or biogenic waste products.
Power-to-Power (P2P) and Power-to-Gas (P2G) describe technology options for short- and long-term stationary energy storage, and additionally for the provision of hydrogen for the mobility sector in the form of a "hydrogen vector". In this way, the energy and transport & traffic sectors can be "de-carbonized". Technologically, P2P is based on electrochemical accumulators (batteries), whereas P2G is based on water and steam electrolysis technology. The process heat from the exothermic conversion processes that take place during reconversion (gas-to-power) can be used to de-carbonize the heat sector through cogeneration (power-to-heat, P2H).
Power-to-Fuels (P2F) describes the use in the form of synthetic fuels. This includes synthetic fuels for passenger cars, as well as for heavy-duty transport, aviation and shipping. In addition, fuels for the provision of industrial process heat can also be produced. When the CO2 used in the electrolysis step is captured from the atmosphere, the option for closed-loop carbon processes in the mobility sector opens up for P2F value chains. The overall circular process is then CO2 neutral.
Power-to-Chemicals (P2C) describes the production of chemical raw materials and basic chemicals for material value creation. In this way, the base material production of the chemical industry can be "de-fossilized", enabling industrial "carbon cycle" processes with neutral and negative CO2 emissions.
An overview of the different ways to represent P2X value chains is illustrated by path interrelationships in Figure P2X-2.
