Abstract Including direct air capture technologies (DAC) in power-to-gas (PtG) approaches offers the opportunity to close the carbon cycle by producing methane on a renewable, carbon neutral basis, while balancing… Click to show full abstract
Abstract Including direct air capture technologies (DAC) in power-to-gas (PtG) approaches offers the opportunity to close the carbon cycle by producing methane on a renewable, carbon neutral basis, while balancing fluctuations associated with an energy supply based on renewable sources. In this respect, various synergies can arise within the integrated process structure, resulting in a strong coupling of process unit operation points. Being both, carbon source and main heat sink within the system, the influence of the DAC unit on the entire process is investigated by detailed simulation and pinch analysis. Strong dependency of overall material and energy balances on DAC operation point is revealed. Slip streams of air in this unit are found to result in an increased catalyst requirement of methanation reaction by more than a factor of six, while minor decline (18%) of catalyst demand with decreasing DAC desorption temperature is observed. Use of electrolysis as heat source for DAC seems not beneficial. Overall, severe influence of DAC operation on integrated process design for autothermal production of methane based on carbon dioxide and water captured from ambient air is confirmed.
               
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