Exergy-based Design Approach for Material Circulation System in Space Platform and its Evaluation

As human activities expand into space, establishing a sustainable circular system is crucial rather than relying on resupplies from Earth. While system mass, including the amount of resupplies, has traditionally been a key factor in design optimization, this study proposes the use of “exergy,” which represents effective energy and incorporates the concept of entropy, as a new design metric for evaluating material and energy circulation. The objective of this study is to compare multiple Environmental Control and Life Support System (ECLSS) approaches, from the conventional physiochemical International Space Station (ISS) method to advanced bioregenerative concepts such as photosynthesis and waste reclamation. To further reflect the cost of delivery from Earth, the concept of “Modified Exergy” is introduced, incorporating gravitational potential into the exergy framework.