This study explores the potential of twisted single-walled carbon nanotube (SWCNT) ropes as a high-energy storage device. SWCNTs, known for their exceptional toughness and mechanical properties, are wrapped in thermoplastic polyurethane (TPU) elastomers to create twisted ropes. These ropes exhibit a remarkable ability to reversibly store nanomechanical energy, with a gravimetric energy density (GED) reaching up to 2.1 MJ kg\(^{-1}\), significantly exceeding the energy storage capacity of mechanical steel springs and advanced lithium-ion batteries. The stored energy remains stable over time and is accessible across a wide temperature range, from 60 to 100 °C, making it safer and more versatile than chemical and electrochemical energy carriers. The study also investigates the effects of different fabrication methods and modifications on the energy storage performance, finding that the yarn method yields the highest GED values. Additionally, the research demonstrates the practical application of these SWCNT ropes in energy conversion, showing that they can drive a circular disc with a maximum angular velocity of 164 rad s\(^{-1}\) and an energy conversion efficiency of 22%. The findings highlight the potential of SWCNT ropes as a sustainable and efficient energy storage solution, particularly for microscale applications and medical devices.This study explores the potential of twisted single-walled carbon nanotube (SWCNT) ropes as a high-energy storage device. SWCNTs, known for their exceptional toughness and mechanical properties, are wrapped in thermoplastic polyurethane (TPU) elastomers to create twisted ropes. These ropes exhibit a remarkable ability to reversibly store nanomechanical energy, with a gravimetric energy density (GED) reaching up to 2.1 MJ kg\(^{-1}\), significantly exceeding the energy storage capacity of mechanical steel springs and advanced lithium-ion batteries. The stored energy remains stable over time and is accessible across a wide temperature range, from 60 to 100 °C, making it safer and more versatile than chemical and electrochemical energy carriers. The study also investigates the effects of different fabrication methods and modifications on the energy storage performance, finding that the yarn method yields the highest GED values. Additionally, the research demonstrates the practical application of these SWCNT ropes in energy conversion, showing that they can drive a circular disc with a maximum angular velocity of 164 rad s\(^{-1}\) and an energy conversion efficiency of 22%. The findings highlight the potential of SWCNT ropes as a sustainable and efficient energy storage solution, particularly for microscale applications and medical devices.