Energy consumption has emerged as a critical constraint in the large-scale deployment of quantum communication technologies, particularly as nations explore quantum-secure networks to support long-term digital sovereignty and critical infrastructure protection. While Quantum Key Distribution (QKD) and emerging quantum networking paradigms offer unprecedented security guarantees, their associated hardware, cooling, synchronization, and classical post-processing requirements introduce non-negligible energy overheads. This paper investigates energy-efficient quantum communication system architectures for sustainable national-scale networks. We propose a multi-layer framework that integrates energy-aware QKD protocols, adaptive key management, intelligent node placement, and hybrid classical–quantum optimization strategies. The methodology combines analytical energy modeling with scenario-based evaluation across metropolitan and inter-regional fiber corridors. Results demonstrate that energy-aware orchestration and selective deployment can reduce operational energy consumption by up to 30–45% without compromising security or service availability. The findings provide a practical foundation for designing environmentally sustainable quantum communication infrastructures aligned with national energy efficiency and carbon-reduction objectives.

Quantum Key Distribution;network operations;artificial intelligence;process innovation