United States Department of Energy
根據美國能源部轄下之定義，「互換性」是指在維持安全性、可靠性及環保性表現的情況下，被終端用戶所消耗或運用的天然氣的可接受份量"（“The acceptable ranges of natural gas that can be consumed by end users while maintaining safety, reliability, and environmental performance.”）"。