The 2nd law of thermodynamics connects to sustainability by focusing on efficiency and reducing waste in processes. When a system is 100% efficient per this law, it uses resources perfectly with no unnecessary loss. This law ties into green practices and ensuring optimal performance in technology and innovation. By examining energy conservation and renewable energy through this lens, we can better understand how to make the most of our resources for a sustainable future. Applying 2nd-law concepts helps us assess how effectively we're developing technologies and innovating to ensure efficient use of resources.