As a mechanical energy engineer, your responsibilities are design, develop, and test mechanical and thermal devices. You may work on a variety of products with mechanical and energy components to help reduce energy costs or boost energy efficiency. Your employer or clients may include residential, commercial, or industrial organizations. You may also prepare for energy audits, create energy modeling, recommend energy fuel, and supervise the manufacturing process. Other duties may involve conducting onsite observations and field inspections to gather data and ensure operations are running accordingly.