Graduate PhD Student Intern (Summer) in Mathematical Optimization based in Golden, CO. This fixed-term, 40-hour/week internship focuses on developing and implementing optimization algorithms for large-scale power systems planning, with an emphasis on transmission and capacity expansion to improve energy system reliability and security. Responsibilities include algorithm development, collaborating with researchers, analyzing results, and contributing to technical reports and presentations. Candidates must be enrolled in a PhD program in a relevant field, with experience in algebraic modeling, programming (Python, Julia), and HPC workflows. Preferred qualifications include experience with optimization tools (Pyomo, JuMP), solvers (Gurobi), and power systems. The position offers a salary range of $51,200–$81,900, benefits, and requires passing a background check and compliance with security and drug-free workplace policies. Applications are accepted for up to 30 days.