2026 Summer Mechanical Engineering Intern

Fourth Power is developing and commercializing the lowest cost energy storage technology on the market to enable the utility grid to operate 24/7/365 on renewable energy. Our batteries store heat in low-cost carbon blocks at up to 2400 degrees Celsius – half the temperature of the sun. The batteries then convert this heat back to electricity using thermophotovoltaics (TPV) on demand.

Fourth Power has a culture of teamwork, continuous innovation based on first principles, andrelentlessness in tackling challenging problems. Fourth Power is looking for highly skilled and motivated individuals who share our passion for mitigating climate change.

Job Description

We are seeking a Summer Intern to join Fourth Power’s Engineering team to support testing and design optimization of key graphite components that comprise our high temperature energy storage system. If you are a student studying mechanical engineering, who enjoys hands-on work and are comfortable in a lab/test environment, we encourage you to apply!

Job Type: Internship

Job Location: Middleton, MA

Your Role

• Assist with experimental setup, execution, and optimization

• Support joint design and mechanical testing apparatuses

Qualifications

• Basic experience with CAD (SolidWorks or similar)

• Familiarity with Microsoft Office (PowerPoint/Excel)

• Background in heat transfer, thermodynamics, or thermochemical systems

• Experience with or interest in vacuum and/or pressurized systems

• Exposure to simulation tools (e.g., ANSYS)

• Excellent organizational skills, attention to detail, and ability to work independently in a fast-paced environment.

• Strong communication skills to effectively collaborate with fellow engineers and technicians.