Soil-powered fuel cell (IMAGE) Northwestern University Caption The fuel cell's 3D printed cap peeks above the ground. The cap keeps debris out of the device while enabling air flow. Credit Bill Yen/Northwestern University Usage Restrictions add credit License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.