Date of Award


Document Type



Santa Clara : Santa Clara University, 2012

First Advisor

Drazen Fabris


The current problem with energy backup and grid stabilization systems is that both either require fuel and constant maintenance, such as diesel generators, or cannot perform at their peak operation and need constant replacement, like batteries. Our solution and the goal of the StorWatts senior design project was to design and create a small-scale compressed air energy storage system to be used in place of traditional energy backup and grid stabilization systems. The StorWatts system does not need fuel in order to store and generate power and therefore does not require constant refueling and maintenance. It also can work in most any climate, not needing environmental control like its battery counterparts. This allows for a standalone system that can perform reliably for years at a time. This StorWatts CAES system will convert electrical energy into mechanical energy by compressing air into a set of air storage tanks. When power is needed, the air will be released from the storage tanks through an expander. The expander, connected to a DC generator, will convert the stored energy into usable electric power. The StorWatts team, with a generous donation from the Biederer family, repurposed an old Briggs and Stratton four stroke gas engine into an air expander. The existing cylinder head was removed and redesigned to allow room for a thermocouple, a pressure transducer, a 500 psi safety release valve and two fast acting solenoids, one for inlet air and one for outlet exhaust air. The solenoids were controlled by an arduino with set open and close times. However, due to safety concerns and time restrictions, we unable to test the system above 70 psi. This created problems as the arduino was set for an inlet pressure of 500 psi. The engine was unable to turn over at 70 psi and no running information was obtained.