US Patent 8146508 Pneumatic mass transportation system

A pneumatic mass transportation system employs a combined cycle turbine power system with digital controls to effect acceleration, deceleration and train propulsion. Combustion turbines can be adapted to use alternative fuels including bio fuels as they are developed. A heat recover steam generator recycles hot exhaust gasses from turbines to generate electricity to be used by the system. A multi-car train is propelled by differential air pressure forward and aft of the vehicle in a pneumatic tube. Air propulsion is achieved by large in-tube impellers driven by the turbines. A digital control system controls turbine speed, pitch of impeller blades and vacuum/pressure release valves in the tubes to maneuver and control the train.