One thing about my degree, it covers mechanical, chemical, electrical, civil, structural, and industrial engineering with a heavy dose of biology.
The PE exam was impossible to study for. You just hope that the test covers classes that you took in school rather than classes offered in other schools.
Here are some sample design areas:
Bioreactors - Think beer and alcholol production, yogurt, cheese, ect....
Water Structures engineering - water ways, culverts, retention ponds, runnoff from parking lots, ect...
Mechanical - flywheels, clutches, brakes, conveyors, blowers, dryers, ovens, tractors, lawn mowers, pto for equipment, hydraulics, aerodynamics (used to separate product from trash or crop dusting), HVAC, ect....
Chemical Engineering - See bioreactors, there is much more that I can't think of....
Industrial Engineering - Economics, process design, ergonimics of machines and workstations....
Civil - Water structures above, waste management, buildings, agricultural buildings, geotechnical, remediation, irrigation, ect.....
Electrical - PID controlers, telemetry, power production, computer engineering, electrical sensors and controls (sprayers that only spray weeds and not the crop), ect....
Think of engineering for anything that has anything to do with biology.
www.asabe.org