"You need Air, Fuel and Spark"
You must not work on many engines then....
Diesel does not need spark.
"but more importantly, neatly all the valves in those plants are controlled by electricity. " And they have geared handwheels on them for emergency backup.. Have you ever been in a Water filtration plant? I worked in one for over 7 years, during that time I had to operate the whole place by myself during two extended power outages, one actually blew up the main transformers on the premise and melted the 7200 volt power lines coming in to run our 350hp electric motors. I had a very hectic 30 minutes to run the 1/2 mile to the other end of the facility during a major thunderstorm to start the generators manually as we did not have auto start back then. Then run all the way back and manually close 4 60" gate valves by hand to shut down half of the water plant as water consumption dropped way down as most of the town was out of power. By the time the emergency response guys showed up and I opened the gates I had the 500,000 Gallon per day pumps running and the water towers in the city above a 75% full point.
What is fun is when you are in a pumphouse and the check valve fails and a 350hp motor is running backwards at full speed and someone does not answer the radio up at the control house and hits START on that motor. the smell of vaporized copper and ozone in the air when the breaker arms exploded and vaporized because 7200 volts at insane amps met a motor running backwards and acting like a direct short. My ears were ringing for a week.