"Streetlights are one of my biggest pet peeves. Within the house I always switch off every light when not in use (and I was always scolded by my parents when I forgot the light on when I was a child). But outside on the streets all the lights are on during the entire night, even if there are no one nearby. And in the quiet street I live there are pretty much no movement after 11pm after people come home from the afternoon shifts. Each sodium vapor fixture consumes about 300-1000W, leds are better but they still consume 100W each. That's still a lot of energy wasted.
Instead of putting streetlights everywhere, we should carry our own lights and use it when we need and where we need it. Vehicle lights should be better, bicycle lights should provide more light other than just signals, night time hikers already use headlights. Engineering should come up with clever solutions to make them convenient and safe to use. Important landmarks should have red navigational lights, and info tables on roads and house walls should be retroreflective to make them easily visible in the dark when you have light."
If you can realize 2% real return on your portfolio then:
300 months worth of living cost is enough for 35 years. 400 months worth of living cost is enough for 55 years. 500 months worth of living cost is enough for 88 years - your entire lifespan 600 months worth of living cost is enough for 237 years - even your grand grand children can enjoy it. 700 months worth of living cost is enough forever.
Disclaimer: Of course you shouldn't inflate your living costs to make this possible.