Eighteen year old Boyan Slat came up with a plan to clean pollution in the ocean using passive flotation devices and the ocean’s own current to pull the sea life under and plastics into the floatation devices.
Rainwater harvesting is one of the oldest and most effective forms of water collection and can help decentralize the water supply. The rain is drained from the roofs into barrels, cisterns, or tanks.
Using some recycled parts and a small rocket stove you can heat and pump hot water without the need for electricity. You can also easily make the rocket stove yourself from four concrete blocks.