Rail-trails and other types of recreational trails, when built carefully, can help improve water quality by acting as buffer zones.

Silicon is best choice for solar planes where the challenge is to create an aircraft light enough to fly but with enough power to get off the ground.

Propylene glycol is mixed with water for use as antifreeze. It has a much lower freezing point than water, and it actually reduces the freezing point of water to prevent pipes from freezing.