Composites are a great material for energy conservation. Their superior stiffness to weight ratio allows for them to replace other materials in sectors like transportation in order to gain weight savings. These weight savings of course require less energy to move and stop the vehicles.

Discovered decades ago by racers of all kinds, reducing mass gains advantage.  Lightweight materials such as fiberglass work very well in that cause. The sailboat guys know it too; the lightweight carbon fiber masts reduce weight versus aluminum to gain a weight advantage. Drag car bodies made of lightweight fiberglass instead of sheet metal or aluminum.

Circle track cars with fiberglass hoods, noses, and bumpers.

Examples of conserving energy with composites, and the racers got it right a long time ago!