Abstract :
A compelling argument in favor of wind and solar power is the fact that the “fuel” is free. Once you invest in a solar panel and the requisite electronics, there is no charge for the sunlight that powers it. This is obvious but remarkable in contrast with the commercial world, where profits depend on recurring sales of gasoline, ink, wireless minutes, and other consumables. Of course, you must purchase the equipment, maintain it, and lease space to install it—so nothing is truly free. But at least sun and wind can´t be depleted.