Energy-harvesting playground equipment is pretty much exactly what it sounds like -- playground equipment that is capable of collecting and storing energy. The kinetic energy from your movements could be used to power everything from outdoor playground lighting to possibly even nearby buildings, depending on how many people use the energy-harvesting equipment (the more people working out, the more electricity generated and collected).
Does this sound far-fetched and futuristic? Designers and engineers are already hard at work on the technology. And just how much electricity can you generate while you're on the playground? When you're engaged in moderate-intensity exercise, you generate about 50 watts of electricity in one hour [source: California Fitness]. In the future, the answer to an energy crisis could be as simple as child's play -- literally.