How Mirrors Could Solve our Energy Problem

It would be less costly to use water and gravity to spin turbines than whats required for solar. There is a man in New Zealand that powers his house with a gutted washing machine containing a turbine and a few hundred yards of 2inch pvc pipe. He runs creek water slightly downward to the turbine. The water gains enough speed to exit as a jet of water that spins the turbine. Or we could just use up all the sand on earth and litter the planet with giant hearers that will probably end ip heating the atmosphere.