electrical power vs water power

electrical power

water power

noun
  • Used other than figuratively or idiomatically: see water, power. 

  • Mechanical or electrical energy derived from running or falling water; originally obtained from a waterwheel immersed in a stream; modern hydroelectric power is obtained from turbines fed from reservoirs. 

  • A site capable of generating power or the right to use a site to generate power. 

How often have the words electrical power and water power occurred in a corpus of books? (source: Google Ngram Viewer )