fossil fuel vs throttle

fossil fuel

noun
  • Any fuel derived from hydrocarbon deposits such as coal, petroleum, natural gas and, to some extent, peat; these fuels are non-renewable, and their burning moves carbon from underground into the atmosphere via the greenhouse gas carbon dioxide. 

throttle

noun
  • A valve that regulates the supply of fuel-air mixture to an internal combustion engine and thus controls its speed; a similar valve that controls the air supply to an engine. 

  • The lever or pedal that controls this valve. 

verb
  • To utter with breaks and interruption, in the manner of a person half suffocated. 

  • To have the throat obstructed so as to be in danger of suffocation; to choke; to suffocate. 

  • To control or adjust the speed of (an engine). 

  • To breathe hard, as when nearly suffocated. 

  • To cut back on the speed of (an engine, person, organization, network connection, etc.). 

  • To strangle or choke someone. 

How often have the words fossil fuel and throttle occurred in a corpus of books? (source: Google Ngram Viewer )