Definition: In this task, you will use your knowledge about language (and common sense) to determine what element the marked number refers to. The numbers are marked with two underlines around them, like: _ number _. Your answer should be chosen from the given text, and should not contain other words.
Input: Himself - President & Co-Founder, The Breakthrough Institute:  We 're basically gon na double the amount of energy we consume by 2050 , we 're gon na triple it or quadruple it by the end of the century .
Himself - President & Co-Founder, The Breakthrough Institute: And meanwhile , if you want to stabilize emissions at some reasonable level , almost all of that energy has to be clean energy .
Himself - President & Co-Founder, The Breakthrough Institute: You 've got to not only create a clean energy infrastructure to replace the fossil - fuel infrastructure we have , but we have to create another _ one _ or maybe two of them between now and 2050 or 2100 in order to reduce our emissions to stabilize the climate .
Himself - President & Co-Founder, The Breakthrough Institute: And that is just nothing that anybody has been talking about or dealing with in the last 20 years .

infrastructure