Calorie

A couple weeks ago, I published Watts. Here is some of the math behind it -

• 1 calorie = 4.184 Joules
  
• 1 Watt = 1 Joule per second
• Recommended Calorie intake from food for an adult is ~2500 kcalories per day ~ 120 Watts. (Link)
• Calories in Food
• Fat – 9 kcal/gram
• Proteins – 4 kcal/gram
• Carbohydrates – 4 kcal/gram
• Petrol – 34.8 MJ/litre – 8317 kcal
  
• 1Kg LPG – 47,320 BTU
• 1 BTU ~ 1KJ
• Global Oil Consumption ~80 million barrels per day.
• US daily oil consumption – 20 million bpd.
• 170m barrels oil= 1 Exa-Joule (10 to the power 18)
• US annual energy usage – 101 Quadrillion BTU (2007)
• 1 Q-BTU ~ 1 Exa-joule
• 1 TeraWatt-year = 31.5 Exa-joule
  
  
  
  
• Global Energy production - 16-18 TW-year (source WattzOn)
• Coal – 3.6
• Gas – 3.2
• Oil – 5.0
• Plants – 5.2
• Other – 1.5
• Personal Usage – ~2400 Watts per person.
  
• Solar production gives ~10-20 Watts/square meter

Confused by so many units? Make sense via Saul Griffith's presentation (link in older post).

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US

Note – In context of food a calorie generally refers to kilo-calorie. Some numbers may not be recent. If you do find some glaring mistake, do comment.

Image source - IEA in a presentation by Margot Gerritsen