6 ms·

I don't think this is a reflection on the amount of usable sunlight on that hits the surface of the earth. It sounds more like a vague, general statement and is

I don't think this is a reflection on the amount of usable sunlight on that hits the surface of the earth. It sounds more like a vague, general statement and isn't backed by calculations in the article. The late Professor McKay (whose book on information theory and ML is neat by the way) published a great book full of climate back of the envelope calculations, Whithout the Hot Air, which is available online[1]. He clearly disagrees with this statement, as seen in the recap figure on page 103[2]. [1] http://www.withouthotair.com/Contents.html http://www.withouthotair.com/Contents.html [2] http://www.withouthotair.com/c18/page_103.shtml http://www.withouthotair.com/c18/page_103.shtml

toomuchtodo 10y ago
http://www.sandia.gov/~jytsao/Solar%20FAQs.pdf http://www.sandia.gov/~jytsao/Solar%20FAQs.pdf "This theoretical potential represents more energy striking the earth’s surface in one and a half hours (480 EJ) than worldwide energy consumption in the year 2001 from all sources combined (430 EJ)." Not back of envelope. Energy calculations worked through.
- patrickg_zill 10y ago
  Isn't 70% or more of the Earth's surface covered in water and thus, quite difficult to build a terrestrial structure upon? Asking for a friend.
  - toomuchtodo 10y ago
    Total land area needed to power the world on solar alone: http://i.imgur.com/Jg31dfw.png http://i.imgur.com/Jg31dfw.png Source: http://www.businessinsider.com/elon-musk-solar-panels-to-power-the-earth-2015-12 http://www.businessinsider.com/elon-musk-solar-panels-to-pow... EDIT: Solar is a better investment than the S&P500. If US corporations were looking for some place to invest those trillions of dollars they won't repatriate [1], seems like renewables would be a perfect fit. "Eight of the biggest U.S. technology companies added a combined $69 billion to their stockpiled offshore profits over the past year, even as some corporations in other industries felt pressure to bring cash back home. Microsoft Corp., Apple Inc., Google Inc. and five other tech firms now account for more than a fifth of the $2.10 trillion in profits that U.S. companies are holding overseas, according to a Bloomberg News review of the securities filings of 304 corporations. The total amount held outside the U.S. by the companies was up 8 percent from the previous year, though 58 companies reported smaller stockpiles." [1] http://www.bloomberg.com/news/articles/2015-03-04/u-s-companies-are-stashing-2-1-trillion-overseas-to-avoid-taxes http://www.bloomberg.com/news/articles/2015-03-04/u-s-compan...
  - awj 10y ago
    Good thing an hour and a half is well less than 30% of the day, then.
- supergarfield 10y ago
  McKay uses something very close to this (as you said) theoretical value as the starting point of its calculations for how much can effectively be extracted.

toomuchtodo 10y ago

http://www.sandia.gov/~jytsao/Solar%20FAQs.pdf http://www.sandia.gov/~jytsao/Solar%20FAQs.pdf "This theoretical potential represents more energy striking the earth’s surface in one and a half hours (480 EJ) than worldwide energy consumption in the year 2001 from all sources combined (430 EJ)." Not back of envelope. Energy calculations worked through.

patrickg_zill 10y ago
Isn't 70% or more of the Earth's surface covered in water and thus, quite difficult to build a terrestrial structure upon? Asking for a friend.
- toomuchtodo 10y ago
  Total land area needed to power the world on solar alone: http://i.imgur.com/Jg31dfw.png http://i.imgur.com/Jg31dfw.png Source: http://www.businessinsider.com/elon-musk-solar-panels-to-power-the-earth-2015-12 http://www.businessinsider.com/elon-musk-solar-panels-to-pow... EDIT: Solar is a better investment than the S&P500. If US corporations were looking for some place to invest those trillions of dollars they won't repatriate [1], seems like renewables would be a perfect fit. "Eight of the biggest U.S. technology companies added a combined $69 billion to their stockpiled offshore profits over the past year, even as some corporations in other industries felt pressure to bring cash back home. Microsoft Corp., Apple Inc., Google Inc. and five other tech firms now account for more than a fifth of the $2.10 trillion in profits that U.S. companies are holding overseas, according to a Bloomberg News review of the securities filings of 304 corporations. The total amount held outside the U.S. by the companies was up 8 percent from the previous year, though 58 companies reported smaller stockpiles." [1] http://www.bloomberg.com/news/articles/2015-03-04/u-s-companies-are-stashing-2-1-trillion-overseas-to-avoid-taxes http://www.bloomberg.com/news/articles/2015-03-04/u-s-compan...
- awj 10y ago
  Good thing an hour and a half is well less than 30% of the day, then.
supergarfield 10y ago
McKay uses something very close to this (as you said) theoretical value as the starting point of its calculations for how much can effectively be extracted.