On Thu, 18 Jun 2015 08:15:31 -0400 Meade Dillon via Mercedes <mercedes@okiebenz.com> wrote:
> The key point that I am trying to drive home is the limit on the amount > of solar power available. This is a hard limit: ~1000 watts/square > meter is the peak under ideal conditions. A more usable number is 200 > watts during daytime, which takes into account average cloud cover and > reduced energy reaching ground when the sun is low in the sky. > > By comparison, 1 gallon of diesel has the potential energy of 130,000 > BTU's. 200 watts of solar power is the equivalent of about 3400 BTU's / > hour. That ~40 order of magnatude difference is why we drive cars and > trucks with internal combustion engines and why we don't have solar cars > (or airplanes) that can do useful things. 1000 Watts = 3412 BTU/hr 200 Watts = 682.4 BTU/hr 130,000 ------- = 190.5 682.4 So, it's roughly a factor of 190, not 40 orders of magnitude (= 10^40). Craig _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
