Energy : Hurricanes, heat engines, etc.. Alternatif Energy

Looks like it's going to be a wet few days, with the arrival of Harvey.   I've mentioned previously that hurricanes and tropical storm systems are heat engines - they basically use the temperature difference between the heated water in the ocean and the cooler air in the upper atmosphere to drive enormous flows of matter (air currents, water in vapor and liquid form).  A great explanation of how this works is here.  Even with very crude calculations one can see that the power involved in a relatively small tropical rain event is thousands GW, hundreds of times greater than the power demands of a major city.   Scaling up to a hurricane, you arrive at truly astonishing numbers.  It's likely that Harvey is churning along at an average power some 200 times greater than the electrical generating capacity of the planet (!).  Conservative predictions right now are for total rainfall of maybe 40 cm across an area the size of the state of Louisiana, which would be a total amount of 5.2e10 metric tons of water.   Amazing.  I'm planning to write more in the future about some of this, time permitting.

Update:  For what it's worth, Vox has an article about Harvey, and they say it deposited 14-15 trillion gallons of water.  Each gallon is 3.78 kg, meaning that the total mass of water deposited for 14 trillion gallons is 5.3e10 metric tons.  How's that for estimating accuracy in the above?