Saturday, October 24, 2009

Energy in a thunderstorm

Enough time was spent by me on the hydrogen nonsense so now to some real powerful stuff. My friend in South Africa just emailed me that they had a terrible thunder storm with tons of rain and hail last night in Johannesburg. Tree limbs and leaves all over her garden and the street in front of her home. This got me thinking about how much energy is in a thunderstorm. As a first approximation I will just calculate the lost potential energy in the rain and hail that falls out of thunderstorm clouds. As an assumption I will estimate that the rainfall in the storm is two inches, the storm lasts for one hour, the clouds are 10,000 feet above the ground, and that the storm dumps rain on 1,000 square miles. Doing really tedious arithmetic and with the help of a calculator I estimate that this storm lost 1.2 billion kilowatt hours of potential energy in that hour of storming. For comparison the entire USA uses about 600 million kilowatt hours of electricity on average each hour. Therefore this one storm over Johannesburg last night dumped sufficient rain and hail to power two United States’ worth of electricity had we been able to capture the potential energy of just the water in the storm cloud. Add the wind associated with the thunder storm and the storm could have power the entire world’s electricity requirement for that hour. The world uses four times as much electricity as the USA and I am making the assumption that the wind was as powerful as the rain.

This simple illustration shows us how powerful nature is and that we simply have not developed the methods other than hydroelectric dams to capture the power nature is inflicting on some place on earth whether in a thunderstorm, hurricane, gale, forest fire, or earthquake. Back to how powerful that storm over Johannesburg was, you need to consider the following. Each and every second for that hour the 1,000 square mile area was receiving at total of 1.2 billion kilowatts of power. What is 1.2 billion kilowatts of power? Well a Porsche Carrera has an engine that has a peak power of about 300 kilowatts. Therefore the power of the storm over the 1,000 square miles was like having 4 million Porsche Carreras racing their engines at maximum speed in that 1,000 square mile area. This is 4,000 Porches running at full throttle in one square mile. Kind of like four million Porches spaced every 80 feet revving at 7,000 rpm on a grid covering a 1.000 square miles. In money terms if the National Hydrogen Association got their way and they could build 1.2 billion kilowatts of fuel cell power, this would require a budget of almost a quadrillion dollars or twenty times the yearly global economy. I think I will stand in awe the next time a thunderstorm passes. I will also make sure I take refuge as I do not want to personally experience the power of a lightening strike.