The “green” electricity conundrum

in 2005 total electrical world production was at 18.31 TWh  (Terrawatt hours)

in 2010 total electrical world production was at 21.25 Twh

For simplicity of math, we will call that a 16% increase in 5 years

extrapolating out, that would (assuming a linear growth rate) be roughly 181% increase per 20 years.

So in 2030 we would require 38.5 TWh of electricity

I do not believe the growth rate of electricity will be linear.  Even accounting for compounding, it has not been anything close in the past.  It is even less likely as more countries claw their way out of the third world.

So we have talked about the problem in pure numbers, depressing as they may be.  What are the solutions?

Lets talk solar.

With current peak experimental technologies peaking at 20% efficiency, we can turn roughly 1/5 of the received solar radiation into electricity.  By using collection mirrors we can bounce light to reduce dependence on sun angle as well as “increase” saturation for a net increase in efficiency. Effectively you turn most of the day into high noon and reflection technology is less than half the cost of solar cells.  We are talking about peak solar here and a method of simulating that for most of the day.  But a good rough number (assuming the plant is equatorial) is 1000W per square meter.  Using that number, as we have a way to cheat.

The most efficient models yields max at 40-60W per square meter per hour.  This includes night time lack of production.  Since we are setting up a reflection array to maintain peak efficiency, we will assume the higher number and multiply by 1.5.  This technique will allow us to produce 90W per square meter per hour.  We should call that 90Wh (watt hours) per square meter.

Some math:

1 megawatt = 1,000,000 watt hours

1,000,000Wh / 90Wh=11,112  square meter of solar panels

Assuming my very generous assumptions, no space for mirrors or ancillary equipment and not accounting for losses for converting from DC to AC and the like,  2.75 acres of panels would produce 1 megawatt hour of electricity.  In reality, the site would likely be closer to 8-10 acres.  This of course assumes a solar dense location like Florida or Arizona.

So our 8-10 acre solar power plant would power roughly 1000 US homes.

Comparatively speaking, the Port St Lucie, Florida nuclear plant is rated to 2700 Mwh of electricity. For a scale comparison, a nimitz class supercareer has two nuclear plants that each generate 550 Mwh.  Not accounting for the cooling lakes or canals needed by generation one nuclear power plants, a 40 acre physical plant will easily power 2,700,000 homes.

Homes per acre:

solar – 125 (@ 8 acre site) 

nuclear – 67,500 (@ 40 acre site)

** the nuclear plant has LOTS of land as buffer – both for our safety in case of a mistake and to protect against mischief.

below is a link to land usage per energy production type.

And lets just sum up biofuel as a complete waste of electrons and pixels to even talk about.


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