March 30th 2009. Join the Group Read. Chapter 18. A first balance
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This is the first chapter attempting to balance-up consumption and production. While the story told so far of the raw energy potential from renewable sources shows an ecouragingly close race to maintain our rich lifestyles with sustainable energy sources, a little digging provides much disappointment. Between the potential and the realisation lies a factor of over 100! From a production potential of 180 kWh per day per person, we get to an actual production figure of just 1 kwh/d/p and a "realisable" estimate of 18 kwh/d/p---a full ten times less than our consumption.
Looking at the heart of the physics problem, David MacKay points to the geographically diffuse nature of renewables: each person needs a huge amount of land, tidal exposure, wind per person to make the sums add up. The sustainable potentials, as David emphasises, need "country-sized solutions". "To get a big contribu- tion from wind, we used wind farms with the area of Wales. To get a big contribution from solar photovoltaics, we required half the area of Wales. To get a big contribution from waves, we imagined wave farms covering 500 km of coastline. To make energy crops with a big contribution, we took 75% of the whole country."
Yet protection of species, habitats, nature, beauty etc. all move the same people who want to reduce fossil fuel dependency to limit the installations. Something will need to give to balance our energy ...