[EQAB-list] carbon reduction targets and S-curves

[Robert G Kennedy III, PE]

Dear Colleagues,

regarding my comments at the meeting last Friday about S-curves,  
please refer to the crude ASCII diagram below. You will need to view  
this message in a monospaced font, like Courier.

The vertical axis is carbon footprint as a fraction of today's, which  
is 100% of course.
The horizontal axis is time between now and mid-century.

-----------------------------------------------
180%                                          +

160%                                +

140%                      +

120%            +

100% *    x     x
           -          x
  80%            -         x
                      -
  60%                      -    x
                                -
  40%                                -
                                     x    -
  20%                                     x   -x

   0%
     '10       '20       '30       '40       '50
-----------------------------------------------
key:
*: now
+: growth, business as usual
-: linear path to 80% reduction
x: likely "S"-shaped path


The upper curve (+) represents the forecast carbon footprint under the  
business-as-usual scenario. Some subtle variation in curvature is not  
visible at this resolution. At roughly 1.5% growth per annum in energy  
use as projected by the /Economist/ magazine, the USA is expected to  
consume 180 quads of primary energy by 2050. If we make no changes,  
the carbon footprint will grow commensurately, by 180%.

The lower curve (-) depicts a simple linear profile to achieve the 80%  
reduction in carbon footprint by 2050, like the President says. Note  
that energy use wouldn't have to fall that much, if at all, if we  
shift to low-carbon forms of primary energy. Note also that the slew  
rate (or second derivative) at the two inflection points at either end  
of the (-) curve is effectively infinite.

But human institutions, like all dynamic organisms, take time to react  
and adapt. Real-world systems don't have infinite rates of change. The  
middle curve (x) reflects this fact. Progress in the first decade will  
initially be glacial, like a supertanker turning in midocean or a  
heavy train pulling out of the station. Later, in order to not  
overshoot the target at the far end (crash thru the destination's wall  
in the train analogy), the system will have to decelerate in the  
fourth decade, so apparent annual progress will again be slow. These  
two end-constraints mean that most of the change will occur in the  
middle two decades, and the rate of that change (look at the slope of  
the x-curve in the middle) will be quite breathtaking. There are other  
interesting consequences.

The nature of real systems informed the carbon reduction targets I  
recommended to you-all.

Too bad the whole meeting turned out to be moot, but that's another story.

Robert

-- 
Robert G Kennedy III, PE
www.ultimax.com