sustainability - SUNY College of Environmental Science and Forestry

Sustainability 2011 , 3
1921

weighting factors to reflect how much above or below the world average energy intensity (EiW) is to be
allowed for. Table 3 below is organized for option 3 and used for option 2 where appropriate.
Option 1, of course, saves a great deal of time for quick estimates.

Figure 5. To avoid double-counting $T, the economic value of TE at average intensity EiW,

is taken from the item costs, $E, before applying the scaling factor Eii for the proxy measure.

2.3. Calculations for System Energy Assessment

For world energy intensity (EiW) we use the EIA world marketed energy consumption and global
domestic product corrected for purchasing power parity (WMEC/GDP-PPP). World GDP-PPP was
$59,939 billion ($2005) with 472 quads of purchased energy [27] for an average intensity of
7,630 btu/$ or 8050KJ/$ in 2006. To standardize on electrical energy units we convert kWh:

2. 24 kWh$2006

3 , 410 BtukWh

7 , 630 Btu$2006

3 , 410 BtukWh

59,939e 9 $2006

472 e 15 Btu

EiW( 2006 )= = = (1)

Average economic energy intensity varies widely between national accounts[28], but world energy
intensity displays remarkably smooth change and proportionality to GDP. The variation between
national accounts appears to reflect comparative advantages for specialization in products and services
so we choose to use the global average as the default assumption. The world average shows a regular
rate of decline of ~1.3%/yr using an exponential fit to the historic data, by Equation (2), where x is the
number of years after 2006 [27,33, Appendix I]. For example, in 2020, at the midpoint of our 20 year
project starting in 2010, the current value of EiW will have decayed to 1.87 kWh/$2006. Differences in
price and value (utility) for different kinds of fuels (e.g., oil, coal, electricity, etc. having different uses
and prices per Btu) [ 3,16,19], were not used for shares of the global mix of purchased fuels.

G