Systems Analysis of Zaragoza Urban Water - SWITCH - Managing ...

Systems Analysis of Zaragoza UWS
Guillermo Penagos
consumption would be 0.16 and 0.51 Gwh per year for 10% and 30% recycling
respectively. However the energy savings supposed by tap water recycling are so
significant, that Zaragoza taken as a whole system will be actually consuming slightly
less energy if Industrial water recycling is implemented (see figure 22).
4.4.3.3.4 Effect of water recycling on CO 2 emissions to the atmosphere
Figure 23 shows an analysis of CO 2 emissions, considering the described figures for
energy consumption, the National Plan on Energy and the expected increase on
organic matter loads to the sewage by 2020.
25
Direct load Indirect due to electricity use Indirect due to transportation
CO 2 emissions (10 3 ton)
20
15
10
5
14.4
10.3 10.2 10.1
8.2 9.4 9.4 9.4
0
2006 2020 no water
recycling
2020 with 10%
Industrial water
Recycling
2020 with 30%
Industrial water
Recycling
Figure 23. CO 2 emissions from Zaragoza UWS in 2006 and 2020 scenario with different levels of
Industrial water recycling strategy
As previously described, the major contribution to atmospheric emissions by
Zaragoza UWS is indirectly by electricity use. As expected from figure 23, the joint
effect of the National Energy Plan and the reduction on energy consumption
supposed by decreasing water withdrawal, imply a significant reduction of
atmospheric emissions from 22,600 ton in 2006 to 19,700 in 2020.
As organic matter loads to the sewage are expected to increase 14% (see section
4.4.3.3.4) direct emissions will increase likewise, going from 8,200 to 9,400 ton per
year. Indirect emissions by transportation of chemical products and sludge seem
negligible in the figure, but those will increase from 250 in 2006 to 291 ton in 2020.
The savings on energy supposed by industrial water recycling would represent an
additional reduction of 50 and 100 ton per year for the 10% and the 30% strategies
respectively.
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