Environmental Engineering Reference
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1.3 Characterizing the WEF Nexus
The central role played by water and energy resource use and governance in
assuring food suf
ciency and security required, even forced, the systematic syn-
thesis of siloed resource management regimes. Yet this is not synthesis for its own
sake, a question of intellectual or conceptual elegance. The nexus approach requires
that interrelating factors be brought together, those that previously had been con-
sidered separated, indeed even isolated. As we will demonstrate, the nexus is
fundamentally about resource recovery, closing the loop and capturing true effi-
-
ciency gains instead of simply displacing or masking increased resource use
(Lankford
2013
; Scott et al.
2014
). Understanding and acting upon this core of the
nexus is central to diminishing the human footprint on planetary boundaries. Thus,
resource recovery is the fundamental biophysical expression of the nexus approach.
Figure
1
indicates the interlinkages of water, energy and food on three planes:
biophysical resources, institutions and security. Linkages between any two of the
(a)
Water
Security
WEF
Nexus:
Human
well-being,
Resilient ecosystems,
Planetary boundaries
Institutions
Energy-food nexus
Energy
Food
Resources
(b)
Energy
challenges from
water
perspective:
Food
challenges from
water
perspective:
Water footprint of multiple energy portfolios
Production shifts poleward, higher elevation
Energy generation degrades water quality
Climate change raises irrigation demand
Dry cooled thermo-generation potential/limits
More groundwater pumped w/variable climate
Low water footprint solar PV and wind
Diminishing institutional influence of irrigation
Water
Water
challenges from
energy
perspective:
Food
challenges from
energy
perspective:
Local food chains minimize transport energy
Climate change raises water needs of energy
Ensure water allocation to energy generation
Energy intensity of farm operations
Rising demand for carbon-free hydropower
Climate change increases food cooling needs
Energy intensity of desalination, water reuse
Extended crop seasons, night-time operation
Energy
Water
challenges from
food
perspective:
Energy
challenges from
food
perspective:
Biofuel must not compete w/ food production
High water footprint of agriculture
Ensure water allocation to irrigation
Energy intensification of agriculture
Supplemental irrigation of rainfed land
Energy intensification of food transport
Water, land degradation (e.g., salinization)
Mitigate hydropower-farming trade-offs
Food
Wastewater use for food production
Fig. 1 a Water-energy-food nexus interlinkages at multiple levels. b Water-energy-food nexus tri-
opticon challenge perspectives
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