Desalination and the commons: tragedy or triumph?

Figures & data

Table 1. Production capacity, capital cost, energy consumption and GHG emissions for San Diego, Almeria and Riyadh.

	ML/day	$ millions	GWh/year	CO2e tons/year
San Diego	190	900	246	61,000
Almería	60	102	55	13,570
Riyadh	420	1,595	2,540	1,960,000

Notes:

These figures reflect total capacity, use and cost in San Diego. In Almería, use is less than capacity, even with subsidies to costs. For Riyadh, figures reflect 20% of installed capacity, i.e. the marginal supply that allows consumption to rise from 224 to 280 litres per capita per day (C. Doublet, Operations Director of Veolia Water Saudi, Personal communication, 21 May 2014,). Energy and CO2e statistics from Voutchkov (2008) and GWI (2015), respectively. The largest shares of operating costs – and externalities – result from energy use. Saudi Arabia’s energy consumption and carbon output are much higher due to differences in desalination technology. Facilities in California and Spain use reverse-osmosis (RO) technology while many Saudi plants use thermal multi-stage flash (MSF) or multi-effect distillation (MED). According to Anderson et al. (2008), RO produces 1.8 kg CO₂/m³ while MSF and MED produce 23.4 and 18.0 kg CO₂/m³, respectively.

Figure 1. San Diego charges a low, average-cost price (P₁) on water, such that quantity demanded (Q₁) justifies the more expensive desalinated supply (S_d). Prices at P₂ (representing the marginal cost of desalinated water) would result in a lower quantity demanded (Q₂) and thus no need for additional, desalinated supplies. Source: Author elaboration.

Figure 2. Satellite photo of Campo Dalías, Almería. Source: NASA Jet Propulsion Laboratory (2011).

Figure 3. Farmers can afford to pay for desalinated water (S_d) although it costs more than groundwater (S_b), but weak regulations allow them to unsustainably over-draft groundwater for lower-valued uses, such that quantity Q₁ is demanded, rather than the sustainable quantity Q₂. Source: Author elaboration.

Figure 4. The cost of supply from groundwater (S_b) and desalination (S_d) is much higher than the price of water (P₁). Excess demand at that price is cut back by interruptions in service, such that the shadow price of water is P₃ and the quantity demanded is Q₃. Source: Author elaboration.

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GWI. (2015). Desalination data website. Global Water Intelligence. Retrieved May 25, 2015, from http://desaldata.com

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NASA Jet Propulsion Laboratory. (2011, 10 May). Almeria, Spain. NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team. Retrieved Dec 10, 2015, from http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA14146

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