Evaluation of carbon and water policies in the optimization of water distribution networks involving power-desalination plants

This paper presents an optimization approach for water distribution networks. The system includes power-desalination plants as well as taxes and tax credits applied to carbon emissions and water management. To find the optimal design of the system, the profit is maximized, whereas the impact of economic penalties and compensations on environmental and social functions is analyzed. The model considers energy and water demands for distinct users (domestic, agricultural and industrial), which can be satisfied by using fossil fuels, biofuels, solar energy, water storage tanks, water from natural sources (aquifers and dams) as well as water and energy generated in dual-purpose power plants. A water management problem in the Sonoran Desert from Mexico is addressed as a case study. Results show important economic benefits, reduction in emissions and generation of jobs, especially when carbon tax credits are involved. With the greatest compensation, the avoided emissions are 59,984 ton CO2/year, likewise, the maximum values for the number of jobs and profit are attained (12,647 generated jobs and 1635 MM$/year). Similarly, water taxes and tax credits contribute to finding high profit values as well as benefits in the environmental functions, such as reductions in water extractions and rises in the recharge of aquifers. For instance, with the highest tax, the water extraction decreases to 179 x 10(6) m(3)/year (104 x 10(6) m(3)/year lower than the reference case) and the recharges of two of the aquifers evaluated in the case study achieve their maximum values (75 x 10(6) and 73 x 10(6) m(3)/year).