Resumen de The potential of water reuse in Spain: photovoltaic self-consumption and water pricing
The current pressure on water bodies is a structural problem that may compromise the satisfaction of future water demand and the good status of the natural environment. Activities such as wastewater reuse or desalination provide an additional source of water resources to meet demand without the need to increase natural water abstractions. In addition, reuse also contributes to improving water quality by limiting abstractions and reducing discharges. However, reuse has not been widespread as a source of supply in resource-rich contexts. In resource-abundant areas, the high cost of reusing water is a strong disincentive to its use, which puts the focus on reducing pollution through discharge without assessing the potential of reuse as an additional source of resources. The use of reclaimed water has a great margin for development that should be exploited in the coming years to obtain a guarantee of supply and an improvement in the environmental quality of water in the current context of increasing scarcity. However, the financial and environmental situation of reuse requires the involvement of the public sector. In this work, two instruments with the potential to facilitate the development of reuse have been studied. The first of these is photovoltaic self-consumption, in order to reduce the cost of energy consumption of wastewater treatment plants, given that this is their main financial operating cost. This possibility, however, has shown little capacity to reduce these costs since, except in the case of the floating photovoltaic installation, the cost of electricity from self-consumption is higher or similar to the market price. If we consider the reduction of greenhouse gas emissions derived from self-consumption, this alternative is much more competitive. The situation is, once again, of an activity that presents financial losses and environmental benefits derived from the current excess of emissions. The responsibility lies with the public sector in the same way as in the case of reuse. Water tariffs, as one of the main revenues from water treatment, is an instrument that can be evaluated with a view to increasing revenues through an increase in the price of water. The results obtained show large differences in the impact of such an increase depending on the region but make it clear that the potential for additional revenue from this possibility is small. This analysis has also shown that there is a problem in the current tariffs that reduces their effectiveness by not valuing the type of household. The problem lies not in the structure of the tariff or the number of household members, but in the characteristics of the household. By not taking these into account and calculating the bill without these details, the tariffs are not fully effective. In conclusion, both reuse and photovoltaic self-consumption are beneficial activities for society, but the financial costs involved in their implementation require the involvement of a public sector with a reduced capacity to increase current revenues.
