The water-energy nexus: A sustainability assessment of water supply in Costa Brava, Spain

June 2nd, 2014

Chelsea Burns, American University, United States

The Costa Brava in the Northeastern Mediterranean region of Catalunya, Spain is a hotspot for tourism during the summer months. Population increases from 240,000 to over 1 million between June and August. For Tossa de Mar and Lloret de Mar, two of the most visited municipalities along the Costa Brava, local water resources have proven insufficient during the peak season since the 1970s. In the last decade, issues of salt-water intrusion due to the overexploitation of the Tordera aquifer during the summer months has forced authorities to develop other supply alternatives, such as desalination and water reuse.

Energy intensity of supply alternatives

In a recent study, we analyzed the entire water life cycle of extraction, treatment, and conveyance to end users in Tossa de Mar and Lloret de Mar from 2007-2011.1 Although desalination can guarantee a supply source in times of drought, the energy intensity of this alternative makes it an expensive alternative, and in a part of the world beset by economic challenges, an inherently unsustainable supply alternative. Water authorities in Catalunya are consequently forced to limit deployment and this restriction significantly compromises the overall utility of desalination.2 As water availability is predicted to become more variable in the future due to climate change, authorities need to question the viability of this supply alternative, whose sustainability is subject to economic shocks.

Regarding the individual energy components of the water life cycle, analyzing the energy intensity of conveyance proves a relevant exercise. For example, desalinated water must first be conveyed from the treatment plant in Blanes to the treatment plant in Tordera and then later transferred to municipalities. In comparison, tertiary treated water, an advanced wastewater treatment process that improves effluent quality beyond the traditional sewage treatment process, is treated and conveyed within municipal boundaries. In Tossa de Mar, when treatment costs are included, the total energy cost for tertiary treatment was 0.79 kWh/m3 versus 3.69 kWh/m3, for desalination. Therefore, it is less energy intensive in treatment and conveyance costs to augment supply through tertiary treatment than through desalination.

Other sustainability considerations

Although water reuse presents some advantages over desalination, it involves limitations as well. Water reuse is currently only available for non-potable applications throughout the Costa Brava, meaning it is not treated to drinking water standards. Treating reclaimed water to meet potable standards is also energy intensive. Furthermore, additional infrastructure, such as new pipeline networks and depositories, are required for conveyance and maximized efficiency. Budget constraints challenge the overall sustainability of this supply alternative.

Need for sectoral integration

In Spain, water policy is managed in a variety of ways from the national to the municipal level. Energy policy, on the other hand, is primarily regulated at the national level. The complexity of the political and institutional structures behind water supply and energy policy makes sectoral integration difficult. The decision-making process is multidimensional: supranational, national, and local policies influence the overall management scheme. Therefore, policies passed within the entire institutional web have direct impacts on the local municipal supply.

Currently, representation from the energy sector only resides in one leg of the decision-making process. The National Water Council advises the Ministry of Environment on how national water plans, agricultural, energy, industrial, or land-use plans impact water resources.3 The head of the Directorate General for Energy Policy and Mines, Ministry of Industry, Tourism and Commerce, as well as a representative from the Spanish Association of Electrical Industry, advise national water policy makers.4 According to a source at the Catalan Water Agency, these members of the energy sector sit within the council to ensure that their electricity production interests are satisfied. They do not offer advice on how the water sector can better incorporate energy planning. This absence of integration means regional and local water authorities never come into contact with national energy planners, and thus, water supply decisions are made independent of the energy sector.5 This is insufficient and inefficient. It is critical that energy consumption remains a parallel concern under each subset of the overall decision-making framework for water planning.

Discussion

Water authorities face specific energy intensity and sustainability challenges. These variables must be accounted for in all future water management plans. For example, water reuse has the potential to redirect pressure from local aquifers to tertiary wastewater treatment, but certain limitations impede the sustainability of the supply mechanism. If conveyance and treatment values are compared, it is clear that further development of tertiary treatment facilities in Tossa de Mar and Lloret de Mar would be a superior option to desalinated water if an equivalent volume of drinking water could be replaced. However, keeping the limitations of tertiary supply in mind is critical. Applying reverse osmosis to the tertiary treated water to bring it up to drinking water standards results in increased energy consumption. Thus far it is unclear if this method is comparable to desalination.

At a global level, it is critical to remain aware of future projections of water supply alternatives that could shift overall energy consumption. Between 2006 and 2011 global desalination production increased from 25 million m3 to 72 million m3 per day. By 2015, the projection stands at 100 million m3.6 In Spain, the 2005 National Hydrological Plan under the A.G.U.A program promotes increased construction of desalination and water reuse treatment facilities. Catalunya’s regional water management plan follows a similar trend. While these supply alternatives meet increasing demand for fresh water resources, they are associated with increasing energy costs. Although desalination has the potential to maintain healthy aquifer levels and avoid additional pipeline construction over hundreds of miles, it results in high energy costs and creates a greater demand for energy producing natural resources. Detailed energy-for-water production data is important for policy makers to integrate energy considerations at each institutional level throughout the entire water resource management hierarchy.

References:

Burns, C. (2013), ‘Important Water-Energy Nexus Considerations: A Sustainability Assessment of Water Supply in Two Municipalities of Costa Brava’. Consorci Costa Brava. Girona. Spain. http://ccbgi.org/docs/publicacions_revistes/Chelsea%20Burns%20water%20energy%20nexus%20report.pdf Pers. comm. Agencia Catalana del Agua, 2013 Varela Ortega, C. & Hernández-Mora, N. (2010), ‘Institutions and Institutional Reform in the Spanish Water Sector: A Historical Perspective’, in A. Garrido & M. Ramón Llamas (Eds.), Water Policy in Spain (p. 117-130). Leiden: CRC Press. OECD (2012), ‘Meeting the water coherence challenge’, in OECD, Meeting the Water Reform Challenge, OECD Publishing, Paris. doi: 10.1787/9789264170001-7-en Pers. comm. Agencia Catalana del Agua, 2013 Olsson, G. (2012), Water and Energy: Threats and Opportunities. London, UK: WA Publishing.

In August 2013, Chelsea graduated with dual masters’ degrees in International Relations and Natural Resources and Sustainable Development from American University in Washington. D.C. and the University for Peace in Costa Rica. Currently, Chelsea works as a consultant for a Smart Grid Technology company. She conducts market research regarding conservation technologies and regional water/energy nexus initiatives in order to assess how water agency programs might benefit from Advanced Metering Technologies (AMI) and community outreach programs.

This article summarizes “Important Water-Energy Nexus Considerations: A Sustainability Assessment of Water Supply in Two Municipalities of Costa Brava,” a water-energy nexus analysis of two coastal tourist destinations in Northern Catalunya. The goal of the report was to evaluate the fluctuation of water supply across the year and to examine the relative energy costs of each of the major sources used to meet water demand. Extraction, treatment, and distribution data sets for volume (m3) and energy consumption (kWh) were compiled monthly between the years 2007 and 2011 for each water supply source. From these data, ratios (kWh/m3) were calculated to determine specific and relative energy consumptions. For full text see published version on the Catalan municipal wholesale water supplier, Consorci Costa Brava’s, website.

The views expressed in this article belong to the individual authors and do not represent the views of the Global Water Forum, the UNESCO Chair in Water Economics and Transboundary Water Governance, UNESCO, the Australian National University, or any of the institutions to which the authors are associated. Please see the Global Water Forum terms and conditions here.