Published on IDRA Global Connections Summer 2020 Issue
By Mr. Fermin Lopez Unzu
The Mediterranean area of Spain is characterized by hot dry summers and mild wet winters with periods of intense rainfall in spring and autumn. The water cycle associated to this Mediterranean climate frequently results in droughts and floods. This region is also one of the economic leading areas of Spain which depends on the availability of clean water resources.
The combination of a high demand for water to maintain the economy coupled with the scarcity of natural resources results in very well-known problems like permanent drought situations, over-exploitation of groundwater with a subsequent decrease in quality, restriction situations for irrigation and even for drinking purposes, environmental and economic damage due to flooding, and lack of water resources to maintain ecological protected areas.
Furthermore, recent studies carried out by the Climate Change office of the Spanish Ministry for the Ecological Transition and the Demographic challenge assessing the impact of climate change on natural water resources over the whole country show a future global reduction of natural river flows. The analysis, which used two global warming scenarios, six climatological models and one rainfall runoff model, indicate by 2040 there will be a reduction of 3% to 7% of natural water flow in the whole country. By 2040-2070, the reduction average is expected to be between 11% and 14%, and in the last part of the century (2070-2100), the reduction will reach 13% to 24%. Rivers in the Mediterranean area will suffer higher reductions of natural flows. To deal with these problems, the government of Spain established Acuamed to take actions in five large infrastructure programs that respond to two main objectives: generation of new resources (Desalination and Wastewater reuse) and improvement of management and protection of the environment as it relates to water quality improvement, flood protection, environmental restoration, water resource infrastructure and irrigation methods.
In accordance with the scarcity scenario, generation of new water resources has accounted for more than half of the investment of the utility. The desalination program is principal and includes the construction and operation of 12 desalination plants able to supply up to 409 hm3/year. Two big water transfers and several water distribution systems were also built and are now operated.
The Levante is the Spanish principal area of intensive, irrigated horticulture. Orange groves, fruit orchards and even some rice fields are all characteristic, with vegetables crops being a landmark of the region. Farther to the south, vast swathes of the landscape are covered with greenhouses producing high quality fruits and vegetables to feed the European market. As a result, 6 out of the 12 desalination plants are destined to supply water for irrigation purposes also; this use represents around 40% of the total production capacity. Such volume of irrigation water is able to guarantee the supply of water to 250,000 hectares. On the other hand, the available capacity for drinking water guarantees a supply for 3,000,000 people.
Most users of water for irrigation are highly efficient farmers associated in large communities sharing common water distribution systems, and in some cases, even owning private desalination plants. They grow highly valuable crops and they also have developed efficient irrigation systems including drip irrigation and even in some cases, hydroponic crops. These communities have access to other resources like surface water, water transfers, groundwater and reused water, and they tend to blend them but using mostly the cheapest. But as all these resources are to be used accordingly to the permits issued by catchment water authority, in recent years the authority is starting to rule the use of desalinated water with priority, at least when drought alert levels are declared, bearing in mind that other resources can be stored for later use. Farmers are also slowly switching their minds in this direction.
Currently, there are 11 plants in operation and 1 under construction. As an illustration of how these plants are helping to alleviate the scarcity of surface water resources, the following graph shows the evolution of the volume of water that the utility has provided to its users, classified on the origin of the water: desalination, water treatment (which includes waste water reuse) and surface water (inter-basin transfers and major pipelines).
The oldest plants (Carboneras, Marbella, and el Atabal) started operation in 2005, and during the first eight years levels of desalinated water production remained relatively stable (and low). During this period surface water delivered through major pipelines and interbasin transfers between catchment areas was equivalent to desalinated water.
However, in 2012 the desalination productionstarted to increase, with a significant jump in 2016. In that year the River Segura catchment area and Almería were entering a first water scarcity period with pre-alert and alert levels declared. Since then levels of desalinated water production have been steadily increasing. Last year it reached a total maximum of 281 cubic hectometers. In six years, desalination production has increased threefold.
In the period from 2004 to 2015 the principal destiny of desalinated water was for urban supply. Since 2015, however, agriculture has been the main user, as it needs a constant and regular water supply in order to cope with contracts signed with the major food distribution companies across Europe, and other water resources were scarce or even inexistent.
The five biggest desalination plants which are also the plants providing resources to agriculture: Torrevieja, Aguilas, Valdelentisco, Carboneras and Campo de Dalias have been operating almost at full capacity.
Acuamed’s desalination plants have reached a high and stable rate of operation, mainly in the Segura and the Andalusian Mediterranean basins, providing a very significant volume of total water resources. During these years of low rainfall and drought, no city has suffered from water cuts, and the agriculture-based companies were able to maintain their market share. This high rate of use and demand by users has led to undertake studies to assess the possible expansion of desalination plants inthe Segura Basins and the province of Almería, based on the determinations of the basin authority. This expansion could provide an increase in the desalination capacity of 91 hm3 / year, so raising the total capacity to 500 hm3/ year.
Desalination plants have proven to be an effective tool to fight the effects that global warming and climate change are having on water resources, but at the same time, they are also heavy energy consumption installations. As such, an energy efficiency program has been implemented, and a zero-emission practice is in place. Permanent energy monitoring is carried out to compare specific consumption of all the equipment in each plant with average energy ratios, by means of a monthly evolution analysis. Energy audits are also carried out to comply with the Government Decree 56/2016 and EU Directive 2012/27 aimed at the promotion of energy efficiency.
Regarding the use of renewable energy, 100% of the energy currently consumed by Acuamed comes from renewable sources as specified in the annual tenders for the acquisition of energy. This implies a slight cost overrun, corresponding to the guarantees of origin, but this is the way to promote renewal energy installation.
It may be concluded that as climate change is affecting the availability of natural water resources, desalination and reuse coupled with renewable energy are very powerful tools that can help deal with water scarcity. But in order to improve water security, desalination plants and reuse installations are to be integrated in wider water distribution networks to improve the resilience of the systems.
The operation of desalination plants must be done with utter respect to the environment and on a zero-carbon emission basis.