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The Water-Energy Nexus Issue

The Water-Energy Nexus Issue

The Magic Nexus team

There is an increasing demand for energy to alleviate water scarcity pressures, and, vice-versa, a growing water footprint required to produce many energy forms – including new energy technologies. The governance of water and energy then is crucial if we are to safely manage these finite resources into the future.

In our first article, Zora Kovacic explores the origins of the term ‘nexus’ from its original use spearheaded by the food and beverage industry as part of the ‘green growth’ agenda, to become attached to applications as diverse as water modelling to multidisciplinary social-ecological systems analysis initiatives today. She uses the context of these varied applications to question whether the ‘nexus’ concept will help or hinder future water governance efforts.

Broaching the topic of hidden water flows, Maddalena Ripa and Violeta Cabello crunch the numbers to investigate the characteristics and size of an often invisible, yet important water flow – non-consumptive use in the energy sector.  These authors highlight the shortcomings and challenges in quantifying water flows in the energy sector today, and break down the sectors that are not – and should be - properly accounted for. The article then explains how we can improve water governance using better-defined and more comprehensive accounting methods.

Finally, Juan de La Fuente and Baltasar Peñate explore the topic of desalination as a water-energy nexus technology in the Canary Islands, Spain. These authors explain how this controversial technology, known for its large energy footprint, is a viable technology in cases where renewable energy sources are readily available. They show how the Canary Islands archipelago has alleviated its water scarcity problem using desalination technologies, thanks to solar and wind resources available in the area together with effective management to balance costs, energy availability and environmental effects.

We hope you enjoy this our final issue for 2018. Don’t forget to subscribe to receive future issues coming in 2019. You can subscribe at the bottom of the homepage https://magic-nexus.eu/.

The origins of the “nexus”: a water governance concern

10 December 2018

The origins of the “nexus”: a water governance concern

Zora Kovacic

The “nexus” has become a buzzword (Cairns & Krzywoszynska, 2016), used in many different contexts for many different purposes. It indicates the interlinked nature of resource management, and is used as an inclusive tool to address environmental, climatic and land use issues. The most popular formulation of the nexus refers to “water, energy and food”, but the term is used with reference to a broad range of topics. In this article, we trace back the emergence of the term “nexus” and ask: what did the concept mean to achieve?  The term “nexus” hails from the water community, and although it may be seen as a means to articulate concerns and policy priorities of actors involved in water governance, we also show that the term was used in many different ways from the onset.

The term “nexus” was put forward by the '2030 Water Resources Group', which was founded in 2008 and brought together companies from the food and beverage industry, including the likes of the Barilla Group, Coca-Cola Company, Nestlé, SABMiller, PepsiCo, New Holland Agriculture, Standard Chartered Bank and Syngenta AG (Leese and Meisch, 2015). The idea of a “water-energy  nexus” was mainstreamed through the Bonn2011 conference organized by the World Economic Forum Water Initiative. In its early formulations, the nexus was tied to business concerns of a variety of corporations, whose interests ranged from securing access to water resources, to using water resources “efficiently”. Shaped in this way, the nexus has been presented as a means to ensure economic growth that is compatible with resource availability, which Leese and Meisch link to the green growth agenda.

The nexus has also received considerable attention from modellers. Shannak and colleagues (2018) provide an overview of the models that analyse the nexus, and find that most modelling efforts are centred on water. Such models include: the Water Evaluation and Planning Model (WEAP); the Global Policy Dialogue Model developed by the International Water Management Institute; the “water energy and food security nexus” developed by Hoff (2011), which is centred on water availability; the Climate, Land, Energy and Water Strategies (CLEWS) that estimates the suitability of different crops and biofuels under rain-fed and irrigated conditions for current and future climates; the “Diagnostic tool for investment in water for agriculture and energy” developed by the UN Food and Agriculture Organisation. Water is often an “invisible” input needed to produce other goods, such as food, or used in production processes that require cooling, washing, etc. The “virtual water” approach also highlights the importance of taking into account water uses embedded in other products. For this reason, modelling the nexus can be seen as a useful tool to give visibility to water use.

Also with regard to public policy at the European level, the term “nexus” can be found in the realm of water governance. For instance, the MAGIC project responds to the call “WATER-2b-2015 - Integrated approaches to food security, low-carbon energy, sustainable water management and climate change mitigation” which asks proposals to “develop a better scientific understanding of the land-water-energy-climate nexus” (https://cordis.europa.eu/programme/rcn/664566_en.html).

The term “nexus” has emerged in policy and academic parlance as recently as the early 2010s, and it has been a buzzword almost from the onset.  The term does not necessarily lack definitional clarity. Rather,  it is associated with many definitions and used in many contexts. Some see the nexus as yet another rehearsal of older debates about interdisciplinary research, questioning the novelty of the idea. We suggest that the popularity of the term may in some ways help meet the aim of rendering water use more visible, and mainstreaming resource management in business practices. At the same time, the term “nexus” may acquire a life of its own, becoming a new problem in need of governing, requiring new metrics and models, and new institutional arrangements that make it possible to work “across silos”. As the nexus becomes an issue in its own right, it may or may not be a good ally to water governance.
 

References

Cairns, R., & Krzywoszynska, A. (2016). Anatomy of a buzzword: The emergence of ‘the water-energy-food nexus’ in UK natural resource debates. Environmental Science & Policy, 64, 164-170.

Leese, M., & Meisch, S. (2015). Securitising sustainability? Questioning the'water, energy and food-security nexus'. Water Alternatives, 8(1).

Shannak, S., Mabrey, D., & Vittorio, M. (2018). Moving From Theory to Practice in the Water-Energy-Food Nexus: An Evaluation of Existing Models and Frameworks. Water-Energy Nexus, April 2018.

VIDEO: The paradox of energy efficiency

Water for energy: quantifying the massive amounts of water that go unaccounted for

14 November 2018

Water for energy: quantifying the massive amounts of water that go unaccounted for

Maddalena Ripa & Violeta Cabello

Water and energy systems are inextricably linked. According to the Energy Efficiency Directive (European Parliament, 2012), the water sector consumes up to 3.5% of EU’s electricity for purposes such as water treatment, pumping or desalination. Similarly, water is essential for cooling power plants, for the generation of electricity and the production of bio-fuels, and for the the extraction, mining, processing, refining and disposal of fossil-fuel residues.The International Energy Agency projected an 85% rise in global demand growth in water use for energy production between 2012 and 2032 alone (IEA, 2017)./p>

These changes are driven by a combination of factors. First among these is human population growth, which is estimated to rise from 7.4 billion people today to  between 9.6 and 12.3 billion by 2100. Another important factor is the improvements in access to energy for the 1.4 billion people who currently have no access to electricity and the billion people who currently only have access to unreliable electricity networks. Last but not least, the progressive electrification of transport and heating as part of efforts to reduce dependence on fossil fuels and reduce greenhouse gas emissions is expected to be a key driver in the surge of water consumption (The Conversation, 2016). While it is important to consider these factors in policy making, it is equally important to establish an adequate accounting framework to assess the viability of increments in the use of water by the energy sector. In this article we discuss some conceptual and methodological challenges we encountered when searching for European energy and water statistics.

Water for energy: accounting gaps in Eurostat

The challenge of data availability at relevant spatio-temporal scales for analyzing the water-energy nexus is well documented (Larsen and Drews, 2019). While in general energy systems can be considered to be well-monitored, the availability of integrated data sets covering water and energy domains is often severely limited at the relevant levels of aggregation in relation to nexus calculations, that is, beyond the site-specific level. Water and energy accounting are poorly harmonized in European statistics. Eurostat accounts for only one water-energy relation, the use of water for electricity generation (Eurostat, 2012). This broad category encompasses water use for cooling and the rest of water use for electricity production, without specifying the types of electricity production systems. While water for cooling accounts for a relevant share of water uses in some European countries, other relevant uses of water along the energy supply chain are neglected by Eurostat. For instance, fossil fuel extraction and processing are assimilated within the broader ‘mining and quarrying’ category, hindering nexus analysis. Water for biofuel crops and processing are included in the agriculture and manufacturing sectors, respectively.

Water for energy: consumptive vs non-consumptive uses

In order to better inform decision-makers, care should be taken to understand the differences between water use, water withdrawal (or water abstraction*), water consumption, and what the categories represent (Kohli et al., 2010). In this regard, two additional conceptual considerations are noteworthy. First, while Eurostat distinguishes between water abstraction/withdrawal** and water uses (European Environment Agency, 2018), the separation between consumptive and non-consumptive*** water uses is not included in the statistics. In fact, most water used for cooling purposes is non consumptive. This means that water is either recycled or returned to water bodies after use. A small share of withdrawn water is evaporated (consumed) along the cooling chain, falling into the consumptive use category. Second, hydroelectricity is excluded from the accounting because it is an in-situ use (Eurostat 2014, p. 43). However, hydroelectricity does also evaporate water (consumptive uses) and uses tremendous volumes in a non-consumptive manner.

 

Figure 1 - Water use for energy production in European countries 2012 (m3/p.c).

The quantitative multi-scale approach used in MAGIC allows maintaining the distinction between green water, consumptive blue-water and non-consumptive blue-water. In particular, in a recent report of the MAGIC project (Ripoll-Bosch and Giampietro 2018), we calculated water use for the energy sector in different European countries (Germany, France, Italy, Romania, Spain, Sweden and United Kingdom). The water consumed for refineries, evaporated during electricity production and biofuel crop irrigation, as well as the water used in the mining and extraction of Primary Energy Sources (which can be contaminated due to acid mine drainage), was considered to be consumptive. The water for cooling and for hydropower (excluding the water evaporated during the process) was accounted for as non-consumptive.

Figure 2 - Contribution of different processe to the non-consumptive water share (%)

If this distinction between consumptive and non-consumptive water uses for energy supply is introduced, and hydroelectricity is included in the accounting, the resulting picture for European countries is quite interesting: Most water uses for energy supply fall within the non-consumptive category (figure 1). Within this category, the pattern significantly varies among countries depending on how much hydroelectricity they have developed (figure 2). When looking at the consumptive share (figure 3), electricity generation is still the largest water consumer in all analysed countries. Whereas this share looks negligible in comparison to non-consumptive uses, it gains relevance when contrasted with other consumptive uses such as water for agriculture or households.

Figure 3 - Contribution of different processes to the consumptive water share (%).

The announced expansion of electrification will generate competition for water not only between sectors, but also between different consumptive and non-consumptive uses of water in energy generation. Moreover, the impacts of increments in electricity demand on surface water bodies need to be evaluated against the disaggregated contribution of different energy supply processes. Therefore, it is imperative to advance to a more comprehensive water-energy nexus accounting framework that can quantify and characterize all water uses together across sectors.

 

*Eurostat (2014, p. 43) defines water abstraction as ‘Water removed from any source, either permanently or temporarily. Mine water and drainage water are included. Water abstractions from groundwater resources in any given time period are defined as the difference between the total amount of water withdrawn from aquifers and the total amount charged artificially or injected into aquifers. Water abstractions from precipitation (e.g. rain water collected for use) should be included under abstractions from surface water. The amounts of water artificially charged or injected are attributed to abstractions from that water resource from which they were originally withdrawn. Water used for hydroelectricity generation is an in-situ use and should be excluded.’

**Groundwater abstraction is the process of taking water from a ground source, either temporarily or permanently (European Environment Agency, 2018).

***A use of water is consumptive if that water is not immediately available for another use. Losses to sub-surface seepage and evapotranspiration are considered consumptive, as the water that is polluted or degraded to insufficient quality for reuse. Water that can be immediately treated or directly returned to water bodies in a continuous loop is considered non-consumptive. Therefore, a non-consumptive use is when water use does not diminish the source or impair the future water use.


References

European Environment Agency, 2018. Groundwater abstraction [WWW Document]. URL https://www.eea.europa.eu/themes/water/wise-help-centre/glossary-definitions/groundwater-abstraction (accessed 11.2.18).

European Parliament, 2012. Directive 2012/27/EU of the European Parliament and of the Council of 25 October 2012 on energy efficiency. Off. J. Eur. Union Dir. 1–56. doi:10.3000/19770677.L_2012.315.eng

Eurostat, 2014. Data Collection Manual for the OECD/Eurostat Joint Questionnaire on Inland Waters. Version 3.0. Available at: https://ec.europa.eu/eurostat/documents/1798247/6664269/Data+Collection+Manual+for+the+OECD_Eurostat+Joint+Questionnaire+on+Inland+Waters+%28version+3.0%2C+2014%29.pdf/f5f60d49-e88c-4e3c-bc23-c1ec26a01b2a

Eurostat, 2015. Annual detailed enterprise statistics for industry (NACE Rev. 2, B-E) [WWW Document].

Eurostat, 2012. Water use by supply category and economical sector (env_wat_cat) [WWW Document]. URL http://appsso.eurostat.ec.europa.eu/nui/show.do?dataset=env_wat_cat&lang=en

International Energy Agency, 2017. World Energy Outlook 2017.

Kohli, A., Frenken, K., Spottorno, C., 2010. Disambiguation of water use statistics 1.

Larsen, M.A.D., Drews, M., 2019. Water use in electricity generation for water-energy nexus analyses: The European case. Sci. Total Environ. 651, 2044–2058. doi:10.1016/J.SCITOTENV.2018.10.045

The Conversation, 2016. Energy sector is one of the largest consumers of water in a drought-threatened world [WWW Document]. URL https://theconversation.com/energy-sector-is-one-of-the-largest-consumers-of-water-in-a-drought-threatened-world-59109 (accessed 10.31.18).

Ripoll-Bosch and Giampietro (Editors). 2018. Report on EU socio-ecological systems. MAGIC (H2020–GA 689669) Project Deliverable 4.2. 31 March 2018. Available at: https://www.magic-nexus.eu/documents/d42-report-eu-socio-ecological-systems

Is Shale Gas Dead?

Is Shale Gas Dead?

Cristina Madrid-Lopez

It’s been a rough ride for the shale gas sector. The market boomed in 2008 shortly after natural gas prices reached USD $6 per million BTU ($/MMBTU). Then, lower gas-prices during 2014-2016 marked what many considered the beginning of the end of the shale gas extraction era – producers could hardly afford the high costs of horizontal drilling and hydraulic fracturing at a time when prices were close to USD $2/MMBTU. But then, as prices inched up in mid-2018 to USD $3/MMBTU, there was a mixed reaction. While shale gas enthusiasts regained optimism about the sector’s future and its potential contributions to energy policy objectives, critics were and still are skeptical of its potential due to the impacts and financial costs of extraction. With such uncertainty then, is there cause for optimism for shale gas, or is the market facing a bleak future?

Finding consensus on the answer to this question is going to be difficult because shale gas extraction is a component of what Stephenson has called “the fracking phenomenon”. In other words, “fracking” is a complex issue and as Roger Strand has put it, it is more useful to accept that some questions might not have one straight answer, but many valid ones. And that is fine.

Considering different answers as valid is not the same as falling into vague or “unscientific” methods. Analysts that follow the principles of Post-Normal Science (PNS) often use the same tools as other scientists and take into account factors other than facts, such as people’s perceptions and knowledge. Consequently, they do not look at quantitative results as an absolute truth but understand them as the final step of an analytical process influenced by a (mostly social) context.

 

The Bioeconomics view

Bioeconomics is a useful lens with which to understand the energy and material flows associated with a productive activity such as shale gas extraction. Figure 1 maps the productivity of all wells in Pennsylvania, US, at different ages where three main stages can be observed. During the early stage of drilling and fracturing, productivity increases. At the same time, the adverse impacts on water, air and land and the local population also increase. During the production phase, the well is capable of providing enough gas to recover production costs and the environmental impacts are usually minimal. Finally at the decay stage, gas production is too low to provide benefits and adverse impacts are usually the result of a lack of proper maintenance.

 

Figure 1: Average productivity and life stages of a shale gas well (from Madrid-Lopez, under review)

 

The point at which a well leaves the production stage and enters the decay stage is determined by the price of the gas. Clearly, once a well enters the decay stage, the gas company might prefer to plug it up and open another one, creating a more significant impact on land and water ecosystems. In a situation of lower gas prices, the production stage is minimized. The shale gas sector can only maintain a regular level of daily production if the number of wells (and their impacts) are increasing.

 

The Geopolitical view

When shale gas is saved for the times when gas prices are higher, however, the production of natural gas decreases, endangering the energy security of the producer. Wood Mackenzie reports that China’s shale gas extraction has doubled since 2016 and that, despite the relatively higher costs of shale gas development in China, the government’s commitment to the sector is grounded in energy security and geostrategic reasons. Since mid-2016 the sector’s productivity in the US has increased again, even when prices are close to USD $4/MMBTU which is about the average cost of production in the US. The Trump administration has heavily supported shale gas producers in Pennsylvania and other states, partly in order to fulfill local-development campaign promises that made Pennsylvania swing from a Democrat to a Republican majority state and partly to maintain a strong influence over the world energy market.

With Dutch natural gas reserves close to exhaustion and the international relations between Europe’s main gas provider, Russia, and the European Union in a critical moment, being a trade partner of Europe sounds like an appealing option for exporting countries. Consequently, despite low gas prices and high environmental and social impacts, governments might choose to promote shale gas development for strategic reasons.

 

Power relations and public participation

Power relations play an important role in defining political agendas and, consequently, what actions are taken. Trade-offs between global, national and local strategic policies are very important to determine the future of shale gas development. It can be argued that the high income states of New England in the US suffers from a global scale ‘NIMBY’ effect, meaning that they benefit from a regular and low-cost gas supply, while extraction has been banned in most of the state.

In order to ensure that the analysis that we are carrying out will provide answers to questions that are relevant for stakeholders, the obvious step is to involve them in the analysis. Traditionally, public participation is included in research either to gather information about a case study prior to the analysis or to gather feedback afterwards. In MAGIC, public participation is also included before the design of the analytical method. Thus, in the WP6 case study on shale gas we include a consultation to key actors in the European Commission.

 

Innovation to policy

Shale gas fracking can be viewed from different perspectives, as discussed here with framings from Bioeconomics or Geopolitics. What does this mean in terms of policy measures, and more broadly for the governance of innovations? The contribution of technological innovations to policy objectives is uncertain but can nevertheless be studied. Some have argued that having shale gas at hand will delay the energy transition to renewables. However, natural gas, due to its market-readiness and its potential for use in decentralized systems, has been proposed as an energy source that can contribute to achieving a Low Carbon Economy.

Shale gas development might not have the potential to make a major contribution to climate or energy policy. However, it has a high geopolitical value. It would be wise for Europeans to keep an eye on its mid-term development in the current scenario of fracturing diplomatic relations among the major external gas providers, which happen to coincide with the depletion and closure of one of Europe’s most productive gas fields, the Groningen field in the Netherlands.

What if energy imports mattered?

27 March 2018

What if energy imports mattered?

Maddalena Ripa & Louisa Jane Di Felice

During the past few hundred years, growing numbers of people have obtained their energy from further and further afar, and supply has become inextricably linked to distant locations and events, expanding the spatial and temporal chain linking energy supply to demand. This is particularly true of oil, but also of all the other energy sources that can be moved across borders: coal, electricity, natural gas, and nuclear fuel (Overland, 2016). In 2012, the EU imported 53% of all the energy it consumed, at a cost of more than €1 billion per day. Looking at energy imports reveals how the decline in energy use per unit of GDP (i.e., Economic Energy Intensity) in EU advanced economies is not necessarily because they have become much more efficient in terms of energy and resources use, but because they increasingly rely on other countries to fulfil their supply of primary energy sources. Energy makes up more than 20% of total EU imports - a fifth of the EU's total import bill (European Commission, 2018). Implicit in the import of energy products is the indirect import of labour and resources, such as water and primary energy sources, embodied in the production process and transport of these products.
 

Specifically, the EU imports:

  • 88% of its crude oil
  • 66% of its natural gas
  • 42% of its solid fuels
  • less than 4% of its renewables (mostly concentrated on biomass)
  • 95% of its uranium
     

If we consider embodied fossil energy imports (also known as ‘virtual imports’), as for example the oil embedded in the import of diesel, the gap between fossil energy consumption and production (one traditional measure of energy security) in the EU is even larger than commonly assumed. This has prompted the MAGIC project to investigate the narrative of energy security as a nationally bounded imperative.
 

Figure 1. Percentage of fossil primary energy sources outsourced abroad – direct import in orange and virtual import in dark red
(DE – Germany, ES – Spain, FR – France, IT – Italy, NL – Netherlands, RO – Romania, SE – Sweden, UK – United Kingdom). More details available in MAGIC Deliverable 4.2.

MAGIC research has shown that the percentage of fossil primary energy sources directly and indirectly outsourced is higher than 80% in all most EU countries: Figure 1 shows the percentages of outsourced fossil primary energy sources, including coal, oil, gas produced outside the country, directly and indirectly required (virtual) to produce the total energy metabolized by UK, Sweden, Romania, Netherlands, Italy, France, Spain and Germany. 

Misrepresenting the share of inputs sourced from foreign suppliers can introduce a significant bias in the analysis. Indeed, the level of outsourcing of economic sectors heavily affects their performance. A country outsourcing the production of inputs that are particularly “costly” in terms of resources or labour requirement may appear more efficient than a country producing its own input.

In the EU, similar to other global economies, pressure for greater energy self-sufficiency is rooted in the narrative of preventing major supply disruptions (European Energy Security Strategy, 2014). This means that broader discourses on the socio-economic implications of the energy globalized trade are systematically ignored.

 

Figure 2. Percentages of working hours employed to produce the energy metabolized (directly and indirectly) by eight EU countries.
The blue part of the bar shows the percentage of working hours employed locally, whilst the red part of the bar expresses the outsourced percentage.

Figure 2 shows the percentage of labour (one key nexus element in MAGIC analysis) that is directly and indirectly required and outsourced (red bar) to produce the energy needed to sustain the country. This percentage is comparatively high and for some EU countries (e.g., Spain and Netherlands) it is higher that the local labour investment. In addition, the missing nexus link is that the EU workers whose job is moved offshore do not stop using energy, even if they become permanently unemployed or retire as a result of the change. And the beneficiary of the job transfer offshore will use more energy, as the accompanying increase in income translates into a standard of living that affords more consumer goods, and possibly a move to lower deinsity housing.

 

Table 1. Origin of oil imports (in %) for selected EU countries
(Regions of origin: RER -Europe , RU – Russia, RAF – Africa, RNA – North America, RLA – Latin America, RMS – Middle East, RAS – Asia and the Pacific)

Labour is an essential but often neglected nexus element that is of paramount importance to study the broader socio-economic implications of EU economies and provide trans-disciplinary insights. For example, Table 1 shows the origins of EU oil imports. The largest share of oil is derived from developing countries, where low income and illegal, low security jobs pose ethical issues that are not adequately tackled by the current EU legislation.

Globalization has demonstrated an unexpected ability ‘to manage the non-resolution of its problems, accommodate its dysfunctions, even drawing renewed strength from this state of affairs’ (Barca, 2017). These side-effects are serious and, if left unchecked, will impose limits on the ultimate extent of globalization's spread. Addressing this will require novel approaches and may result in some counter-intuitive solutions. Through the MAGIC project, our aim is to provide better quantitative framings of the issue at hand, in order to aid decision makers who are confronted with the complex challenges associated with an increasingly globalized world.

 

References

Barca, S. (2017). Labour and the ecological crisis: The eco-modernist dilemma in western Marxism(s) (1970s-2000s). Geoforum, (June), 0–1. https://doi.org/10.1016/j.geoforum.2017.07.011

European Commission, 2018. Press Release. http://europa.eu/rapid/press-release_MEMO-14-379_en.htm

European Commission, 2014. European Energy Security Strategy [COM(2014)330]

Overland, I. (2016). Energy: The missing link in globalization. Energy Research and Social Science, 14, 122–130. https://doi.org/10.1016/j.erss.2016.01.009

Desalination is a viable nexus technology: but local conditions are key

Desalination is a viable nexus technology: but local conditions are key

Juan A. de La Fuente and Baltasar Peñate

The world population is expected to increase from the current 8.5 billion to 11.2 billion by 2100 (World Population Prospects, United Nations 2017). By 2050, global demand for energy will nearly double, while water demand is set to increase by over 50%. To overcome the increasing constraints the world faces, we need to rethink how we produce and consume energy in relation to the water sector.

The authorities responsible for water and energy are generally separated. Each has its own priorities and there seems to be little incentive to collaborate in the planning and development of new policies. At the same time, the water and energy sectors have always operated independently and there may be some resistance to a better integration of both sectors. Often, studies on the interconnection between water and energy have been initiated and driven by specific local circumstances, such as water and energy crises.

Seawater desalination is an important option for addressing the world's water supply challenges, but current desalination plants use huge quantities of energy causing several environmental issues. The energy intensity of desalination processes has dramatically decreased over the past 30 years, from slightly more than 15 kWh/m3 in the 1970s to approximately 2.5 kWh/m3 today thanks in large part to reverse osmosis (RO) technology improvements. Still, several physical constraints limit the ability to reduce the energy intensity of RO much further. This means that energy efficiency in RO has almost reached its biophysical limits.  

Brine discharge into the sea can have a negative environmental effect on the marine ecosystems due to its high salt concentration and other chemicals. Devices like Venturi diffusers for brine discharge can be used to improve the dilution process and reduce their environmental impact. It has been shown that the capacity to improve the dilution of Venturi system is greater than 2.3 times the dilution obtained with conventional diffusers. Another option could be the valorisation of brine, by using it for the culture of the microalgaes for the production of molecules such as β-carotene and polyunsaturated acids. The biomass obtained can be used in animal nutrition and Nutraceutics.

It is very likely that the water issue will be considered, like fossil energy resources, to be one of the determining factors of world stability. Desalination processes involve a recurrent energy expense which few of the water-scarce areas of the world can afford. Even if oil were much more widely available, could we afford to burn it in such a manner so as to provide everyone with fresh water? Given the current understanding of the greenhouse effect and the importance of carbon dioxide levels in the atmosphere, environmental pollution caused by burning fossil fuels for desalination is a major concern.

Renewable energy (RES) technologies, mostly solar and wind energy systems, can provide access to a cost-effective, secure and environmentally sustainable supply of energy that can be used for water desalination. As RES technologies continue to improve, and as freshwater becomes scarce and fossil fuel energy prices rise, utilising RES for desalination becomes more viable economically. RES may provide water desalination cost reductions due to lower greenhouse gas emissions. For example, a seawater RO desalination system operating on traditional fossil fuel-based energy sources produces 1.78 kg and 4.05 g of CO2 and NOx per 1 m3 of desalted water, which can be reduced to 0.6 kg/m3 – 0.1 kg/m3 and 1.8 kg/m3 – 0.4 kg/m3, respectively, with electricity generated from wind or solar energy  (Raluy RG, Serra L, Uche J. 2005. Life cycle assessment of desalination technologies integrated with renewable energies. Desalination 183(1–3):81–93).

On the other hand, the role that desalination could play in the integration of electricity produced by renewable sources in the electricity grid is also an interesting topic.

The major constraint on increasing penetration of RES is their availability and intermittency, which can be addressed through using energy storage or smart control, when available, to balance renewable energy generation with energy demand.

The Canary Islands archipelago in Spain is a perfect example of how a region with water shortage and presence of RES resources has alleviated its water scarcity problem using desalination technologies, exploiting in turn the sun and wind resources available in the area.

The water – energy nexus has been one of the key R&D lines of the Canary Islands Institute of Technology (ITC). The ITC has developed and tested prototypes of different renewable energy driven desalination systems, operating in off-grid mode, since 1996. The ITC facilities in Pozo Izquierdo (Gran Canaria Island) are an ideal platform for testing RES desalination systems thanks to the excellent local conditions: direct access to seawater, annual average wind speed of 8 m/s, average daily solar radiation of 6 kWh/m2. Up to 18 different combined systems of renewable energy generation and desalination processes have been tested at the ITC.

Depending on the local environmental conditions, regulation and policy, desalination is a viable technology where RES resources are readily available. With planning and an adequate policy, desalination should be an alternative water resource. However, the energy dependence and the relatively high water cost must be analysed on a case by case basis before proposing specific arrangements.