In the future, we’ll all be drinking the sea – if we can…

Access to water is the very definition of an absolute necessity. Those of us in higher and lower latitudes are perhaps currently shielded from any availability concerns, as we have abundant water resources to draw on. We absolutely and confidently expect that we turn the tap and out flows essentially unlimited liquid. However, many regions of the world are not as lucky as us and suffer from water scarcity or water stress. The World Resource Institute reports that at least 50% of the world’s population live under highly water stressed conditions for at least 1 month per year. As we look to exceed our 1.5 degree climate warming target, water stress and scarcity will likely increase, heightening existing water challenges and creating new ones.?

Globally, climate change is already making an environmental impact by way of elevated average temperatures, altered precipitation patterns, desertification, and the subsequent depletion and contamination of ground waters by saltwater intrusion (due to rising sea levels, already a concern in Bahrain, Kuwait and the UAE). On the flip side, unusual rainfall patterns and sudden extreme weather lead to challenges related to urban stormwater management and public health. Climate change seems keen to provide mounting challenges in managing excess rainfall in some periods whilst on the other hand increasing the likelihood of droughts in other seasons – quite the conundrum…?

Tackling the root causes of climate change through reducing greenhouse gas emissions is the obvious solution, but we’re not moving quickly enough so mitigation and adaptation is the order of the day. (It’s interesting to note that this only adds to the costs that we could be allocating to fixing the root cause of climate change, which does smack of fixing the symptoms not the cause…) Adaptation strategies that focus on sustainable water management, conservation, and technological innovation will be crucial, but they are unlikely to give sufficient benefit to get anywhere close in scale to fixing all of the issues. So, it becomes progressively more important that we implement measures to produce freshwater cost-effectively, conserve available water resources, and adopt methods to recycle and reuse treated wastewater.?

In an upcoming era of widespread water scarcity and stress, efficient desalination of sea water will become essential and more prevalent. Over recent decades seawater desalination as an activity has grown rapidly. There are currently almost 20,000 desalination plants in place globally (of various sizes) with a total capacity of approximately 100 million cubic meters of potable water production every day. These plants are expensive to build and operate, which explains why they predominate in developed countries. The Middle East has about 70% of all plants, which is unsurprising given the local climate and the region’s rapid population/economic growth. However, climate change is ambivalent and unselfishly distributes its challenges. For developing or resource-strapped countries, implementation of desalination at a scale large enough to cater to their needs is often outside of their financial capacity. Work at TII is seeking more economical large- and small-scale solutions to these problems and we are onto a couple of technologies that could provide real step changes in capability – watch this space.?

While desalination presents a promising solution to water scarcity, desal is still relatively expensive compared to obtaining water from traditional water sources such as abstraction from river and aquifers. The energy required for the process, although decreasing over time as we improve the technology and way we operate these plants, remains a significant operational cost and emissions generator. In regions with abundant renewable energy sources these issues may be addressed, but if fossil fuels are used this only exacerbates climate concerns. This leads to? an unvirtuous circle of climate change;? leads to water production which leads to increased energy needs and thus to increased pollution and back to more climate change. The coupling of desalination with renewable energy sources will therefore become an absolute necessity as the prevalence of these plants increases.

In addition to accessibility and cost issues, the environmental impact of the disposal of brine, which is the concentrated saltwater left behind after fresh water is extracted, is often cited as a key concern. Brine can harm marine ecosystems if not properly managed. Work within the research community has identified that these concerns are quite localized to the few meters surrounding the brine outflow, and that the brine quickly dilutes to non-harmful levels away from the exit point.? This is often achieved at the expense of (pre-discharge) diluting the brine with fresh water obtained from the core desalination process, which seems somewhat wasteful and counterproductive. System designs must continue to hold this brine discharge issue high on their agendas as the total brine volume increases; we cannot afford cheap, low-quality system designs to emerge that poison our oceans.. The ultimate aim of future systems designers is to come up with ‘perfect’ designs that do away with these outflows entirely, the so called ‘zero liquid discharge’ ambition that a previous blog discussed. That concept removes all the fresh water and may even enable or enhance separation of the minerals and valuable materials from the brine in a further process called Brine Mining. If we can do that cost effectively, desalination will become not only a savior on the potable water supply front, but also a source of democratized mineral supply for some of the world’s critical technology needs. The team at TII are working on that currently, and it does appear to be entirely realizable as a goal… again, watch this space.

As the world adapts to the realities of a changing climate, desalination will undoubtedly be part of the solution to the global water crisis.. In line with SDG #6, and with ongoing innovation, careful management, and investment in renewable energy, desalination could be the key to a secure, water-resilient future for the billions of people around the globe.? We must do this right, with due consideration and ambition for sustainability and equality of access for all.