This article originally appeared in WQP June 2020 issue as "Off-Grid Solution"
Crowds of people lined up to stock up on water, abandoned swimming pools and dried-up dams. In spring 2018, such images from Cape Town, South Africa, splashed across the world media as the city was experiencing the worst water crisis in its modern history.
Fortunately, the city managed to avert Day Zero–the day the taps were predicted to run dry. However, even though times when 90-second showers were possible have passed, there is no guarantee that Day Zero will not happen again.
Cape Town is not alone. In recent years, cities around the globe from Melbourne, Australia, to Sao Paulo, Brazil, found themselves on the brink of their own Day Zero. Overall, almost 25% of the world’s population today live in countries with high water stress. Most of these countries are in the Middle East and North Africa, yet many other nations in Asia and South America, as well as small island developing states, are at risk of running out of freshwater.
As the world’s population grows and demands more food while climate change causes longer and more severe droughts, the problem of water shortages will become even more acute. Such water crises lead to grave consequences, including hunger, rising poverty, worsening sanitation, the spread of water-borne diseases, infrastructure damage, loss of biodiversity and even political instability.
One may ask how is water shortage even possible given that 70% of the Earth’s surface is water-covered? Well, out of all this abundance only 0.7% is drinkable and accessible, while the vast majority is either saline water in the oceans or freshwater locked away in glaciers and the polar ice caps. Thus, turning seawater into freshwater seems to be an obvious solution. Indeed, desalination technologies are already commonly used in the world, with the Middle East being a leader so far. For example, Israel produces 55% of its drinking water from seawater.
By trying to resolve one development problem in such a manner, we risk aggravating others. Conventional desalination technologies require a tremendous amount of energy, which today is for the most part generated from fossil fuels. In practice, this means that many communities simply cannot afford such an energy-intensive method. Let alone the fact that we now need to start cutting down our carbon emissions to avoid the worst climate change impacts and to not produce even more trying to convert salt water into drinkable water.
Making Water Safe & Affordable
A small community in the town of San Juan, which is in La Union province in the Philippines, can teach us how to desalt seawater with zero harm to the environment. In the past, the community lacked any source of freshwater and relied on trucked-in water that was of questionable quality upon delivery. Moreover, it was expensive for the community members with a tariff of $6 per cubic meter. With no alternatives available, members of the community had to spend a major portion of their income on water and remained dependent on its external supply.
To improve the quality of potable water and become self-reliant in its supply, the community, with the support of a Dutch clean technology company Elemantal Water Makers, built a solar-powered seawater reverse osmosis (RO) plant. It took only two weeks to build the station. It now provides the community with 5,000 liters of freshwater a day with zero carbon emissions.
Apart from making the water supply local and reliable, the solution is also economical. Through using resources that are in abundance there, including ocean water and sunlight, the cost of water was reduced to $2 per cubic meter as opposed to $6 when water was trucked in.
“There are four major issues in the provision of potable drinking water in Southeast Asia: water cost, quality, access and environmental impact,” said John Jadczak, managing partner of NXTLVL Water, a Philippines water purification company. “And solutions like the one used in San Juan enables [communities] to invest locally into decentralized water production and helps to overcome each of these challenges.”
Water For All
The experience of the San Juan community may help many other communities around the world to cope with the problem of water scarcity. Elemental Water Makers came up with the desalination technology through the process of RO that is powered by solar, wind or other renewable energy sources.
“Today, not only governments and international organizations are concerned about water scarcity. From our experience, we see that stakeholders at many levels are seeking to make desalination greener and, most importantly, at a reduced cost,” said Sid Vollebregt, managing director of Elemental Water Makers. “We work with a wide range of clients both from private and public sectors. It can be, for example, resorts or private island owners who strive to lower their utility bills, or local municipalities and utility companies who want to make water better and more affordable for people in a community, as it was the case of the La Union’s village.”
The manufacturer uses different approaches to building desalination stations to ensure that it can work anywhere in the world. In the case of the San Juan community, the technology is powered by solar energy. The seawater is delivered with an intake pump and first travels through the pre-filtration system to capture larger particles. The pre-filtration system is tailored to site-specific conditions and can involve sand, cartridge or other types of filtration. Then, desalination takes place through an RO membrane. The produced freshwater is stored in high corrosion-resistant modular tanks.
The whole system fits in a kiosk the size of a shipping container and can be installed in just a few days. The solar panels are placed on top of the container facing the right angle for optimal performance. In addition, the company adds an energy recovery device to the system, powered by re-using the brine pressure remained after the RO process, which reduces energy consumption by 75%.
Even though the system can be quickly and easily constructed, the quality and reliability are not sacrificed in the process. All the components are built from corrosion resistant material that can withstand seawater to ensure their long lifetime. The RO membranes are automatically flushed with freshwater at every shut-down to avoid frequent replacement.
If the elevation is available on site, the RO solution can work without batteries by using the natural force of gravity. This solution uses solar, wind or wave energy to fill a salt water buffer tank on a hill. The water buffer provides the required pressure to drive the water directly to the RO membranes when the source of renewable energy is unavailable, such as at night or during heavy rain. Therefore, the system can work non-stop providing a constant supply of seawater.
“However, [the] technology is not limited only to these two situations,” Sid Vollebregt said. “If you already enjoy renewable energy or currently have an affordable energy solution in place, we can hook you up with an energy efficient desalination solution that’s easy to operate and maintain.”
The set-up of such a technology in a remote developing community may pose another challenge: how do you take care of it if people with needed skills and knowledge are often lacked? To solve this, the Elemental Water Makers makes its unit easy to maintain and operate through the remote control system and automation. The units are equipped with GSM-based that enables real-time monitoring of a water supply online from anywhere and anytime with text messaging if something goes wrong.
Furthermore, the off-grid solution may be particularly suitable for places at risk of emergency conditions. When hit by floods or tsunamis, communities often get cut off from electricity grids and aqueducts for days or even weeks. However, the off-grid solution powered by renewable energy sources can provide safe and low-cost drinking water in such situations.