No Batteries Needed: Can Low-Cost Solar Desalination System “Green” Namibia’s Desert Coast?

Water quality and scarcity is a growing issue the world over, including in Namibia, which has been struggling to cope with a prolonged drought and the effects of a changing climate. New, low-cost solar-powered desalination technology from Finland’s Solar Water Solutions holds out prospects of a “greener” future.

Conventional, as well as other solar-powered, desalination technology is energy-intensive and costly, making it economically unfeasible for anything but large-scale installations. Solar Water Solutions’ desalination technology changes the equation by reducing the life-cycle costs of solar-powered desalination by more than 70%. Furthermore, the containerized system is decentralized, modular and scalable, according to CEO Antti PohjolaSolar Magazine Interviewee Avatar.

Solar Desalination System to “Green” Drought-Stricken Namibia

Sam Nujoma, Namibia’s former and founding president, officially commissioned the first of Solar Water Solutions’ 100% solar-powered desalination systems along the beach line adjacent to the University of Namibia’s Henties Bay campus. A joint development initiative on the part of the University of Namibia and Finland’s University of Turku, which funded the project at an undisclosed, but estimated, approximate cost of around 3.2 Namibian dollars (~USD212,000), the plant is able to produce 3,000 liters of potable freshwater per hour with zero in the way of operational or energy costs and without the need for batteries. In addition to salt, the system removes bacteria, chemicals, viruses and other impurities and not only from seawater, but practically any source of water.

Solar desalination, no batteries needed

Enough to meet the daily water needs of some 1,000 in one hour, the clean freshwater produced by Solar Water Solutions’ desalination plant will be used primarily for irrigation, but also for drinking purposes, Pohjola said. “The impact we hope to receive through this plant is to contribute to food security and increase energy supply while simultaneously combating and mitigating the effects of climate change. We can make Namibia green,” UNAM Vice-Chancellor Professor Kenneth Matengu was quoted as saying in a press release.

Commissioning Ceremony of the UNAM Solar Desalination Plant

Solar Water Solutions’ technology is based on the same process of reverse-osmosis used in water desalination plants the world over. Reverse-osmosis is energy-intensive and costly, however. Other solar-powered, reverse-osmosis desalination systems require batteries, diesel-fueled, or some other form of, power generation or energy storage system, Pohjola pointed out in an interview.

In contrast, Solar Water Solutions’ technology “enables direct use of solar power obtained from photovoltaic (PV) panels, with no need for expensive and harmful batteries or diesel, in desalinating sea or saline borehole water, while the water feeds into the reverse osmosis system can be fluctuating according to the obtained solar irradiance. Other solar-powered desalination, reverse-osmosis systems require batteries to operate as decentralized systems,” Pohjola told Solar Magazine.

Eliminating the need for batteries, diesel or other types of power generation or storage technology is the key to the dramatic reduction in cost Solar Water Solutions has been able to achieve. Pohjola highlighted the key components and characteristics of the UNAM solar desalination system:

  • A 3,500-liter per hour clean drinking water production capacity system making use of ocean water requires 80 PV panels (250–290 Watts-peak each) and a 15-kilowatt (kW) motor
  • Clean quality water can be produced locally from any water source—seawater, saline and contaminated borehole, rivers or processed wastewater
  • Operates 100% with free solar energy with zero energy costs
  • Complete independence from external water supply
  • The fully automatic, standalone system can be expanded on a modular basis and complemented by water storage anytime
  • Lowest life-cycle costs vs. any other system as no batteries needed
  • All-in, total cost of ownership around USD200,000 with all infrastructure included.

Solar Water Solutions worked with various university research groups over the course of the last five years to develop its technology, Pohjola explained. The company worked closely with researchers at Aalto University’s Energy Technology Group in Finland during the product development stage. It began working with the University of Turku and UNAM to develop the solar desalination project at the Henties campus last year.

Drought and water scarcity in Namibia

Groundwater is the source for about 80 percent of Namibia’s freshwater resources. Those resources are being depleted as a result of prolonged drought and climate change, along with population growth, development and increased demand.

The chief executive officer of Windhoek, Namibia’s capital city, recently declared a water crisis and announced stricter water conservation measures will go into effect July 1. Looking out over the next four years, Namibia may find itself in an “absolute water scarcity dilemma” due to a reduction of run-off and groundwater, according to Namibia’s Minister of Environment and Tourism.

Then Namibia’s Minister of Environment and Tourism, Pohamba Shifeta way back in 2015 highlighted studies that concluded water availability across the country will diminish as a result of climate change.

Decreases in freshwater runoff and a drop in underground water tables are expected by 2020, they projected at the time.

There is a great need for the exploration of sustainable alternative sources of potable water for both human consumption and economic activities, in order to address this acute water problem in Namibia.

—Shifeta reportedly said at the time.

The Namib-Skeleton Coast National Park, spans the entire length of the country, stretching 1,569 kilometers (975 miles) north-south. Seawater desalination holds out the promise of addressing Namibia’s water scarcity problem, as well as spurring a “greening” of its arid-desert coastal areas.

Desalination technology advances, costs decline as adoption increases

Fortunately, water desalination technology has matured and production and operating costs have been dropping, Almar Water Solutions’ CEO Carlos Cosin highlights in a recent blog post. Cosin analyzed the decrease in costs worldwide based on developing plants via the BOOT (Build, Own, Operate and Transfer), the business model that has come to predominate in the market, representing 50% of the contracts for desalination plants.

A wide variety of variables come into play when determining the projected costs of building and operating a desalination plant. Ready access to cheap energy, the largest element of project costs, is at the top of developers’ assessment agendas. Declines in cost have been evident for fifty-plus years now, driving investment growth and capacity deployment, Cosin highlights.

Elaboration of the Interior Structure and Composition of UNAM Solar Desalination System

“Since the 1960s, the cost of Multistage Flash Distillation (MSF) to desalinate water has dropped by around 90%, from approximate unit costs of USD10 per cubic meter (m3) to less than USD1/m3 in 2010,” Cosin wrote. As of 2017, the cost of MSF had decreased an additional 20% as compared to 2010 in some regions due to capacity development and lower energy prices, he noted.

At present, the average price range of desalinated water globally ranges between USD0.5/m3 and USD1.5/m3. “The lower end of this range includes the regions with lower electricity costs (for example, the Middle East) and at the high end, we found the regions with higher electricity costs (for example, Australia, where electricity is sometimes required to be generated using renewable energies),” Cosin elaborated.

Greening Namibia’s arid-desert coastal zone

Solar Magazine: Solar Industry News and Insights

The UNAM solar desalination plant is part of a broader-based research initiative investigating ways to address Namibia’s need for sustainable water, energy and development. Researchers are exploring the potential of coastal agriculture and plants and crops for effective carbon binding. Israel has long been an innovator and leader in the development of agricultural water conservation and desert agriculture methods and technology. More recently, research and project development coming under the banner of the nascent, growing field of “agrovoltaics” has been on the rise.

Namibia has a policy and institutional framework that guides and informs the management of its water resources. At its core is an “Integrated Water Resources Management Plan which aims to enable the country to achieve a sustainable water resource management regime contributing to social equity, economic efficiency and environmental sustainability.

Working with the Climate Technology Centre Network (CTCN), a branch of the UN’s Sustainable Development Goals Partnership Program and South Africa-based CTCN consortium partner, the Council for Scientific and Industrial Research, Namibia developed a two-year (2015–2017) joint research and development project that prioritized, supported and strengthened the funding of technologies to address water scarcity in Namibia and find long-term, sustainable and comprehensive solution to water shortages.

Decentralized solar-powered desalination systems such as Solar Water Solutions’ hold out the prospect of resolving water scarcity issues in off-grid islands and communities worldwide, Pohjola asserted. He pointed out that by deploying these systems carefully drinking and irrigation water could be produced locally in places where there is no community water infrastructure.

Nujoma urged the Namibian government to prioritize and fast-track implementation of a large-scale desalination system in advance of the Solar Water Solutions system’s commissioning ceremony. “Ironically, Namibia is blessed with 1,500 kilometers of the Atlantic Ocean that provides us with unlimited water resource. Hence, the time is now to abstract seawater and desalinate seawater for human consumption,” he was quoted in a news report. Nujoma went on to encourage the Namibian government to “embrace the concept of desert agriculture and use desalinated water to convert the desert into a large-scale green scheme for crop production and animal husbandry.” comment↓

* Photos from Solar Water Solutions


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