at Save the Water | October 10, 2023

Solar energy is being explored as a promising way of creating a sustainable freshwater supply. In theory, using solar energy in this way is cheap and effective. However, advances in this technology have been set back by performance degradation that results from salt build-up. For a long time, the dream of being able to use solar energy to produce freshwater seemed out of reach.

Climate change has caused the drying of many important freshwater sources. Thus, scientists have prioritized the search for a sustainable and effective way of creating drinking water. People may be facing a large-scale drought soon unless new solutions are found. This urgency has resulted in cross-collaboration between engineers, energy scientists, environmental researchers, and policymakers.

Using New Solar Energy Technology  

A recent article shows that the logistical problems that researchers were facing with performance decay could be reduced by using “a confined saline layer as an evaporator.” The evaporator layer works by using sunlight heat to evaporate water. Then, the vaporized water gets funneled to another section of the device. This leaves the salt behind, allowing it to be separated from the seawater and create drinking water.

This device has been shown to be highly effective. It’s said to have a high water production rate than other solar water desalination techniques that are being studied. Additionally, it has a higher salt rejection rate than those techniques.The researchers have predicted that if this device was scaled up to the size of a small suitcase, it would be able to produce four to six liters of drinking water every hour. Furthermore, it would last years before needing any replacement parts. This means that it can be sent to other countries that are at a higher risk of drought at a low cost.

This technology is promising because it can also be used in households. For example, a scaled-up device would be able to produce enough drinking water to meet the daily needs of a small family. Moreover, scientists have suggested that the technology would be very helpful for off-grid coastal communities. It would provide a way for them to access much-needed drinking water.

Why is Solar Energy Technology Important?

Water scarcity is a real threat to many communities around the world. Many regions are already struggling with the worst consequences of not having enough water to conduct their day-to-day activities:

• Economic decline due to the inability to produce crops
• Increased disease due to lack of sanitary water
• Higher rates of anxiety, stress, or depression related to water insecurity 
• Extreme food insecurity and famine
• Increased chemical contamination of water supply

Researchers predict that we’re on the verge of an imminent water crisis. The United Nations and other organizations expect that demand will outstrip supply for freshwater by 40% at the end of the decade. Due to the seriousness and urgency of the situation, many nations have prioritized this crisis. 

What Comes Next for Solar Energy ?

“For the first time, it is possible for water, produced by sunlight, to be even cheaper than tap water,” co-author Lenan Zhang, a mechanical engineer at MIT’s Device Research Laboratory, said in a statement. If the device works as predicted, it will mean that we’re one step closer to ensuring that people around the world won’t run out of freshwater supply. Although one caveat is that the device is still small for now, researchers have plans of upscaling it and making it more efficient in water production.

This device may open up doors for other innovations that will benefit humanity in the long run. It’s essential for governments globally to invest in ensuring water security for all their citizens. This push can’t be done by one nation or organization alone. Collaboration is the only way forward. The device that was developed at the Massachusetts Institute of Technology was composed of an international team, showing that diverse ideas can guide our pathway towards water security.

By Harry Petaway, Staff Writer and Researcher for Save the Water | May 31, 2020

Clean water is essential during a pandemic

Time will tell the real impact of COVID-19. However, this crisis and the fundamental strategy to fight the virus bring both disparities and concerns about access to clean water for both drinking and sanitation. Clean water is essential during a pandemic. Many of us volunteer for organizations like Save the Water because we recognize the importance of clean, safe water. I joined the organization after my experience living 20 minutes away from the water crisis in Flint, Michigan, which captured national headlines in the United States.

Access to water before the pandemic

Flint, Michigan, was a classic tale of the disparities that exist across communities for access to clean water. Thousands of residents were exposed to excessive levels of lead due to the failure of governing bodies to treat the water and supply access to city residents correctly. Subsequently, water was not safe to drink. Unfortunately, this phenomenon of contaminated drinking water continues throughout the United States and extends beyond lead, with emerging pollutants and chemicals such as PFAS and other toxins. Furthermore, residents in communities across the country must use bottled water and hand sanitizer instead of dirty and contaminated water sources. Water in other cities like Detroit, Michigan, has been shut off for many residents that could not afford to pay their bills. Globally, water scarcity is a threat for over 40% of the world’s population.

Water crisis during the pandemic

Today, humans worldwide have attacked the COVID-19 curve through behaviors like “shelter in place.” The World Health Organization (WHO) emphasizes that safe water and sanitation practices like hand washing is crucial during the pandemic. To that end, there are countless campaigns to increase the time and frequency of hand washing. This brings the frustration and debate about clean water and access to water back to the surface, creating difficult decisions by community leaders on how to approach the problem. The fear of these unfamiliar circumstances  drove many consumers to deplete bottled water supplies from local stores. This was especially impactful in lower-income communities that already had limited access to stores that supply both food and water.

Similarly, hand sanitizer is also in short supply. Residents in cities like Flint had the difficult decision of whether or not to use the tap water in their homes. It also creates a difficult decision for community leaders to determine when water sources that were deemed unsafe should be turned back on.

Furthermore, communities have had to make difficult decisions on how to restore water services for residents whose water was shut off because they could not pay their bills. For example, more than 23,000 homes lost water service in Detroit in 2019, leading thousands of residents to apply for Detroit’s Coronavirus Water Restart Plan. Other communities across the United States offered similar programs in March for more than 57 million residents across 90 cities and states. However, there is no national database that tracks US households that do not have water.

Poor communities in the US struggled with access to available water for people that could not pay their bills. Other countries like Ethiopia and India have broader challenges with water shortages, which also existed before the pandemic.

What can we do?

Clean water is essential during a pandemic. Countries like Ethiopia have taken innovative steps like solar-powered wells to bring water to their residents. They have also employed sophisticated monitoring technology such as drones to track and store data to determine how water resources are allocated. Local organizations in the United States have stepped in to try and mediate the water crisis. Some have taken measures to pay for water services for residents that could not pay their bills. Others created bottled water distribution supply chains for older and ill residents receiving donations from charitable organizations before social distancing measures took effect. We should continue to support organizations that keep essential topics like water quality and water scarcity in front of mind. This is especially true as they become exacerbated amid public health crises such as severe weather events and disease outbreaks.

References

Lakhani, Nina. March 2020. “90 US cities and states suspend water shutoffs to tackle coronavirus pandemic.” The Guardian. Retrieved from https://www.theguardian.com/world/2020/mar/16/90-us-cities-and-states-suspend-water-shutoffs-to-tackle-coronavirus-pandemic

Nicol, Alan. May 2020. “The Pandemic is Laying Bare a Global Water Crisis.” Foreign Policy. Retrieved from https://foreignpolicy.com/2020/05/12/coronavirus-pandemic-global-water-crisis/.

Nguyen, Erika and Somayajula, Namratha. March 2020. “Access to Water Vital in COVID-19 Response”. Human Rights Watch. Retrieved from https://www.hrw.org/news/2020/03/22/access-water-vital-covid-19-response-0

Sunderland, Elsie M; Hu, Xindi C; Dassuncao, Clifton; Tokranov, Andrea K; Wagner, Charlotte C; Allen, Joseph G; . 2018. “A review of the pathways of human exposure to poly-and perfluoroalkyl substances (PFASs) and present understanding of health effects.” Journal of exposure science & environmental epidemiology. Retrieved from https://www.nature.com/articles/s41370-018-0094-1

Shah, Khushbu. April 2020. “The pandemic has exposed America’s clean water crisis.” Vox. Retrieved from https://www.vox.com/identities/2020/4/17/21223565/coronavirus-clean-water-crisis-america

The Need for an Alternative

As the global population and demands on urban water systems increase, renewable, environmentally-conscious infrastructure in the agricultural sphere become more important. Urban water systems are often inefficient in terms of the environmental health of agricultural communities. This is especially true in highly-populated, primarily agricultural areas, such as parts of China, India, and Africa. In these communities, conventionally, groundwater is extracted through the use of electric water pumps, powered by diesel. However, these systems not only require costly, regular servicing and fuel, they emit large quantities carbon dioxide pollution into the atmosphere.1

Solar Photovoltaic Water Pumping Systems

An alternative to these diesel-powered water pumping systems, notably, is a solar-powered, photovoltaic water pumping system. Solar photovoltaic cells, commonly known as solar cells, power these systems. Rather than diesel, these solar cells are the backbone of standard solar panels. These cells directly convert solar radiation into electric current through a process known as the photovoltaic effect, closely related to the photoelectric effect. The cells vary in their size and specifications but are commonly composed of crystalline silicon semiconductor materials.2 A primary draw to solar photovoltaic water pumping systems is that they can be adapted to individual locations and needs. However, the initial price of implementing the solar cell limits their use.

How do they Work?

Through the photovoltaic effect, photons of light absorbed by a semiconductor can transfer their energy to electrons, allowing the electrons to flow through the material as electrical current.3 From this point, a solar-powered water pumping system functions very similarly to a standard diesel-powered system. Electrical motors drive water pumps. These motors convert electrical energy into mechanical energy. In the case of solar pumping, photovoltaic cells produce the electrical energy. Most motors typically run on either direct current or alternating current. For direct current, the electrical flow does not switch direction periodically in the wires. By contrast, for alternating current, the electrical flow switches direction periodically. Direct current is the more common and efficient option in systems with low water demand.2

Notable Benefits

Photovoltaic water pumping systems hold various benefits over standard diesel-powered systems. Primarily, the renewable nature of solar energy as a power source would largely trump the nonrenewable nature of diesel. The renewable power source would also assuage the environmental detriments that may come with using diesel as a power source. Communities that must make environmentally conscious decisions would value the renewable power source. These communities are often those in which solar photovoltaic water pumping systems would be implemented.

Furthermore, using solar panels as a source of energy, after the initially higher cost, may prove cheaper than constantly requiring diesel as a power source. This cost may also depend on the solar panels’ access to sunlight, including geographic location, and the economic foundation of the surrounding society. Also, the cost of solar technology has dropped a lot in recent years. Prices for the solar panels used in these systems have dropped up to 80 percent. These panels last around 25 years, requiring little maintenance throughout this time.5

Possible Limitations

However, a variety of factors may limit solar photovoltaic water pumping systems. For one, solar power naturally fluctuates more intensely and more often than diesel or other common nonrenewable energy sources. While many solar cells include mechanisms to store excess solar energy received as daylight for darker periods of time, this may make solar-powered water pumping systems more unreliable. Furthermore, this reliance on a relatively-constant source of solar energy may limit the implementation of solar-powered systems to geographically applicable locations. Additionally, if the public power grid is reliable and in proximity to the site (generally less than a quarter mile), then solar power may be a suboptimal choice.

Additionally, the initial cost of implementing a solar-powered water pumping system can be significantly more than the expense of connecting to the local power grid.4 However, the economic benefits of solar power as an energy source will likely overcome that deficit in later periods. Furthermore, security is an important aspect of a solar-powered system, as the accompanying technology may be at risk of theft. Protective provisions are often suggested, for this reason, such as the placement of a small fence around the array with enough set-back that it does not cast a shadow on said array.4

References

1. World Bank. May 30, 2017. “Solar Water Pumping for Sustainable Water Supply.” http://www.worldbank.org/en/topic/water/brief/solar-pumping
2. Kristoffer Welsien. 2018. Solar pumping : the basics (English). The World Bank Group. http://documents.worldbank.org/curated/en/880931517231654485/Solar-pumping-the-basics
3. Solar Energy Technologies Office. August 16, 2013. “Solar Photovoltaic Cell Basics.” Office of Energy Efficiency & Renewable Energy. https://www.energy.gov/eere/solar/articles/solar-photovoltaic-cell-basics
4. R. Van Peltm, et al. August 2012. “Solar-powered Groundwater Pumping Systems – 6.705.” Colorado State University. http://extension.colostate.edu/topic-areas/natural-resources/solar-powered-groundwater-pumping-systems-6-705/
5. Solar Energy Industries Association. “Photovoltaic (Solar Electrict).” https://www.seia.org/initiatives/photovoltaic-solar-electric