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According to the World Bank, approximately 840 million people currently live without electricity worldwide. This figure motivated Colombian renewable energy start-up E-Dina to develop a cordless light, called WaterLight, that converts salt water into electricity.

The portable device only needs to be filled with half a liter of seawater– or urine in emergencies – to emit 45 days of light. WaterLight was designed to be used as a more reliable alternative to solar lamps in off-grid communities.

OK, so it might not be as simple as that, otherwise, saltwater lakes would be glowing all day every day! However, simple chemistry could provide safe and valuable light sources for those who need it most. This particular use of salt water is not new and is an example of electrochemistry. 

Electrochemistry has been around for years, generating electricity from chemical reactions.

The saltwater lamp is an example of an electrochemical cell. An electrochemical cell is a battery or device that can generate electrical energy from chemical reactions. This can also happen the other way around, by introducing electrical energy to start a chemical reaction, this is how rechargeable batteries are recharged.  

Electrolytes are liquids that conduct electricity, in this case, the salt water found in the lamp. The electrolyte closes the circuit in the cell (or battery).

An electrode is a piece of material that conducts electricity when it touches a non-metallic part of a circuit, i.e. the saltwater in the lamp. Electrodes are often metal rods, such as zinc and copper.

Two electrodes are found in the saltwater lamp, one acting as an anode, and one as a cathode, like you, would find in a regular battery.

Once the salt water is added, the circuit is closed and the battery (or cell) can power the lamp to produce light.

Inventions such as the lamp below, which use basic scientific principles, will be invaluable in areas where there is not a lot of electricity available. Having light at night means that people can work later in the evening to boost their income and children can do more homework which can greatly improve their prospects as they grow up. 

The saltwater lamp was created by a Colombian renewable energy start-up "E-Dina" and "WPP’s Wunderman Thompson" Colombia division, it can use the energy generated to charge a smartphone, and in an emergency can run on urine instead of water. 

"Once filled with salt water (water holding capacity 500 ml), the energy delivery is immediate while solar lanterns need to transform solar energy to alternative energy to charge batteries and they only work if there is the sun." WaterLight works 24 hours a day through ionization, which sees electrolytes in the saline liquid react with magnesium and copper plates on the interior of the lamp to produce electricity. Although this is a long-established process, E-Dina has developed a way to sustain the chemical reaction over a prolonged period of time so that it can be used to power a light source. Throughout its life, one light can provide around 5,600 hours of energy, which equates to two to three years of use depending on how often it is needed. The light has a cylindrical case made of Urapán wood with a circuit integrated into its base and a perforated cap on top that allows water to flow into the device while the hydrogen gas created during the ionization process can escape. After the salt particles have evaporated, the lamp can be emptied and refilled while the used water can be repurposed for washing or cleaning

There is also a safety benefit to using these lamps compared to standard kerosene or paraffin lamps. Standard lamps release fumes into the air when burning and if used indoors can be as harmful as smoking two packets of cigarettes a day. The fuel is also harmful to people and the environment if spilled and the lamps can easily start fires if dropped or knocked over. 

The saltwater lamp does have some drawbacks, the chemical reaction that produces the electricity erodes the anode which means it will need to be replaced after a certain number of hours. And you do need a supply of seawater or salt and water, although these are usually easy to find in most places. 

But used together with rechargeable solar-powered lamps, wind-up lamps, and other new technologies (bioluminescence) it can provide a much safer and easy-to-use lighting solution for communities in developing countries. 

Wundermann Thompson explains that inspiration came from the traditional practices of the Wayuu, an indigenous community in the La Guajira peninsula on the Colombia-Venezuela border. The desert landscape is surrounded by the sea and has limited access to electricity. It’s hoped that the WaterLight will help the community use the seawater to sustainable power their lives without needing to travel to find power. One intended use is to help with night fishing. The device is waterproof and made from recyclable material and has an expected lifetime of around 5,600 hours which equates to two or three years of use, according to Wunderman Thompson. Wunderman Thompson global chief creative officer Bas Korsten says: 

“WaterLight demonstrates how the holy trinity of technology, creativity, and humanity can produce a genuinely groundbreaking idea – one which holds the potential to transform life for millions of people.”

WaterLight is poised for a worldwide roll-out, according to the company, adding that many nations such as Sierra Leone and Syria are in similar positions to La Guajira. The product is available for purchase by NGOs, governments, and private organizations.

Union Minister Jitendra Singh has launched India's first saline water lantern named ‘Roshni’, which uses seawater to power LED lamps. He unveiled the lantern during a visit to Sagar Anveshika, a Coastal Research Vessel, operated and used by the National Institute of Ocean Technology (NIOT), Chennai for coastal research, according to the Ministry of Earth Science.

The minister said that saline water lanterns will boost Prime Minister Narendra Modi's Ujala scheme launched in 2015 for the distribution of LED bulbs across the country.

“Roshni lamps along with Power Ministry's schemes like solar study lamps will be driving a vibrant renewable energy program aimed at achieving energy security, energy access, and reducing the carbon footprints of the national economy," he said.

He further pointed out that this technology can also be used in hinterlands, where seawater is not available, as any saline water or normal water mixed with the common salt can be used to power the lantern, which is not only cost-effective but very easy to operate.

Singh appreciated the NIOT team for inventing the Roshini lamp and advised them to transfer the technology to the industries for mass production of this multipurpose lamp which can be of immense help in rural and remote areas and in times of disasters.

Afterward, the Union Minister along with the Secretary of the Ministry of Earth Science, Dr. M. Ravichandran extended the Har Ghar Tiranga campaign and visited the laboratories to hoist the tricolor on board the ship.

Singh also reviewed the progress of NIOT-developed Low-Temperature Thermal Desalination (LTTD) technology for conversion of seawater to potable water, which has been successfully demonstrated in Lakshadweep islands and informed that three desalination plants based on the LTTD technology have been developed and demonstrated at Kavaratti, Agati and Minicoy Islands of Union Territory of Lakshadweep.

Apart from launching Roshni, Union Minister Dr. Jitendra Singh also reviewed the progress of NIOT-developed Low-Temperature Thermal Desalination (LTTD) technology for the conversion of seawater to potable water, which has been successfully demonstrated in Lakshadweep islands.

He informed that three desalination plants based on the LTTD technology have been developed and demonstrated at Kavaratti, Agati, and Minicoy Islands of the Union Territory of Lakshadweep. The capacity of each of these LTTD plants is 1 Lakh liter of potable water per day.

Importantly, based on the success of these plants, the Ministry of Home Affairs (MHA) through Union Territory (UT) Lakshadweep has entrusted the work of establishing 6 more LTTD plants at Amini, Androth, Chetlet, Kadmat, Kalpeni, and Kiltan with a capacity of 1.5 lakhs liters/day. The total cost of these LTTD plants in Lakshadweep islands is around Rs. 187.75 crores.

Further, the LTTD technology is found suitable for Lakshadweep islands where the required temperature difference of about 15⁰ C between sea surface water and deep-sea water is found in the vicinity of Lakshadweep coasts only as of now.

Notably, the cost of desalination plants depends on a number of factors inter alia which include the technology used and the location of the plant.

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