Humans have been searching for ways to desalinate seawater to provide drinking water for centuries. Especially in arid areas of the world, governments and private companies have explored many technologies to convert saltwater into fresh water, using the abundant ocean to provide safe drinking water to areas facing acute freshwater shortages. However, this has been prohibitively expensive and impractical in the past. But now a Norwegian firm thinks it has created a new way to turn water using the power of waves.
The main reason companies shy away from desalination operations is high energy costs. It requires about ten times more energy than any other water source and also produces significant amounts of carbon emissions. Therefore, large-scale desalination projects require their own power plants to operate.
Desalination operations traditionally relied on boiling seawater to get rid of the salt. However, in recent decades more countries have been using reverse osmosis techniques, relying on high pressure to force salt water through a membrane and trap it. This process requires less energy, although it is still far from low energy, with only 4 kWh needed to produce one cubic meter of drinking water. In addition to high energy usage, desalination operations have significant installation costs that require expensive infrastructure and maintenance to run. For this reason, water conservation and reuse is more popular in areas where other water sources are available.
However, desalination has long been a popular technique in the Middle East, much of which is very arid and has difficult access to fresh water. Saudi Arabia introduced two special distillation condensers in the city of Jeddah in the early 1900s as the demand for potable water increased. Later, an independent government agency, the Saline Water Conversion Corporation (SWCC), was established in 1974 to oversee desalination projects. And in the UAE, desalination operations provide about 42 percent of the country’s drinking water needs.
Currently, many desalination operations run on fossil fuels, which means they generate high levels of greenhouse gas emissions. As populations grow and desalination plants are built in the Middle East, there are concerns about their impact on climate change. However, plants can be powered by renewable energy sources such as solar energy, making them cleaner. But everything is not so simple. Laurent Lambert, Associate Professor of Water-Energy-Climate Public Policy at the Doha Institute for Graduate Studies, explains, “The first fundamental problem with plants is that most desalination infrastructure is not solar-ready. Second, solar panels need to be cleaned often, so you need water. Cleaning these panels will increase the existing water tension.
Now a Norwegian firm thinks it has the right way to ensure greener desalination operations. Ocean Oasis has built a wave-powered prototype device that it hopes will provide a blueprint for floating desalination operations. The ten-meter-high, seven-meter-diameter plant was installed in Las Palmas, Canary Islands, to test its productivity. Ocean Oasis believes its technology will enable “the production of fresh water from ocean waters by using wave energy to desalinize and pump drinking water to coastal users.”
Innovation Norway, Grieg Maritime Group, Gran Canaria Economic Promotion Society and other organizations provided financing for the project. The firm hopes the project will provide a more affordable way to desalinate the area, which has abundant saltwater resources. Low rainfall, high soil permeability, and overexploitation of aquifers means the region is facing water scarcity, seeking alternative ways to supply fresh water. The new technique will reduce dependence on fossil fuels to power desalination operations.
After the test, Ocean Oasis plans to build a second, expanded structure with the required capacity to produce water for consumption. Since wave and tidal energy projects are relatively few compared to other renewable energy sources, there are high hopes for the project’s use of wave power. Governments are beginning to increase funding for research and development of ocean energy projects, but this remains largely untapped.
The Canary Islands are not the only area looking to develop innovative desalination techniques, the US Department of Energy (DoE) has launched a competition with a $3.3 million prize for the most innovative wave-powered desalination proposals. In the Waves to Water Award, participants were asked to design, build and test devices that use wave energy to produce drinking water from salt water. Oneka Technologies has been awarded a $500,000 grand prize for its Oneka Snowflake device after a successful trial in North Carolina.
After years of trying to develop cost-effective desalination operations, the best large-scale projects we have to date remain extremely low-carbon. With the support of state governments, new innovative projects are now being seen that have the potential to convert brackish water into clean drinking water without damaging the environment. However, these projects remain at an early stage and will require significantly more funding to be implemented on a large scale.
By Felicity Bradstock for Oilprice.com
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