Drinkable water is essential to life; yet in some places, is dangerously scarce. As climate change advances, the problem is only expected to grow worse. Converting ocean water to fresh water through desalination could provide abundant drinking water. The reverse osmosis process used to remove the salt from ocean water, however, consumes enormous amounts of energy. This can be both financially and environmentally costly, since fossil fuels are often used. Wave energy can fuel reverse osmosis in a way that's both clean and affordable.
Around the world, more than 20,000 desalination plants provide water for more than 300 million people every day. Some of this is in inland desert areas but much of it is along coastlines and on islands. Desalination also has been explored as a source for drinking water in disaster areas where floods or other disasters render the area's water system unusable.
How reverse osmosis desalination works
In osmosis, a solvent of lower concentration moves through a membrane into a solvent of higher concentration until the concentration of both is about equal. So fresh water would move into salt water until they were both equally salty.
In reverse osmosis, it goes the other way. Salt water is forced into fresh water. The sea water must be pumped into the system and forced through many filters to remove progressively smaller particles until it gets to the membrane that keeps the salt on one side while the fresh water travels through to the other. That explains the need for so much energy to arrive at newly desalinated water.
Why wave energy is ideal for desalination
Seabased wave energy power technology is an ideal power source for a desalination plant. Wave energy is an abundant, reliable, predictable source of power and it's already in the ocean. A wave energy park could be built as a dedicated source for a desalination plant. Desalination can also be fueled by a wave power park that provides grid-ready electricity in which the desalination plant is operated as a side benefit, an offtake.
When a wave power park is connected to a grid system, the grid typically only uses some of the energy converted from the waves, getting some of its power from other sources. The wave power that is not used to create a baseload of renewable power for the grid could easily be channeled into fueling a reverse osmosis desalination plant. And since it comes from CO2-free, renewable, reliable wave power, the electricity produced would be gentle on the environment. In fact, Seabased wave energy power parks can become artificial reefs.
Water covers 70% of the Earth's surface and 80% of the world's largest cities are on the coasts. So wave energy could fuel desalination plants in many coastal population centers and islands. Seabased's wave power plants are designed to work in moderate wave climates, so huge waves are not required. In many markets, the price of fueling desalination with wave could be significantly lower than fossil fuels.
Desalinating sea water in a way that's both affordable and environmentally sound, in conjunction with conservation, is going to be essential to ensuring that drinkable water is available. Wave energy is one great way to make that happen.
