‘Green, affordable’ and Suited Exactly for the V.I.

By Stephen Cheslik

 

July 30, 2015

 

 

What started as an idea at a college in the Netherlands has finally become a reality an ocean away in the British Virgin Islands.

Elemental Water Makers, founded by Sid Vollebregt and Reinoud Feenstra, has just completed the world’s first commercial installation of a new type of desalination system on Great Camanoe – one of the smaller British Virgin Islands with only 50 to 60 homes on it and no easy access to fresh water.

Water in the Caribbean is expensive. Municipal water, like that made by the V.I. Water and Power Authority or the BVI Water and Sewerage Department, costs $20 to $25 for a thousand gallons, according to Vollebregt.

“Water trucking is 10 times more expensive,” he said.

So, when a homeowner on Great Camanoe went looking for a more affordable water solution for their home, their architect turned to Vollebregt and Feenstra, who had been in the British Virgin Islands pitching their idea.

The system installed on Great Camanoe is cutting the homeowners water bill by 63 percent a year, Vollebregt estimates.

If the homeowner had easy access to V.I. Water and Power Authority that savings would be closer to 20 percent to 25 percent, he said.

The company’s system combines two mature technologies, a variable renewable energy source, solar power, with a traditional reverse osmosis system to create fresh water, according to Vollebregt.

“The difficulty was to couple the two,” he said.

Reverse osmosis works by pushing water through a membrane with tiny openings in it that are so small that the individual molecules of water can get through, but salt ions and other contaminants cannot. Think of your screen door allowing the breeze into your home, but keeping the mosquitoes out.

Most reverse osmosis systems use electric pumps to create the pressure that pushes the water through the membranes, and solar power could provide that power.

However, there are several drawbacks to using solar power, said Vollebregt, who first started working on the problem as his final project in college.

The most obvious problem is of scale, Vollebregt said, pointing out that a system that runs continuously is much more efficient and can be much smaller than a system that only runs for a portion of the day when the sun is shining.

And, once the system shuts down at night, air starts to get into the system, allowing bacteria to grow and reduce the lifespan of the reverse osmosis membranes, Vollebregt said.

The first solution would be to use batteries to store the sun’s power, but according to Vollebregt, traditional batteries like those that power laptops or are in cars would add significant cost to each gallon of water made.

The solution created by Elemental Water Makers is to create a seawater-powered battery by pumping water into a tank at a high elevation and letting gravity supply the power needed to operate the system at night.

That might sound easy at first, but Vollebregt ran into a problem. The seawater tank would have to be located 1,600 feet above the membrane. Only five skyscrapers in the world hit that mark and, in the Virgin Islands, you would need a 44-foot extension ladder at the very top of Crown Mountain on St. Thomas to get that high.

Vollebregt and his team then discovered that “the elevation level required is greatly reduced by re-using the excess pressure in the salt water flow, making use of a mechanical form of energy recovery.”

Simply reusing this waste energy – energy left over after water is pushed through the membranes – allowed him to lower the seawater battery – a cistern or other tank – from 1,600 feet above the reverse osmosis equipment to only 290 feet.

And it turns out, the Virgin Islands is one of the best locations in the world for this approach to creating fresh water, said Vollebregt who searched the globe for places that had limited rainfall and high energy prices – creating a list of places that also included the Canary Islands and Cape Verde off the coast of Africa, Indonesia, located between Asia and Australia, and the Netherlands Antilles in the Caribbean.

The system is created mainly out of existing components.

“What we can buy locally, we do,” Vollebregt said. “And what we need we bring in from the rest of the world.”

Previous to the BVI installation, the partners had created a small-scale, 660-gallon-per-day demonstration system in Bali, Indonesia.

And while the system on Great Camanoe produces only 3,300 gallons of water a day for a single homeowner, much bigger systems are possible, Vollebregt said.

Elemental Water Makers is working on its first municipal project in Cape Verde, a former Portuguese colony.

“We hope to be back soon,” Vollebregt said. “Especially with the drought it is clear people want an independent and reliable supply – especially if it is green and affordable.”

 

 

Re-posted from: http://virginislandsdailynews.com/news/green-affordable-and-suited-exactly-for-the-v-i-1.1920132

 

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