• Float Venice to save it from rising seas, study says

    Manuel Silvestri / Reuters

    In this file photo, tourists take photos of each other in the flooded Saint Mark's square in Venice.

    By John Roach, Contributing Writer, NBC News

    To protect Venice from periodic floods that are increasingly heightened by the double whammy of rising seas levels and sinking land, a team of Italian researchers suggests lifting up the canal-laced city by pumping seawater into the aquifers below it.

    Doing so could result in a uniform uplift of about 30 centimeters over a 10-year period of steady, coordinated pumping via a series of 12 wells that circle the city, according to a study reported in the journal Water Resources Research.

    The idea isn't entirely new, but until now its applicability was clouded by a limited understanding of Venice's underlying soils.

    The researchers overcame this obstacle by combing through seismic data — obtained in the 1980s by an Italian oil and gas company — to create a 3-D reconstruction of the soils.

    "This allowed them to confirm the presence of a continuous layer of impermeable clay below which injected water could increase pore pressure," Scott K. Johnson reports for Ars Technica.

    Pore pressure corresponds to water between grains of sediment that can bear some of the load. Subsidence occurs when water is pumped out — as occurred in Venice in the mid-1900s — and the grains pack together, causing the land to sink.

    In theory, pumping water back into the soils could reverse this trend, but in reality a full recovery isn't possible, notes Ars Technica.

    However, the achievable uplift is sufficient to curb some of Venice's periodic flooding.

    Importantly, the coordinated injection of the seawater can prevent one side of the city rising up faster than another, which could crumble the infrastructure — buildings, roads, etc. — that the project aims to protect.

    While the cost of the undertaking has been estimated at more than $100 million, the raised up land would reduce operating costs for the MOSE flood gate project meant to stop the rising waters from entering the city at all.

    And given that tourism generates at least $2 billion a year in Venice, according to National Geographic, that seems like a small price to pay even for a country at the forefront of the European debt crisis.

    What's more, if this approach works in Venice, it might also find use in other parts of the world threatened by rising seas, including Shanghai, New York, New Orleans, Miami, Cairo, Amsterdam and Tokyo.

    More on Venice and rising seas:

    John Roach is a contributing writer for msnbc.com. To learn more about him, check out his website. For more of our Future of Technology series, watch the featured video below.

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  • Wanted: 'Smart Pot' to purify water instantly, cheaply

    University of South Florida

    A challenge has been issued to develop a pot that disinfects water for the millions of people in the world who lack access to clean and safe drinking water.

    By John Roach, Contributing Writer, NBC News

    Imagine a pot or jar that you could carry to any water source in the world, fill it up and be guaranteed a container full of clean and safe drinking water.

    Such a pot is the goal of a new a challenge issued Nov. 17 to inventors in developing nations by the University of South Florida's Patel School of Global Sustainability.

    Contaminated water causes more than half of the world's diseases such as cholera, typhoid and diarrhea, killing an estimated 1.5 million children a year, according to world health officials. 

    The "Smart Pot" challenge is for a technologically advanced, yet low-cost and easy-to-use water purification system that fits seamlessly with the pots and cans already used to collect water.

    The treatment of the water will happen automatically at the point of collection. Users, who already have difficulty retrieving the water, won't have to take any extra steps.

    Philanthropist Kiran Patel believes a prototype of the Smart Pot is feasible within a year.

    The challenge is open to applicants from academic and research institutions, consulting firms and NGOs registered and located within developing countries in Africa, Asia, and Latin America.

    Pre-proposal submissions are accepted through March 2012. Five short-listed applicants will get $8,000 to prepare full proposals. The winner will get an additional $100,000 to build a prototype.

    For more information, check out the Patel School of Global Sustainability.

    More stories on clean water technology:

    John Roach is a contributing writer for msnbc.com. To learn more about him, check out his website. For more of our Future of Technology series, watch the featured video below.

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  • How seawater can quench global thirst

    Yale University

    Freshwater is becoming an increasingly scarce resource on a planet with a surging population, emerging economies, and a changing climate. Improved desalination technologies are required to provide water for people and crops, experts say.

    By John Roach, Contributing Writer, NBC News

    New membrane technologies could more efficiently turn billions of gallons of seawater full of salt, decomposed fish, and other bits of unappetizing organic matter into thirst-quenching liquid for people and crops, according to experts in desalination technology.

    The problem is that these membrane technologies don't yet exist in the right form to efficiently turn seawater into freshwater, they said in a review article aimed at spurring lab-level research with molecular models.

    Desalination plants use membranes in a process called reverse osmosis. Seawater is forced through the membrane to filter out the salt in seawater to help make it drinkable and available for irrigation. The process requires a minimum amount of energy to do.

    "If you have a clean room, it gets messier and messier over time and in order to sort that you, you've got to expend energy to clean your room up. Separating salt water from seawater is kind of the same thing," William Phillip, a chemical engineer at the University of Notre Dame, told me on Monday.

    Membrane tech
    Advances in membrane technology, such as using novel materials such as carbon nanotubes to reduce the amount of energy required to push the water through it, are allowing researchers to approach this theoretical limit in energy expenditure.

    This means that desalination remains an energy-intensive process that is much less efficient than the technologies used to make freshwater available for drinking as well as the cost savings gained through water conservation, reuse and recycling, the researchers note.

    But separating salt water from seawater is only part of the equation in the desalination process. While membranes are close to the minimum limit of energy required, desalination plants spend up to twice as much energy in pre- and post-treatment processes.

    For example, plants need to filter out decomposing fish and seaweed as well as other forms of particulate and organic matter before it is passed through the membrane. Chemicals such as boron and chloride are filtered out after the membrane pass to make the water suitable for agriculture.

    "Finding ways to not use as much energy to pre-treat the water is somewhere we think that science and technology can help," said Phillip, who wrote the paper with Menachem Elimelech, while he was a post-doctoral student at Yale University.

    Their idea is to develop membranes that filter out all the other stuff as well as salt from the seawater, but do so in a way that the membranes don’t get gunked up with fish scales and seaweed and thus require constant cleaning.

    "If you can make a membrane that stuff didn't stick to, or didn’t adhere to the membrane surface as easily, then you could relax pretreatment demands and use less energy," Phillip explained.

    While this so-called anti-fouling technology doesn't yet exist for desalination, these surfaces have been created for other uses such as medical implants, noted Phillip. A membrane, however, has to let freshwater pass through while blocking all the other stuff, but not allowing it to stick.

    That's a tall order, but one that the researchers, writing in the Aug. 5 issue of Science, said they can begin to tackle with "detailed molecular models that establish structure-property relationships between membrane surface structure and chemistry."

    Appropriate use
    A breakthrough with an anti-fouling membrane fitted into commercial-scale desalination plants is at a minimum on the order of five to 10 years out, Phillip said, but developing the technology within that time frame could make improved desalination technology available for when and where it is needed.

    Freshwater is an increasingly scarce resource on a planet with a surging population, emerging industrial economies and a changing climate, the researchers note. In some parts of the world such as Israel, Singapore and Spain, desalination is the "only viable means to provide the water supply necessary," they write.

    This is true even though desalination requires three times more energy than conventional methods to treat river water, lakes, and groundwater for potable use, Elimelech noted in an email exchange with me.

    In addition, environmental concerns such as trapping juvenile fish during intake and discharging highly concentrated saltwater mixed with chemicals into the marine environment must also be considered, the authors note in their review paper.

    Elimelech added: "If you still want to have desalination as part of the water supply portfolio, we need to continue to improve the energy efficiency to make it a sustainable technology. At the present time, the bottom line — if you have other less energy/cost consuming options, use them first."

    More on desalination:

    John Roach is a contributing writer for msnbc.com.

  • Carbon nanotubes to clean water?

    Carbon  nanotubes, seen here in a scanning electron microscpe image, are being considered for use in filters to remove contaminants such as water soluble drugs from municipal water supplies.

    By John Roach, Contributing Writer, NBC News

    Scientists are eyeing carbon nanotubes to clean up municipal water supplies contaminated with water soluble drugs and other compounds that sneak past common charcoal filters.

    The teeny tiny tubes of carbon are a factor of 1,000 more effective at filtering out the aromatic molecules in water soluble drugs, Thilo Hofmann, who heads up the department of environmental geosciences at the University of Vienna, explained to me in an email on Friday.

    This trait makes carbon nanotubes ideal for inclusion in "filtration membranes for water treatment … the technique for all major league cities," he said.

    However, safety concerns about carbon nanotubes abound. One study, for example, found that longer threads of the stuff mimic the toxic qualities of asbestos. Another study found that common sized tubes can get into the lungs and increase the risk of developing cancer. 

    Such risks have prompted Hofmann and his colleagues to cautiously probe the potential of carbon nanotubes for water filtration. 

    A test on the interaction between the tubes and polycyclic aromatic hydrocarbons — a class of organic contaminants — reveal a "high potential" for use in treating municipal water supplies, Hofmann said.

    Key among the findings, the team notes, is that at concentrations likely to occur in the environment, the tubes removed 13 tested PAHs from contaminated water, allaying concerns that the pollutants would compete with each other and some would not attach to the tubes, rending the technology ineffective.

    The results were published this June in the journal Environmental Science and Technology.  

    While more research is needed, Hofmann said these results prompt him to keep pursuing the use of carbon nanotubes for water treatment in large cities. In rural areas, he noted, "there is not the same need to filter out pharmaceuticals."

    More on carbon nanotubes and water treatment:

    John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).

  • Green machine takes root in Jordan

    Sahara Forest Project / Screenergy

    A conceptual drawing of the Sahara Forest Project is shown here. The system uses sunlight and seawater to produce food, fuel, and drinking water. A pilot plant will be constructed near the Red Sea in Jordan.

    By John Roach, Contributing Writer, NBC News

    A green machine that promises to turn sun and seawater into food, fuel and drinking water will be tried out in the desert near the Red Sea in Jordan, project partners announced.

    The Sahara Forest Project has the potential to turn deserts into green oases that soak up carbon dioxide from the atmosphere and thus curb global climate change. It’s the sort of thing environmentalists who aren't afraid of geoengineering might describe as dreamy.

    How it works
    The machine integrates a 10-megawatt solar power plant with a high-tech greenhouse and desalination system to turn readily available sun and seawater into life essentials that are increasingly difficult to acquire affordably in the Middle East.

    Here's how it works: Saltwater pumped from the Red Sea is evaporated from grilles at the front of the greenhouse to create cool and humid conditions, which are good for growing food and algae. The algae can be used to produce more food or fuel.

    As the cool and humid air leaves the growing area, it passes over a second evaporator containing seawater heated by the sun, which warms the air so it can hold even more water. This hot and humid air then meets a series of vertical pipes that have been cooled by seawater, which causes the freshwater vapors to condense and trickle as freshwater droplets down the tubes for collection.

    This freshwater is then heated by a concentrated solar power plant, which creates steam to turn turbines that generate electricity. The electricity powers the pumps and fans used to bring saltwater in from the Red Sea and grow crops and algae in the greenhouse. Leftover freshwater will be used to re-green the area around the greenhouse, creating that carbon-soaking vegetative sponge.

    Funding and rollout
    Project partners signed a deal to build a demonstration machine on a 50-acre site in Aqaba with funding from the Norwegian government. The designers estimate the construction cost to be $110 million (80 million euros). In addition, the project has rights for expansion onto 500 acres.

    In-depth feasibility studies will be conducted throughout 2011. Construction of the pilot plant is slated for 2012, with commercial-scale development eyed for 2015.

    Partners in the Sahara Forest Project include London-based Max Fordham Consulting Engineers, Seawater Greenhouse, Exploration Architecture and the Oslo, Norway-based Bellona Foundation.

    “The Sahara Forest Project is a fiercely ambitious effort from Bellona, but ambitious is exactly what we must be,” Bellona Foundation President Frederic Hauge said in a statement. “A critical prerequisite for solving both the climate crisis and the world’s food problem is to enable developing countries to produce their own food, their own water, and their own clean energy, instead of importing oil from us.”

    More on green energy:

    John Roach is a contributing writer for msnbc.com. Connect with the Cosmic Log community by hitting the "like" button on the Cosmic Log Facebook page or following msnbc.com's science editor, Alan Boyle, on Twitter (@b0yle).