Low Cost Fresh Water From Icebergs?

Even though plans to extract from one dates back to the 1950s, can Antarctic icebergs ever be a viable source of low cost fresh water? 

By: Ringo Bones 

Young Turks these days may have only heard of the scheme from a 2012 Dassault Systèmes advert often aired on the BBC but believe it or not, the idea of obtaining low cost fresh water from icebergs dates as far back as the 1950s. After complex logistical issues are taken into account do icebergs – as in Antarctic icebergs – really provide low cost drinking water for our increasingly thirsty civilization? 

During the 1950s, the US state of California’s number one community problem – and still probably is today – is where to get a low cost supply of fresh water fit for both domestic and industrial use. Back then, an oceanographer from the Scripps Institution of Oceanography named John Isaacs has suggested that icebergs be fetched up from the Antarctic to ease the state of California’s local water shortage. Even though the idea seems too fantastic at the time (and even for this day and age) – Isaacs’ colleagues from the Scripps Institution says not at all when they made the requisite mathematical calculations and found, somewhat to their astonishment, that it is the one dreamboat that might really float. 

Being formed from glaciers, icebergs are completely salt-free and unlike their smaller North Atlantic variety, Antarctic icebergs are big enough to make the idea worthwhile – as in economically viable. A good sized Antarctic iceberg is typically 10 miles long, half a mile wide and 600 feet thick can even be considered “small” when talking about Antarctic icebergs. 

Using 1950s era slide rules to crunch the numbers, the scientists of the Scripps Institution of Oceanography together with John Isaacs calculated that in two months time, three ocean-going tugboats could work a 10 mile long, half a mile wide iceberg drifting in the Antarctic into the Humboldt Current running up the west coast of South America. Where the Humboldt Current slows down off Peru and Ecuador, the tugboats would steer the icebergs into other favorable ocean currents that would lead it in a long, lateral loop almost to Hawaii and eventually to Los Angeles. 

Given that these favorable currents move at around 2 to 3 knots, the whole trip would take about a year and along the way the iceberg might lose as much as half of its vast bulk. But it would still represent about 300 billion gallons of fresh water. Authorities could ground the iceberg on an offshore shoal and surround it with a floating dam extending about 20 feet or so below the surface. This would keep the fresh water penned in around the iceberg as the ice melted. 

Because it is lighter, the fresh water would stay on top of the surrounding salt water and the city of Los Angeles could just pump it out as needed through pipes leading to the mainland. One iceberg that was originally 10 miles long when it was toed back from the Antarctic would be enough to supply the city’s then normal needs of fresh water for about a month – using 1950s water consumption figures. 

Back in the 1950s, the total cost of the water so delivered – mainly the then rate of one million US dollars for a year’s hire of the three ocean going tugboats – works out to be something like one-third of a US cent per thousand gallons, a minute fraction in comparison to what the city of Los Angeles pays back in the 1950s for its regular source of drinking water. Calculated to be financially feasible for California using 1950s prevailing costs, this method of “outsourcing” fresh water might still be appropriate for the water needy arid regions of the Southern Hemisphere – like South Africa, Australia and the Peruvian desert communities. 

Shanghai River Dead Pigs: Inauspicious World Water Day For 2013?

The timing could have been much worse but is the recent Shanghai pig carcasses in the river that number in the thousands a portent of our inability to manage our precious and dwindling fresh water resource? 

By: Ringo Bones 

Shanghai’s Huangpu River had recently gained global notoriety for the pig carcasses that on last count now had numbered 14,000 had been oft cited as an example of most government’s inability across the world to effectively manage their dwindling fresh water resource. And the pig carcass debacle could not have come much worse when back in March 22, 2013 we've just observed World Water Day. And many water supply watchdogs are increasingly concerned that most governments across the world are just too cavalier when it comes to formulating long-term plans to maintain the cleanliness of their main water supplies. 

Strange as it seems, Shanghai’s city officials say the river still meets national water quality standards. I mean how poor are their criteria for water quality standards can be when 14,000 pig carcasses strewn across the Huangpu River was deemed not a factor to downgrade the prevailing water quality standard of the said river? Clean water is not only vital in maintaining the health and well being of the populace but also vital for industrial and manufacturing activity as well. The powers that be also seem just too cavalier in their economic assessments when it comes to water supply security. By the way, we've been celebrating World Water Day since 1993.

As the world watches the “Shanghai River Pig Carcass Debacle” unfurl, authorities say they believe that many of the pigs came from the nearby city of Jiaxing in the Zhejiang Province where there are major pig farms. Many suspect that the thousands of pig carcasses strewn on the river is due to the government crackdown on pig farms back on November 2012 where a number of pig farms were ordered to be closed for using dead pig carcasses that died from sickness in making sausages and other processed meat products.   

Flash Distillation: The Most Energy Efficient Desalination Method That Was?

Before the advent of the discovery of an efficient polymer based membrane for reverse osmosis, was flash distillation the most energy efficient method of desalinating seawater during its heyday?

By: Ringo Bones

Back in the 1950s, when polymer-based membrane for use in an energy efficient reverse osmosis desalination plant use were still decades away, a way of converting seawater to potable freshwater called flash distillation was deemed the most energy efficient method of desalination at the time. But what makes Flash Distillation Desalination Plants so energy efficient compared to say merely distilling seawater at normal atmospheric pressure?

The boiling point of water – at 212 degrees Fahrenheit or 100 degrees Celsius – is largely determined by the prevailing atmospheric pressure of 1 atmosphere – or 14.7 pounds per square inch or 760mm of Hg at sea level.  At about 60,000 feet above sea level, where the prevailing atmospheric pressure is only 2 percent that at sea level, water now boils at human body temperature of 98 degrees Fahrenheit or 37 degrees Celsius – thus this is why we need pressure suits / space suits when we ascent at higher altitudes – and this is the working principle behind the flash distillation desalination system.

When superheated water enters a chamber at reduced pressure, the water flashes almost instantaneously into steam, this is the basis of flash distillation where seawater first enters the system in a pipe which forms coils as it passes through successive evaporating chambers. The pipe carries the water past a heating furnace where it is superheated (heated above boiling point without boiling it) to 250 degrees Fahrenheit. As the superheated seawater flows into and through the reduced pressure evaporators, each of the chambers is filled with steam. A steady inflow of seawater keep the coils cool and the resulting steam condenses on them and drips into drains that leads to storage tanks and since salt is not carried into the steam, the resulting condensation is fresh water while a briny residue many times saltier than the seawater is drained away.

Back in 1958, the city of Freeport in the US state of Texas was selected by the US government as the site to build an experimental flash distillation desalination plant to solve the chronic thirst of what then the city’s 11,800 inhabitants. Freeport got the priority because even the water obtained from the local artesian wells was deemed too salty for long-term consumption even though it is several times less salty than the seawater taken from the Gulf Coast.

Back then, it cost 1.2 million US dollars to build, the experimental Freeport Flash Distillation Plant uses extremely low pressures to cause water to boil, or “flash” almost instantaneously while leaving salt behind. And as a bonus, less energy is required - in the form of heating oil or natural gas – to convert the incoming seawater into steam. The method proved so efficient that Freeport’s first flash distillation desalination plant’s first batch of fresh water output produced had too little salt in it that the residents complained that what came out of their taps tasted too flat – almost akin to triply-distilled water used in a typical chemistry lab. To remedy the situation, the distilled water had to be mixed with the slightly “briny” water from Freeport’s local artesian wells so that some of its “taste” could be restored.

Back in the late 1950s, even the experts predict that within 20 years, flash distillation desalination plants located at critical spots will be producing up to 500 million gallons worth of potable freshwater a day, enough to supply even the largest cities. Well, this was way before reverse osmosis went industrial and there was even a nuclear fission powered flash distillation desalination plant being planned to supply the city of New York with low-cost freshwater during the critical summer months. How times have changed indeed.

Sun Powered Desalination Plants: Sill Workable Ancient Desalination Technology?

The ancient concept seems ingenious, but why doesn’t everyone use the free heat energy from the sun to desalinate seawater into drinking water anymore?

By: Ringo Bones

Believe it or not, the knowledge that salty seawater can be made into safe fresh drinkable water is more that 2,000 years old. Ancient Mediterranean sailors embarking on long seafaring voyages have supplemented their stores of shipboard drinkable fresh water by placing pots of seawater under the sun and trapping the condensed vapor. This very same technique – in an updated scaled-up form – had been tried in some large-scale experimental desalination plants back in the 1960s.

Surprisingly, the concept of using the sun’s free thermal energy to convert salty seawater to potable fresh water can easily work when scaled up to a several thousand-gallon-a-day capacity. Back in the 1960s, the 4,083 inhabitants of Symi, an island near Greece, used to get all of their potable fresh water from a newly constructed experimental solar-distillation unit which can supply about 4,000 gallons a day. It works by tapping the sun’s free thermal energy – i.e. heat – to turn seawater into fresh water by first piping seawater into a flat shallow trough enclosed under a transparent plastic dome. The sun’s heat causes the water to evaporate that re-condenses into chemically pure fresh water on the cooler underside of the dome. This pure salt-free water then trickles down the dome, drips into collecting trough at the edges of the unit and is then collected. The briny residue that’s left behind – which is several times saltier than seawater – is then flushed away back to the sea.

The method is very inexpensive given that the energy source used to desalinate the seawater is virtually free, unlike the more popular reverse osmosis method used today which uses electricity to pressurize seawater up to several thousand pounds per square inch to be squeezed though banks of salt-filtering polymer membranes. But using the sun’s free thermal or heat energy to convert seawater into drinkable fresh water is for all intents and purposes an inefficient and impractical process in most cases because the yield is quite low: at best only 0.13 gallons per square foot of basin area per day. This makes a typical solar thermal desalination plants that can be able to compete the output of a typical modern reverse osmosis desalination plant occupy a prohibitively large real estate for every gallon of fresh water produced.

Reverse Osmosis: Most energy Efficient Desalination Process?

First developed during the heyday of NASA’s Apollo program, is reverse osmosis still the most energy efficient desalination process we have so far?

By: Ringo Bones

Back in the heyday of the Apollo program, reverse osmosis – due to lack of an efficient polymer filtering membrane – can only be able to desalinate or purify human urine into fresh drinkable water. After a few decades of development, polymer chemists had finally been able to develop a reverse osmosis membrane that can actually be able to turn the full-on salinity of sea water into potable fresh drinking water. Not only that, reverse osmosis has since more or less became the most energy efficient way to desalinate sea water for drinking purposes – dethroning its previously most energy-efficient desalination method called low-pressure flash distillation process.

A typical reverse osmosis desalination membrane – usually there are banks of them – turns salt water into fresh water when salty sea water is pressurized through it at 1,000 pounds per square inch. Only the smaller molecules of water can go through the structure of the “filtering fabric” in a typical reverse osmosis membrane while the larger molecules of sodium chloride and other salts are left behind. And what makes a typical reverse osmosis plant more efficient that its predecessors is that the highly pressurized salt water and used briny effluent can be reused to run an electric turbine en route to its release back into the normal prevailing atmospheric pressure.

Despite of energy efficiency figures, it still costs 17 million US dollars annually to run a typical large scale reverse osmosis plant that has the capacity to turn enough sea water to fresh drinking water to supply a typical metropolis – 10 million US dollars of which pays for the yearly electric bill. And compared to other sources of tap water, a reverse osmosis desalinated tap water typically costs around 3.38 US dollars per 1,000 gallons. While a river or lake sourced treated tap water costs around 2 US dollars per 1,000 gallons while subsurface groundwater sourced treated tap water costs around 1 US dollars per 1,000 gallons – something to think about when you decide which water utility company you chose to supply your household needs. 

Renewable Energy Desalination Plants: Viable Solution To A Global Thirst?

Even though humankind has faced water shortage way before the dawn of civilization, will the use of renewable energy resources to power desalination plants provide a viable solution?

By: Ringo Bones

Even though reverse osmosis is currently the most energy efficient and most economically viable scheme we have of turning briny seawater to potable freshwater, it is still energy hunger and the running costs are still very prohibitively expensive to the ones who needed it most in the world’s poorest countries. Will the utilization of renewable energy sources – for example wind and solar – provide a viable solution for meeting the needs to quench the thirst of the planet’s monetarily disadvantaged?

Dr. Corrado Sommariva, president of International Desalination Corporation, says innovations in water desalination that harness renewable energy sources is the only hope for the long-term solution of the desalination industry. Earth-friendly renewable energy sources – like wind turbines and solar photovoltaic cells – had just recently been widely applied in large-scale industrial electricity generation during the first decade of the 21^st Century.

 So far, Earth-friendly renewable energy sources use in the desalination industry is still the exception – not the rule and even most high-pressure reverse osmosis desalination plants still get their electric power from conventional fossil-fueled power plants. Will future trends see more use of renewables in the water desalination industry?

Pykrete: Maritime Engineering Material of the Future?

First conceived as an alternative to steel which was then in increasingly short supply in constructing warships during World War II, is Pykrete really deserve the claim as the maritime engineering material of the future?

By: Ringo Bones

For those too young to remember the more esoteric events of World War II first hand, the only time we ever heard of Pykrete was probably in MythBusters when they tested out an ice-based composite material once seriously considered for maritime engineering construction – i.e. naval ship building – when steel was in increasingly short supply back in World War II. Usually made by freezing water with sawdust in suspension (14% sawdust by weight and 86% by water by weight), Pykrete takes up to 20 times longer to melt than ordinary frozen water and is slightly more than 30 times stronger than ordinary water ice and is even bulletproof.

This wonder material was originally invented by Geoffrey Pyke, a British journalist, part-time spy and full-time inventor in the UK Blue Sky Research Department. When Geoffrey Pyke invented Pykrete, the wonder material immediately got the attention of Lord Louis Mountbatten – the then chief of combined operations. Mountbatten then bought a specimen of Pykrete the size of a lunchbox to then UK Prime Minister Winston Churchill. Churchill was in his bathtub at the time when he summoned Mountbatten in and the specimen of Pykrete was accidentally dropped into the warm bathtub water. To Mountbatten and Churchill’s surprise, the Pykrete managed to stay solid for half an hour in the comfortably warm bathtub water.

Due to this demonstration, Pykrete was instantly promoted as a viable solution to the steel shortage of the Allied Nations during World War II in constructing large naval vessels – namely ultra-large aircraft carriers. Unfortunately, creating a fabrication plant to turn Pykrete into a fleet of naval vessels required more steel than a conventional aircraft carrier needs. Even if the Pykrete fabrication plants were located in the frigid reaches of the Arctic Circle. Despite of this, a 60-foot prototype Pykrete boat was built and it took almost a year to completely melt back into water and sawdust.