Safe Water Delivery Using Artificial Porous Materials

We can have an endless, but not infinite, supply of safe drinking water if we could only extract the water in the air we breathe. 
Wiping Air with a Sponge or an Eraser

Source - redbookmag.com

This extraction of water can be visualized as a gizmo that acts like a sponge or a chalkboard eraser when we move it in the air where we need to extract safe water.
This gizmo would "clean" the air around us of water molecules, with the same motion that we use to wipe a blackboard clean of chalk!
Later, once the gizmo fills up with extracted water, we could squeeze out (literally speaking) this water.
Luckily, materials that may be very suitable for just such an action already exist.
MOFs - Metal-Organic Frameworks

Source - ucla.edu

Source - labroots.com

MOFs are structures consisting of organic molecules and metal ions. The organic molecules hold metal ions in a 3-D grid pattern that is porous to another, a third, material.
The structures can have virtually any 3-D configuration - the configuration essentially depends upon the organic molecules and the metal ions that comprise the structure.
As we may also expect, the combination of organic molecules and metal ions define what materials will be absorbed by a specific structure.
Cavity size, number of cavities and absorption rates can also all be controlled.
Water Absorption
Chemistry of organic molecules can, in the presence of moisture and under different ambient temperatures, get compromised but a list of water-stable combinations have been developed. The focus, however, has been on using MOFs for energy applications like hydrogen and other gas absorption, storage and release.
All that remains is to focus this research on water absorption, storage and release! 
A local supply of safe drinking water using a MOF that extracts moisture from the air we breathe can be a reality in our very near future!

The Energy-Freshwater Nexus

Humanity has created an inter-dependency between water and energy that would be impossible to take apart. The most recent example of this inter-dependency are the recent blackouts in India.
600+ million people without electricity

Auto traffic at a standstill
Source - geekosystem.com

Candle light for a haircut
Source - theaustralian.com.au

While the causes of the blackouts of July 2012 are still being determined, a root cause has been suggested: "... northern states may have been drawing more than their allocated power quota to help stricken farmers pump groundwater from bore wells ..." (The Financial Times dated 30 July 2012).  This large and unprecedented demand for ground water was fueled by a large monsoon deficit.
Hydropower

Tehri Hydroelectric Power station - India's largest
Source - wikipedia.org

Freshwater is also the fuel for 19% of India's electric power supply.
As in most parts of the world, the first electric power generating station in India was also a hydroelectric station commissioned in 1897.
This nearly one-fifth of India's electricity generating capacity requires reservoirs of freshwater which, in July 2012, dropped to just 24% of their capacity.


Water Consumption for Different Energy Fuels

Source - World Economic Forum

• Minimal water is consumed in production of traditional oil and gas resources - 3 to 7 liters/GJ   (GJ=gigajoule)
• Enhanced oil recovery require 50-9000 liters/GJ
• Oil sands require 70-1,800 liters/GJ
• Petroleum refining requires 25-65 liters/GJ
• Unconventional gas resources require 36-56 liters/GJ
• Corn grown for bio-fuels require 9,000-100,000 liters/GJ
• Soy grown for bio-fuels require 50,000 - 270,000 liters/GJ
• Coal mining requires 5-75 liters/GJ
• etc

Energy production is water-intensive just like water production is now energy-intensive

Freshwater - One Reason to Nix Solar?

Solar power, like every other fossil and renewable source of electric power (other than wind-generated power) is dependent upon adequate supplies of fresh water. The amount of water required varies with the type of process used to convert sunlight into electricity.
2 Major Types of Solar Generators

PV-based Solar Panel Power Generation
Source - europlas.co.uk

Solar Thermal Power Generation
Source - treehugger.com

Photo-voltaic (PV) and Solar Thermal are the two predominant technologies for converting sunlight into electric power.
Solar Thermal requires orders of magnitude more fresh water supplies than does photo-voltaic power generation. For example,a proposed Solar Thermal Power Plant to be located in Amargosa Valley, Nevada, required 1.3 billion gallons of water per year. This volume represents 20 percent of the Valley's available ground water supply - water that the desert Valley badly needs for other uses. This water usage level is of the order of use required by a coal-fired plant.
Photovoltaic power generation, on the other hand has a very minimal water requirement once it is installed and running. But its power generation capability is also limited to that of a single home or two. 
Sustainability

Shale gas extraction
Source - news.consumerreports.org

Depending upon definition, when water use is a criteria, some renewable energy sources begin to look unsustainable.
Even shale gas, will be deemed unsustainable when its water use is a criteria
Sustainable Electric Power Generation

Wind Power
Source - treehugger.com

Wind power is the only electricity generating option that has virtually no dependency on freshwater.

Freshwater - A Singular Resource

Singular, according to the American Heritage Dictionary, means "Being only one; individual, Deviating strongly from the norm." Yes, water, and in particular, freshwater is unlike any other resource.


Water is MORE than just another Commodity

Commodities
Source - tradecommodity.com.au

Water is a commodity in the sense that it is a material that can be bought and sold. 
Being basic to all life is what makes water a commodity with a difference.
Not only was water the medium for incubating life, water is also continuously required for sustaining and maintaining life.
We cannot, therefore, just think of buying and selling water - we must also factor in how humans, all other living species and nature's ecosystems are impacted by us moving water around.


Water is Distributed WORLDWIDE

Freshwater Distribution
Source - rusrev.org

Water is the most widely distributed substance on Earth. It is available everywhere. While the specific amount of water differs in different locations, there is no place on Earth with, literally, no water.
All other natural resources are also widely distributed, but each and everyone is not available everywhere even in the smallest of amounts. Some amount of freshwater is available everywhere on Earth.


Water has NO Substitute
There is no other substance, natural or synthetic, that can replace water. It is hoped that the world will migrate away from fossil fuels to renewable energy. No such transition is possible with water.


Water exists simultaneously in multiple forms: Vapor, liquid and solid

3 forms of water
Source - fcwa.org

No other resource exists in more than one form in the same location. Huge amounts of water are also bound into soil and other materials in every location.
Every other resource exists in a single form, usually as a liquid, in the same location.


We cannot MAKE new water

Periodic Table of Elements
Source - elementsdatabase.com

We humans cannot make any element of the periodic table or the basic compounds that combinations of these elements form in nature.

Water formation Equation
Source - scienceforums.net

Making water is a particularly tough proposition because of the amount of energy released. We simply have no way of containing this energy release.


We cannot DESTROY water
When we burn oil, no more oil remains, as the oil disintegrates into different chemical compounds.
Water, on the other hand, does not ever disintegrate into its components. Water gets polluted, changes color, acquires an odor or simply evaporates into the atmosphere or disappears into the ground.


Water is in Constant MOTION

Water Cycle
Source - kidzone.ws

Unlike every other natural resource, water is in constant motion. It is constantly moving between its three forms - from liquid to vapor, from vapor to liquid, from solid to liquid and every other possible transformation. Water is always moving in rivers and churning in lakes and oceans.
NO other natural resource exhibits this perpetual motion behavior. 


Water's Singularity
Water's perpetual motion, it's simultaneous existence in multiple forms, it's availability everywhere and its role as the basis for all life make it singularly unique.


We seem to want to treat water in ways similar to how we think and act with other resources. This may be our greatest error in dealing with water, and especially, finding ways to alleviate water scarcity everywhere on Earth.


We should, instead be looking at harnessing the unique characteristics of water to end water scarcity everywhere on Earth. 

The Tropics - The Engine of the Global Water Cycle

Precipitation is highest around the equator and drops as latitude increases.

The Tropical Band
Source - Earthobservatory. nasa.gov

Rain Forests
Rain forests is our name for places that have the highest rainfall. 
As the atmosphere over the Tropics have some of the highest water vapor concentrations, the most rainfall occurs in the latitude band created by the Tropic of Cancer and the Tropic of Capricorn.


Latitude and Precipitation

Precipitation & Latitude
Source - roperld.com

As expected, the precipitation (rainfall) is highest between the bands created by the two Tropics.
The amount of water vapor available in the tropical atmosphere is orders of magnitude greater than that available elsewhere. In other words, the water cycle in the tropics circulates greater volumes of water than the water cycle does in other parts of the Earth, recognizing the existence of Temperate Rain forests that are the result of local variations in atmospheric moisture content, local temperature and other factors.
The tropics are the engine of the global water cycle (aka, the Global Hydraulic Cycle).

Sun+Atmosphere = A Moisture Pump

An energy imbalance in the atmosphere moves air, and the moisture it contains, from the tropics to higher latitudes.

Energy for Atmospheric Circulation

Sunlight
Source - digitalart.org

The most energy from the sun, falls on the Earth's equator. The least energy from the sun falls on the polar regions. 
This difference in energy creates an energy potential that moves air (mass) from the equatorial region to the polar regions through a series of complex steps and air movement patterns.

Source - geology.wmich.edu

The Tropics - A Moisture Source

As temperatures rise, more water evaporates and is contained in the atmosphere. The most water, thus, exists in the atmosphere over the tropics and equatorial region, while less moisture exists in the air over the poles. 

As the air moves from the warmer to the cooler areas, this air acts like a moisture pump. While a number of global and local influences impact this pump's operation, the tropics are a dominant source of moisture to higher latitudes.