Ieee-rwep 14 1299786009 Cdi Background Lecture Final

8/13/2019 Ieee-rwep 14 1299786009 Cdi Background Lecture Final

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Water Desalinationvia Energy-Efficient

Capacitive Deionization (CDI)

Technology

Background Lecture

Instructor

University


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Water:Becoming a scarce resource

The IWMI's (International Water Management Institute) Comprehensive

Assessment of Water Management in Agriculture says one third of theworld population face some form of water scarcity (BBC News, August

21, 2006).

Population growth, climate change, widespread mismanagement and

increasing demand for energy could lead to a major global water crisis,according to the UN World Water Development Report. (United Nations

Environment Programme News Release, March 16, 2009)

Water use has been growing at more than twice the rate of population

increase in the last century, and, although there is no global water scarcity

as such, an increasing number of regions are chronically short ofwater. By 2025, 1 800 million people will be living in countries orregions with absolute water scarcity, and two-thirds of the world

population could be under stress conditions. (Food and Agriculture

Organization of the United Nations,http://www.fao.org/nr/water/issues/scarcity.html)
http://www.fao.org/nr/water/issues/scarcity.htmlhttp://www.fao.org/nr/water/issues/scarcity.html


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Global Perspective: Water Scarcity

Areas of physical and economic water scarcity. (2008). In UNEP/GRID-ArendalMaps and Graphics Library. From http://maps.grida.no/go/graphic/areas-of-physical-

and-economic-water-scarcity.

Water is a precious resource, which israpidly becoming scarce in many partsof the world In addition to the physical waterscarcity, there is also economic waterscarcitywhich is characterized by lack

of capital to render potentially availablewater usable by local population Brackish waters (lakes, lagoons,springs) in such areas can become asource of potable water IF a cheap,easy to manufacture and maintain

system for brackish water desalinationis developed
http://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcityhttp://maps.grida.no/go/graphic/areas-of-physical-and-economic-water-scarcity


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Global Perspective: Water ScarcityJust a couple of examples:

Egyptimports more than half of its food because it does not have enoughwater to grow it domestically.Australiais faced with major water scarcity in the Murray-Darling Basin as aresult of diverting large quantities of water for use in agriculture. (BBC News,

August 21, 2006).

Australia, inland from Brisbanelandscape after a severe drought.

Photo: Jonathan Wood/Getty Images (From IEEE Spectrum, April 2008)


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Desalination: Emerging necessity

Currently, there are 18 countries classified as water scarce (i.e. their percapita yearly fresh water resources are below 1000 m3/cap/y). The majorityof these countries are in the Middle East and northern Africa, however, a fewcountries are found in Europe, Asia and the Caribbean. By 2025,approximately 29 countries in the world are expected to experience waterscarcityDesalination, along with wastewater reuse and water importation,

can provide a means of increasing the supply of available fresh water in theregions of the world where water is scarce From How water scarcity willaffect the growth in the desalination market in the coming 25 years by I.

Bremere, et al., Desalination, Vol. 138, no. 1-3, pp. 7-15, Sept. 2001.

Jubail water desalination plant (Saudi Arabia)the largest in the world

(From www.water-technology.net)


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Desalination: Ongoing investmentExample: Across Australia and the world, governments are turning todesalination as the most reliable method of guaranteeing water supply for thelong-term.

A desalination planthas recently beencommissioned in Perth,

with another oneplanned, while the GoldCoast has begunconstruction and a newplant is planned forSydney. (The Source,

Melbourne Waterpublication, June 2007)

From Melbourne Water, Australia


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Desalination: Ongoing investment

Fromhttp://www.gewater.com/what_we_do/water_scarcity/desalination.jsp
http://www.gewater.com/what_we_do/water_scarcity/desalination.jsphttp://www.gewater.com/what_we_do/water_scarcity/desalination.jsp


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but there is a catch

From: http://www.pacinst.org/reports/desalination/desalination_report.pdf

Desalination offers both advantages anddisadvantages in the face of climatic extremesand human-induced climate changes.
http://www.pacinst.org/reports/desalination/desalination_report.pdfhttp://www.pacinst.org/reports/desalination/desalination_report.pdf


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Who can afford it?

Water in Africa (From International conference on groundwater and climate in Africa

News article, http://www.ucl.ac.uk/news/news-articles/0808/08081303)
http://www.ucl.ac.uk/news/news-articles/0808/08081303http://www.ucl.ac.uk/news/news-articles/0808/08081303http://www.ucl.ac.uk/news/news-articles/0808/08081303http://www.ucl.ac.uk/news/news-articles/0808/08081303


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Desalination: Quest for energyefficiency and low-cost solutions

To reduce costs, many coastal desalination plants are designed to treat

large volumes of water, often 50 mgd* or greater, and are co-located withcoastal power plants to take advantage of common intake and outfallstructures and less expensive power. These strategies enable coastalfacilities, such as the Tampa Bay Desalination Facility, to maintain

desalination costs as low as $2.00-$2.50 per 1000 gallons of waterproduced. Similar facilities in inland areas may cost twice as much tooperate because of smaller plant sizes, higher concentrate disposal costs,higher water pumping costs, and higher energy costs (U.S. Bureau ofReclamation, 2002).(From Desalination of Inland Brackish Water:Issues and Concerns by Mike Hightower - Sandia National Laboratories,

http://wrri.nmsu.edu/tbndrc/inland.html)

* mgd = million gallons a day, or approximately 3.78 million liters a day
http://wrri.nmsu.edu/tbndrc/inland.htmlhttp://wrri.nmsu.edu/tbndrc/inland.html


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What are possible solutions?

Fresh Water For The World's Poorest

ScienceDaily (Jan. 9, 2008) Lack of water causes great distress among thepopulation in large parts of Africa and Asia. Small decentralized water treatmentplants with an autonomous power supply can help solve the problem: Theytransform salty seawater or brackish water into pure drinking water.

(ScienceDaily. Retrieved October 26, 2009, from http://www.sciencedaily.com/releases/2008/01/080104140733.htm)

More than one out of six people lack access to safe drinking water around the

world. Thats roughly 1.1 billion people. Analysts are increasingly raising

concerns about possible water wars which may occur in the near future as waterbecomes more and more scarce. One possible solution for large parts of Africaand Asia is the creation of small decentralised water treatment plants with anautonomous power supply. These treatment centres can help transform saltyseawater or brackish water into pure drinking water for the immediatepopulation. (From European Research Headlines, January 2008).


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Example of one possible solution

SolarSpring is a devicedeveloped by Fraunhofer-Gesellschaft (one of the worlds

major international researchorganizations based in

Germany). It is capable ofproducing about 120 liters offresh water per day, at a cost of10 euros for 1000 liters. Thetechnique used is distillation. The

only energy source required issolarthe device includes sixsquare meters worth of solarpanels.

Mini-plant installed on the rooftop in Jordan(Image courtesy of Fraunhofer-Gesellschaft, 2008)


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So, we are going to

Learn about new technologies, engineeringdesign process and how engineers help tomake our world better

We will accomplish this by looking at aparticular solution for a design to providefresh water: Small-scale, decentralized system for water

desalination

Low power consumption and low cost Ease of coupling the system with solar/wind

power elements


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The First Question: What makessalty water salty?

Fresh water

+

+

+

+

+

+- -

--

- -

Na+(sodium cations)Cl-(chloride anions)

Salt ions


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So, we need to get rid of the saltions

and Charles-Augustin de Coulomb cameup with a clue for the solution about 220years ago:

-

++which is due to the electric

fields associated with the

charges


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So, we need to apply an externalelectric field to salty water!

Fresh water

+

+

+

+

+

+- -

--

- -

No external electric field appliedthe water is electrically neutral and salt ions are flowing freely within it

Fresh water

External electric field causes the salt ions to flow towards the opposite polarity of

the field and away from the same polarity

Externalpositivecharge

Externalnegativecharge

-

-

-

--

-+

+

++

+

+


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and if only we had a way to keep

the ions away!

We could use a lot of power and keep theions stuck to the points of application of theelectric field despite the water flow

but that would violate our requirement oflow power!

Instead, we can try to use some sort of anion-absorbing material at the electric field

application points So, the conceptual engineering design can

be as shown in the next page


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Lets Name It! Actually, the name for such a technology has been around since the 1960s

Capacitive Deionization (CDI)but the technology itself has not receivedmuch attention until fairly recently

1950s

The idea of using electricity to separate compounds was introduced.

1960s

Ideas to use CDI for water treatment developed.

1980s

The technology began to pick up popularity again.

1990s

Testing was done in laboratory settings with the first industrial CDIprototype under development during the late 1990s.

Present

Lawrence Livermore National Laboratory (LLNL) is currently using CDItechnology for industrial waste, municipal waste, medical applications,and mineral extraction.

Present

Several research groups around the world are trying to bring CDI tocommercial implementation.


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Two specific questions

Now that we have a concept for ourdesign, we should then start the designprocess

Two questions then will emerge:

Whats the ion sponge?

How do we create the electric field between

the electrodes?


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Ion Sponge

Q: What are we trying to trap?A:Na+and Cl-ions Q: What size pores do we need to hold the ions?(A: e.g.

see http://www.chemicool.com/elements/) Turns out, the ionic diameters are on the order of 200-300

pm (thatspicometers), or 0.20.3 nanometers Thus, the sponge material should be such that the pores

are at least several times the size of the ions; however, theycant be much larger than this, as the sponge capability to

trap the ions will deteriorate if pores are too big
http://www.chemicool.com/elements/http://www.chemicool.com/elements/


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Ion Sponge:

Overview of possibilities

From the website of MarkeTech International, Inc.

Discovered in 1997 by Andrei V. Rodeand co-workers at the Australian NationalUniversity in Canberra, Australia Produced by firing a high-pulse, high-energy laser at graphite or disordered solidcarbon Electrically conductive, high capacitance A synthetic, low density lightweight foam Very high porosity, high surface area Fine cell/pore size (nano-scaledimensions)


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Commercially Available CN

Properties of Carbon Nanofoam

Available Ranges

Density 0.4-0.5 g/cm3

Surface Area ~600 m2/gram

Average Pore Size 75-80 nm

Electrical Resistivity 0.010 - 0.040 ohm-cm

Capacitance 2830 F/gram

Color Black



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The downside


As with almost any new material, CN is quite expensiveand not (yet) widely available , e.g.:

https://www.mkt-intl.com/aerogels/pages/aerogel_order.html

http://www.reade.com/western-region-(usa)/8826
https://www.mkt-intl.com/aerogels/pages/aerogel_order.htmlhttp://www.reade.com/western-region-(usa)/8826http://www.reade.com/western-region-(usa)/8826http://www.reade.com/western-region-(usa)/8826http://www.reade.com/western-region-(usa)/8826http://www.reade.com/western-region-(usa)/8826http://www.reade.com/western-region-(usa)/8826https://www.mkt-intl.com/aerogels/pages/aerogel_order.htmlhttps://www.mkt-intl.com/aerogels/pages/aerogel_order.htmlhttps://www.mkt-intl.com/aerogels/pages/aerogel_order.html


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Alternatives?...

High porosity (up to 100 pores per inch available),high conductivity, low density and low flow resistance

Example:Duocel RVC Foam

(http://www.ergaerospace.com/foamproperties/rvcproperties.htm)

Pore size below 500 mm available, low flowresistance, high durability

Example:Nickel RECEMAT foam(http://www.recemat.com/en/index.html)

Fiber sizes down to 2 mm and densities from 2%to over 70% are available, high durability, wide range of metals

Example:GMT Separation Materials (http://www.gmt-inc.com/products/separation-materials)
http://www.ergaerospace.com/foamproperties/rvcproperties.htmhttp://www.recemat.com/en/index.htmlhttp://www.gmt-inc.com/products/separation-materialshttp://www.gmt-inc.com/products/separation-materialshttp://www.gmt-inc.com/products/separation-materialshttp://www.gmt-inc.com/products/separation-materialshttp://www.gmt-inc.com/products/separation-materialshttp://www.gmt-inc.com/products/separation-materialshttp://www.gmt-inc.com/products/separation-materialshttp://www.recemat.com/en/index.htmlhttp://www.ergaerospace.com/foamproperties/rvcproperties.htm


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+

-

Attach the ionsponge material

to the electrode(or use it asanelectrode) (how??discuss)

Attach powerwires (how??discuss)

Provide for a constantseparation betweenthe electrodesitdefines the strengthof the electric fieldinside (how??discuss)

Choose your low-power source (how??

discuss)

Make the

electrodeschoose size,shape, material(how?? discuss)

and then comes the

water!


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Water Flow The cheapest option is to make gravity do the jobno

motor/pump is necessary, thusno extra powerrequirements; although the throughput may be small

Depending on water salinity and the ability of the ion spongeto trap and retain the salt ions, timing requirements fordesalination process will vary

We can adjust the flow/timing by dialing the flow valve in/out

http://www.rei.com/product/618168

Vessel example:Reliance Aqua-Tainer7 gallons(Approx. $16)

Cut out fora place toinsert aCDI cell
http://www.rei.com/product/618168http://www.rei.com/product/618168


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Put the system togetherwhat then?

Engineering is based upon the concept oftesting and improving a design

We need to test the device to ensureproper functionality

If test results are unsuccessful we shouldgo back and check the design


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Water salinity tests: Brackish Water

First of alldetermine the range of salinityvalues we will be targeting: We are interested inbrackish water, so

Fresh Water Brackish Water Sea Water Brine

50 ppt

http://www.sciencedaily.com/articles/b/brackish_water.htm

Brackish water is water that is saltier than fresh water, but not as

salty as sea water.

ppt = parts per thousand
http://www.sciencedaily.com/articles/b/brackish_water.htmhttp://www.sciencedaily.com/articles/b/brackish_water.htm


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Brackish Water: Where? Brackish water is found in river estuaries, tidal pools and under

ground, among other places

Desalination of brackish water is of much importance: Theres even

the Brackish Groundwater National Desalination Research Facility(Alamogordo, NM)

Within the U.S. alone there are numerous places which can benefitfrom power-efficient brackish groundwater desalinationsee map:

General location and extent of brackish saline ground water resources in the

United States (From http://wrri.nmsu.edu/tbndrc/inland.html )
http://wrri.nmsu.edu/tbndrc/inland.htmlhttp://wrri.nmsu.edu/tbndrc/inland.html


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Salinity Testing

We need a device that can measure the levels ofsalinity from about zero to a maximum of 30 ppt

The finer the resolutionthe better

Example:KoiMedic Digital Salt Meter:

Range:0 to 10 pptResolution:0.1 ppt

Price:~$85

Inexpensive, very accurate, but range goes to 10 ppt onlyhttp://www.pondpetsusa.com/water_test_kits/koiMedic_salt_meter.htmlAnother option: http://www.hannainst.com/manuals/manHI_98203.pdf
http://www.pondpetsusa.com/water_test_kits/koiMedic_salt_meter.htmlhttp://www.hannainst.com/manuals/manHI_98203.pdfhttp://www.hannainst.com/manuals/manHI_98203.pdfhttp://www.pondpetsusa.com/water_test_kits/koiMedic_salt_meter.html


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Complete Solution: Summary

Prepare the water vessel witha flow valve

Assemble the CDIcell and put into

the vessel

Prepare the brackishwater solution withthe known salinitylevel (use the salinity

meter to verify)

Run the test, while timing yourmeasurements; plot the graphof salinity vs time


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Conclusionand let the fun begin!

Water is becoming a precious and scarce resource in manyparts of the worlddesalination of brackish and salty watermay be the solution for a variety of regions

Technology is at the frontlines of innovation and socio-economic impact and CDI is one such example

Solearn as much as you can, dont be discouraged by thecomplexities of engineering design and test and prepare tomake a difference in the world (well, maybe not right away

perhaps after the graduation)

Documents

Ieee-rwep 14 1299786009 Cdi Background Lecture Final