Water for Energy and Energy for Water Energy Workshop... · Andrea Achilli, PhD, PE Assistant Professor. Chemical & Environmental Engineering. University of Arizona. Southwest Regional

Water for Energy and

Energy for Water

Andrea Achilli, PhD, PEAssistant Professor

Chemical & Environmental EngineeringUniversity of Arizona

Southwest Regional Energy Workshop – Institute for Energy SolutionsMarch 14, 2018

Sustainability

2

Water-Energy-Sustainability

Membrane Contactor Processes

Energy for Water

Water for Energy

Fuel Production

Extraction & RefiningHydropower

Thermo Electric Cooling

Extraction and Transmission

Drinking Water Treatment

Energy Associated with Uses of Water

Wastewater Treatment

3

Membrane Contactor Processes

Mass transfer across the membrane is due to properties of the two fluids and the membrane characteristics

Salinity gradients – Temperature gradients

Salinity Gradients

Osmosis

4

Osmosis in Biological Systems

5 Campbell, 1999

Osmosis

High salinity solution

Semi-permeable membrane

Δπ

Low salinity solution

6

Osmosis in Engineered Systems

Equilibrium Forward Osmosis

(FO)

7

Pressure Retarded Osmosis

An osmotically driven membrane process similar to RO and FO

PRO

Pressure (ΔP < Δπ)

FO RO

Pressure (ΔP > Δπ)

High salinity solution

Semi-permeable membrane

Δπ

Low salinity solution

Presenter

Presentation Notes

In Forward Osmosis – or just Osmosis, water passes though the membrane to dilute the brine. At equilibrium, the difference in pressure head is the osmotic pressure difference. In Reverse Osmosis, we apply a pressure that exceeds the osmotic pressure… In PRO, similar to RO, we apply a hydraulic pressure that is less than the osmotic pressure so that, similar to FO, the flow of water is still from the feed water to the brine. And in a few slides, I will show you how this water salination can produce energy PRO can be viewed as an intermediate process between FO and RO, hydraulic pressure is applied to the draw solution (similar to RO) but the net water flux is still in the direction of the concentrated draw solution (similar to FO). PRO can be seen as the inverse process of RO. Whereas RO uses hydraulic pressure (i.e., energy) to oppose and exceed the osmotic pressure of an aqueous feed solution (e.g., seawater) to produce purified water (i.e., fresh water), PRO uses the osmotic pressure of seawater to salinate fresh water and induce hydraulic pressure (i.e., energy).

ΔP

RO

PRO

FO

ΔP = Δπ0

Wat

er fl

ux (J

), L/

h∙m

2

Adapted from: K.L. Lee, R.W. Baker, H.K. Lonsdale, “Membrane for power generation by pressure retarded osmosis”, Journal of Membrane Science 8 (1981) 141–171.

J=A(ΔP-Δπ)

Wmax

ΔP = Δπ/2

Pow

er d

ensi

ty (W

), W

/m2 W=-JΔP

Feed solution

Draw solution

8



Global energy production from mixing in estuaries: 2,000 TWh/yCurrent global energy production from all renewable sources: 10,000 TWh/y



A means for capturing solar energy from the mixing of freshwater with saltwater

9

R.S. Norman, “Water Salination: A Source of Energy”, Science 186 (1974) 350-352.

Presenter

Presentation Notes

The energy spent by the sun to evaporate water from the sea is captured in an estuary where freshwater meets the sea

10

Current River-to-Sea PRO Process Schematic

Diluted seawater

Low pressure

pump

Low pressure

pumpPressure exchanger

Circulation pump

Diluted seawater

Fresh waterFlushing solution

Hydroturbine and generator

Draw solution side

Feed solution side

Seawater

Diluted seawater

Pumps Net power

H

L

Seawater

Membrane

A. Achilli, T.Y. Cath, A.E. Childress, “Power generation with pressure retarded osmosis: an experimental and theoretical investigation”, Journal of Membrane Science, 343 (2009) 42-52. Adapted from: S. Loeb, “Large-scale power production by pressure-retarded osmosis, using river water and sea water passing through spiral modules”, Desalination 143 (2002) 115–122.

Presenter

Presentation Notes

The ideal site has freshwater and seawater resources which require minimal pumping and treatment

11

Resource Utilization: Specific Energy

?

Vfeed (River Water)

Vdraw in(Seawater)

Vdraw out

PRO Dilution = V feedV draw solution out

12

River-to-Sea PRO Resource Utilization

Units: kWh/m³

G. O’Toole, L. Jones, C. Coutinho, C. Hayes, M. Napoles, A. Achilli, River-to-Sea Pressure Retarded Osmosis: Resource Utilization in a Full-Scale Facility, Desalination, 389 (2016), 39-51.

Presenter

Presentation Notes

Built with the aid of SankeyMatic, by Steve Bogart. Sankeymatic.com. 2015

Promising PRO Applications?

Hybrid Desalination Systems

Urban Water Cycle

14

Seawater

DesalinationFacility(RO)

Drinking Water

High-Salinity Brine


Facility

Wastewater

Treated Wastewater

Presenter

Presentation Notes

A novel, still unexplored way to use PRO is to couple it with RO.

“California Model” of Desalination

Seawater

Drinking Water

High-Salinity Brine


Facility

Wastewater

Treated Wastewater

State Water Resources Control Board, “Amendment to the Water Quality Control Plan For Ocean WatersOf California Addressing Desalination Facility Intakes, Brine Discharges, and the Incorporation of other

Non-Substantive Changes”, Final Staff Report, 2015.

How can we maximize the benefits from this resource?

Forward Osmosis & Pressure Retarded Osmosis

15

Presenter

Presentation Notes

So, what we call the “CA model” of desalination is California’s response to the “brine issue“ by passing the Desalination Amendment to the Ocean Plan that specifies that desal plants must be located next to WWTPs, so that the brine can be diluted with treated WW effluent before being discharge. But, one of our main questions: is a way to use the WW resource that exceeds the benefits of simple dilution. With two membrane processes, called forward osmosis and pressure retarded osmosis, we believe we can make more efficient desal systems.

Why Forward Osmosis or Pressure Retarded Osmosis?

• Low fouling and high rejection of forward osmosis

• Energy recovery of pressure retarded osmosis

0 1000 2000 30004

2

0

-2

-4

Wat

er fl

ux (J

w), 1

0-6 m

/s

Hydraulic pressure (∆P), kPa

J experimental J model -4

-2

0

2

4

Powe

r den

sity (

W),

W/m

2

W experimental W model

0 1500 3000 4500 600012

8

4

0

-4

-8

-12

Wat

er fl

ux (J

w), 1

0-6 m

/s

Hydraulic pressure (∆P), kPa

J experimental J model

-12

-8

-4

0

4

8

12

Powe

r den

sity (

W),

W/m

2

W experimental W model

A. Achilli, T.Y. Cath, A.E. Childress, “Power generation with pressure retarded osmosis: an experimental and theoretical investigation”, Journal of Membrane Science, 343 (2009) 42-52.

35 g/L NaCl 60 g/L NaCl

16

Drinking water

Brine

Seawater

Hybrid Desalination Systems

17

Presenter

Presentation Notes

The way that forward osmosis can help the desal process is to implement it before the RO process. Seawater is used as high saline solution, and the treated WW is used as the low salinity solution. Thus, water is extracted from the treated WW and dilutes the seawater before being used in the RO process, lowering the osmotic pressure of the seawater and thus lowering the pressure that is needed to apply to desalinate. This treatment scheme is direct potable reuse, and by having two tight membrane barriers between the WW effluent and the drinking water, it is an intelligent way to do so. Additionally, previous studies have showed that by using two barriers, 97% of ammonia and nitrate effectively removed and 99.9% of various CECs were also removed.

Drinking water

WastewaterDiluted Brine

SeawaterConcentrated waste water

Diluted seawater

T.Y. Cath et al., “A multi-barrier osmotic dilution process for simultaneous desalination and purification of impaired water”, Journal of Membrane Science. 362 (2010), 417-426.

Forward Osmosis - Reverse Osmosis

18

Presenter

Presentation Notes

The way that forward osmosis can help the desal process is to implement it before the RO process. Seawater is used as high saline solution, and the treated WW is used as the low salinity solution. Thus, water is extracted from the treated WW and dilutes the seawater before being used in the RO process, lowering the osmotic pressure of the seawater and thus lowering the pressure that is needed to apply to desalinate. This treatment scheme is direct potable reuse, and by having two tight membrane barriers between the WW effluent and the drinking water, it is an intelligent way to do so. Additionally, previous studies have showed that by using two barriers, 97% of ammonia and nitrate effectively removed and 99.9% of various CECs were also removed.

Drinking water

Wastewater

Feed

Pressurized Feed

ConcentratedWastewater

Brine

DilutedBrine

Reverse Osmosis - Pressure Retarded Osmosis

J.L. Prante, J.A. Ruskowitz, A.E. Childress, A. Achilli, “RO-PRO desalination: an integrated low-energy approach to seawater desalination”, Applied Energy, 120 (2014) 104-114.

19

Presenter

Presentation Notes

The way that pressure retarded osmosis can help is to implement it after the RO process, where the concentrated brine produced from RO is used as the high saline solution for PRO and the treated wastewater is used as the low saline. The increased osmotic pressure difference between the brine and treated WW allows for increased water flux, and the power produced by recovering the energy of water crossing the membrane is used to help pre-pressurize the RO feed solution via pressure exchangers. This process uses no potable reuse, and instead is dilution of the brine utilizing energy recovery.

20% Recovery 30% Recovery

RO Alone kWh/m3 6.51 5.25

RO-PX kWh/m3 3.80 3.38

RO-PRO with 2nd PX kWh/m3 3.08 2.64

Specific Energy Consumption Summary

≅36%

≅22%

A. Achilli, J.L. Prante, N.T. Hancock, E.B. Maxwell, A.E. Childress, “Experimental results from RO-PRO: a next generation system for low-energy desalination”, Environmental Science and Technology, 48 (2014) 6437-6443.20

Gen II RO-PRO System and FO-RO• Projects funded by California Department of Water Resources and NSF-EPRI

• Larger system to operate at 40-50% RO recovery• Long-term operation utilizing seawater and impaired water sources• Directly compare RO-PRO with FO-RO experimentally and at the system level• Develop a computational fluid dynamics model of the FO and PRO processes to

describe the membrane module geometry

21

Temperature Gradients

Distillation

22

Membrane Distillation

Driving force: vapor pressure gradient

Heated Feed Stream Cooler Distillate Stream

Hydrophobic, Microporous Membrane

Presenter

Presentation Notes

On one side you have a heated aqueous feed sream On the other side is a coolder distillate stream These streams are separated by a hyrdophobic, microporous membrane The hydrophobic nature of membrane prevents penetration of aqueous solution into pores so a liquid–vapor interface exists at each pore entrance Water evaporates through the pores due to the temperature – or vapor pressure – diference. It is important to note that vapor pressure gradient is only minimally reduced at very high salt concentrations. Thus, unlike RO, the driving force will not be lost when treating brine solutions. people sweat by increasing body temperature, usually thought nerves or exercise, then sweat glands in your skin give out fluid (sweat) onto the skin to allow it to evaporate and cool you down.��Read more: http://wiki.answers.com/Q/How_do_people_sweat#ixzz1aZsXrSGY When you sweat, the only way you cool down is through evaporation of water from your skin. But if the air is holding too much water already, the sweat stays on your skin and you get little to no relief from the heat. A high Heat Index value shows a small chance of evaporative cooling from the skin. You even feel like it is hotter outside because you can't rid your skin of the excess water. In many areas of the world, that sticky, humid feeling is nothing more than...

Advantage: Vapor Pressure Driving Force

Driving force not significantly reduced at high salt concentrations

http://scidiv.bcc.ctc.edu/wv/08/0008-0013-vp.gif

25

Membrane Distillation Modeling

Photos by Kellie Brown R.D. Gustafson, J.R. Murphy, A. Achilli, “A Stepwise Model of Direct Contact Membrane Distillation for Application to Large-Scale Systems: Experimental Results and Model Predictions”, Desalination, 378 (2016) 14-27.

26

Specific Energy ConsumptionMembrane ModuleFeed

Distillate

1 Membrane10 MembranesHeat

Recovery

27

HOT Water: A Hybrid Optical Technology for Water(Achilli, Hickenbottom, Norwood, and Li)

Thank you!

[email protected]

Documents

Water for Energy and Energy for Water Energy Workshop... · Andrea Achilli, PhD, PE Assistant Professor. Chemical & Environmental Engineering. University of Arizona. Southwest Regional