1. Sam Aminfard CATEE 2017 – Texas Energy Summit November 15, 2017
Technical and Economic Potential of Purifying Brackish Groundwater on Texas State Lands Using Integrated Renewables and Desalination Facilities
Sam Aminfard
CATEE 2017 – Texas Energy Summit
November 15, 2017

2. The energy required to desalinate water was estimated using the well data for salinity and depth
High : 19.5 kWh/kgal
Low : 2.0 kWh/kgal
Desalination Energy Intensity
High : 19.5 kWh/kgal
Low : 2.0 kWh/kgal
Desalination Energy Intensity
The energy intensity of desalinating water rises with salinity.

3. High resolution maps of capacity factor for wind and solar resources were employed

4. Local water prices can determine the economic viability of desalination

5. We identified 193 sites that have estimated water costs lower than local municipal prices.
Water Cost [$/kgal]
Wind
Solar
Down-Selected Sites for Local Economic Viability
Min Max Mean #
Solar
Wind

6. Projected water need can also be used to select sites in water stressed areas.
2020 Annual Water Need by County [billion gal]
Water Cost [$/kgal]
Wind
Solar
Min Max Mean #
Solar
Wind

7. Sam Aminfard F. Todd Davidson, Ph.D. sam.aminfard@utexas.edu
Graduate Research Assistant
Webber Energy Group
The University of Texas at Austin
Research Associate | Lecturer
Webber Energy Group | Energy Institute
The University of Texas at Austin

8. Backup

11. Compared to 2014, TX is expected to consume 30% more water annually by 2020*
* Texas Water Development Board, “2017 State Water Plan”, Austin, TX (2016)

12. Compared to 2014, TX is expected to consume 30% more water annually by 2020*
* Texas Water Development Board, “2017 State Water Plan”, Austin, TX (2016)

13. How will we address potential shortages?
Compared to 2014, TX is expected to consume 30% more water annually by 2020*
How will we address potential shortages?
Conservation of existing fresh water resources
Increase supply of fresh water
* Texas Water Development Board, “2017 State Water Plan”, Austin, TX (2016)

14. There are major barriers to this strategy:
Desalination of brackish or saline water can vastly increase fresh water supplies
There are major barriers to this strategy:
High capital costs
Significant energy demands

15. TX has significant brackish groundwater resources
TX has significant brackish groundwater resources. With sponsorship from the Texas General Land Office, we studied the technical and economic potential to purify brackish groundwater on state lands using integrated renewable energy.

16. Executive Summary
We investigated 1,445 TX GLO sites to determine the cost of desalinating brackish groundwater with wind and solar
Estimated costs were lower at 193 sites
Wind was cheaper at 145 sites
Solar was cheaper at 48 sites
Many sites with relatively low desalination costs are in regions with high projected water demand

17. Desalinating brackish groundwater with renewable energy can be cost-competitive.

18. Desalinating brackish groundwater with renewable energy can be cost-competitive. The strategy is most competitive in water stressed regions with shallow, low salinity aquifers and abundant renewables resources.

19. Methods

20. Well data was gathered from the Texas Water Development Board database

21. Well data was gathered from the Texas Water Development Board database
Sea Water ~ 35,000 mg/L TDS

22. Wells shallower than 10 ft with salinity below 1000 mg/L were removed

23. Well depth was interpolated across Texas for wells >10 ft and >1000 mg/L
Well data from TWDB used to create maps

24. TDS was interpolated for wells >10 ft and >1000 mg/L
Well data from TWDB used to create maps

25. Regions without brackish groundwater were removed
Well data from TWDB used to create maps

26. The interpolated data for well depth and salinity levels were overlaid to determine energy requirements for desalination
Well Depth +
Well Salinity

27. Renewable Resources

28. Class 3 and higher regions are generally considered suitable for utility-scale wind turbine applications

29. Solar energy resources are abundant but vary across the state
For comparison
Germany has kWh/m^2/day

30. Texas receives almost double the solar energy per square meter as Germany every year
For comparison
Germany has kWh/m^2/day
Source: NREL

31. The best wind and solar resources are in Western Texas

32. Infrastructure

33. Presence of water infrastructure indicated by public wells and surface water intakes.

34. The distance to wells and surface water intakes was calculated across Texas
We assume that the maximum pipeline length will be the distance to the nearest well or intake. Additional investigation might find closer connections.

35. Estimating Cost

36. Cost estimates are generated using the TWDB’s Unified Costing Model
TWDB developed a publicly-available tool for estimating the cost of water infrastructure projects to unify and support regional and state water plans.
We adapted the formulas and interpolated data tables in this tool to generate cost estimates for desalination plants and their supporting infrastructure (pipelines, pumps, wells, etc)
Our model tags the local resource data in the previous slides to each GLO site. These are used as inputs to size a renewables-integrated brackish water reverse osmosis project and estimate the cost of water at each site

37. The cost of desalinated water varies significantly based on the location
1 MGD Water Cost w/ PV [$/kgal]
Estimated
prices for using Solar Power
Mean: 4.25
Municipal Rates: 0.10 – $/kgal

38. A concentrated brine is produced during the desalination process that needs to be disposed of -- disposal can be outsourced or a salt water injection (SWI) well can be drilled or purchased. We assumed that a >0.25 MGD (~6000 bbl/day) SWI well would be drilled onsite at an estimated cost of $3 million. This well could handle the disposal needs of a 1 MGD desalination plant with an assumed recovery rate of 80%.

39. The cost of desalinated water varies significantly based on the location
1 MGD Water Cost w/ PV
and Disposal [$/kgal]
Estimated
prices for using Solar Power
Mean: 5.05
Municipal Rates: 0.10 – $/kgal

40. The cost of desalinated water using wind is approximately $0. 16 -- $1
The cost of desalinated water using wind is approximately $ $1.12/kgal less expensive than solar.
1 MGD Water Cost w/ Wind [$/kgal]
Estimated
prices for using Wind Power
Mean: 4.21
Municipal Rates: 0.10 – $/kgal

41. The cost of desalinated water using wind is approximately $0. 16 -- $1
The cost of desalinated water using wind is approximately $ $1.12/kgal less expensive than solar.
1 MGD Water Cost w/ Wind
and Disposal [$/kgal]
Estimated
prices for using Wind Power
Mean: 5.01
Municipal Rates: 0.10 – $/kgal

42. Local water prices can determine the economic viability of desalination
Min. Muni. Water Price[$/kgal]
Mean: 4.82

43. Local water prices can be used to limit potential projects to areas where production costs are competitive
1 MGD Water Cost w/ PV
and Disposal [$/kgal]
Estimated
prices for using Solar Power
Mean: 4.23

44. Using wind power produces similar results as solar for determining which sites are competitive with municipal water
1 MGD Water Cost w/ Wind
and Disposal [$/kgal]
Estimated
prices for using Wind Power
Mean: 4.17

45. Summarized Results

46. Combining the previous maps gives the lowest water production cost using wind or solar power
Water Cost [$/kgal]
Down-Selected Sites for Local Economic Viability
Min Max Mean #
Solar
Wind

47. Projected water need can also be used to select sites in water stressed areas.
2020 Annual Water Need by County [billion gal]
Water Cost [$/kgal]
Wind
Solar
Min Max Mean #
Solar
Wind

48. Conclusions
Desalinating brackish groundwater with renewable energy can be cost-competitive
The large number of economically competitive sites shows potential for desalination on Texas GLO land using renewable energy
Further research must be done to more precisely determine the cost and viability of projects at specific locations
El Paso County presents an interesting mix of results and variables worth further investigation
Wichita Falls for cheap wind
Hudspeth and Presidio Counties for cheap solar
Reeves County for GLO availability, aquifer data, O&G markets. Mix of wind and solar.

49. Only considering GLO land with Class 3+ Wind limits the number of potential sites
1 MGD Water Cost w/ Wind
and Disposal [$/kgal]
Estimated
prices for using Wind Power
Mean: 4.20
Municipal Rates: 0.10 – $/kgal

50. Local water prices can be used to limit potential projects to areas where production costs are competitive. These results do not include disposal.
1 MGD Water Cost w/ PV [$/kgal]
Estimated
prices for using Solar Power
Mean: 3.52

51. Using wind power produces similar results as solar for determining which sites are competitive with municipal water. These results do not include disposal.
1 MGD Water Cost w/ Wind [$/kgal]
Estimated
prices for using Wind Power
Mean: 3.47

52. Adding disposal costs and limiting to Class 3+ Wind areas constrains the available sites even further
1 MGD Water Cost w/ Wind
and Disposal [$/kgal]
Estimated
prices for using Wind Power
Mean: 4.21

53. The energy intensity of desalinating water rises with salinity.

54. Acknowledgements Dr. F. Todd Davidson Dr. Michael Webber
TX General Land Office
Mark Adams
Andrew Hart
TX Water Development Board
Sanjeev Kalaswad
John Meyer
Erika Mancha
Environmental Defense Fund
Kate Zerrenner