The Implications of Brackish Water Desalination in Texas Tabish Khan Texas Water Policy PA 388K, Fall

Transcription

1 The Implications of Brackish Water Desalination in Texas Tabish Khan Texas Water Policy PA 388K, Fall

2 Introduction Texas is experiencing drastic population growth with a large-scale shift to urban population centers. The Texas Water Development Board (TWDB) has identified this trend and has produced a water plan to address this issue. According to the TWDB s 2012 Water Plan traditional water supplies will no longer be able to meet the demand of our state s expanding population. One method that will see increasing use is brackish groundwater desalination. Brackish desalination is the process of purifying brackish water that contains 1,000 10,000 milligrams of dissolved solids per liter. It is by no means a new approach as Texas already has 46 municipal brackish ground and surface water desalination facilities, which can produce about 25,000 gallons of freshwater per day (20). According to Dr. Sanjeev Kalaswad, Director of Conservation & Innovative Water Technologies at the TWDB almost every aquifer in the state has brackish groundwater, and there are 30 designated aquifers in the state (8). These aquifers are reported to contain about 2.7 billion acre-feet (~880 trillion gallons) of brackish groundwater, which dwarfs the state s fresh water supply (1). This amount of water is enough to cover all of Texas (268,820 miles 2 ) in a depth of more than 15ft (1). It is estimated that it would last at our current consumption levels for 150 years (1). Five out of 16 regional water planning groups recommended groundwater desalination in the 2012 Regional Water Plan to meet projected water needs in 2060, and even more regions are expected to recommend it in the 2017 plan (8). However, desalination is a more expensive and energy intensive process than traditional methods of water production. Energy production in Texas is predominately fossil fuel based which requires water and introduces a negative feedback loop into the process. Energy is required to desalinate water and water is required for energy. Desalination also produces a concentrated briny byproduct that adds additional disposal costs to production. Therefore, increasing use of

3 desalination will likely cause the price of water to increase. The Texas legislature is attempting to prepare for this inevitability with multiple bills passed during the 84 th legislative session that seek to expand brackish groundwater desalination as well as address the impacts of this method. It is important to understand the implications of this expansion of our water production methods into more expensive and extreme methods. Consideration must be given to the potential of water becoming increasingly expensive to the end users, negative environmental consequences, and the best ways to mitigate these consequences. Brackish Water Policy Many of Texas s water related issues can be traced to the fact that there is simply no universal set of standards to coordinate and collaborate policies between the myriad of organizations that administer Texas water policy. For example a precise multi-agency definition for what constitutes brackish water does not exist in Texas (1). A simple lack of definitions can lead to disagreements and eventually litigation down the road. Litigation in the realm of water policy is inevitable, however, minimization will be important if we are to manage our resources effectively. Brackish water policy has evolved significantly over the 83 rd and 84 th legislative sessions. The 83 rd legislative session saw two bills related to brackish water production introduced; however, they both failed. One of those bills, SB 1284, sought to support development of brackish water desalination projects, provide local water supplies, help improve brackish water treatment technology, and support reliable power generation to the Electric Reliability Council of Texas (ERCOT) (12). Another, HB 2578, would have required regional planning groups to identify opportunities for, and benefits of, developing large scale desalination facilities for brackish groundwater with the purpose of streamlining and reducing the cost and regulation of

4 desalination (4) (13). It seems that in the 83 rd legislative session, senators were reluctant to pass bills that would take away authority from the groundwater districts, which they believed, were more capable of addressing the issues they were facing (10). During the 84 th legislative session however, multiple bills related to the development of brackish groundwater were proposed of which several were signed into law. Successful bills included the following: HB 30, which amended the Texas Water Code to require the TWDB s biennial desalination progress, report to include identification and designation of local or regional brackish groundwater production zones in certain areas of the state (18). The TWDB is actively engaged in carrying out this legislation and on 30 October 2015, they actually held a public hearing for discussion on identifying and designating local or regional brackish groundwater production zones (2). HB 1232 also expanded the TWDB s role in brackish water development by requiring the TWDB to study, define and map the quality and quantity of groundwater in confined and unconfined aquifers in the state (16). Legislation to address the inherent drawbacks of desalination were also passed and signed into law during the 84 th session. SB 991 was passed to address the fact that desalination is energy intensive and as most of the energy in Texas comes from fossil fuel powered steam generation, desalination would, under most current methods of power generation, be water intensive (7). SB 911 required the General Land Office (GLO) and the TWDB to study the economic and geophysical potential of using

5 wind and solar PV energy to desalinate brackish groundwater, with a plan to add additional renewable technologies for seawater desalination in the study (7). HB 2230 attempts to help address the inevitable byproduct by desalination operations, which is concentrated salty brine. Previously this concentrate could only be disposed of in Class V injection wells permitted by the Texas Commission on Environmental Quality while Class II injection wells are permitted by the Texas Railroad Commission (TRC) for the disposal of waste from oil and gas exploration (3). This bill allows the TCEQ to authorize the disposal of desalination plant concentrate into Class II injection wells, which should decrease the cost of inland desalination operations (3). This is promising considering the abundance of oil and gas operations and therefore disposal wells in Texas, however, the environmental implications of injection disposal must be acknowledged. Injections wells have the potential to leak and contaminate the surrounding environment (21). There may also arise some regulatory overlap as the EPA is also involved in the regulation of injection wells (21). Regulations require operators of class II injection wells to conduct mechanical integrity tests every 5 years and in 2010, one out of every three wells in Texas were found to be in violation of regulations (21). It is clear that the attitudes towards brackish desalination have changed but that is to be expected given the recent droughts and the rising fear of water shortages. However, there is still some hesitation from local stakeholders, after this round of legislation Tim Andruss, the general manager of the Calhoun, Victoria, Refugio and Jackson County GCDs stated: "I don't want there to be the appearance that there is a resistance to allowing groundwater development. The districts want to see the management of groundwater resources carried out in a way that brings about a long-term sustainability of the resource, while only allowing a level of impact that is considered acceptable by local officials accountable to their residents" (10). "In

6 general those projects that have local impacts on local resources should be regulated by locally elected officials" (10). The issue with local control by locally elected officials is that aquifers transcend the boundaries of the GCDs, which mean local controls, and regulation would inherently be ineffective at properly managing this resource. The images below highlight the incongruence between aquifer boundaries, groundwater management areas, and groundwater conservation districts.

7 Current brackish operations Out of the 46 current desalination plants that are operational in Texas 34 use brackish groundwater (1). As of January 2014, El Paso had the world s largest inland desalination plant and San Antonio is building an inland desalination plant that is scheduled for completion by October 2016 (1) (15). In its first phase, the San Antonio plant is expected to have the ability to produce 10 million gallons of fresh water daily and further planned expansions in 2021 and 2026 could potentially raise its daily output to 25 million gallons per day (1). One must consider however, that production volumes will be limited to as needed due to the high cost of desalination. For example, the El Paso plant known as the Kay Bailey Hutchison Desalination Plant is capable of producing 27.5 million gallons of freshwater per day. However, of that total

8 production capacity its desalination capacity is 15 million gallons per day, and as of September 2010 its Desalination Plant Report shows that it was only desalinating an average of 3 million gallons per day as more is not needed yet (19). - Image courtesy of Texas Water Report a publication of Texas Comptroller of Public Accounts Brackish desalination costs The cost of desalinating water depends on a variety of factors, including the salinity of the source water, size of the plant, and the available methods for brine disposal (1). In addition, energy requirements can account for half the cost of desalination (1). The vast majority of Texas desalination operations utilize reverse osmosis (RO), which pushes water at high pressure

9 through a semi-permeable membrane (8). Freshwater diffuses through the membrane and leaves a highly concentrated salty brine on the other side (8). This technology is very energy intensive but has become slightly more efficient since its first operational use in the 1970s, however, that has only reduced the original energy requirement by 10% (8) (1). The energy requirement for RO is about 289 to 815 kilowatt-hours per acre-foot and by comparison 800 kilowatt-hours can power a computer and monitor for eight hours every day for a year (1). This may seem like a high cost, however, it is often less expensive than importing water through pipelines (1). For example, a study conducted in 2011 assessed that out of El Paso s available water supply options, brackish desalination would cost $534 per acre-foot while importing water would cost $1,309-$2,535 per acre-foot (1). El Paso is currently producing its desalinated water at 2.1 times more than its cost for fresh groundwater and 70% more than surface water, according to the local utility (8). As of 2012, the TWDB reported that desalinated water from recently completely plants in Texas ranged from $357 to $666 per acre-foot (1). A project that resulted from SB 991 in Seminole, TX seeks to test the use of wind energy to power its RO desalination plant. The TWDB has funded the project and while it is not finished yet the results are promising (8). Environmental Concerns A multitude of environmental concerns should be taken into account as well as brackish groundwater development expands. These issues include formation dewatering, saline intrusion, and subsidence, which can be an issue in aquifers with a high clay content (9). Many experts are well aware of these potential issues and agree more research is needed to understand these potential consequences.

10 Formation dewatering is effectively the drainage of a formation which leads to subsidence and cannot be reversed as the land compresses into where the water previously was. With regards to saline intrusion, Dr. Bridget Scanlon, a senior research scientist at UT Austin s Bureau of Economic Geology (BEG) noted, it s important to look at each aquifer s geology and determine if or how brackish water supplies are connected to freshwater, so that you know how extracting brackish water might impact freshwater (5). For example, we don t have a lot of data or geophysical logs for brackish [groundwater], she said. In some parts of Canada, they have policies requiring the oil companies to log from the land surface down, so that you have more information in that shallow zone, where you have brackish water. Having that type of information would be beneficial in the United States (8). Scanlon also explained that pumping brackish water would impact freshwater in the case of a dipping aquifer (8). A dipping aquifer is an aquifer that dips down toward the Gulf Coast with the freshwater grading into deeper brackish water that is connected to the freshwater (8). Greg Sengelmann Gonzales County Underground Water Conservation District general manager stated, Brackish water tends to underlie freshwater zones, but the level of separation between the zones can vary from one aquifer to another (9). In aquifers such as the Carrizo-Wilcox, the brackish and freshwater zones are separated by hundreds of feet of less permeable rocks such as siltstone and shale while in others the two are more closely connected flow into each other (8). According to Dr. Sanjeev Kalaswad, of the TWDB, the state (TWDB) is mapping the location of brackish aquifers and characterizing the depth, amount and quality of brackish groundwater through the Brackish Resources Aquifer Characterization System (BRACS) (8). BRACS was established by the Texas legislature in 2009 (8). BRACS has done studies on the Pecos Valley

11 Aquifer in West Texas, and it is currently studying the Gulf Coast Aquifer in the Rio Grande Valley as well as two other aquifers in south-central Texas (8). Kalaswad said the TWDB eventually hopes to conduct BRACS for all Texas aquifers (8). Several methods of brine disposal are available for inland desalination plants and they include deep well injection, discharge to surface waters, a municipal sewer system, an evaporation pond, and/or land application. These all have their unique environmental and cost drawbacks. The TCEQ has different permits for each disposal method, however, HB 2230 should make it easier to receive permits for more deep well injections (8). A Way Forward Given the uncertain nature of brackish groundwater desalination, some water project developers are focusing on even more expensive seawater desalination which doesn t have some of the externalities that groundwater brings with it (9). There's no question of who has the water rights, said Greg Neal, a project developer with RWL Water, which builds water and wastewater treatment as well as desalination plants (9). "I'm very focused on seawater desal right now," Neal said. "In my opinion inland brackish is just - until the rules are established - it's just too difficult to determine the business model" (9). The Texas Comptroller s recent report urged innovative new technologies for new water, including brackish groundwater (8). The report encouraged research to produce better membranes that reduce potential for fouling and increase the flow of water through them at a given pressure to reduce energy use (8). In addition, a more effective method for the disposal of the brine concentrate is also needed (8). Alternative desalination methods such as forward

12 osmosis and capacitive desalination, which are much more energy-efficient than RO, are under development as well (8). Forward osmosis utilizes a process that combines osmosis with heat, which is preferably waste heat from a power plant s cooling water discharge. Water flows across a selectively permeable membrane from brackish water to salty water prepared with specific salts (8). Freshwater is then removed from the salty water by applying the harvested heat (8). According to the Comptroller s report, forward osmosis plants are already in place in countries such as Gibraltar and Oman in the Persian Gulf (8). - HTI Water Technology Capacitive desalination is a process in which charged molecules in the water are removed by electrostatic attraction to a solid surface that has an electrical potential (8). The ions of sodium and chloride can then be removed and released into a waste brine for disposal (8). At the moment, inland desalination systems recover up to 80 percent of the water extracted from underground, and dispose the remaining 20 percent of water heavily concentrated with salt (6).

13 Seawater desalination plants have the luxury of being able to discharge their brine straight into the ocean; however, inland desalination operations do not have this method available to them. Different methods of brine disposal and mitigation are being researched to alleviate the cost of inland desalination brine disposal. Zero-liquid discharge systems would also extend the range of places where desalination could be used since they would not require an injection well, access to the coast, or evaporation ponds (8). Conclusion Desalination has several drawbacks, however, it seems as though it may be the only choice as a long-term method of meeting Texas s water requirements. As Dr. Kalaswad said, The technology is there; it s just a matter of availability of the resource and how much people are willing to pay for water (8). Even though brackish desalination only accounts for a small percentage of our current water plan, Kalaswad expects it to become a prominent part of our water supply in the future (8). Identification of resources and mitigation of risk will be necessary for this to happen. This in addition technology could then eventually provide access to inexpensive desalinated water while minimizing waste and environmental damage.

14 References 1. Combs, Susan. Texas Water Report: Going Deeper For the Solution. Rep. no Austin, TX: Texas Comptroller of Public Accounts, Online. 2. "Request for Public Input on Brackish Groundwater Production Zones." Texas Desalination Association (06 Oct. 2015): n. pag. Texas Desalination Association. 06 Oct Web. 3. Pankratz, Tom, ed. Water Desalination Report: Texas Legislature Addresses Desal. Rep. 26th ed. Vol. 51. Houston, TX: Global Water Intelligence, Online. 4. Dowell, Tiffany. "Water Bills Summary of the 2013 Texas Legislative Session." Weblog post. Texas Agricultural Law Blog. Texas A&M Agrilife Extension, 01 July Web. 5. Lee, Leslie. "Underground and Under Scrutiny: A Changing State Increasingly Turns to Groundwater." TxH2O (Summer 2014): n. pag. Texas Water Resources Institute. Web. 6. "UTEP Desalination Project Nears 100 Percent Efficiency Goal." Conservation Matters (Feb. 2013): n. pag. Texas Water Resources Institute. Web. 7. Zerrenner, Kate. "A Roundup of Energy, Water, and Climate Bills in the 84th Texas Legislative Session." Web log post. Texas Clean Air Matters. Environmental Defense Fund, 19 Mar Web. 8. Wythe, Kathy. "Everybody Is Talking About It: Is Brackish Groundwater the Most Promising "New" Water." TxH2O (Summer 2014): n. pag. Texas Water Resources Institute. Web. 9. "Con: Brackish Desal Needs More Research." Victoria Advocate. N.p., 08 Feb Web. 10. Frazier, Kyle. "Pro: Legislation Could Define Management of Brackish Water." (11 Feb. 2015): n. pag. Texas Desalination Association. Web. 11. Frazier, Kyle. "Texas Legislature Addresses Desal." (14 July 2015): n. pag. Texas Desalination Association. Web. 12. Texas. Senate. Natural Resources Committee. By Charles Schwertner. 83rd Cong., R sess. S. Bill Apr Web. 13. Texas. House. By Lyle Larson, William A. Callegari, Rodney Anderson, and Jason Villalba. 83rd Cong., R sess. HR Web. 14. Márquez, Marisa. "Texas Legislature Actions HB 1088." Texas Legislature Online. N.p., 20 Apr Web. 15. Horne, Justin. "SAWS Desalination Plant Halfway through Construction." Online Posting. KSAT 12. ABC News, 17 July Web.

15 16. Lucio, Eddie, III. "Texas Legislature Actions HB 1232." Texas Legislature Online. N.p., 28 May Web. 17. Larson, Lyle. "Texas Legislature Bill Stages HB 835." Texas Legislature Online. N.p., 21 Jan Web. 18. Texas. House. Texas Legislature. By Lyle Larson and Charles Perry. 84th Cong., R sess. HB 30. N.p., July Web. 19. Desalination Plant Report. 01 Sept Raw data. Kay Bailey Hutchison Desalination Plant, El Paso, TX "Desalination FAQ." Innovative Water. Texas Water Development Board, n.d. Web. 21. Lustgarten, Abrahm. "Injection Wells: The Hidden Risks of Pumping Waste Underground." Propublica.org. Pro Publica, 21 June Web