Desalination R&D and Applications in Electric Power Generation

Transcription

1 Desalination R&D and Applications in Electric Power Generation EPRI Workshop on Advanced Cooling July 8-9, Mike Hightower Sandia National Laboratories mmhight@sandia.gov, Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

2 Desalination: A National Perspective National Academy of Sciences April 2008 Costs are no longer the primary barrier to implementing desalination technologies Desal costs are going down while other water supply alternatives are going up Concentrate biggest emerging concern for both inland and coastal desalination Environmental and ecological issues of management and disposal of the salt R&D funding is fragmented Reductions in government funding for water and desal research Industry funding is not focused on high-risk research

3 Desalination Capacity Growth Trends (NAS Desal Roadmap 2008)

4 Desalination vs. Fresh Water Costs $ / 1000 gal Years Desal Desal Fresh Fresh

5 Growth in U.S. Membrane Treatment Plants All plants Desalting Plants Two-Year Period (Mickley 2003) Cumulative Number of Plants

6 Emerging Desalination Costs Relative to Traditional Water Supply Options (Affordable Desal Coalition 2008)

7 Desalination Technology Use In the U.S. by Sector (NAS Desal Roadmap 2008)

8 Water Supply Type for Desalination in the U.S. (NAS Desal Roadmap 2008)

9 Water Quality for Various Desalination Feed Waters (NAS Desal Roadmap 2008)

10 Recent Non-traditional Water Treatment Research and Development Funding (NAS Desal Roadmap 2008) Non-industry Research and Development Funding Decreasing Focus on evolutionary vs. revolutionary innovation? Will this limit desal cost and performance improvements?

11 Desalination Research Issues Energy Use and Efficiency Energy use is ~40-60% of desal water cost Thermal processes: distillation, Membrane processes: reverse osmosis, membrane pump heat concentrate concentrate Pretreatment Robust, cost-effective, and low chemical use needed Concentrate Management Disposal is major environmental and economic problem for inland desal and emerging coastal desal issue

12 Desalination: A National Perspective National Academy of Sciences Priority R&D Improve concentrate disposal and management and reduce ecological impacts Assess quantity and distribution of brackish water resources Improve membrane pretreatment approaches Improve membrane performance Higher permeability, fouling and oxidant resistant, hybrid processes (RO/ED) Reduce energy requirements Advanced energy recovery, utilize waste heat, colocation of energy and water facilities

13 Application of hybrid RO/ED to minimize waste and recover saleable products Tom Davis, Univ. of S. Carolina, ZDD Problem: Fresh water recovery limited by low solubility of CaSO 4, scaling. Technical Approach: Control scaling using a metathesis reaction scheme. Increase water recovery by removing calcium ions and sulfate ions to precipitate offline. Pretreated Feed Water NaCl + C A C SA SC - RO Drinking Water Mg-salt Solution Precipitation SO 4 = Ca +2 CaSO 4 (solid) CaSO 4 crystals formed when concentrate streams were mixed in graduated cylinder

14 Emerging Consideration of Desal Evaporation Ponds for Algal Biodiesel Production Micro algae have extremely high lipid content Micro algae might be adaptable to water quality levels exceeding 35,000 ppm TDS Need to improve production by optimizing CO2, sunlight, temperature, and nutrient additions DARPA currently funding research program to assess and accelerate commercial viability

15 Saline aquifers in the continental U.S. The shading refers to the depth to the aquifer. With appropriate treatment, inland brackish water could be an increasingly important source of water for electric power plant use. (Data from Feth, 1965) U.S. Saline Water Resources

16 Brackish Groundwater National Desalination Research Facility In Alamogordo, NM, and opened in August 2007, Designed as a user facility to accommodate visiting researchers and projects, Water qualities of 1500, 3500, and 5000 ppm TDS, Six indoor test bays at 30 gpm, evaporation ponds and five acres for concentrate reuse research, Three large outdoor research pads for large-scale desalination testing at up to 100 gpm each, and Five acres for evaluation of renewable energy (wind, solar, and geothermal) and system integration testing.

17 What is the next generation membrane technology? What will make a difference? increased transport efficiency increased salt rejection decreased fouling susceptibility Ion Transport How do we get there? Block Random nano-structured membranes electrostatic or biomimetic control of ionic transport fouling resistant coatings optimized fluid dynamics of membrane modules

18 Readily accessible fresh water supplies are limited Increased energy for pumping at deeper depths and longer conveyance Non-traditional Water Supplies are more Energy Intensive 5000 Power requirements for current and future water supply Today Future New technologies to access and/or treat non-traditional water resources will require more energy per gallon of water Energy is 80% of municipal water production, treatment, and distribution costs kwh per acre foot of water Public Water Supply Systems Sea Water Desalination Water and waste water sector currently is 3-4% of U.S. energy demand Source: EPRI (2000), Water Desalination Task Force (2003) 1000 Brackish Water Treatment

19 Emerging Desalination Research and Development Directions Use of high efficiency pumps and energy recovery approaches could reduce energy demands by 30-40% System designs to be compatible with lower cost and lower energy use micro, ultra, and nano filtration membranes Hybrid RO/ED evaluations of potential for 10-15% cost, energy, and performance improvements Distillation membrane and other thermal process improvements to utilize waste heat Forward Osmosis Low flux but low fouling and low energy water treatment membranes that can use waste heat for draw solution (Yale process) DARPA has asked for proposals for 2 order of magnitude higher flux membranes Issues will be tradeoffs in costs, fouling potential, and energy demands vs. performance

20 Desalination Planning Reference Guide