The Use of Potential Renewable Energy Resources for Developing Sustainable Water Supplies

Tamim Younos

Virginia Water Resources Research Center and Department of Geography, Virginia Tech

STATEMENT OF THE PROBLEM

Safe and adequate water supplies are needed to protect public health and to sustain economic productivity. The Engineer of 2020, a National Academy of Engineering publication quotes: “The question of water is at the heart of a 600-page world water development report issued by the United Nations in 2003. It’s projected that within the next 20 years virtually every nation in the world will face some type of water supply problem.” In coming decades, significant increased water demand is expected in Northern Virginia, Hampton Roads and population and industrial centers in Virginia. To meet future global water demand, in addition to developing conventional surface and groundwater sources that are quickly diminishing, it will become necessary to develop alternative water sources. Potential alternative water sources include urban storm water runoff, municipal wastewater treatment plant discharges, saline and other waters that are impure for human consumption and economic uses. Currently, advanced and highly effective water purification systems using technologies such as membranes and thermal (distillation) processes are being developed for this purpose. However, these advanced water purification technologies are energy intensive and feasibility of implementing these technologies are directly affected by energy consumption.

ABSTRACT

There is a significant need to integrate renewable energy resources into water production systems. Potential renewable energy resources include solar energy (e.g. photovoltaic and solar energy concentrators/collectors), wind energy, geothermal energy, and ocean energy (tidal power, wave energy, and thermal energy). This poster presentation provides an overview of the potential use of renewable energy resources for developing sustainable water supplies that implement advanced water purification technologies.

The presentation addresses the potential and limitations of these alternative energy resources for production of sustainable water supplies in Virginia and the need for developing interdisciplinary research, institutional framework, and policy making to meet future global water demand.

Acknowledgments:

Kimberly Tulou assisted with research, Jane Walker with editing, and Kelly Davis with developing the poster.

INTEGRATING RENEWABLE ENERGY RESOURCES TO PRODUCE SUSTAINABLE WATER SUPPLIES

Potential Renewable Energy Resources Alternative Water Sources

WATER PURIFICATION TECHNOLOGIES AND ENERGY CONSUMPTION

Membrane Technologies

Membrane water purification processed use either pressure-driven or electrical-driven technologies or a combination of these technologies. Reverse Osmosis (RO), a pressure-driven process, is the most common technology in the United States. Energy is needed to operate the process.

Thermal Technologies

Thermal technologies use evaporation and distillation processes to purify water. The process is highly energy intensive and uncommon in the United States. Advanced technologies such as Mechanical Vapor Compression (MVC) integrate thermal and mechanical energy.

Water Purification Technology Type of Energy Work* Consumed (kwh/m 3 ) Reverse Osmosis (RO)

Mechanical Energy With Cogeneration & Steam

Electrodialysis (ED)

Electric Energy

Multistage-Flash Evaporation (MSF) Low Temperature Multi Effect Evaporation (LT- MEE) Multi Effect Evaporation Thermal Vapor Compression (MEE-TVC) Mechanical Vapor Compression (MVC)

Thermal Energy + Mechanical Energy With Cogeneration Thermal & Mechanical Energy With Cogeneration Thermal and mechanical Energy Mechanical Energy

Hybrid RO/ME

Thermal & Mechanical Energy 4.2 – 10.0

2.3 – 5.8

1.7

18.8

23.2

4.7

5.0

2.1 – 4.6

9.0 – 17.0

6.0 – 18.5

1.35-1.6

Solar Wind Geothermal Ocean

Advanced Water Purification Technologies Sustainable Water Supplies

Wastewater Runoff Saline Water Other

GLOBAL EXAMPLES USING RENEWABLE ENERGY RESOURCES FOR DEVELOPING WATER SUPPLIES

Photovoltaic arrays convert solar energy into electricity through the transfer of electrons. The arrays are made of silicon chips because silicon effectively and efficiently transfers electrons. When sun rays shine on the silicon chips, the electrons jump to another orbit. This movement creates a voltage that can be used to power pumps for water purification.

Wind energy rotates windmills creating mechanical energy that can be converted to electrical energy. Turbines utilizing wind energy for low power (10 kW-100 kW), medium power (100 kW-0.5 MW), and high power (> 0.5 MW) are mature technologies.

APPROACHES TO MEET ENERGY DEMAND

•Energy Conservation •Increase Output of Traditional Sources (coal, oil, nuclear) •Using Renewable Energy Sources (solar, wind, geothermal, ocean)

Location

Perth, Western Australia Jeddah, Saudi Arabia North of Jawa, Indonesia Vancouver, Canada* Red Sea, Egypt Hassi-Khebi, Argelie

Power Generated (kW) Technology

1.2

8 RO RO 25.5

4.8

19.84 2.59

RO RO RO RO

Capacity (gal/d)

634-3170 845 3170 264 13210 6023

Location

Shark Bay, Australia Borj-Cedria, Tunisia Fuerteventura Island, Spain Ile du Planier, France Helgoland, Germany Ruegen Island, Germany Gran Canaria, Spain

Power Generated (kW)

32

Tech nology

RO RO + ED

Capacity (gal/d)

44380 & 34340 200 RO RO RO MVC RO 14794 3170 6086000 31700-79250 52830

APPLICATION POTENTIAL IN VIRGINIA

Renewable Energy Sources Direct Solar Energy (Stills) Advantages

Affordable and easy to maintain, good efficiency

Disadvantages

Requires large land area and sunlight

Cost

Low

Applicability in Virginia

Not applicable as a significant energy source in Virginia - applicable for remote areas with lots of sunlight

Indirect Solar Energy (Photovoltaic & Solar Collectors) Wind Energy Geothermal Energy

Good energy collectors Mature technology that can generate large amounts of energy Large amounts of resources available in some areas Low efficiency, and high manufacturing costs, requires large arrays Wind is intermittent Technology is undeveloped for application to desalination Med .

?

Has potential for use as a power supplement. Research is needed to increase efficiency and determine potential in Virginia Applicable but may not have enough winds to be cost-effective in Virginia coastal areas.

Research is needed to determine the potential.

?

Not applicable as a significant energy source in Virginia - there are not enough geothermal reserves in Virginia

Ocean Energy Tidal

Tides occur at every coastline, fairly efficient Energy is intermittent High Applicable but may not have enough difference in elevation between tides to be cost-effective.

Research is needed to determine the potential.

Ocean Energy Wave

Cost effective for large plants, less expensive than diesel or hydropower Wave heights vary Med .

Applicable Research is needed to determine the potential.

Ocean Energy Thermal

Research in progress Few areas where ocean has significant temperature variations with depth, expensive, low efficiency High Applicable but not practical until technology is further improved and costs are decreased.

RECOMMENDATIONS

1.

2.

3.

Develop an atlas of potential renewable natural resources in Virginia with regard to their availability and potential in a Geographic Information System (GIS) environment Form an interdisciplinary research team of experts in energy, water purification technologies, water resource economics, and geospatial analysis to develop a template for overall research needs and costs Create a statewide task force that includes representatives from regulatory agencies, utilities (water and power), academia, and citizens that will develop the framework for institutional infrastructure and implantation strategies for using renewable energy for water production.

REFERENCES

Younos, T (Ed.). 2005. Desalination – A Primer. Journal of Contemporary Water Research & Education. Universities Council on Water Resources, Carbondale, Ill. 52 pp. To order e-mail: [email protected].

Younos, T. 2004. The feasibility of using desalination to supplement drinking water supplies in Eastern Virginia. VWRRC Special Report SR25-2004. Virginia Water Resources Research Center, Virginia Tech, Blacksburg, VA. 114 pp. Available Online: www.vwrrc.vt.edu/publications/recent.htm