Presentation on theme: "Dr. M. S. Al-Ansari University of Bahrain Dr. Nader Al-Masri Water Research Expert Muscat, December, 19-21, 2010 Sustainable Desalination Technologies."— Presentation transcript:
Dr. M. S. Al-Ansari University of Bahrain Dr. Nader Al-Masri Water Research Expert Muscat, December, 19-21, 2010 Sustainable Desalination Technologies For GCC Future Third SQU-JCCP Joint Symposium Environmental Challenges & Mitigation Approaches for Sustainable Development in the Oil & Gas Industry
Presentation Outline Water stress regionally and globally. Hybird desalination plants MSF-RO plant Nanofilteration and MSF Hybirdization of Nuclear-powered MSF-RO Environmental Impact of desalination plants Energy sources for desalination Futuristic development on membrane systems Conclusions
Water Stress Globally 2.3 billion live in water-stressed areas, 1.7 billion out of them live in water-scarce areas. This situation – in some countries-is expected to be worth as a result of climate change phenomena. Thus, UN General Assembly set a target to halve the world population who are unable to access safe drinking water by the year Possible options include: Better Water Conservation Better Water management Pollutaion control Water reclamartion Water Desalination
Water Stress Regionally Water use in GCC countries is expected to increase by about 36% in the period The increase is mainly due to population increase, the high living standards, and economic development. ( Ref: ESCWA, 2005 ) Water Uses in GCC countries
Water Stress Regionally GCC population is likely to hit 53 million capita by the year 2025 ( ESCWA, 2005 ) with the vast majority of people under 25 years.
Water resources include conventional resources (surface water and groundwater) and Nonconventional sources (treated wastewater, desalination, and agricultural drainage water). The total water resources is about 14 billion cubic meter, 44.5% is surface water, 29.5% is groundwater, 19.9% desalinated water, 5% is treated wastewater, and 1.1% is agricultural drainage water. 68.8% of total water resources is located in KSA, followed by Oman and UAE in ratios 12.3% and 11.4% respectively. Other GCC countries account for only 7.5%. Development of conventional sources has low potential while development of nonconventional sources is very costly and has impacts on the environment. Water Stress Regionally ( Ref: ESCWA, 2005 )
The annual per capita conventional water resources ranges from 598 CM in Oman to 71 CM in Kuwait. The annual per capita nonconventional water sources ranges from 306 CM in UAE to 45 CM in Oman. The total annual per capita water ranges from 643CM in Oman to 234 CM in Kuwait. ( Ref: ESCWA, 2005 ) All countries are well below the water poverty limit set by WHO at 1000 CM per capita. Water Stress Regionally
Development of nonconventional water sources is very promising especially the treatment/desalination costs are gradually decreasing with more attention given to the environmental impacts. The cost of desalination has dropped, while the cost of water produced in conventional treatment plants has risen, due to over-exploitation of aquifers, intrusion of saline waters in coastal areas. Water Stress Regionally Ref: Wangnick, 2004
Desalination is an energy and capital-intensive process. It consumes significant amounts of energy and materials whose costs have risen in the past few years. Thus, desalination projects have to balance these two factors and make further technological advances in order to minimize the costs. Given that global water demand growth is expected to require an investment of $40–50 billion on desalination projects over the next ten years, We have to look for new ideas on hybridisation, energy recovery and more effective materials and chemicals. We have to learn how to extend the life of existing plants and upgrade existing desalination facilities. In an era of high energy and material cost, technology with an integrated use can compensate the impact on rising cost. DesalinationDesalination
The following chart4 was adapted from the US Bureau of Reclamation Desalting Handbook for Planners and illustrates the relationship between production capacity and water cost.
Recent technological developments and new methods of project delivery are driving this heightened level of interest to the point that desalination is now being seriously evaluated on projects where it would not have been considered ten years ago. The most significant trend in desalination is the increased growth of the reverse osmosis (RO) market. Technological improvements have both dramatically increased the performance of RO membranes. Todays membranes are more efficient, more durable, and much less expensive. Improvements in membrane technology are complimented by improvements in pretreatment technology, which allow RO membranes to be considered on a much wider range of applications. Energy costs are directly related to the salt content of the water source, and may represent up to 50% of a systems operational costs. There has been a growing trend to reduce energy costs through improvements in membrane performance and by employing modern, mechanical energy recovery devices that reduce energy requirements by 10-50%. Plant Size The design complexity and operation of a large-scale RO plant is not significantly different than that of a smaller plant, and economies-of-scale can contribute to a considerable reduction in the cost of water production. Development and permitting costs are much more dependent on siting-related issues than they are to a plants production capacity
The hybrid desalting concept is the combination of two or more processes in order to provide a better and lower cost product than either alone can provide. In desalination, there are distillation and separation processes which under hybrid conditions can be combined to produce water in a way that is economical. There are two or three elements that can be integrated to tailor hybrid desalination. They include Distillation (MSF, MED, and VC), Membrane separation (RO, and NF), and Power (power plants or electricity) In the simple hybrid MSF/RO desalination power process, a SWRO plant is combined with either a new or existing dual- purpose MSF or MED desalination plants. The first simple hybrid systems reported are Jeddah, Al Jubail and Yanbu- Madina power desalination. Hybrid desalination plants
Hybridization of SWRO and MSF technology was considered to improve the performance of latter and reduce the cost of the produced water. idle power in winter (seasonal surplus of unused power) was mainly utilized by RO to further reduce the cost of the hybrid system for six months of the year. Spinning reserve was also used to further reduce the cost of the proposed hybrid system. Integration of the three processes of MSF, MED, and RO desalination technologies could be made at different levels through which the resulting of water cost will depend on the selected configuration and the cost of materials of construction, equipment, membrane, energy, etc. Thus, the capital and annual operating costs were calculated. It was reported that for all plant capacities, integrated hybrid systems resulted in most cost effective solution. Hybridization MSF-RO plant
Fujairah hybridiz MSF-RO plant is the largest seawater desalination and power plant in the world hybrid configuration of thermal processes and reverse osmosis to be implemented up to now. The Fujairah plant due to hybridisation generates 500 MW net electricity for export to the grid, and 662 MW gross is used for water production of 455,000 m 3 /d. Hybridization MSF-RO plant Hybird System SchematicFujairah Desalination Treatment System
Removal or significant reduction of hardness in seawater, lowering of TDS and removal of turbidity from the feed to seawater desalination plants should lead to an improvement in the conventional seawater desalination processes by lowering of their energy requirement and chemical consumption, by increasing water recovery with the ultimate benefit of lowering the cost of fresh water production. This has been shown to be feasible by a combination of NF with the conventional seawater desalination processes. Nanofiltration membrane softening technology increases the capacity of existing MSF plant from nominal 22,700 m 3 /d to 32,800 m 3 /d (+40%). Hybridization of nanofiltration and MSF
Rising Costs, uncertain availability, environmental concerns of fossil fuel have led to the need to use renewable and other sustainable energy sources, including nuclear. Desalination of seawater using nuclear energy is an option with a proven track record ( over 200 reactor-years of operating experience ). Water cost from nuclear seawater desalination are in the same range as costs associated with fossil-fuelled desalination. Utilizing waste heat from nuclear reactors have been proposed to further reduce the cost of nuclear desalination. Safety concerns have to be addressed including the possibility of radioactive contamination. Nuclear desalination has the potential to be an important option for safe and sound, economic and sustainable supply of large amounts of desalinated water. Hybridization of Nuclear- powered MSF-RO
MSF plants often use low-pressure steam as an energy source while RO plants are operated by electrical power to derive the high-pressure pumps and other plant auxiliaries. RO power consumption depends mainly on water recovery and the working pressure. Low pressure and temperature steam extracted from nuclear heating reactors may be used for supplying the necessary energy to derive the MSF units. Electricity can be generated from the nuclear power reactor to derive the high-pressure pumps of the RO desalination plants. Coupling RO and MSF with nuclear steam supply system will yield some economical and technical advantages. The hybrid RO-MSF system has potential advantages of a low power demand, improved water quality and possible lower running cost as compared to stand-alone RO or MSF Hybrid RO-MSF: option for nuclear desalination
The worlds first nuclear-powered MSF-RO hybrid desalination plant is established at MAPS, Kalpakkam, India. This plant is based on indigenous MSF technology developed in India. Although this plant is a small capacity demonstration plant ( 6300 m 3 /d capacity hybrid MSF-RO ), it has provided very useful data for design of large size nuclear desalination plants in future. The experience has indicated safe operation of such plants for providing water for domestic as well as industrial needs. Kalpakkam hybrid desalination project
Desalting processes are normally associated with rejection of high concentration waste brine in addition to thermal pollution in case of thermal processes. These pollutants increase seawater temperature, salinity, water current and turbidity. They also harm the marine environment, causing fish to migrate while enhancing the presence of algae, nematods and tiny molluscus. Sometimes micro-elements and toxic materials appear in the discharged brine. The impact encompass CO 2 emissions, that with the current environmental concerns worldwide due to climate change, are likely to be taxed in future. In general a carbon credit to be available for clean processes will vary from $15/ton to $25/ton. Environmental impacts of desalination
Relevant airborne emissions produced by desalination systems based on fossil fuels include: (Ref: different literatures ) Environmental impacts of desalination ROMEDMSFEmission per m3 desalted water 1.78 ± ± ± 1.52kg CO ± ± ± 0.52g dust 3.87 ± ± ± 1.32g NOx 1.10 ± ± ± 0.54g NMVOC ± ± ± 1.82g SOx MEDMSFEmission per m 3 desalted water 1.11 ± ± 0.02kg CO ± ± 0.04g dust 2.38 ± ± 0.42g NOx 0.59 ± ± 0.02g NMVOC ± ± 0.21g SOx Relevant airborne emissions produced by MSF and MED when driven by waste heat include: (Ref: from different literatures)
Previous results show a drastic reduction in the emissions per cubic meter of desalted water produced in the thermal desalination plants utilizing waste-heat sources. In case of nuclear and renewable energy-driven desalination plants, there will always be lower emissions compared to fossil-driven plants. As most of the desalination capacity is needed in the water- scarce areas of developing countries, there could be a greater incentive of availing carbon credits as part of the Clean Development Mechanism (CDM) and a resulting cost reduction, if the heat for desalination is obtained from clean energy sources such as renewable or nuclear energy ( the latter will also be accepted as CDM under the Kyoto protocol ). Environmental impacts of desalination
The world energy requirements are presently met from oil (39%), coal (25%), gas (22%), hydro (7%), nuclear (6%) and renewable energies (1%). The contribution of non-fossil sources to worldwide energy is 13% while renewable sources (wind, solar, and geothermal is only 1%. Energy Sources for Desalination The co2 emissions from non-fossil sources range from 0.01 to kg/kwh compared to 0.96, 0.85, and 0.64 kg/kwh for coal, oil, and gas respectively. The current contribution of renewable energy to desalination is about 0.05%. In recent years wind and solar sources are being considered for sea water desalination. Nuclear power is suggested for large scale desalination plants.
Nuclear powered desalination system Nuclear energy is carbon-free generation and is a sustainable solution and potentially competitive with fossil fuels. It is necessary to consider it for desalination projects. All nuclear reactor types can provide the energy required by various desalination processes. However, Small and Medium Reactors have the largest potential as coupling options to nuclear desalination systems. The coupling scheme is usually dictated by the maximum economic and practical benefits that can be achieved, in terms of water and electricity production. In general, coupling is technically feasible but imposes conditions such as avoiding radioactivity cross-contamination and minimising the impact of the thermal desalination plant on the nuclear reactor. hybrid system coupled to a nuclear power plant Reactor Steam Generator Reheaters MS H.P. Turbine FW Pump Turbine L.P. Turbine Generator Condenser Air Ejector Multistage Flash Distillation Brine Heater Transfer Pump Pretreatment System Booster Pump High Pressure Pump RO Membrane Energy Recovery System Permeate Water Seawater Distilled Water Brine Blow down Reject Brine Packing Exhaust Reactor Steam Generator Reheaters MS H.P. Turbine FW Pump Turbine L.P. Turbine Generator Condenser Air Ejector Multistage Flash Distillation Brine Heater Transfer Pump Pretreatment System Booster Pump High Pressure Pump RO Membrane Energy Recovery System Permeate Water Seawater Distilled Water Brine Blow down Reject Brine Packing Exhaust
Wind powered desalination system The present worldwide capacity of wind power is about 160 Gwe and is witnessing an annual growth of 25–30%. Wind-powered desalination is one of the most promising uses of renewable energies for seawater desalination. The worlds first large size windmill-powered SWRO plant of 140,000 m 3 /d capacity has been installed in Australia in The RO plant power consumption varies from 4 to 6 kWh/m3 as seawater temperature varies from 16°C to 24°C. The availability of the plant is around 90%. The cost of the water produced is reported to be Aus$1.17/m3, which is higher than that in conventional SWRO plants. In addition, there are two wind-powered RO systems in Spain in addition to a few small wind-driven desalination plants operating in Italy, Algeria and Indonesia.
Solar desalination system The worldwide capacity of solar electric power is merely 800 Mwe. Solar desalination has been studied in many countries on a small to medium size utilizing conventional solar stills and collectors. The limitations include space requirements, lower availability, and the need for appropriate heat storage system. The largest size solar MED desalination plants reported are 3000 m 3 /d at Dead Sea in Israel and 6000 m 3 /d plant in Arabian Gulf. These plants meet the need of small community in remote areas. The higher costs of water from these units are not important in view of their meeting water needs of remote isolated localities. There is however a good potential of solar thermal desalination in future and efforts need to be directed tothis area.
Futuristic Developments on Membrane Systems There has been no significant breakthrough in the membrane specifications in the last 20 years. Following developments in the last few years are likely to impact the cost-effectiveness of desalination with favorable environmental impact. They include: 16 dia 1.5 m long spiral module developed by Koch Membrane Systems The Affordable Desalination Collaboration (ADC) has been studying since many years on increasing the energy recovery as well as the permeate recovery to produce fresh water from SWRO plants at affordable cost.
ConclusionsConclusions Cost of desalinated water moved close to conventional water supply and expected to decrease the production cost in future. A number of technological upgrades and innovations in the past few years have resulted in reduced cost of desalted water to below $1.0/m3. The increasing costs of materials and chemicals and rising fuel costs in recent years have been challenging. The hybrid desalination systems are proved to be technically feasible, economically attractive, and environmentally favorable. Use of alternate renewable energy sources including nuclear, wind and solar should be considered for a sustainable fresh water source.