Desalination energy

Nanofiltration water desalination, energy consumption in, 26 87 Nanogold technology, 12 701 Nanoimprinting, optical, 15 193-195 Nano Indentor, 21 743 Nanoinhibitor design, 10 343 Nanomachines, 24 61-62 Nanomaterials, for sensors, 22 266 NanoMatrix, Inc., collagen nanofiber research, 1 723 Nanomedicine, 10 343... 

The total current through the stack is given by Equation 5.21 and the average resistance is given by Equation 5.26. Combination of the two Equations and multiplication by the number of cell pairs in the stack gives the desalination energy ... 

The specific desalination energy, that is, the energy used per unit product volume is given by ... 

Here, fcdes and Edesspc are the desalination energy and the specific desalination, l is the total current, t is the time of operation Cfd and Cfc are the equivalent concentrations of the diluate and the concentrate at the cell inlet, C1 and C° are the concentrations ofthe diluate and the concentrate at the cell outlet, A is the equivalent conductivity of the salt solution, f" and rcm are the area resistances of the anion- and cation-exchange membrane, A is the cell thickness, is the current utilization, and is the diluate... 

Environmental concern about the C02 greenhouse effect associated with the use of hydrocarbon fuel has led to the goal of supplying desalination energy from... 

Elimelech, M. and Phillip, W.A. 2011. The future of seawater desalination Energy, technology, and the environment. Science 333 712-717. 

Desalination. Desalination of seawater and brackish water has been and, as of the mid-1990s, is the primary use of RO. Driven by a need for potable water in areas of the world where there is a shortage, this industry has developed. Desalination involves the reduction of the total dissolved soHds (IDS) concentration to less than 200 mg/L. RO offers several advantages over other possible desalination processes such as distillation (qv), evaporation (qv), and electro dialysis. The primary advantage of RO over the traditionally used method of distillation is the energy savings that is afforded by the lack of a phase change in RO. 

Desalination. A special case of distillation is water desalination. In places where energy is abundant but fresh water is not, eg, the Arabian Peninsula, water may be produced from seawater ia flash evaporators. Low pressure turbiae steam is extracted to provide heat for the evaporators. Coadeased steam is returned to the cycle. Such units may be particularly prone to corrosion by salts. Sizes vary, but a plant scheduled for completion in 1996 had six units and a total capacity of 345,600 m /d. Power generation was expected to be 17,500 MW (36). 

Bromley and co-workers (36) have calculated the minimal energy of separation of water from seawater containing 3.45 wt % salt, at 25°C, to be 2.55 kj/(kg fresh water) for the case of 2ero fresh water recovery (infinitesimal concentration change) and 2.91 kj/(kg fresh water) for the case of 25% fresh water recovery. is, however, severalfold smaller than the energy necessary for water desalination ia practice. 

The performance ratio of ME plants is just slightly lower than the number of effects, which is deterrnined as an optimized compromise between energy efficiency and capital cost. Six effects ate typical, although plants with as many as 18 effects have been built. Eurther detail about ME desalination can be found in (56,59). 

Fig. 18. Flow schematic of an open-cycle ocean—thermal energy conversion (OTEC) and desalination plant (77), where (—) represents liquids (-),...

Table 5. Energy requirements of four industrial desalination processes. (Source International Atomic Energy Agency 1992.)...

Despite the fact that OTEC systems have no fuel costs and can produce useful by-products, the initial high cost of building such power plants (up to 5,000 per kilowatt) currently makes OTEC generated electricity up to five times more expensive than conventional alternatives. As such, at the present time OTEC systems are largely restricted to experimental and demonstration units. One of the major facilities for OTEC research is the Natural Energy Laboratory of Hawaii Authority at Keahole Point on the island of Hawaii. An experimental OTEC facility located there has had a maximum net power production of 100 kilowatts, at the same time producing 5 gallons per minute of desalinated water. 

Pearce GK (2008) UF/MF pretreatment to RO in seawater and wastewater reuse applications a comparison of energy costs. Desalination 222 66-73... 

The conditions utilized in the above development of minimum energy are not sufficient to describe electrodialysis. In addition to the desalination of water, salt is moved from a saline feed to a more concentrated compartment. That free-energy change must be added to the free energy given in Eq. (20-107), which describes the movement... 

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