Water costs could be reduced if more favorable financing is available or if electric power is sold at prices higher than those we have considered. The subcommittee report shows the sensitivity of water costs to different methods of financing and different power values. The cost of water conveyance to the user is an important item, varying greatly from one location to another, which must be added to the figures cited above. Efficient coupling between nuclear powerplants and water desalination plants requires that plants of matched capacity be available at the same time. With respect to large size, nuclear technology is currently further advanced than water desalination technology. Single-unit nuclear plants could be built today under firm price and performance guarantees offered by reputable manufacturers, which could have an electrical capacity of 240 megawatts and simultaneously provide the heat energy for a waterplant producing 170 to 220 million gallons per day. Nuclear plants requiring minimum additional research and development could up these figures by 1970 to 500 to 600 megawatts plus 300 to 350 million gallons per day depending on the reactor type to be used. The development of reactors of larger size would require significant funds, a reasonable estimate being $100 million to develop a plant of 8,300 thermal megawatts by 1975. This figure becomes $130 million if accumulated interest, compounded at 4 percent per year, is included. A plant of this size would produce 1,300 to 1,900 electrical megawatts and 500 to 800 million gallons per day. Perhaps an additional $55 million, including accumulated interest, would be needed to pay the Government portion of costs (totaling $267 million) of two intermediate scale-up prototypes. These estimated nuclear plant research and development costs are not included in present Federal research and development programs. Distillation processes are the only water desalination techniques sufficiently developed to permit detailed consideration in this report. The largest such unit now in operation in the United States has a capacity of about 1.4 million gallons per day. The scale-up of successive prototype units, in order to remain within the limits of sound engineering practice, should progress in approximately the following steps: 10, 50, and 150 to 200 million gallons per day. Scaling economies in a distillation waterplant may reach a maximum in units of about 150 million gallons per day; beyond this level it may become economically desirable to link units in parallel rather than to increase individual unit size. Development of distillation units of optimum size, proceeding in the steps described above, would require 10 to 15 years with costs over this period estimated to total about $70 million, and perhaps an additional $20 to $40 million for the Government portion of the cost (totaling $357 million) of intermediate size demonstration plants. The $70 million becomes $88 million if accumulated interest compounded at 4 percent per year until 1975 is included. On the order of half these estimated waterplant research and development costs are included in existing or planned programs. It is important to point out here that promising sea water desalination techniques other than distillation are under intensive study by the Office of Saline Water, that these techniques have different characteristics in terms of energy use, and that successful development of these technologies might obviate the need for the dual-purpose operations considered here. Some of these processes would prospectively use significantly less energy per unit of product water than the distillation process, and the energy would be largely electrical rather than thermal. This could make possible the conversion of the same amount of water with a smaller energy unit than would be possible for the distillation process. The timing of the need for water from dual-purpose nuclear plants thus has a manifold effect on the optimum development schedule. We believe the need is sufficiently urgent and near term, so that intermediate-scale distillation plants should be developed as soon as possible to obtain the necessary engineering data for the large plants we have envisioned. At the same time a close watch should be kept on other developing technologies so that a shift in emphasis can be made if and when one of these shows a clear promise of economically surpassing distillation. We foresee the eventual need in U.S. coastal areas for several very large dualpurpose units. Half a dozen such units would easily suffice to justify development costs. The apparent possibilities in industrialized or urban regions within the next two decades seem to include one or more for the southern California area, one or more for Arizona, several for the gulf coast, and one or more for the Greater New York area, perhaps especially on Long Island. It is possible to compare the attractiveness of a combined electric power and desalination plant with alternative methods of water supply only in the context of a specific time and place. While our analysis indicates that an installation could be built by 1975 in the southern California area to supply 500 to 1,000 million gallons of water per day to Los Angeles reservoirs at a price of about 30 cents per thousand gallons, this figure needs to be compared with cost estimates for alternative sources using a common set of ground rules. In our opinion, such a comparison would show the desalination approach to be competitive. From the technical point of view, we conclude that the following steps would constitute a logical program of action: 1. Development and construction of a water desalination plant of the distillation type, in the next largest feasible scale in size, presumably on the order of 10 million gallons per day. A desalination plant of this order or size is currently under study by the Department of the Interior. The Department of the Interior and the Atomic Energy Commission are studying the possible use of a nuclear energy source for a dual-purpose plant. 2. Coordinated planning and feasibility studies by the Department of the Interior and the Atomic Energy Commission, looking toward a combined reactor desalination and electric powerplant of the range of 200 megawatts of marketable electrical power and 50 million gallons of water per day. Such a plant is a logical goal to obtain the definition of performance parameters that will be needed for designing larger installations, and is of the order of size (600 to 1,000 thermal megawatts) currently included in the AEC's prototype power reactor program. 3. Continuation by the Department of the Interior of its vigorous program of research and development aimed toward alternative water desalination technologies. These alternatives need to be continuously evaluated for their economic comparability with large dual-purpose installations using the distillation process. 4. Detailed feasibility studies by the Department of the Interior and the Atomic Energy Commission on specific plants for specific sites, compared with alternate methods of water supply, as a basis to define further the criticality of the need for large combination plants. These studies should consider various time horizons, probably encompassing 1975, 1980, 1985, and 1990, and should include comparative evaluations of the economics of fossil fuel sources of thermal energy. 5. Specification by the Atomic Energy Commission of the reactor types most suitable for development in sizes of around 8,000 thermal megawatts under alternative methods of capital financing. These studies should indicate the approximate development costs of these alternative reactor types. ROGER REVELLE. The following States are Members of the International Atomic Energy Agency: The Agency's Statute was approved on 23 October 1956 by the Conference on the Statute of the Permission to reproduce or translate the information contained in this publication may be obtained by writing to the International Atomic Energy Agency, Kärntner Ring 11, Vienna I, Austria. Printed by the IAEA in Austria FOREWORD The purpose of the present publication is to outline the status of desalination of water at the end of 1963, and is intended as a general review of the subject. Since the International Atomic Energy Agency considers that nuclear energy may, in the near future, be important in the conversion of sea and brackish water into fresh water, the following pages will deal mainly with different aspects of desalination on a large scale. These aspects will be discussed in the light of progress made using demonstration plants as well as results obtained in recent design studies. But in no way is it intended to put forward definitive statements on the advantages or disadvantages of using one or another kind of energy or any particular desalination proThis publication should serve as a technical report intended to help in a preliminary evaluation of projects that may be considered. The scientific and technical aspects of desalination will be the subject of further study by the Agency. cess. 38-024 O 64-4 |