Evaluation of Desalination Costs with DEEP

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Simon Nisan
on April 11, 2008
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S. Nisan , Linda Volpi
Int. Journal of Nuclear desalination N°3 (2003 )

ABSTRACT:
In the context of the EURODESAL project, we were recently led to perform economic evaluations of desalination with existing and innovative reactors and to effectuate comparisons of the desalination costs with fossil and renewable energy sources. [See for exemple, A comprehensive economic evaluation…..].
Since the power cost data regarding various nuclear and non nuclear systems, as built in DEEP, dates back from the early nineties (collected for a predecessor of DEEP, known as CDEE) and because of the importance of power costs in desalination cost estimations, it was decided in EURODSAL and future studies to use the well validated CEA code SEMER [2] for power costs calculations. This data was then input into DEEP.
Detailed analysis then showed several discrepancies and pitfalls of coupling an economic evaluation code, such as SEMER to DEEP. This paper resumes our findings, which may be of interest to other DEEP users. The paper in particular deals with the following issues:
- Why is it that power costs from nuclear systems are systematically higher in DEEP than those given by the economic evaluations made by individual organisations, (In in our case, the SEMER code for example), even when the calculated construction costs are input into DEEP? This is clearly shown in IAEA TECDOC 1186.
- Why corresponding power costs for fossil energy systems are lower?
- Why in particular desalination costs from Gas-Turbine Combined Cycle power system, which is now considered to be the cheapest fossil fuel option, are higher than desalination costs by Pulverised Coal system?
- Why DEEP calculation results with the backup heat source are 40 % higher than those without the backup heat source?
- In a classical distillation system coupling, the vapour is extracted from the turbine blades at a given temperature and a given mass flow rate to produce a given amount of water. Thermodynamic analysis shows that this should lead to a loss of electrical power, depending upon the vapour temperature and desired product water capacity. This “lost shaft power” is indeed taken into account in the water costs calculations in DEEP. However, it is calculated by an older correlation which may not be any longer valid for innovative reactors. How can this be modified to take into account the real thermodynamic situation?

FOR MORE INFORMATION AND TRAINING ABOUT DEEP UTILISATION, Contact NDS

Extraction of Rubidium from from the concentrated brine rejected by integrated nuclear desalination systems

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Simon Nisan
on March 20, 2008
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by
S. Nisan, F. Laffore, C. Poletiko, N. Simon.
Desalination (2008)

Rubidium is one of the elements present in the concentrated brine rejected by desalination systems. In view of the potentially high price of the pure metal, it is worthwhile to investigate its extraction, even though presently the available Rb resources are adequate enough to meet the current demands..
Two methods have been reported. The first makes use of the ion exchange resins and the second of the complexation of Rb with specific molecules (calixarenes) followed by one or more nanofiltration/reverse osmosis stages.
First results of calculations indicate that the two methods would be technically very attractive but much experimentation would still be required before an industrial scale extraction process can be evolved.

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A Dynamic Simulator (INFMED) for the MED/VC Plant

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Simon Nisan
on March 20, 2008
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by
G Kishore, S. Nisan, S. Dardour, A.K. Adak, V.K. Srivastava, P.K. Tewari
Desalination (2008)

This paper describes INFMED (Indo-French MED simulator) Software Version 1 that is being developed, under the Indo-French collaboration, to simulate the steady state and the dynamics of a Multi-Effect Distillation Mechanical Vapour Compression (MED-VC) Desalination system.
The main objectives of the simulator are:
· To permit a thorough understanding of the steady state design and to study the behaviour of the plant under various transients.
· Training of potential operators, engineers and students.
· To allow the further development of new strategies for control as well as for process optimisation.
INFMED is basically designed for parallel feed configurations of MED plant coupled to MVC (mechanical vapour compression) but thermal vapour compression models currently under development would also be incorporated later on.
INFMED is built in Visual Basic and can be installed on computers running on the Windows 9x/2000/XP operating systems. It offers a very user-friendly graphical user interface for simulating steady and dynamic states and also for viewing the results in both tabulated as well as in a graphical forms.
The dynamic state model of an effect was taken from the CEA MED simulator, which is derived from basic mass, energy and momentum conservation equations and supplementary correlation for heat transfer and physical properties.
Results of a test case, derived from an operating BARC MED-VC installation, show that the behaviour of multiple variables in the steady state and in the case of postulated transients is indeed very well represented. A complete validation of the simulator results against data from the just completed, 50 m3/day BARC MED-VC installation will be reported later.

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A Comprehensive Economic Evaluation of Integrated Desalination Systems, Using Fossil Fuelled and Nuclear Energies, and Including their Environmental Costs

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Simon Nisan
on March 20, 2008
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by
S. Nisan, N. Benzarti
Desalination 229 (2008)

Seawater desalination is now widely accepted as an attractive alternative source of freshwater for domestic and industrial uses. Despite the considerable progress made in the relevant technologies desalination, however, remains an energy intensive process in which the energy cost is the paramount factor.
This study is a first of a kind in that we have integrated the environmental costs into the power and desalination costs. The study has focused on the seawater desalination cost evaluation of the following systems. It is supposed that they will be operating in the co-generation mode (simultaneous production of electrical power and desalted water) in 2015:
· Fossil fuelled based systems such as the coal and oil fired plants and the gas turbine combined cycle plant, coupled to MED, and RO
· Pressurised water reactors such as the PWR-900 and the AP-600, coupled to MED, and RO.
· High temperature reactors such as the GT-MHR, the PBMR, coupled to MED, with the utilisation of virtually free waste-heat provided by these reactors.
The study is made in real site-specific conditions of a site in Southern Europe.
Sensitivity studies for different parameters such as the fossil fuel prices, interest and discount rates, power costs etc., have also been undertaken.
The results obtained are then used to evaluate the financial interest of selected integrated desalination systems in terms of a detailed cash flow analysis, providing the Net Present Values, Pay Back Periods and the Internal Rate of Returns.
Analysis of the results shows that among the fossil fuelled systems the power and desalination costs by circulating fluidized bed coal fired plant would be the lowest with current coal prices. Those by oil fired plants would be highest. In all cases, integrated nuclear energy systems would lead to considerably lower power and water costs than the corresponding coal based systems.
When external costs for different energies are internalised in power and water costs, the relative cost differences are considerably increased in favour of the nuclear systems. Financial analysis further confirms these conclusions.

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Seawater desalination by nuclear reactors

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Simon Nisan
on March 14, 2008
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“Today, 1.2 billion people do not have access to potable water; 2.5 billion live in unsanitary water conditions; two million persons, a large majority of which are children, die every year because of water borne diseases and related hygiene This is equivalent to a Boeing 747, full of children, crashing every two hours!
It is in this context that seawater desalination could bring an economic and sustainable solution to this terrible problem”

Abstract

This paper recalls the reasons that have already produced, and would continue to do so in the future, acute water shortages in different regions of the world. In this context seawater desalination, as an alternative source of potable water, is examined. The various desalination processes are described in detail. The environmental impact of desalination by conventional fossil energy based sources is also discussed. It is shown that, notwithstanding small scale desalination systems by renewable energy based systems, for large scale seawater desalination the use of nuclear energy could save several millions to thousands of tons/year of GHG and particle emissions.
The environmental costs of fossil, renewable and nuclear energies have been evaluated.
The safety aspects of nuclear reactor coupling to desalination processes are analyzed.
Results of detailed economic evaluation of integrated nuclear desalinations systems show that compared to fossil energy based systems, the desalination costs by the nuclear options could be 30 to 60 % lower even for low fossil fuel prices ( < 70 $/bbl ).
When external environmental costs are internalised, the difference between the desalination costs by nuclear and fossil energy based systems is considerably increased in favour of the nuclear options.
THIS PAPER IS A MUST FOR THOSE WHO DO NOT KNOW DESALINATION POCESSESS AND NUCLEAR DESALINATION SYSTEMS

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Published
by
Simon Nisan
on February 5, 2007
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[ sciencedirect.com link ]

Utilisation of waste heat from GT–MHR and PBMR reactors for nuclear desalination

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Simon Nisan
on February 3, 2007
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The gas turbine–modular helium cooled reactor (GT–MHR) is currently being developed by an international consortium; the pebble bed modular reactor (PBMR) is to be constructed in South Africa. In both these reactors, circulating helium that has to be compressed in two successive stages cools the reactor core. For thermodynamic reasons, these compression stages require pre-cooling of the helium to about 26°C through the use of pre-cooler and intercooler helium-water heat exchangers. Considerable thermal power (≈300 MWth) is thus dissipated in the precooler and the intercooler. This thermal power is then evacuated to the heat sink. Depending upon the specific designs, the temperature ranges of the water in these exchangers could be between 80 and 130°C. This is an ideal range for desalination in a multiple-effect distillation (MED) plant, which can be coupled between a mixer (of the flows from the pre-cooler and the intercooler) and the switch- cooling unit, evacuating the heat to the heat sink (sea or river). It is thus interesting to evaluate the desalination costs of such a system, utilising virtually free heat. The usual code for desalination cost evaluation is the DEEP software, developed by the International Atomic Energy Agency. Actual versions of DEEP do not have models for GT–MHR and the PBMR providing heat for desalination. This paper describes the successive steps that led CEA to the development of these models from basic thermodynamic considerations and their integration in the new, CEA version of the DEEP code. The models are then applied to a realistic case study based on the TUNDESAL project [1]. It is shown that the desalination cost of a GT–MHR + MED system is 34% lower than that of a gas turbine, combined cycle plant + MED system, for a fossil fuel price of about 21 $/bbl and a discount rate of 8%. Under the same conditions, this cost is 2% lower for the PBMR + MED systems.

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Financing of an integrated nuclear desalination system in developing countries

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Simon Nisan
on February 1, 2007
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This paper focuses on a case study of financing a project of an integrated nuclear desalination system at la Skhira site in Tunisia. More specifically, it shows the financial characteristics of this project, known as TUNDESAL, the main financing mechanisms that can be used, and the principal actions required to attract the potential investors and lenders. The paper describes the basic requirements for the deployment of nuclear energy in a developing or an emerging country, with no previous experience of nuclear power; the specific financial considerations corresponding to the particular characteristics of nuclear desalination projects: high capital costs, high level of risks and uncertainties related in particular to long construction lead times and social and environmental concerns; the main risks of these projects; the profitability study of the TUNDESAL project: application of the discounted cash flow analysis; the main financing sources for the project; the financing schemes that can be used for project implementation and comparison between these schemes in terms of benefits generated, after covering project costs and repayment of lenders and investors; the main actions to be done for making the project financially attractive in order to gain the confidence of investors and international financial institutions (optimal allocation of project risks and uncertainties, a suitable and flexible energy and water tariffs policy, etc.). The analysis has shown that in particular conditions of Tunisia, the most attractive financial scheme could be the “project financing + leasing”.

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Extraction of strategic materials from the concentrated brine rejected by integrated nuclear desalination systems

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Simon Nisan
on November 1, 2005
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Seawater usually contains sixty elements from the Periodic Table. The brine, rejected by a desalination unit, is a concentrate of all compounds contained by seawater. However, some of the elements are very scarce on land and/or are very expensive. There is thus a strong motivation for extracting these materials. Current practice in countries using large-scale desalination is to reject brine back to the sea. Increasing ecological objections are now being voiced since this rejection leads to a degradation of local fauna and flora. Extraction of materials and subsequent brine conditioning for surface storage would therefore be also another advantage for these integrated desalination plants, making them more environmentally friendly. This paper summarizes our preliminary investigations to achieve the above objectives. Elements of interest were first selected on the basis of several economic, physical-chemical and technical criteria. Research was then undertaken to elaborate a common extraction method. After several different solutions, the protocol finally retained comprises a first extraction of Phosphorus through purification by alum. The next step is the recovery of Caesium through an innovative liquid–liquid extraction approach, based on the use of Calixarenes. Indium is then recovered by another liquid–liquid extraction with the help of organic acids. In the final phase germanium and magnesium are extracted. The remaining solution is principally composed of sodium and potassium chlorides, which are separated by hot lixiviation techniques, using the different solubilities of NaCl and KCl. The protocol of extraction thus elaborated would now require exhaustive economic evaluation and experimental verification. These are currently in progress.

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A new method for the treatment of the reverse osmosis process, with preheating of the feedwater

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Simon Nisan
on November 1, 2005
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This paper summarises our investigations on the conceptual studies of the Reverse Osmosis (RO) process with preheating of the feed-water, which is expected to lead to lower specific power consumption and higher water production, thus further reducing the cost of desalination by this advanced RO process.

There are, however, no adequate calculation methods to take into account the effect of temperature on the RO system performance parameters such as the recovery ratio, feed pressure, feed flow and the permeate salinity.

The work presented here tries to fulfil this need through the elaboration of mathematical correlations expressing the variation of these parameters as functions of the input parameters such as feed temperature, feed salinity, and the desired production capacity.

The principle of the method used is to first dimension the RO system with the help of the software ROSA and the membrane SW30 HR380 for a series of calculations (504 cases) giving the variation of the above performance parameters for a large range of the input conditions.

Numerical methods were then used to obtain the correlations giving the complete variation of the performance parameters as functions of the input parameters.

The correlations were then integrated into the desalination cost evaluation code, DEEP, developed by IAEA and in the course of continued development at CEA.

The revised version of the code was then applied to a specific project of nuclear desalination (the TUNDESAL project), currently being carried out in the context of a collaboration agreement between France and Tunisia, under the aegis of the IAEA regional cooperation programme.

[ sciencedirect.com link ]