Sustainability ranking of desalination plants using Mamdani Fuzzy Logic Inference Systems

As water desalination continues to expand globally, desalination plants are continually under pressure to meet the requirements of sustainable development. However, the majority of desalination sustainability research has focused on new desalination projects, with limited research on sustainability performance of existing desalination plants. This is particularly important while considering countries with limited resources for freshwater such as the United Arab Emirates (UAE) as it is heavily reliant on existing desalination infrastructure. In this regard, the current research deals with the sustainability analysis of desalination processes using a generic sustainability ranking framework based on Mamdani Fuzzy Logic Inference Systems. The fuzzy-based models were validated using data from two typical desalination plants in the UAE. The promising results obtained from the fuzzy ranking framework suggest this more in-depth sustainability analysis should be beneficial due to its flexibility and adaptability in meeting the requirements of desalination sustainability

Potential of heat pipe technology in nuclear seawater desalination

The official published version of this article can be found at the link below.Heat pipe technology may play a decisive role in improving the overall economics, and public perception on nuclear desalination, specifically on seawater desalination. When coupled to the Low-Temperature Multi-Effect Distillation process, heat pipes could effectively harness most of the waste heat generated in various types of nuclear power reactors. Indeed, the potential application of heat pipes could be seen as a viable option to nuclear seawater desalination where the efficiency to harness waste heat might not only be enhanced to produce larger quantities of potable water, but also to reduce the environmental impact of nuclear desalination process. Furthermore, the use of heat pipe-based heat recovery systems in desalination plant may improve the overall thermodynamics of the desalination process, as well as help to ensure that the product water is free from any contamination which occur under normal process, thus preventing operational failure occurrences as this would add an extra loop preventing direct contact between radiation and the produced water. In this paper, a new concept for nuclear desalination system based on heat pipe technology is introduced and the anticipated reduction in the tritium level resulting from the use of heat pipe systems is discussed

A multi evaporator desalination system operated with thermocline energy for future sustainability

All existing commercial seawater desalination processes, i.e. thermally-driven and membrane-based reverse osmosis (RO), are operated with universal performance ratios (UPR) varying up to 105, whilst the UPR for an ideal or thermodynamic limit (TL) of desalination is at 828. Despite slightly better UPRs for the RO plants, all practical desalination plants available, hitherto, operate at only less than 12% of the TL, rendering them highly energy intensive and unsustainable for future sustainability. More innovative desalination methods must be sought to meet the needs of future sustainable desalination and these methods should attain an upper UPR bound of about 25 to 30% of the TL. In this paper, we examined the efficacy of a multi-effect distillation (MED) system operated with thermocline energy from the sea; a proven desalination technology that can exploit the narrow temperature gradient of 20 °C all year round created between the warm surface seawater and the cold-seawater at depths of about 300–600 m. Such a seawater thermocline (ST)-driven MED system, simply called the ST-MED process, has the potential to achieve up to 2 folds improvement in desalination efficiency over the existing methods, attaining about 18.8% of the ideal limit. With the major energy input emanated from the renewable solar, the ST-MED is truly a “green desalination” method of low global warming potential, best suited for tropical coastal shores having bathymetry depths of 300 m or more

Desalination Processes’ Efficiency and Future Roadmap

For future sustainable seawater desalination, the importance of achieving better energy efficiency of the existing 19,500 commercial-scale desalination plants cannot be over emphasized. The major concern of the desalination industry is the inadequate approach to energy efficiency evaluation of diverse seawater desalination processes by omitting the grade of energy supplied. These conventional approaches would suffice if the efficacy comparison were to be conducted for the same energy input processes. The misconception of considering all derived energies as equivalent in the desalination industry has severe economic and environmental consequences. In the realms of the energy and desalination system planners, serious judgmental errors in the process selection of green installations are made unconsciously as the efficacy data are either flawed or inaccurate. Inferior efficacy technologies' implementation decisions were observed in many water-stressed countries that can burden a country's economy immediately with higher unit energy cost as well as cause more undesirable environmental effects on the surroundings. In this article, a standard primary energy-based thermodynamic framework is presented that addresses energy efficacy fairly and accurately. It shows clearly that a thermally driven process consumes 2.5-3% of standard primary energy (SPE) when combined with power plants. A standard universal performance ratio-based evaluation method has been proposed that showed all desalination processes performance varies from 10-14% of the thermodynamic limit. To achieve 2030 sustainability goals, innovative processes are required to meet 25-30% of the thermodynamic limit

Desalination Processes’ Efficiency and Future Roadmap

For future sustainable seawater desalination, the importance of achieving better energy efficiency of the existing 19,500 commercial-scale desalination plants cannot be over emphasized. The major concern of the desalination industry is the inadequate approach to energy efficiency evaluation of diverse seawater desalination processes by omitting the grade of energy supplied. These conventional approaches would suffice if the efficacy comparison were to be conducted for the same energy input processes. The misconception of considering all derived energies as equivalent in the desalination industry has severe economic and environmental consequences. In the realms of the energy and desalination system planners, serious judgmental errors in the process selection of green installations are made unconsciously as the efficacy data are either flawed or inaccurate. Inferior efficacy technologies' implementation decisions were observed in many water-stressed countries that can burden a country's economy immediately with higher unit energy cost as well as cause more undesirable environmental effects on the surroundings. In this article, a standard primary energy-based thermodynamic framework is presented that addresses energy efficacy fairly and accurately. It shows clearly that a thermally driven process consumes 2.5-3% of standard primary energy (SPE) when combined with power plants. A standard universal performance ratio-based evaluation method has been proposed that showed all desalination processes performance varies from 10-14% of the thermodynamic limit. To achieve 2030 sustainability goals, innovative processes are required to meet 25-30% of the thermodynamic limit

The use of simulated whole effluents in toxicity assessments: A review of case studies from reverse osmosis desalination plants

Seawater desalination is an increasingly common means to meet the demand for freshwater. Resulting wastewater discharges can, however, impact biota of the surrounding environment. Concern exists that interactive effects specific to the outputs of each desalination plant may result in unique impacts difficult to predict by studying existing plants or assessing the effects of individual chemicals found in waste streams. Given this, we highlight an alternative approach to assess potential toxicity of desalination outfalls. Specifically, we review three recent case studies from Australia in which simulated whole effluents were used in toxicity assessments before desalination plants were constructed. This approach enabled potential toxic effects of wastewater to be considered before the plants became operational and, in one case, even facilitated consideration of potential effects of different treatment processes and suppliers. As in many whole effluent toxicity assessments, the time required for testing and restricted range of species considered were limitations. Given the benefits of this method, however, the use of simulated whole effluents is a development that could facilitate an improved capacity to forecast impacts of proposed desalination plants

The carbon footprint of desalination: An input-output analysis of seawater reverse osmosis desalination in Australia for 2005–2015

This study examines greenhouse gas emissions for 2005–2015 from seawater desalination in Australia, using conventional energies. We developed a tailor-made multi-regional input-output-model. We complemented macroeconomic top-down data with plant-specific desalination data of the largest 20 desalination plants in Australia. The analysed capacity cumulates to 95% of Australia's overall seawater desalination capacity. We considered the construction and the operation of desalination plants. We measure not only direct effects, but also indirect effects throughout the entire value chain. Our results show the following: We identify the state of Victoria with the highest emissions due to capital and operational expenditures (capex and opex). The contribution of the upstream value chain to total greenhouse gas emissions increases for capex and decreases for opex. For capex, the construction of intake and outfall is the driving factor for carbon emissions. For opex, electricity consumption is the decisive input factor. Both in construction and operation, we identify the critical role of the electricity sector for carbon emissions throughout the supply chain effects. The sector contributes 69% during the zenith of the construction phase and 96% during the operating phase to the entire emissions. We estimate the total emissions for 2015 at 1193 kt CO2e

An exergy approach to efficiency evaluation of desalination

This paper presents an evaluation process efficiency based on the consumption of primary energy for all types of practical desalination methods available hitherto. The conventional performance ratio has, thus far, been defined with respect to the consumption of derived energy, such as the electricity or steam, which are susceptible to the conversion losses of power plants and boilers that burned the input primary fuels. As derived energies are usually expressed by the units, either kWh or Joules, these units cannot differentiate the grade of energy supplied to the processes accurately. In this paper, the specific energy consumption is revisited for the efficacy of all large-scale desalination plants. In today's combined production of electricity and desalinated water, accomplished with advanced cogeneration concept, the input exergy of fuels is utilized optimally and efficiently in a temperature cascaded manner. By discerning the exergy destruction successively in the turbines and desalination processes, the relative contribution of primary energy to the processes can be accurately apportioned to the input primary energy. Although efficiency is not a law of thermodynamics, however, a common platform for expressing the figures of merit explicit to the efficacy of desalination processes can be developed meaningfully that has the thermodynamic rigor up to the ideal or thermodynamic limit of seawater desalination for all scientists and engineers to aspire to

Predictive Control Applied to a Solar Desalination Plant Connected to a Greenhouse with Daily Variation of Irrigation Water Demand

The water deficit in the Mediterranean area is a known matter severely affecting agriculture. One way to avoid the aquifers’ exploitation is to supply water to crops by using thermal desalination processes. Moreover, in order to guarantee long-term sustainability, the required thermal energy for the desalination process can be provided by solar energy. This paper shows simulations for a case study in which a solar multi-effect distillation plant produces water for irrigation purposes. Detailed models of the involved systems are the base of a predictive controller to operate the desalination plant and fulfil the water demanded by the crops