Techno-Economic and Environmental Evaluation of Introducing Renewable Energy Systems in a Reverse Osmosis Desalination Plant
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Date
2016-06
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The British University in Dubai (BUiD)
Abstract
It is quite conspicuous that the population tends to increase in the coming decades which would evidently increase the global demand for fresh water. In Middle Eastern regions, the source of fresh water is usually a desalination plant which provides water for agricultural and drinking purposes. This research project concentrates on a Reverse Osmosis (RO) desalination plant located in UAE. RO plants come under the membrane technology and have high electricity consumption (which leads to high associated CO2 emissions considering the use of fossil fuels). Considering the location, this research probes into the introduction of solar photovoltaic energy systems, wind energy systems and hybrid PV-WT systems into the existing RO desalination plant and evaluates its technical, economic and environmental feasibility under varied conditions and combination of systems. With simulations as the core research methodology, HOMER Energy and IES VE are used for the technical, economical, and environmental analysis of the systems. The simulations in HOMER Energy is done in a step by step series from 25%, 50%, 75%, 100% renewable fraction connected to the grid to a standalone system with 100% renewable fraction.
The results observed from the various configurations are that the hybrid PV-WT systems and PV systems have a viable technical and economic feasibility whereas WT systems fare poorly in the region. In these systems, the primary loads are met in most case configurations in an optimal way. It is seen that in the 25% renewable fraction case configurations all configurations fare well especially the PV system and hybrid case configuration with 0% unmet load , 0% excess electricity and 0% capacity shortage. In the 50% case configurations, 15% excess electricity is produced by the hybrid system whereas the other case configurations concerning the PV systems and Wind turbine system produce no excess electricity. No capacity shortage or unmet electric load is observed in any of the systems in the 50% case configuration. However, from the simulations concerning the 75%, 100% and standalone case configurations, excess electricity is produced in the PV and Hybrid system. The system components tend to increase exponentially from the 50% case configurations onwards with the high annual electrical load demand of 8,341.26 kWh/day. There is also a reduction in the PV panel requirement for the hybrid configuration from 50% case configuration onwards. These parameters make the hybrid case configurations a more technically viable option.
However, from the economic analysis it is seen that the renewable electricity cost is not viable considering the current costs levied on the desalination unit .The net present cost is used to identify the economic feasibility of the systems used in the study which show that the least cost incurring system is when the unit is connected to the grid with the NPC of $1,195,957.98. This is followed closely by configurations where 25% renewable fraction is integrated with PV systems and hybrid systems with NPC $3,683,774.00 and $3,964,293.00 and respectively. However, through many propositions which may not be always technical, a change to renewable energy can be introduced in this region such as; introduction of net metering, feed in tariffs, government incentives, improving the desalination process, more efficient and cheaper renewable system components through new noble technologies. Finally, it is observed from the study that carbon emissions are reduced when the renewable system is connected to the grid. In the case of PV system which has just 25% renewable fraction and the rest connected to the grid shows a carbon dioxide reduction from 2563674 kg/year when only connected to the grid to 1879703 kg/year. The case where the renewable fraction is more, the carbon dioxide produced is also seen to be lesser. Though these renewable case configurations may give a higher cost for electricity, it is seen clearly from the emissions reduced how this transition from fossil fuel to renewable will help save the world from a point of never coming back.
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Keywords
renewable energy systems, reverse osmosis, desalination plant, United Arab Emirates (UAE)