A Novel Photovoltaic Powered Reverse Osmosis with Improved Productivity of Reverse Osmosis and Photovoltaic Panel

Ultra-low energy reverse osmosis with thermal energy recovery from photovoltaic panel cooling and TFC RO membrane modification

Reverse osmosis (RO) is a well-known process for desalinating seawater and brackish groundwater. Desalination is energy-intensive, so using photovoltaic (PV) panels to power the process is an attractive and cost-effective concept, especially for community-scale systems. Increasing the system efficiency will lower the total cost of water produced, making the systems more economically competitive for a greater number of geographic locations. It is noted in this paper that the amount of water produced by a PV-powered RO (PVRO) system can be increased if the temperatures of the solar panel and the reverse osmosis feed water are actively managed. For a given level of solar radiation, a photovoltaic panel produces more power at a lower temperature. Also, for a given power, an RO system produces more clean water at a higher input (feed) water temperature. An active thermal management system is needed to exploit these complementary characteristics by cooling the solar panel and warming the RO feed water, increasing the amount of fresh water produced. This can be accomplished by running the RO feed water through a heat exchanger attached to the back of the solar panel, cooling it. Furthermore, the ability to cool the solar panels permits the addition of low-cost, flat-plate concentrating mirrors to be used with the PV panels, which further increases the PV power output. The flow of the water through the respective units must be actively controlled as there are limits for the maximum temperatures of both the RO water and PV panels. In this paper, a concept for an active PVRO thermal control system is presented. Simulations and experimental results show the effectiveness of this approach. In experiment, a 57% increase in fresh water production was achieved. These experimental results agree well with simulation models.

The electrical efficiency of solar photovoltaic (PV) panel decreases with increase in its temperature because of its negative temperature co-efficient. This problem has been identified and attempts have been made to cool the photovoltaic panel by transferring heat by researchers the world over. The capitalization of the transferred heat for useful purpose is of prime importance since the conventional solar PV panel has the conversion efficiency of only 5%–17%. This means, about 83%–95% of incident energy is wasted and the proposition of recovering energy from solar PV panel can tap more thermal energy than electrical energy generated by PV panel itself. The present paper addresses this objective. The heat was transferred by direct contact heat exchange with flowing water from top of the panel. The direct contact heat exchange from top surface was found efficient in recovering energy as well improving the performance of PV panel. The refraction of light as it passes through the water layer straightens the incident radiation. The straightened radiation along with lower temperature of PV panel synergistically increases photovoltaic conversion efficiency. The computational fluid dynamics simulation of PV panel temperature closely resembles experimental data. There is a potential to recover energy at larger scale for large scale solar PV installations. Thus, the present paper proposes the win-win scenario of improved panel performance and maximum energy recovery.

In the research, the performance characteristics of Reverse Osmosis (RO) Spiral Wound (SW) membrane are evaluated. The effects of feed water concentration, temperature, pressure and flow rate on the performance of this membrane are investigated. The product recovery () of SW membrane is found to increase with feed water temperature and pressure, but decrease with increasing feed water concentration and flow rate. Salt passage (SP) increases with feed water temperature and concentration, but decreases with increasing feed pressure and flow rate. Under the tested feed water conditions, of SW varies from 6% - 18% and permeate salinity is approximately 130ppm. In addition, validity of the Complete Mixing Model is verified and successfully extended to the derivation of water and salt transport parameters of SW membrane. Plots of I/SR' versus l/Jw display linear relationships, as predicted in the model.

An optimization strategy for a forward osmosis-reverse osmosis hybrid process for wastewater reuse and seawater desalination: A modeling study

Performance evaluation of two RO membrane configurations in a MSF/RO hybrid system

Desalination of seawater: an experiment with RO membranes

An optimal design approach of forward osmosis and reverse osmosis hybrid process for seawater desalination

Optimal configuration of integrated energy system considering heat enhancement and combined operation of low head seawater pumped storage and reverse osmosis

This study evaluated the filtration performance and energy consumption of three different reverse osmosis (RO) membranes (ESPA2-LD, RE4040-BE, and TMG10D) for treating semiconductor wastewater. A ceramic membrane combined with ozone for RO pre-treatment and the influence of ozone injection on the filtration and energy consumption efficiency of RO were investigated. A flat-sheet ceramic membrane comprising Al2O3/SiO2-ZrO2 was used to treat real and synthetic semiconductor wastewater as feed water. The deionized water (DI) permeabilities of RO membranes were 144.6, 94.22, and 156.6 LMH/bar, respectively. The microfiltration process that used ozone reduced the permeability of all RO processes, and the total organic carbon (TOC) removal rate decreased when ozone was applied. The application of ozone on power consumption was inconclusive, and its effect was unclear indicating an increase 3.37%, 4.48%, and 11.6% when filtrated with ozone, respectively. TMG10D showed the highest permeability followed by ESPA2-LD and RE4040-BE, for both, the real and synthetic wastewaters. However, ESPA2-LD showed the highest salt and TOC rejection followed by RE4040-BE and TMG10D. TMG10D exhibited the lowest energy consumption per ton of filtered water followed by ESPA2-LD and RE4040-BE. ESPA2-LD was determined to be the most suitable membrane in terms of the water quality stability and energy consumption in RO to treat semiconductor wastewater.

Synergistic Tandem Solar Electricity-Water Generators

An optimal design approach of gas hydrate and reverse osmosis hybrid system for seawater desalination

Novel photovoltaic (PV) technologies are currently investigated and evaluated as approaches to contribute to a more environmental friendly energy supply in many countries. One of the driving forces are the aims to reduce the emission of green house gases and the dependency on importing fossil energy resources from political unstable countries. Additionally the wish to replace nuclear power by greener and less threatening technologies will enhance the development of regenerative energy supply in many countries especially after the recent nuclear catastrophe at Fukushima nuclear power plant in Japan in March 2011. This will include the more rapid implementation of existing mature PV technologies but also the development and improvement of novel PV approaches such as organic PV (OPV) and dye-sensitized solar cells (DSSCs) together with new efficient strategies for energy storage and distribution to make electric power, deriving from PVs, available whenever and wherever it is needed. The so-called 1st generation of solar cells based on e.g. bulk crystalline and polycrystalline silicon is still dominating the PV market. However, so-called 2nd generation solar cells mainly consisting out of thin film solar cells based on CdTe, Copper Indium Gallium Selenide (CIGS), and amorphous silicon gained distribution of ca. 25% in market share today worldwide. It is expected that this number will increase significantly within the next years. While for the 1st and 2nd generation solar cells commercial solar panels are available with decent power conversion efficiencies (PCEs) and lifetimes, the emerging 3rd generation solar cells such as OPV and DSSCs technologies are still in the development phase. Some commercially available products have recently entered the market such as e.g. solar bags representing niche products, which are so far not suitable for competing with traditional large scale applications of solar panels of the 1st and 2nd generations. In traditional solar panels the differences between best solar cell and average solar cell efficiencies are much smaller than for the emerging solar cell technologies with the consequence that modules of 3rd generation solar cells still suffer from too low performance. In Table 1 the best cell and module efficiencies of different PV technologies are compared. It has to be mentioned that especially for the emerging new PV technologies the average efficiencies are significantly lower than the results of the best cells.

Analysis of reverse osmosis membrane performance during desalination of simulated brackish surface waters

Chapter 2 - Membrane-Based Desalination Technology for Energy Efficiency and Cost Reduction