Innovative desalination technology

Seawater desalination is a technology that provides drinking water for millions of people around the world. With increasing industrialization and water usage and lack of recycling or reuse, the demand for fresh water is increasing at the fastest rate. Industries such as power plants use bulk of water for cooling purpose and chemical industries use water for their processing. Agriculture is also a major user of water and countries like India exploit ground water for this purpose. To supplement fresh water, Governments and industries in many parts of the world are now turning to desalinated seawater as a potential source of fresh water. However, desalination of seawater to generate fresh water is an expensive option, due to its large energy usage. However, due to frequent failure of monsoon rains and uncertainties and changing weather pattern due to global warming, seawater desalinations is becoming a potential source of fresh water, despite its cost and environmental issues. Seawater desalination technology has not undergone any major changes during the past three decades. Reverse osmosis is currently the most sought after technology for desalination due to increasing efficiencies of the membranes and energy saving devices. In spite of all these improvements the biggest problem with desalination technologies is still the rate of recovery of fresh water. The best recovery in SWRO plants is about 50% of the input water. Higher recoveries create additional problems such as scaling, higher energy requirements and O&M issues and many suppliers would like to restrict the recoveries to 35%, especially when they have to guarantee the life of membranes and the plant. Seawater is nothing but fresh water with large quantities of dissolved salts. The concentration of total dissolved salts in seawater is about 35,000mgs/lit. Chemical industries such as Caustic soda and Soda ash plants use salt as the basic raw material. Salt is the backbone of chemical industries and number of downstream chemicals are manufactured from salt. Seawater is the major source of salt and most of these chemical industries make their own salt using solar evaporation of seawater using traditional methods with salt pans. Large area of land is required for this purpose and solar evaporation is a slow process and it takes months together to convert seawater into salt. It is also labor intensive under harsh conditions. The author of this article has developed an innovative technology to generate fresh water as well as salt brine suitable for Caustic soda and Soda ash production. By using this novel process, one is able to recover almost 70% fresh water against only 40% fresh water recovered using conventional SWRO process, and also recover about 7- 9% saturated brine simultaneously. Chemical industries currently producing salt using solar evaporation are unable to meet their demand or expand their production due to lack of salt. The price of salt is steadily increasing due to supply demand gap and also due to uncertainties in weather pattern due to global warming. This result in increased cost of production and many small and medium producers of these chemicals are unable to compete with large industries. Moreover, countries like Australia who have vast arid land can produce large quantities of salt with mechanized process competitively; Australia is currently exporting salt to countries like Japan, while countries like India and China are unable to compete in the international market with their age old salt pans using manual labor. In solar evaporation the water is simply evaporated. Currently these chemical industries use the solar salt which contains a number of impurities, and it requires an elaborate purification process. Moreover the salt can be used as a raw material only in the form of saturated brine without any impurities. Any impurity is detrimental to the Electrolytic process where the salt brine is converted into Caustic soda and Soda ash. Chemical industries use deionized water to dissolve solar salt to make saturated brine and then purify them using number of chemicals before it can be used as a raw material for the production of Caustic soda or Soda ash. The cost of such purified brine is many times costlier than the raw salt. This in turn increase the cost of chemicals produced. In this new process, seawater is pumped into the system where it is separated into 70% fresh water meeting WHO specifications for drinking purpose, and 7-10% saturated pure brine suitable for production of caustic soda and Soda ash. These chemical industries also use large quantities of process water for various purposes and they can use the above 70% water in their process. Only 15-20% of unutilized seawater is discharged back into the sea in this process, compared to 65% toxic discharge from convention desalination plants. This new technology is efficient and environmentally friendly and generates value added brine as a by-product. It is a win situation for the industries and the environment. The technology has been recently patented and is available for licensing on a non-exclusive or exclusive basis. The advantage of this technology is any Caustic soda or Soda ash plant located near the seashore can produce their salt brine directly from seawater without stock piling solar salt for months together or transporting over a long distance or importing from overseas. Government and industries can join together to set up such plants where Governments can buy water for distribution and industries can use salt brine as raw material for their chemical production. Setting up a desalination plants only for supplying drinking water to the public is not a smart way to reduce the cost of drinking water. For example, the Victorian Government in Australia has set up a large desalination plant to supply drinking water. This plant was set up by a foreign company on BOOT (build, own and operate basis) and water is sold to the Government on ‘take or pay’ basis. Currently the water storage level at catchment area is nearly 80% of its capacity and the Government is unlikely to use desalinated water for some years to come. However, the Government is legally bound by a contract to buy water or pay the contracted value, even if Government does not require water. Such contracts can be avoided in the future by Governments by joining with industries who require salt brine 24x7 throughout the year, thus mitigating the risk involved by expensive legal contracts.

Which is the best storage technology for Renewable energy?

The share of renewable energy is steadily increasing around the world. But storing such intermittent energy source and utilizing it when needed has been a challenge. In fact energy storage constitutes a significant portion of the cost in any renewable energy technology. Many storage technologies are currently available in the commercial market, but choosing a right type of technology has always been a difficult choice. In this article we will consider four types of storage technologies. The California Energy Commission conducted economic and environmental analyses of four energy storage options for a wind energy project: (1) lead acid batteries, (2) zinc bromine (flow) batteries, (3) a hydrogen electrolyzer and fuel cell storage system, and (4) a hydrogen storage option where the hydrogen was used for fueling hydrogen powered vehicle. Their conclusions were: ”Analysis with NREL’s (National Renewable Energy laboratory) HOMER model showed that, in most cases, energy storage systems were not well utilized until higher levels of wind penetration were modeled (i.e., 18% penetration in Southern California in 2020). In our scenarios, hydrogen storage became more cost-effective than battery storage at higher levels of wind power production, and using the hydrogen to refuel vehicles was more economically attractive than reconverting the hydrogen to electricity. The overall value proposition for energy storage used in conjunction with intermittent renewable power sources depends on multiple factors. Our initial qualitative assessment found the various energy storage systems to be environmentally benign, except for emissions from the manufacture of some battery materials. However, energy storage entails varying economic costs and environmental impacts depending on the specific location and type of generation involved, the energy storage technology used, and the other potential benefits that energy storage systems can provide (e.g., helping to optimize Transmission and distribution systems, local power quality support, potential provision of spinning reserves and grid frequency regulation, etc.)”. Key Assumptions Key assumptions guiding this analysis include the following: • Wind power will expand in California under the statewide RPS program to a level of approximately 10% of total energy provided in 2010 and 20% by 2020, with most of this expansion in Southern California. • Costs of flow battery systems are assumed to decline somewhat through 2020 and costs of hydrogen technologies (electrolyzers, fuel cell systems, and storage systems) are assumed to decline significantly through 2020. • In the case where hydrogen is produced, stored, and then reconverted to electricity using fuel cell systems, we assume that the hydrogen can be safely stored in modified wind turbine towers at relatively low pressure at lower costs than more conventional and higher-pressure storage. • In the case where hydrogen is produced and sold into transportation markets, we assume that there is demand for hydrogen for vehicles in 2010 and 2020, and that the Hydrogen is produced at the refueling station using the electricity produced from wind farms (in other words, we assume that transmission capacity is available for this when needed)? Key Project Findings Key findings from the HOMER model projections and analysis include the following: • Energy storage systems deployed in the context of greater wind power development were not particularly well utilized (based on the availability of “excess” off-peak electricity from wind power), especially in the 2010 time frame (which assumed 10% wind penetration statewide), but were better utilized–up to 1,600 hours of operation per year in some cases–with the greater (20%) wind penetration levels assumed for 2020. • The levelized costs of electricity from these energy storage systems ranged from a low of $0.41 per kWh—or near the marginal cost of generation during peak demand times—to many dollars per kWh (in cases where the storage was not well utilized). This suggests that in order for these systems to be economically attractive, it may be necessary to optimize their output to coincide with peak demand periods, and to identify additional value streams from their use (e.g., transmission and distribution system optimization, provision of power quality and grid ancillary services, etc.) • At low levels of wind penetration (1%–2%), the electrolyzer/fuel cell system was either inoperable or uneconomical (i.e., either no electricity was supplied by the energy storage system or the electricity provided carried a high cost per MWh). • In the 2010 scenarios, the flow battery system delivered the lowest cost per energy stored and delivered. • At higher levels of wind penetration, the hydrogen storage systems became more economical such that with the wind penetration levels in 2020 (18% from Southern California), the hydrogen systems delivered the least costly energy storage. • Projected decreases in capital costs and maintenance requirements along with a more durable fuel cell allowed the electrolyzer/fuel cell to gain a significant cost advantage over the battery systems in 2020. • Sizing the electrolyzer/fuel cell system to match the flow battery system’s relatively high instantaneous power output was found to increase the competitiveness of this system in low energy storage scenarios (2010 and Northern California in 2020), but in scenarios with higher levels of energy storage (Southern California in 2020), the Electrolyzer/fuel cell system sized to match the flow battery output became less competitive. • In our scenarios, the hydrogen production case was more economical than the Electrolyzer/fuel cell case with the same amount of electricity consumed (i.e., hydrogen production delivered greater revenue from hydrogen sales than the electrolyzer/fuel cell avoided the cost of electricity, once the process efficiencies are considered). • Furthermore, the hydrogen production system with a higher-capacity power converter and electrolyzer (sized to match the flow battery converter) was more cost-effective than the lower-capacity system that was sized to match the output of the solid-state battery. This is due to economies of scale found to produce lower-cost hydrogen in all cases. • In general, the energy storage systems themselves are fairly benign from an environmental perspective, with the exception of emissions from the manufacture of certain components (such as nickel, lead, cadmium, and vanadium for batteries). This is particularly true outside of the U.S., where battery plant emissions are less tightly controlled and potential contamination from improper disposal of these and other materials are more likely. The overall value proposition for energy storage systems used in conjunction with intermittent renewable energy systems depends on diverse factors. • The interaction of generation and storage system characteristics and grid and energy resource conditions at a particular location. • The potential use of energy storage for multiple purposes in addition to improving the dependability of intermittent renewable (e.g., peak/off-peak power price arbitrage, helping to optimize the transmission and distribution infrastructure, load-leveling the grid in general, helping to mitigate power quality issues, etc.) • The degree of future progress in improving forecasting techniques and reducing prediction errors for intermittent renewable energy systems • Electricity market design and rules for compensating renewable energy systems for their output Conclusions “This study was intended to compare the characteristics of several technologies for providing Energy storage for utility grids—in a general sense and also specifically for battery and Hydrogen storage systems—in the context of greater wind power development in California. While more detailed site-specific studies will be required to draw firm conclusions, we believe those energy storage systems have relatively limited application potential at present but may become of greater interest over the next several years, particularly for California and other areas that is experiencing significant growth in wind power and other intermittent renewable. Based on this study and others in the technical literature, we see a larger potential need for energy storage system services in the 2015–2020 time frames, when growth in renewable produced electricity is expected to reach levels of 20%–30% of electrical energy supplied. Depending on the success in improved wind forecasting techniques and electricity market designs, the role for energy storage in the modern electricity grids of the future may be significant. We suggest further and more comprehensive assessments of multiple energy storage technologies for comparison purposes, and additional site- and technology-specific project assessments to gain a better sense of the actual value propositions for these technologies in the California energy system. This project has helped to meet program objectives and to benefit California in the Following ways: • Providing environmentally sound electricity. Energy storage systems have the Potential to make environmentally attractive renewable energy systems more competitive by improving their performance and mitigating some of the technical issues associated with renewable energy/utility grid integration. This project has identified the potential costs associated with the use of various energy storage technologies as a step toward understanding the overall value proposition for energy storage as a means to help enable further development of wind power (and potentially other intermittent renewable resources as well). • Providing reliable electricity. The integration of energy storage with renewable energy esources can help to maintain grid stability and adequate reserve margins, thereby contributing to the overall reliability of the electricity grid. This study identified the potential costs of integrating various types of energy storage with wind power, against which the value of greater reliability can be assessed along with other potential benefits. • Providing affordable electricity. Upward pressure on natural gas prices, partly as a function of increased demand, has significantly contributed to higher electricity prices in California and other states. Diversification of electricity supplies with relatively low-cost sources, such as wind power, can provide a hedge against further natural gas price increases. Higher penetration of these other (non-natural-gas-based) electricity sources, Potentially enabled by the use of energy storage, can reduce the risks of future electricity.” (Source: California Energy Commission prepared by University of Berkeley).