Energy Storage for Multigeneration: Desalination, Power, Cooling and Heating Applications

Energy Storage for Multi-generation: Desalination, Power, Cooling and Heating Applications is designed to help readers implement and manage highly-efficient energy storage enabled industrial processes. The book provides an overview on energy storage technologies, recent trends around the world, and a discussion on the sustainability components of energy storage in different applications. Case studies for integrated power-water production schemes integrated with energy storage are also included, along with tactics to critically evaluate drivers that influence energy storage integration into power-water production schemes, including desalination, tri-generation and poly-generation concepts and configurations.

This book will provide all engineers and researchers a better understanding of the application of renewable energy in desalination and the thermodynamic processes and laws involved.

• Identifies appropriate power-water production schemes to integrate into energy storage systems
• Determines the returned value of energy storage systems and their lifecycle assessment
• Assesses the techno-economic and socio-environmental aspects surrounding the sustainable integration of energy storage systems

• Language: English
• Publisher: Academic Press
• Release date: Oct 8, 2022
• ISBN: 9780128219218

Book preview

Chapter 1: Energy storage for sustainable desalination and renewable energy integration

Veera Gnaneswar Gude    PNW Water Institute (PWI), Purdue University Northwest, Civil & Environmental Engineering, Mechanical & Civil Engineering Department, Hammond, IN, United States

Abstract

Energy storage technologies have become an integral and indispensable part of a reliable and effective renewable and distributed energy generation portfolio for many communities. This is especially a critical requirement for communities that derive their freshwater supplies from nonconventional water sources through desalination plants. This chapter presents the nexus between the water and energy sources and the critical need for managing both resources effectively and sustainably. First, the different energy storage technologies for power supply management are presented. The advantages and disadvantages of various energy storage technologies are elaborated. Then the application of energy storage technologies in desalination is discussed. Finally, current perspectives and future challenges for renewable energy integrated desalination and energy storage technologies are discussed.

Keywords

Energy storage; Desalination; Thermal energy; Batteries; Flywheels; Biomass; Geothermal; Solar; Wave; Wind

Chapter outline

1.Introduction

2.Energy storage systems

3.Benefits of energy storage

4.Description of energy storage systems

4.1Mechanical energy storage systems

4.2Electrical energy storage systems

4.3Chemical energy storage systems

5.Comparison of energy storage systems

5.1Electrochemical energy storage systems

5.2Mechanical energy storage systems

5.3Thermal energy storage systems

6.Applications of energy storage systems

7.Development needs for energy storage systems

8.Energy-water nexus

9.Desalination for water supplies

10.Energy storage for desalination

11.Summary

References

1: Introduction

The intrinsic connection between water and energy sources is at the core of the sustainable development of our society. It is well known that each resource cannot be generated or produced without the other making their relationship even complex and challenging. The challenges related to the nexus between water and energy sources have been exacerbated by the factors such as variable distribution of both water and energy sources, growing population and increasing consumption, rapid urbanization, resource depletion, and increasing living standards. Considering the case of water production, it is almost impossible to supply clean water without the use of energy source. Although three-fourth of the earth’s surface is covered by water, only 0.15% of it suitable for potable uses (Gude and Nirmalakhandan, 2009). Currently, about 15% of global population lacks access to clean water sources, which is expected to reach 40% by 2050, while the water and energy consumption is estimated to increase by 55% and 33%, respectively (Khan et al., 2017).

Similarly, there is an unprecedented growth in energy demands both in developed and developing countries due to rapid industrial and urban development causing high rise in conventional energy source costs (Hadjipaschalis et al., 2009). Economic development in many regions is also closely tied with energy supplies requiring uninterrupted energy sources. Dependence on conventional energy sources especially importing from other energy-rich countries creates several challenges such as national energy insecurity, economic insecurity, political and socioeconomic issues. Moreover, continued use of fossil-fuel-based energy sources leads to environmental pollution due to greenhouse gas emissions and climate change. Overall, energy issues at local levels can have impact at global levels.

To address the water scarcity and demand issues, use of inexhaustible seawater sources can be considered as an attractive option (Gude, 2016). However, seawater as well as many deep groundwater sources are saline in nature (high dissolved solids) requiring nonconventional treatment techniques such as desalination processes, which include thermal, membrane, and hybrid technologies (Gude, 2018). These technologies are known to be energy demanding. Reliance on already far-stretched or far-fetched conventional energy sources would be unsustainable. For this reason, renewable energy source integration is increasingly employed in desalination plant design and operations.

To address energy shortage issues, renewable energy sources such as biomass (Nandimandalam et al., 2022), geothermal (Lund and Toth, 2021), solar (Kruitwagen et al., 2021), wave (Choupin et al., 2021), and wind energy (Sadorsky, 2021) sources can be considered. While these energy sources possess indisputable advantages over their counterparts, there are many challenges associated with their implementation. These sources are affected by weather and climate conditions and seasonal variations. As a result, managing the output from these methods is not as easy as the other methods (Kumar, 2022). Renewable energy technologies harness power from nature, and their peak power output does not often match the demand. They exhibit large fluctuations in power output hourly, daily, monthly, and yearly. For example, solar power generated by photovoltaic modules depends on the daily solar irradiation, which varies during the day. The solar radiation also varies seasonally. Similar conditions affect the performance of wind energy systems. To enable these technologies as primary energy suppliers, energy storage must be included as a central component. Energy storage unit allows for storage of excess energy produced at times and for discharge of the stored energy when the production levels are less than the required demand.

Acknowledging the interdependent connection of water and energy sources, it is common to device integrated solutions that address the challenges associated with these sources in a combined framework, and energy storage becomes the most critical element of those solutions. Therefore, this chapter will first present different energy storage technologies for power supply management. The advantages and disadvantages of various energy storage technologies are presented. Then the application of storage technologies in desalination is discussed. Finally, current perspectives and future challenges for renewable energy desalination enabled by energy storage technologies are discussed.

2: Energy storage systems

Energy storage systems store energy in different forms and of different qualities. Energy may be transformed into other forms and stored and converted back into the desired form of use. Energy storage systems are classified based on the application (final utilization) and the type of storage system. The applications include different capacities ranging from personal devices and appliance storage to regional electricity supply level. The capacities include: grid-level, utility-level, power quality, microgrid, distributed storage, automotive, and device and appliance storage. Grid-level storage is used in large applications where the storage capacities are mainly tied with renewable energy contribution to account for the demand-supply mismatches. Utility-level storage is necessary to store energy and supply at an optimum cost. The power quality application involves smaller storage capacities to maintain the quality of power supply, i.e., uninterrupted electricity during the times of inclement weather and low renewable energy power production. Microgrid application involves residential and industrial sectors where clusters of buildings are supported by energy storage. The capacity required for this application is significantly lower than the utility or grid-level application. Commercial and business buildings need storage in distributed supply settings. Automotive applications include battery-operated vehicles, electric and hybrid vehicles, and fuel-cell-based vehicles. Household appliances and phones and personal devices also require very small capacity energy storage.

There are many types of energy storage systems, which can be broadly categorized as chemical, electrochemical, electromagnetic, mechanical, and thermal energy storage systems. Mechanical energy systems include pumped hydro systems, compressed air energy systems, flywheels, springs, and torsion bars. Chemical energy systems include all types of batteries, hydrogen-based systems, and fuel cells. Electromagnetic systems include capacitors, supercapacitors, and superconducting coils. Thermal energy storage includes molten salts, phase change, and nonphase change materials and solid materials.

3: Benefits of energy storage

Energy storage offers several benefits at different levels of electricity generation and consumption. At the generation level, energy storage can help optimize the costs by purchasing the electricity at a low wholesale price and meet the demand at peak without inflating the price (Ceballos-Escalera et al., 2020). This practice is energy arbitrage. The purchase and storage of energy when the price is low allow for reducing the need to generate electricity, when the demand is high, usually associate with high costs. Charging during off-peak times and discharging during peak time using energy storage will help meet the adequacy requirements, thereby enhancing the reliability during peak times. This method reduces the need for investing in large-capacity power plants. When renewable energy sources integrated with grid, energy storage can reduce the variability of power generation capacities. Excess energy generated can be stored and delivered when the supply is low. Mandatory requirements (set by regulatory and operational constraints) for including renewable energy sources such as hydro, nuclear, and wind energy sources can be better addressed with energy storage avoiding wastage. Instabilities in grid can be regulated by using energy storage. Unexpected energy shortfalls can be better addressed by energy storage. Voltage can be maintained within an acceptable range to match the demand. Storage helps as a backup during the times of blackout and can be used to restore the operations during power outage. At the transmission level, using energy storage congestion relief can be facilitated by discharging during high-demand times and locations. In addition, shifting the electricity demand to less congested times prevents system overload and reduces the need, the size, or the urgency of new investment in the transmission systems. Grid transmission performance can be improved by increased capacity and voltage maintenance. At the distribution level, storage can help reduce congestion during peak demand time avoiding costly upgrades. Power outages can be better managed during unexpected events. At the consumer level, electricity bills can be lowered by using stored energy during peak times. Emergency power can be supplied during power outage.

4: Description of energy storage systems

Energy storage systems can be broadly divided into four categories as mechanical, electrical, thermal, and chemical (Said and Ringwood, 2021).

4.1: Mechanical energy storage systems

Mechanical storage includes compressed air energy storage (CAES), pumped hydro storage, and flywheels.

CAES is based on using electricity to compress air and store it in underground caverns. The air is released when needed and passed through a turbine to generate electricity. Storage capacities reach up to 500 MW and discharge rates vary from 1 to 20 GWh.

Flywheels rely on kinetic energy from rotor spinning through a nearly frictionless enclosure that can provide short-term power through inertia. Storage capacities reach up to 20 MW, and discharge rates can be up to 5 MWh.

Pumped storage hydro technology stores energy by pumping water from a lower to a higher reservoir and then releasing it back through the connection, passing through a turbine, which generates electricity. This technology is typically used for grid-scale storage. Storage capacities reach up to 3600 MW, and discharge rates can be up to 40 GWh.

4.2: Electrical energy storage systems

Electrical energy storage includes capacitors, supercapacitors, superconducting magnetic energy storage, and ultracapacitors.

Ultracapacitors store energy at the double layer of each electrode separated by a dielectric and can discharge energy instantaneously. Due to lack of chemical reaction, the cycle life is orders of magnitude higher than battery cycle life. Storage capacities are between 250 kW and 2 MW. Discharge rates vary between 2.5 and 20 kWh.

Nonstorage generation combustion turbine converts fuel such as natural gas to mechanical energy, which drives a generator to produce electricity. Storage capacities are between 10 kW and 100 MW.

4.3: Chemical energy storage systems

Of special interest are the electrochemical energy storage systems, which are used in various applications. Some definitions and descriptive characteristics along with electrochemical reactions are presented below.

Sodium-sulfur battery is a molten-salt battery made up of sodium (Na) and sulfur (S) that operates at high temperature ranges and is primarily suitable for > 4-h duration applications. Several kW to few MW, 100 kWh or higher

Discharging reaction:

si1_e

Electrolyte: Beta aluminum

Li-ion battery is based on charge and discharge reactions from a lithiated metal oxide cathode and a graphite anode. This battery technology is used in a wide variety of applications. 1 kW to 100 MW, < 200 MWh

Anode:

si2_e

Cathode:

si3_e

Electrolyte: Lithium salts in organic solvent

Lead-acid battery is made up of lead dioxide (PbO2) for the positive electrode and a spongy lead (Pb) negative electrode. Vented and valve-regulated batteries make up two subtypes of this technology. Storage capacities can reach up to a few MW, < 10 MWh (Khan and Go, 2021).

Anode:

si4_e

Cathode:

si5_e

Electrolyte: Dilute H2SO4

Sodium metal halide battery is made up of nickel (Ni), sodium chloride (NaCl), and sodium (Na), which is kept at a temperature between 270°C and 350°C. Batteries using other materials are being developed to decrease cost and operation temperature. Storage capacities reach up to several MW, and discharge rates vary from 4 kWh to several MWh.

Zinc-hybrid cathode battery is a high-energy density battery storage technology that uses inexpensive and widely available materials. Zinc-hybrid cathode batteries use nonflammable, near-neutral pH aqueous electrolytes that are nondendritic and do not absorb CO2. Storage capacities are at 250 kW subsystem repeat unit up to 2 MW, and discharge rates vary from 1 MWh subsystem repeat unit up to 8 MWh.

Anode:

si6_e

In fluid:

si7_e

Cathode:

si8_e

Overall reaction:

si9_e

Electrolyte: KOH/KOH with solid polymer membrane

In redox flow batteries, the energy storage in the electrolyte tanks is separated from power generation in stacks. The stacks consist of positive and negative electrode compartments divided by a separator or an ion exchange membrane through which ions pass to complete the electrochemical reactions. Scalability due to modularity, ability to change energy and power independently, and long cycle and calendar life are attractive features of this technology. Storage capacities can reach up to 30 MW. Power release capacity varies from 100 kW to 120 MWh (Khan et al., 2019).

Anode:

si10_e

Cathode:

si11_e

5: Comparison of energy storage systems

Energy storage systems are compared based on their figures of merit, which describe the reliability, longevity, charge and discharge efficiency (also known as round-trip efficiency defined as the ratio of energy output of storage system to the energy input), storage capacity (depends on energy storage capacity of the material), energy density (mass per unit energy or volume per unit energy), and cost per unit energy stored or power delivered (Michaelides, 2021). The units of comparison should be same when comparing different storage technologies. The figures of merit (such as self-discharge time, depth of discharge, and cycle life) for comparison also depend on the type of energy storage and the application. For example, low specific energy is of importance to transportation applications, especially aerospace applications, but not so important in applications related to buildings. Energy density, round-trip efficiency, and life cycle are more important in domestic applications. Vanishing self-discharge is of high importance in systems and applications for seasonal energy storage, such as storage of wind power during the winter to be used in the summer. Table 1 shows a comparison of different thermal energy storage systems in terms of their storage characteristics.

Table 1

5.1: Electrochemical energy storage systems

While batteries are widely used in numerous power and water production applications, they offer low $/MW but high $/MWh for significant durations above 2–6 h. Number of cells are added together to scale up the capacity. Some important concerns with batteries are that rare-earth materials such as lithium and cobalt are used for their construction. In addition, degradation of materials and performance over time are prominent. Viable recycling options are yet to be developed. Batteries suffer from issues such as poor thermal management, leakage, or thermal runaway.

5.2: Mechanical energy storage systems

5.2.1: Pumped hydro systems

The potential energy of water using reservoirs at different elevations is the key factor of operation (Rehman et al., 2015). The mature turbomachinery technology has gathered decades of commercial experience. The turbines are reversible (Francis type) pump turbines. The limitations of this technology are that it is site-specific and involves high capital costs. There are several types of modular pumped hydro, subsurface, subsea, and open-loop systems with an expected performance of 70%–85% round-trip efficiency with over 40years of service life.

5.2.2: Compressed air energy storage systems

The energy is stored in large volumes of compressed air and supplemented with heat storage (adiabatic CAES) with centrifugal/axial machinery in existing concepts derived from gas turbine, steam turbine, integrally geared compressor (Lund and Salgi, 2009). The diabatic systems (technology readiness level of 9) are more advanced than adiabatic CAES (technology readiness levels of 5–6). Similar to PHS, CAES are site-specific and require a salt dome. Adiabatic CAES includes heat exchange, storage concepts, reciprocating isothermal CAES, constant-head CAES, hydraulic compression, and subsea CAES with expected round-trip efficiency performances of 40%–50% for diabatic CAES, 50%–70% for adiabatic CAES.

CAES systems have relatively longer life time, lower environmental impact, shorter construction time, higher reliability, and lower installation costs when compared with pumped hydro storage systems, which are generally geographically constrained (site-wise), as they must be appropriate for the construction of dams to pool large volumes of water. However, a lower round-trip efficiency of CAES (50%–70%) in comparison to PHES (85%–90%) is considered a drawback (Razmi et al., 2019); this arises because of significant heat losses in compressors and natural gas turbine exhaust. Thus, various types of auxiliary systems such as heat storage, organic Rankine cycle (ORC) engines, ejectors, refrigeration, and Kalina cycles may be combined with CAES to enhance its performance. In addition, hybrid energy storage (such as including thermal energy storage) and hybrid energy generation systems (such as including solar and wind energy sources) are considered to improve the energy efficiency and economic benefits.

5.2.3: Flywheels

Flywheels store energy as rotating kinetic energy (Awadallah and Venkatesh, 2015). It is a well-established technology. These have high standby losses and low power densities. Flywheels is a mature technology with wide applications and high technical readiness level. However, some of the drawbacks include high standby losses and low power density. Several improvements are warranted in the areas of material weight, minimizing electrical losses, and developing superconducting magnetic bearings. The performance of flywheels is characterized by high round-trip efficiencies (> 90%), nearly infinite cycle lifetime, and very short response time.

5.2.4: Gravitational

This technology is based on the hydraulic lifting of large rock mass using water pumps (Carnegie et al., 2013). Electricity is used for elevation of solid mass in subsurface conditions with wind/hydraulic pumps and above-surface, rail cars or towers are used. The technical readiness level of individual components (which include motor/generator and hydro pump/turbine) of the system is high; however, the overall system readiness level is between 4 and 5. The technical concept is well advanced and proven in many demonstrations; however, there is still a requirement for more experience at higher capacities. Pilot projects are funded for demonstrating the potential of this technology. Technical gaps or areas of improvement include loss minimization; sealing of hydraulic systems; and position control. The round-trip efficiency is expected to be between 80% and 90%. Low specific storage costs are reported, which are 30%–60% of pumped hydro systems. The storage capacity can be between 1 and 10 GWh with a response time of 1–10 s.

5.3: Thermal energy storage systems

Thermal energy storage systems include sensible heat storage, phase change or latent heat storage, and thermochemical storage systems (Gadhamshetty et al., 2014; Sarbu and Sebarchievici, 2018; Alnaimat and Rashid, 2019). Sensible heat storage system raises or lowers temperature of a single-phase material without involving phase change. Molten salts, thermal oil, water, rocks, and concrete are used in various applications. Latent heat storage involves phase change, typically liquid-solid transition, and sometimes vapor generation. Ice is an example of a commonly used phase change material (PCM). Direct (heat transfer and storage with same medium) or indirect systems are developed in either two-tank or thermocline storage configurations. There are some corrosion and thermal or cyclic stability issues with these systems. Low-cost, compact, and high-performance heat exchangers are sought. Molten salt systems can operate above 565°C with salt pumps and tanks. Advanced systems include encapsulated PCMs, particle thermal storage including nanoparticles, and other applications include cold