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Battery Technologies for Small Scale Embedded Generation.

by Norman Jackson, South African Association (SAESA) Content Provider – Wikipedia et al Small Scale Embedded Generation - SSEG • SSEG is very much a local South African term for under 10 Mega Watt.

Internationally they refer to: Distributed generation, also distributed energy, on-site generation (OSG) or district/decentralized energy

It is electrical generation and storage performed by a variety of small, grid- connected devices referred to as distributed energy resources (DER) Types of Energy storage: • storage • Thermal • Electrochemical • Mechanical • Brick storage heater • Compressed air energy storage • Cryogenic energy storage ( Energy • Fireless locomotive • Liquid engine Storage System, • • Eutectic system BESS) • Gravitational potential energy • Ice storage air conditioning • Hydraulic accumulator • Molten salt storage • • Pumped-storage • Phase-change material • Rechargeable • Seasonal thermal energy battery • Electrical, electromagnetic storage • • Solar pond • UltraBattery • • Steam accumulator • Superconducting magnetic • Thermal energy energy storage (SMES, also storage (general) superconducting storage coil) • Chemical • Biological • • Glycogen • Hydrated salts • Starch • storage • • Power to gas • pentoxide History of the battery

This was a stack of and Italian plates, separated by physicist Alessandro -soaked paper Volta demonstrating disks, that could his pile to French produce a steady emperor Napoleon current for a Bonaparte considerable length of time.

Although early batteries were of great value for experimental purposes, in practice their fluctuated and they could not provide a large current for a sustained period. The , invented in 1836 by British chemist John Frederic Daniell, was the first practical source of , becoming an industry standard and seeing widespread adoption as a power source for networks. It consisted of a copper pot filled with a copper sulfate solution, in which was immersed an unglazed earthenware container filled with and a zinc .

A , the first battery 1800 How do chemical batteries work? • Electricity, as you probably already know, is the flow of through a conductive path like a wire. This path is called a circuit. • Batteries have three parts, an (-), a (+), and the . The cathode and anode (the positive and negative sides at either end of a traditional battery) are hooked up to an electrical circuit. The chemical reactions in the battery causes a build up of electrons at the anode. This results in an electrical difference between the anode and the cathode. You can think of this difference as an unstable build-up of the electrons. The electrons wants to rearrange themselves to get rid of this difference. But they do this in a certain way. Electrons repel each other and try to go to a place with fewer electrons. In a battery, the only place to go is to the cathode. But, the electrolyte keeps the electrons from going straight from the anode to the cathode within the battery. When the circuit is closed (a wire connects the cathode and the anode) the electrons will be able to get to the cathode. Primary cells or non-rechargeable batteries • A is a battery (a ) that is designed to be used once and discarded, and not recharged with electricity and reused like a secondary cell (). In general, the electrochemical reaction occurring in the cell is not reversible, rendering the cell unrechargeable. As a primary cell is used, chemical reactions in the battery use up the chemicals that generate the power; when they are gone, the battery stops producing electricity and is useless.

A variety of standard sizes of primary cells. From left:4.5V multicell battery, D, C, AA, AAA, AAAA, A23, 9V multicell battery, (top) LR44, (bottom) CR2 032 Secondary cells or rechargeable batteries

• A rechargeable battery, storage battery, secondary cell, or accumulator is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or primary battery, which is supplied fully charged and discarded after use. It is composed of one or more electrochemical cells. The term "accumulator" is used as it accumulates and stores energy through a reversible electrochemical reaction. Different Types of Rechargeable Batteries. - battery Molten salt battery Flow battery – battery Vanadium battery Nickel–cadmium battery vented cell type Zinc– battery Nickel hydrogen battery Zinc–cerium battery Nickel– battery based battery Nickel metal battery –acid battery Low self-discharge NiMH battery Starter battery Nickel–zinc battery Deep cycle battery Organic radical battery VRLA battery Polymer-based battery AGM battery Polysulfide bromide battery Gel battery -ion battery Glass battery Rechargeable Lithium air battery Rechargeable fuel battery Lithium-ion battery Silicon air battery Lithium ion lithium cobalt oxide -zinc battery Lithium ion manganese oxide battery Silver battery -ion battery Lithium ion polymer battery Sodium–sulfur battery battery Super iron battery Lithium–sulfur battery UltraBattery Lithium–titanate battery Zinc ion battery Thin film lithium-ion battery -ion battery Lead–acid battery • The lead–acid battery, invented in 1859 by French physicist Gaston Planté, is the oldest type of rechargeable battery. Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, its ability to supply high surge currents means that the cells have a relatively large power-to-weight ratio. This technology contains liquid electrolyte in an unsealed container, requiring that the battery be kept upright and the area be well ventilated to ensure safe dispersal of the hydrogen gas it produces during overcharging. Its low manufacturing cost and its high surge current levels make it common where its capacity (over approximately 10 Ah) is more important than weight and handling issues. Starter vs Deep Cycle battery

A deep-cycle battery is a lead-acid battery designed to be regularly deeply discharged using most of its capacity. In contrast, starter batteries (e.g. most automotive batteries) are designed to deliver short, high-current bursts for cranking the engine, thus frequently discharging only a small part of their capacity. VRLA battery (Sealed Lead-Acid) A VRLA battery utilizes a one-way, pressure-relief valve system to achieve a “recombinant” technology. This means that the oxygen normally produced on the positive plate is absorbed by the negative plate. This suppresses the production of hydrogen at the negative plate. The sealed valve regulated lead–acid battery (VRLA battery) is popular as a replacement for the lead–acid wet cell. The VRLA battery uses an immobilized sulfuric acid electrolyte, reducing the chance of leakage and extending shelf life. VRLA batteries immobilize the electrolyte. The two types are: Gel batteries (or "gel cell") use a semi-solid electrolyte. Absorbed Glass Mat (AGM) batteries absorb the electrolyte in a special fiberglass matting. Lithium-ion battery (Li-ion Battery) - LIB 1980 - The electrolyte, which allows for ionic movement of (electrically charge particles of an atom), and the two are the constituent components of a lithium-ion battery cell. The cathode is typically made from a lithium material. The anode is generally made from carbon (). Li-ion Battery Comparison – One to another Lithium-ion battery Power Energy Safety Lifespan Cost Performance Types Lithium Cobalt L H L L L M Oxide Lithium Manganese M M M L L L Oxide Lithium Nickel Manganese Cobalt M H M M L M Oxide Lithium Iron H L H H L M Phosphate Lithium Nickel Cobalt Aluminum M H L M M M Oxide Lithium Titanate M L H H H H Lithium Iron Phosphate – LFP (LiFePo4) 1996 – LFP can be produced by heating a variety of iron and lithium salts with phosphates or phosphoric acid. The major differences between LFP batteries and ordinary lithium batteries are that LFP batteries do not have safety concerns such as overheating and explosion, that they have 4 to 5 times longer cycle lifetimes than lithium batteries and 8 to 10 times higher discharge power. Flow Batteries

• Concept 1930’s main development in the 1980’s • A flow battery, or redox flow battery (after reduction–oxidation), is a type of where chemical energy is provided by two chemical components dissolved in liquids contained within the system and separated by a membrane. The vanadium redox battery (VRB), also known as the vanadium flow battery (VFB) or vanadium redox flow battery (VRFB), is a type of rechargeable flow battery that employs vanadium ions in different oxidation states to store chemical potential energy. The vanadium redox battery exploits the ability of vanadium to exist in solution in different oxidation states, and uses this property to make a battery that has just one electroactive element instead of two. The , sometimes referred to as oxidation number, describes degree of oxidation (loss of electrons) of an atom in a chemical compound. Conceptually, the oxidation state, which may be positive, negative or zero. How to compare different battery Technologies in a BESS ? Typical Battery Technology Spider Chart

We will concentrate on the Following: 1) Temperature. 2) Capacity – SIZE 3) DOD – Depth of Discharge 4) Cycles – How Often. 5) C Rate – Discharge or Charge Rate 6) Cost –Battery & System Cost Temperature – Operating condition of the batteries - OC Nominal battery performance is usually specified for working temperatures somewhere between 20°C and 30°C. The performance and indeed life of a battery can be seriously affected by the onset of extreme temperatures and, despite many consumer beliefs, heat is as big a cause of battery failure as is cold. Capacity. – In BESS we measure it in kilo Watt hours (kWh) Storage systems can level out the imbalances between supply and demand. Because we are looking at the demand side when planning a BESS we measure capacity in kWh. A battery's capacity is the amount of it can deliver at the rated , and is measured in units such as (A·h). Typically a lead Acid battery would be 105Ah at 12V which is 1,260VAh. If we assume a system power factor of 1 that would be 1.26kWh, and if you times that by the energy efficiency of your system (to compensate for conversion losses) you would get your BESS capacity. Depth of Discharge. – (DOD) Measured in % Depth of discharge (DOD) is normally stated as a percentage of the nominal ampere-hour capacity; 0% DOD means no discharge. As the usable capacity of a battery system depends on the rate of discharge and the allowable voltage at the end of discharge, the depth of discharge must be qualified to show the way it is to be measured. Due to variations during manufacture and aging, the DOD for complete discharge can change over time or number of charge cycles. Vanadium Flow Batteries have a 100% DoD with no change to its Cycle life. Cycles – Lifespan or Cycle Stability – Measured in # of Cycles If batteries are used repeatedly even without mistreatment, they lose capacity as the number of charge cycles increases, until they are eventually considered to have reached the end of their useful life. Different battery systems have differing mechanisms for wearing out. For example, in lead-acid batteries, not all the active material is restored to the plates on each charge/discharge cycle; eventually enough material is lost that the battery capacity is reduced. In lithium-ion types, especially on deep discharge, some reactive lithium metal can be formed on charging, which is no longer available to participate in the next discharge cycle. Sealed batteries may lose moisture from their liquid electrolyte, especially if overcharged or operated at high temperature. This reduces the cycling life. C Rate - Charging and Discharging.

You need to calculate or measure what is the Maximum Load or Supply that your BESS should work on. Once you know what is the maximum demand or charge rate is in kW’s you can calculate your C Rate. C Rate = Capacity / Max Charge or Discharge Power Example 1: 20kWh Usable Capacity / 10kW max Discharge is a C2 or C/2 or 0.5C – That means it is possible to discharge the battery fully over 2 hours. Example 2: 20kWh Usable Capacity / 40kW max Charge is a C0.5 or C/0.5 or 2C – Which means that the battery can last for 30 minutes. It is possible to have a different charge C Rate and a Discharge C Rate. Cost – Battery and Balance of System Cost – Battery cost US$ /kWh According to the latest Bloomberg New Energy Finance’s forecast – New Energy Outlook 2018 – falling battery prices will significantly affect the energy market. It’s estimated that lithium-ion battery prices decreased by 80% between 2010 and now. DoD and Cycles have to be taken into account when comparing costs of Technologies. Cost – Balance of System (BOS) Cost US$/ kW Cost –Balance of System Cost US$/ kW