电力存储五分钟指南

Technologies The need for storage Application and technology overview Sodium Sulphur (NaS) Batteries Technology Description Disadvantages -Heating may be required-Potential safety issues withthe molten sodium-Fire issue at a Japan installation A sodium sulphur battery is a molten statebattery constructed from sodium (Na)and sulphur (S). The battery casing is thepositive electrode while the molten core isthe negative electrode. The battery operatesat high temperatures of between 300-350°C,while lower temperature versions are underdevelopment. In charging, the sodium ionsare transported through the ion selectiveconductor to the anode reservoir. Dischargeis the reverse of this process. Becausesodium ions move easily across the ionselective conductor, but electrons cannot,there is no self-discharge. When not in usethe batteries are typically left under charge sothat they will remain molten and be ready foruse when needed. If shut down and allowedto solidify, a reheating process is initiatedbefore the batteries can be used again. Applications There are over 300 grid applications of NaSbatteries worldwide, with the majority of theselocated in Japan. NaS batteries can be usedfor many grid applications such as: powerquality applications, grid stabilisation and theintegration of renewable energy sources.In 2019, UAE integrated 15 systems across10 locations, peaking out at a total capacity of108MW/648MWh.The batteries store the energy generated at night and combine this with the wind farmoutput during the times of greater demand inthe day. Sankey Diagram Advantages -High energy density-Long life cycle-Quick response-Efficient in charge-discharge cycles-Able to tolerate a high numberof charge/discharge cycles Flow Batteries Technology Description Flow batteries are a rechargeable battery using two liquid electrolytes,one positively charged and one negative, as the energy carriers. Theelectrolytes are separated using an ion-selective membrane, which undercharging and discharging conditions allows selected ions to pass andcomplete chemical reactions. The electrolyte is stored in separate tanksand is pumped into the battery when required. The storage capacity offlow batteries can be increased by simply utilising larger storage tanks forthe electrolyte. Several chemistries are possible for the battery. Advantages -Less sensitive to higher depths of discharge-Able to tolerate a large number of charge/discharge cycles-Reduced likelihood of the cells output being reducedto that of the lowest performing cell.-Virtually unlimited capacity Disadvantages -Low energy density-Not commercially mature ApplicationsFlow batteries can be used for many grid applications such as: load Sankey Diagram (VRB) balancing, standby power and the integration of renewable energysources.In Dalian, China, there is a 200MW/800MWh capacity vanadium redox flow battery facility. The facility will provide power at peak times, gridstabilisation and provide back-up supply. Lead Acid Batteries Technology Description Disadvantages -Susceptible to high depths of discharge(unless deep cycle variant)-Low energy density-Potentially hazardous materials Lead acid battery technology is the mostestablished battery technology. There areseveral variants of the technology available.Flooded lead-acid batteries immerse theelectrodes in liquid electrolytes and releasegases upon charging. An example of this is astandard 12 volt car battery. Sealed lead acidbatteries come in two forms: Absorbed glassmat batteries create energy by immobilisingelectrolytes with a micro fiber glass mat.Gel cell batteries have the electrolyte mixedwith silica dust to form an immobilised gel.Sealed batteries do not require the regularaddition of water to the cells and vent less gasthan flooded lead-acid batteries. However,they have a longer re-charge time and shorteruseful life. Advanced lead acid batteries havebeen developed and are particulary suited toenergy storage applications. ApplicationsLead acid batteries are predominantly used for starting vehicle engines as well as for backuppower supplies and for grid energy storage.The technology is mature for use as ancillaryservice such as an Uninterruptible PowerSupply (UPS), with demonstrated applicationsfor bulk energy storage. Lead acid has beendemonstrated as storing between 3 and 10 MWover a period of hours with an example beingthe Metlakatla lead acid battery project with aninstalled capacity of 1MW. Sankey Diagram (Advanced Lead Acid) Advantages -Lead-acid batteries are an establishedtechnology, with existing infrastructurefor end of life recycling already inplace due to the automotive industry-Relatively efficient-Low self-discharge rates Lithium ion (Li-ion) Batteries Technology Description Disadvantages Lithium ion (Li-ion) batteries are a type ofrechargeable battery in which lithium ionsmove from the negative electrode to thepositive electrode during discharge and backwhen charging. They are common