能源储存(英文版).pptx

Energy ChemicalBing Wang Qinghai University1.What should we do about the energy crisis?Energy savingRenewable EnergyEnergy Storageenergy efficiencyWhich one is the most important?Chemical Energy StorageMagnetic Energy Storage.Thermal Energy Storage.Mechanical Energy StorageEnergy Storage System(ESS)can be classified as01Mechanical Energy StoragePrinciple:Energy is stored in the form of Mechanical Energy.Light weight fiber composite materials are used to increase efficiency.Energy density =0.05MJ/Kg,=0.8Fly WheelsCompressed Air Energy StorageOperation:Uses off-peak electricity to compress air and store it in airtight underground caverns.When the air is released from storage,it expands through a combustion turbine to create electricity.Energy density=0.22 MJ/Kg,=0.5Advantages and disadvantages:Fast start-up.Draw back-Geological structure reliance Pumped Hydroelectric Energy StorageOperation:It consists of two large reservoirs located at different elevations.During peak demand,water is released from the upper reservoir.If Production exceeds Demand,water is pumped up and stored in the upper reservoir.Pump used is a Combined Motor and Dynamo.Advantages and disadvantages:Most effective with largest capacity of electricity(over 2000MW).Energy density=0.001MJ/Kg,=0.8 Geographical dependence.The capital cost is massive.Soil erosion,land inundation,Silting of dams.02Magnetic Energy StoragePrinciple:At low-temperatures,electric currents encounter almost no resistance.Stores energy in the magnetic field.Environmental friendly and Highly efficient.ReactorSuper CapacitorsPrinciple:The distance between the two charged layers is very small,resulting in a very large capacitanceLong service life,quick charge and discharge03Electrochemical Energy StorageLead acid Batterylithium batteryPrinciple:They use a chemical reaction to do work on charge and produce a voltage between their output terminals.Energy density is 0.6 MJ/Kg.Comparison of different battery energy storage systems04 Thermal Energy Storage.A salt hydrate acts as a cool heat sink for the air conditioner working fluid.The stored heat is rejected from the salt hydrate during night to heat the surrounding air.Energy density=0.25MJ/Kg,=0.8E.g.:Sodium Sulfate DecahydrateAdvantages:No green house gasesNot much political dependenceMore operating time.Disadvantages:Storage of Hydrogen due to highly inflammable nature of H2.High capital cost due to Platinum catalyst used in the process.Fuel CellsWhich is better?1.Comparing one method of energy storage with another is pointless.The reason-None of them are optimal for all purposes2.Flywheels have a narrow range and are not an answer for large scale operations.3.Different storage methods differ in capacity and maximum usable storage time.4.For large scale storage Underground thermal,pumped hydro and compressed air energy storage systems are preferable.5.Superconductors can store energy with negligible losses.6.Fuel cells are a viable alternative to petrol engines due to their high efficiency.THANK YOU!