1、,1.What should we do about the energy crisis?,Which one is the most important?,Chemical Energy Storage,Magnetic Energy Storage.,Thermal Energy Storage.,Mechanical Energy Storage,Energy Storage System (ESS) can be classified as,01,Mechanical Energy Storage,Principle: Energy is stored in the form of M
2、echanical Energy. Light weight fiber composite materials are used to increase efficiency. Energy density=0.05MJ/Kg, =0.8,Fly Wheels,Compressed Air Energy Storage,Operation:Uses off-peak electricity to compress air and store it in airtight underground caverns. When the air is released from storage, i
3、t expands through a combustion turbine to create electricity. Energy density = 0.22 MJ/Kg, =0.5 Advantages and disadvantages: Fast start-up. Draw back - Geological structure reliance,Pumped Hydroelectric Energy Storage,Operation:It consists of two large reservoirs located at different elevations. Du
4、ring 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 2000 MW).Energy density
5、= 0.001MJ/Kg, =0.8 Geographical dependence. The capital cost is massive. Soil erosion, land inundation, Silting of dams.,02,Magnetic Energy Storage,Principle: At low-temperatures, electric currents encounter almost no resistance. Stores energy in the magnetic field. Environmental friendly and Highly
6、 efficient.,Reactor,Super Capacitors,Principle: The distance between the two charged layers is very small, resulting in a very large capacitance Long service life, quick charge and discharge,03,Electrochemical Energy Storage,Lead acid Battery,lithium battery,Principle: They use a chemical reaction t
7、o 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 systems,04,Thermal Energy Storage,. A salt hydrate acts as a cool heat sink for the air conditioner working fluid. The stored heat is rejected from th
8、e salt hydrate during night to heat the surrounding air. Energy density = 0.25MJ/Kg, =0.8 E.g.: Sodium Sulfate Decahydrate,Advantages: No green house gases Not much political dependence More operating time. Disadvantages: Storage of Hydrogen due to highly inflammable nature of H2. High capital cost
9、due to Platinum catalyst used in the process.,Fuel Cells,Which 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 met
10、hods 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.,
