Energy plays a major part in our everyday life whereby almost all forms of production activities are dependent on energy sources, either as primary, secondary or final energy. Energy is also needed to channel various basic needs to the general population of a country; in transportation, cooking and lighting homes. But with most sources of primary energy being non-renewable, careful and optimal utilization of energy sources is very important. Coupled with this is the fact that the energy consumption pattern of a nation determines the rate at which its energy sources are being depleted. In this respect, historical events have time and again given us painful lesson on being overly dependent on fossil fuels.
Need for Storage of Electricity Power and difficulties.
The demand for electricity power differs according to the load requirement on daily basis. During peak loads lasting for few hours, the total installed capacity of the generating plants should be more than the total active power. This however requires high capital investment. During off-peak loads the installed generating capacity is not utilized fully. The technical term used for such condition is so-called poor load factor.
The Problem of Energy Storage
Below are some problems associated with Energy Storage.
It is difficult to meet peak loads demand and installed capacity is generally insufficient to meet peak load demand. Perhaps some load scheduling is required to be planned in order to maintain the grid frequency.
Increasing installed capacity in order to meet the required peak demand for short duration is uneconomical.
Electrical energy cannot be economically stored in large quantities i.e several Mega Watts.
The Solutions …………Done
Followings are some steps that can be implemented in order to overcome the above problems.
Inter connection between neighboring having different peak demand hour ( UAE National Grid) where energy Ex.-changed is performed between Emirates.
Energy storage in large quantities (several hundred MW) during off-peak. The stored Energy can thereafter be utilized during peak period. The most suitable form of stored energy known worldwide is hydro, pneumatic, thermal, chemical, and solar. During peak demand periods the energy stored in some other form is reconverted into electrical form and is supplied back to the network
Types of Energy Storage Plants and Range ……Check the updated range
Type of plant Plant Capacity
1. Storage Battery Cells Plant Up to 10 MW
2. Pumped Hydro Electric Plant Up to 400
3. Flywheel (Advanced Vacuum Flywheel with Magnetic Bearings)
4. Magnitic Storage. Super conducting magnetic energy storage Up to 500 MWh
5. Thermal Storage.
6. Hydrogen Storage
7. Compressed Air or nitrogen Energy Storage 25 to 200 MW
Storage Battery Energy Storage
Following types of secondary cells are used.
Lead Acid Batteries
Nickel cadmium batteries
Advanced Batteries
Sketch
Cells are connected in series parallel branches to form a Battery-Bank. During off-peak period the circuit -breaker is switched on and the Thyristor convertor is operated in Rectifier mode *by controlling the phase angle to less than 90 deg.* Battery gets charged.
During peak loads on the grid, the thyristor convertor is operated in inverter mode (converting AC power to DC power)by increasing delay phase angle beyond 90 deg.
The batteries supply sat to store energy to the network. For example in certain countries the installation capacity of such installation could provide 1MW up to 10MW of power generation in which the problem with PEAK demand on power generation can be resolved.
Pumped Hydro Energy Storage. …………add somemore about combustion (comp Air)
The above installation stores energy in pumped hydro structure. The plant left in service throughout the day on automatic control mode. During off load the heavy duty high capacity motor takes the power from the Electrical Network and drive the Air Compressor. The compressed Air is sent to the Air storage Tanks. During the peak load, the Energy in compressed air is utilized for driving the Gas Turbine.
Super conducting Magnet Energy Plant.
The super conducting Magnet Energy Plant forms as an electromagnetic energy storage which often used for obtaining very high power for short period. The said unit is installed to enhance the transient stability of the power system.
Sketch & more Description…………….
Thermal Storage
This technology is used in colder countries, mainly Europe, Canada and part of Asia. The above technology is used for heating premises. During off peak periods the power supply is utilized to heat the thermal energy absorver elements in residential buildings, offices, hospitals, universities etc. During peak load, heaters are switched off and stored energy is dissipated through circulating water form heating.
Hydrogen Storage.
This technology has not been commercialized in a wide range. However in many countries where such facilities are installed, Hydrogen and other chemicals are produced and stored. During peak load on electricity network, fuel cell plant uses the fuel and oxidant to generate electricity.
Conclusions
Energy Storage facilities are known to be of high conversion cost. At present the power generation in developing countries (china and India) is mostly by conventional. However, in future the power generation from renewable sources is expected to have more share of entire world's energy generation.
Supercapacitors
The supercapacitors are considered to be one of the most useful methods of energy storage. This is due to the capacitance values which have over any other capacitors type available in the market. The internal construction of Supercapacitors allows to charge and discharge the power continuously without degrading like batteries. The most significant advantage of supercapacitors is that the stored energy can be discharged very quickly comparing to the batteries. Energy stored in the batteries can supply the bulk energy since they can store and carry a great amount of energy over a longer slower period of time.
Super Capacitor construction
Supercapacitors are based on a carbon nanotube technology. This makes them to be different from other capacitors types available in the market. The electrodes and carbon technology used in these capacitors allow them to create an extremely large surface area with a very small separation distance. This large surface area permits for a large amount of ions to be absorbed
The internal construction of supercapacitors consists of two metal electrodes that are separated by a dielectric material. Additionally, a physical barrier is made from activated carbon material and that when an electrical charge is applied to the material a double field is generated. The dielectric has electrical properties that actually affects the entire performance of a capacitor.
