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Energy Storing Mechanisms

Here is a list of but a few mechanisms for storing energy:

(Refer to "Energy Storage: A Non-technical Guide" by Richard Baxter )

1. Pumped Hydroelectric Storage

This consists of two resoviors, one low and one high. During off-peak times, water is pumped from the lower to the higher resorvoir where it is stored ready for running through a hydro station back down to the lower level to generate electricity on demand during peak times.

2. Compressed Air Energy Storage

This uses off-peak electricity to compress air for storage in a vessel. This compressed air is used during peak times to power a gas turbine which would otherwise be using peak electricity to perform this compression for the combustion in the turbine. Efficiency is increased by using exhaust gases to preheat the incoming compressed air.

3. Flow Batteries

These store and release engery through a reversable electrochemical reaction between two electrolytes. They have three major components: the cell, electrolyte tanks and the control system. Instead of the actual cell holding all the electrolyte, separate tanks are pumped through the cell allowing for a quick discharge and a more broad application than a normal cell.

4. Sodium Sulfur Battery

These cells are cylindrical and have a molten sodium negative electrode centrally and a molten sulfur positive electrode on the outside which are separated by a solid beta-alumina electrolyte. Discharging, the sodium, discharges electrons passing sodium ions through the electrolyte to the sulfur, reacting to form sodium polysulfide. Charging, this process is reversed. A good trait they have is they can either provide power long-term or in a short pulse. Each cell is about 2V and are configured in series/parallel to get the desired output.

5. Lead-Acid Batteries

These are low cost and reliable and their energy storage and power rating is based on the size and geometry of the electrodes. The electrodes are used both for the chemical reation and for storing the results from this on their surface. They are the low cost option for remote/off grid storage and for UPS's etc and can most commonly be found as car batteries. Two types are flooded (vented) or valve regulated (sealed).

6. Nickel-Cadmium Battery (NiCad)

There are three types:

High reliability makes them a favourite in many market applications. For reserve power applications they are one of the least expensive, although slightly more expenseive than Lead-Acid batteries they are more reliable and have a longer life cycle.

7. Fly-Wheels

They store energy through accelerating a rotor up to a high speed or in other words storing energy kinetically. They are also used to level out power flow. Energy is stored in proportion to its momentum but at the square of its surface speed, making it desirable to develop high-speed composite flywheels. It releases its energy via a generator and is suitable for deep discharges that are normally too taxing for standard batteries. Also they are more compact and less maintenance is required.

8. Electrochemical Capacitors

Similar to batteries where two electrodes are immersed in an electrolyte and separated by a porous separator. The goal being to have storage capacity of a battery with operating characteristics of a capacitor.

9. Superconducting Magnetic Energy Storage

This stores energy in a magnetic field created by the flow of direct current in a coil of cryogenically cooled superconducting material. Generally used to provide power-grid stability and power quality for manufacturing processes with high susceptibility to voltage instabilities.

10. Thermal Energy Storage

Designed to work with exisiting building's cooling system, it uses the chiller to make ice or chilled water during off-peak hours and stores it in an insulated storage tank where it can be utilised during peak times for air conditioning operating costs and running chillers. Systems and Equipment If any of these storage systems are required Armadillo Engineering has the ability to assist with implementation.