How electricity generated can be stored (electricity is not wheat...)
Electricity is not similar to Wheat...
One can store wheat (or any other material for that matter). One can not store Electricity though; electricity can however be converted to other types of energy that can be stored. These other types of energy can be reconverted back to electricity when Electricity is needed.
Wheat Storage in the Old Testament
"Let Pharaoh proceed to appoint overseers over the land and take one-fifth of the produce of the land of Egypt during the seven plentiful years. And let them gather all the food of these good years that are coming and store up grain under the authority of Pharaoh for food in the cities, and let them keep it. That food shall be a reserve for the land against the seven years of famine that are to occur in the land of Egypt, so that the land may not perish through the famine.”
(Genesis 41:34-36 ESV)
What a breakthrough in Electricity Storage will buy?
A lot of research efforts are visible in the area of electricity generation. However, a breakthrough in Electricity Storage is the key to solving the following problems:
- Storing electricity from the low demand time to be used during high demand hours will eliminate the need to build new Power Generation Plants
- Installations that already use deep cycle batteries will be much more owner friendly user if other means (not available yet) will be implemented
Electricity is a unique Entity
It is a common practice to say that Electricity is generated and that Electricity is stored. Power Plants actually convert one kind of energy (typically mechanical rotation energy) into electrical energy. Linguistically, if to generate is to "cause to arise or come about" (Oxford dictionary definition) than Power Plants generate electricity.
By the same token (and not like wheat), Electricity can not be stored as electricity. Electricity is a stream of electrons and every bit of energy that comes out from the generator (the source) flows happily toward the consumers (load).
When we say Electricity Storage we actually refer to conversion of electricity to some other type of energy that can be stored and later on can be converted back to electricity. And, we do not "store" electricity for "seven years"; we "store" electricity for hours or days in the extreme.
Power Demand Curves
Electricity Supply and Demand
As we have seen, electricity must be freshly supplied as soon as the demand is created. The consumer turns on a light bulb, a washing machine or any other "electrical load" somewhere on the grid this extra electricity must be generated.
The accumulated demand must be followed by an equivalent supply. The demand curve is not flat, it is rather wavy and it has peaks and valleys. The grid must be prepared to supply the peaks! This is a burden on production and transmission costs because there is a built in over capacity.
There are tactics to flatten the peaks:
- To make the grid bigger in size, for example when it is midnight in the East Coast (low demand) it is 9 PM in California (peak demand) so electricity generated in the East Coast can be transmitted over high voltage lines to the West coast and consumed there.
- Encourage customers to use heavier load (such as water boilers, washing machines etc.) during the low consumption hours (this is the main incentive to use "smart meters")
Or, store electrical energy that was generated during the low consumption hours and reconvert it to electricity during the peak demand hours; hence the need for Electricity Storage
Ontario, Canada Pumped Storage facility
Electricity Storage Forms
There are many suggested ways to store electricity, not all of them are in a wide use. The most prevalent electricity storage methods are:
- Pumped Wate
- Thermal storage
- Storage Batteries
The first two are more suited to Grid Scale Electricity Storage (large scale electricity storage). The third one, Storage (deep cycle) batteries are probably the only storage solution known for the small scale users (domestic and small businesses).
A small Heliostat
Thermal Energy Storage
One of the most promising thermal storage technology is molten salt. It is the method of choice for the storage of thermal energy collected by a solar tower (a heliostat) to be used to generate electricity overnight. It was demonstrated in the Solar Two project from 1995-1999. The molten salt is a mixture of 60 percent sodium nitrate and 40 percent potassium nitrate. The mixture not toxic, and the material was used as a legacy technology in the chemical and metals industries as a heat conducting material.Heliostats draw on the vast experience that was gained in those legacy industries.
Salt melts at 430 degrees Fahrenheit and heated conventionally to about 550 degrees Fahrenheit. The fluid temperature is elevated in the solar collectors 1050 degrees Fahrenheit by the focused Sun rays. It is stored in a storage tank to be used when needed to generate steam and run a steam turbine.
There are few operational prototype heliostats employing molten salt storage
Deep Cycle Batteries Background
- The Deep Cycle Battery, the battery for off-grid power storage
The different types of batteries, deep cycle battery, what is important to know before and after you buy?
Deep Cycle Batteries
For small solar power generators and for small wind turbine generators, the most common technology to store electric energy are deep cycle batteries. In essence when batteries are charged they convert Direct Current (DC) into chemically stored energy. When the battery discharged, the chemical energy is converted back to DC electrical power.
Electricity Storage Research
Because there are so many benefits to storing electricity, many are researching this field. One area that is in the focus is to find light weight batteries that will store a lot of electricity. If a good solution will be found - electrical cars will be a more viable approach.