Energy storage is key to developing usable renewable systems, because both solar and wind generation is by nature sporadic. While batteries are the first thought when looking at storage, other methods need to be developed to make new equipment viable as a reliable energy source.
One storage system being explored is thermal, where the energy stored in the form of heat can be released as needed to generate electricity through a turbine system, or through many other generating devices.
Today’s post offers a few looks at thermal energy storage. Enjoy!
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Thermal Storage – An Economical Alternative to High Energy Bills
Are you tired of paying high prices for heating and cooling? Would you like to save the excess heat of summer until you really needed it in winter? Thermal storage might be the answer you are looking for.
By Earl Hunsinger
On a hot summer day, do you think about how cool it was last fall or winter? On cold winter nights, do you dream about lying in the sun on some tropical beach? What if you could save the heat of summer to use in winter, and save some of the cool air of winter to air condition your house during the summer? This concept is called thermal storage.
It is important to understand that heat is a form of energy that can be moved from one place to another (this is how a refrigerator or air conditioner works). Thermal storage refers to a number of different technologies that are used to store this thermal, or heat, energy in a reservoir for later use. While technically cold is simply a term that refers to a relative lack of heat energy, the same thermal storage principle applies to the storage of cold substances, those with a relatively lower quantity of heat. The simplest example of this is one that the older generation may still remember. Before the proliferation of modern refrigeration equipment, farmers used to cut blocks of ice from frozen ponds and lakes in the winter. This ice would be stored in a well insulated building, with much of it remaining frozen until summer. It would be used to keep milk and other farm products from spoiling.
Most thermal storage equipment today is usually designed to store heat for only a few hours or days. This is done for a number of practical or economic reasons. Thermal storage units are often used with solar heating equipment to save the heat of the day for use during the night. An example that combines heat collection with heat storage is the device manufactured by the Solar Components Corporation. This device is a simple water filled vertical tube. These tubes capture heat from the sun during the day and release it at night. Since no mechanical equipment is involved, this is what is known as a passive system. Active systems are also available, where a pump or blower moves heated water or air from one place to another, often to a thermal storage tank.
Another reason why thermal storage is used involves the electrical usage rate structures used by many power companies. Because of the high cost of building new generating plants, power companies often charge more for electricity used during peak hours. This creates an incentive for large commercial and industrial users to limit their energy usage during these peak hours. One way to do this is running heating or refrigerating (including air conditioning) equipment during off peaks, usually at night. How can they do this? Thermal storage.
As an example, consider the problem of how to provide air conditioning to an office building during the day, by running the air conditioning equipment at night. In most cases, large commercial air conditioning systems are used to cool water and then this water is pumped to different parts of the building and used to cool the air going to the office space. If you chill the water at night, how do you keep it cold until it is needed during the day? The Cryogel company sells a product that many of us would find very familiar. When packing a picnic lunch, you might go to your freezer and take out a blue pack to keep your food cold. Their product is similar. Sealed balls filled with water are placed in an insulated tank. The chilled water (or glycol) is pumped through the tank, causing the balls to freeze. Later, warm water is circulated through the tank, the balls cool it, and this chilled water can be used to air condition the office building.
While it is obviously easier to maintain the temperature of a substance for a few hours, seasonal heat storage is also possible. An example of this is Britain’s Beaufort Courthouse, which is designed to be a zero emissions building.
Because of the cost and the work involved, thermal storage is probably more commonly used in commercial and industrial applications than by the average homeowner. However, with a little ingenuity and a modest investment, there is no reason why you too couldn’t save the sunshine of summer for those long winter nights.
| By Buzzle Staff and Agencies Published: 7/9/2007 |