GB2229265A - Method of storing energy produced by a wind powered generator - Google Patents

Description

1 METHOD OF STORING ENERGY PRODUCED BY A WIND POWERED GENERATOR When when

using the wind to generate electric power this power is generally not produced continuously and evenly.---When there is no wind or an insufficient wind velocity absolutely no electric power may be produced whilst on the other hand when the wind velocity is sufficient to produce electric power it is not always possible to use the power immediately and directly in electrical devices. It was previously only possible to store such excessive electric energy in relatively expensive power stores, such as accumulators.

It is known, for instance from DE-CE-3130671 and US-A4269170 that energy, eg. solar energy, can be stored in a storage medium operating by means of water sorption, such as silica gel or zeolite, and that the stored energy can be withdrawn from the storage mediumf when required.

It is the object of the present invention to store the energy of excessive electric power produced by wind generators without using expensive accumulators, whereby the stored energy can be withdrawn at the desired subsequent point in time without incurring the substantial energy losses which inevitably occur, for instance, when storing energy in electrical form in accumulators due to self discharge.

According to the present invention there is provided a method of storing energy produced in the form of 2 electrical energy by a wind powered generator in which the electrical energy is converted into heat which is used to dry zeolite or silica gel charged with water.

In the method in accordance with the invention the electric power is used to produce heat, ie. converted into heat and zeolite or silica gel charged with water is dried with this heat. The drying advantageously occurs at temperatures above 2000C, but can also be conducted at lower temperatures. In this connection, reference is made to the method described in DE-A3022583 in which such drying can also be effected at temperatures of only 400C.

The 'zeolite or silica gel which is freed of water, ie. dried, can be stored for any desired length of time so long as care is taken reliably to exclude atmospheric air. If heat is subsequently required, a carrier medium, for instance air, substantially or completely saturated with water vapour is supplied to the dried zeolite or silica gel so that it again becomes charged with water and at the same time a considerable quantity of heat is liberated in a manner known per se.

In this manner it is possible to store any energy produced by a wind generator which is excess to current requirements and then to withdraw it at any desired, subsequent point in time in the form of heat. Such heat can be used, for instancei for heating purposes, particularly for heating greenhouses.

it is advantageous to transport the heat to the zeolite or silica gel by means of a carrier medium. For this 1 3 purpose the excess energy produced by the wind generator is converted into heat by means of suitable resistive heaters and this heat is conducted away by means of a suitable carrier medium, eg. air, and the air, heated to a suitable temperature, is used to dry the zeolite or silica gel charged with water. As an alternative to air an inert gas can be used as the carrier medium. This is advantageous in so called closed systems, for instance as are described in DE-CE3130671 and DE-CE-3424298. It is also particularly advantageous to perform the method in a so called open system, ie. a system in which air is used as the carrier medium and is heated by the electric power and used to dry the zeolite or silica gel charged with water whilst when subsequently using the energy stored in the dried zeolite or silica gel air charged with water is passed through it. For this purpose, either air which has a sufficient humidity due to the atmospheric conditions, probably in the region of 100% relative humidity, can be used, or the air supplied to the dried zeolite or silica gel can be previously humidified to increase the temperature which may be achieved, in use, as is described in DE-CE-3130671.

It is further of advantage in the present method if the zeolite or the silica gel is used in loose form. It is then possible to conduct the method in individual columns, as is described in more detail in DEA3022583.

However, in another advantageous embodiment the zeolite is used in the form of a storage brick. It has been found that when using zeolite in the form of a storage 1 4 brick, eg. with dimensions of 10 x 15 x 30 cm, a satisfactory transport of water is achieved both when drying the zeolite and when using the energy stored in the zeolite, ie. when recharging the dried zeolite with water. Such a storage brick can advantageously have pores in order that the maximum diffusion distances do not become too large. eg. as in a so called apertured brick.

The use of a zeolite storage brick is advantageous since a resistive heater connected thereto in a thermally conductive manner can be used to dry it, when charged with water, as is disclosed in, for instance, DE-B2546597. In this event it is of course necessary to pass a smaller amount of the carrier medium, eg. air, past it in order that the water exiting from the zeolite storage brick in the form of water vapour can be conducted away. When using the energy stored in a dried zeolite storage brick in the form of withdrawn heat, the procedure is the same as in the case of a loose filling, ie. a carrier medium, particularly air, with sufficient relative humidity or which has been brought to a sufficient relative humidity by additional steps, is passed over the dried zeolite storage brick and is heated up due to the adsorption of the water vapour from the carrier medium.

In a further preferred embodiment of the present method the conversion of the electric current into heat and the drying of the zeolite or silica gel charged with water is conducted in respective units or modules which are coupled together in a modular manner. Such a mode of operation is particularly economical since such 1 units need not be constructed to cope with the maximum possible amount of excess power from a wind power generation installation since it is possible, in the event that the capacity of such a unit is insufficient to cope with the energy from a given wind generation installation, to connect a plurality of such units, which may be coupled together in parallel or in series. It is thus easily possible to match the capacity of the energy storage installation to the amount of excess energy which is produced.

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Claims (7)

1. CLAIMS v 1. A method of storing energy produced in the form of electrical

   energy by a wind powered generator in which the electrical energy is converted into heat which is used to dry zeolite or silica gel charged with water.
2. 2. A method as claimed in claim 1 in which the heat is transported to the zeolite or silica gel by means of a carrier medium.
3. 3. A method as claimed in claim 2 which is conducted in an open system.
4. 4. A method as claimed in any one of the preceding claims in which zeolite is used in loose form.

   1.
5. 5. A method as claimed in any one of claims 1 to 3 in which zeolite is used in the form of a storage brick.
6. 6. A method as claimed in claim 5 in which the zeolite storage brick is dryed by a resistive heater which is connected to it in a thermally conductive manner.
7. 7. A method as claimed in any one of the preceding claims in which the conversion of the electrical energy into heat and the drying of the ze olite or silica gel charged with water is conducted inrrespective units which are coupled together in a modular manner.

   1 Published 1990 at ThePatentWice.Siate House. 66 71 High Holborn. London WC1R4TP. Purther copies maybe obtained from The Patent Office Sales Branch, St Mary Cray. Orpngton. Kent BR5 3RD. Printed by Multiplex techniques ItcL St Mary Cray. Kent. Con. V87