GB2448333A

GB2448333A - Turbine energy storage

Info

Publication number: GB2448333A
Application number: GB0706976A
Authority: GB
Inventors: David Paul Spankie
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-04-11
Filing date: 2007-04-11
Publication date: 2008-10-15
Anticipated expiration: 2027-04-11
Also published as: GB0706976D0; GB2448333B

Abstract

A fluid driven vertical axis turbine assembly 10 comprises a base 24 and a rotor rotatably mounted thereon, the rotor having at least two vertically extending hollow blades 12. A generator 14 is coupled to the rotor to generate electricity from the rotation thereof. The turbine assembly 10 further comprises at least one source of liquid 18, and a pump 32 which pumps the liquid into the hollow blades 12, the liquid being allowed to drain there from, to generate power, dependent on the rate of fluid flow across the rotor. The draining liquid may pass through nozzle jets which causes rotation of the rotor. Alternatively the draining liquid may generate power using a second generator. The interior of the hollow blades 12 may be separated into separate vertically arranged chambers, the flow of liquid to and from each chamber being independently controlled. The turbine rotor may be driven by wind or water, and the liquid pumped into the hollow blades 12 may be water.

Description

TURBINE

This present invention relates to a fluid driven turbine for the generation of electrical power.

The use of turbines to convert the kinetic energy in renewable sources, such as the flow of fluids like wind and water, into mechanical energy has been utilised for centuries as a means of generating power. Wind turbines generally fall into two groups, horizontal-axis wind turbines (HAWT's), whereby the turbine rotates around a horizontal axis, and vertical-axis wind turbines (VAWT's), whereby the turbine rotates about a vertical axis. HAWT's are the most commonly used group of wind turbine as they have been shown to be more efficient than VAWT's. However, VAWT's have several benefits over HAWTs. They are generally easier to maintain as all of the mechanical parts (i.e. the generator, bearings and valves) are located at ground level, they have a high starting torque, are generally safer and can handle turbulence much better than HAWT's. However, the main advantage is that they work equally as well no matter which direction the wind is coming from. There are several issues that need to be considered when designing both HAWT's and VAWT's in order to harness the power of wind. Wind generation is often unpredictable and wind strength is by no means constant, as such there is difficulty in designing wind turbines to produce a constant power output. The amount of power required also varies depending on the electrical demand. Most known prior art turbines take these issues into consideration and are designed with some sort of power control. In order to protect the turbine in the case of very strong winds or to reduce the power output, power control is generally achieved by varying the pitch of the blades (known as pitch control), or the blades are designed aerodynamically so as to avoid a lifting force acting on the rotor (known as stall control). In the case of no or minimal wind they rely on electricity being provided by other forms of backup generation, such as gas or coal-fired power plants.

It is a principal aim of the present invention to provide an improved vertical axis fluid driven turbine for the generation of power. it is a further aim to provide a turbine with an advanced control mechanism that maximises efficiency by capturing energy at times of high fluid flow rates for use at times of low fluid flow rates.

According to the present invention there is provided a fluid driven vertical axis turbine for the generation of power comprising: a base; a main rotor assembly rotatably mounted on the base and having two vertically extending hollow blades; a main generator coupled to the rotor assembly to generate electricity from the rotation thereof; and at least one source of liquid and means for pumping that liquid into the hollow blades and allowing it to drain therefrom, dependent on the rate of fluid flow across the rotor assembly.

The draining of the liquid form the blades can be used to generate electricity, because the potential energy of the liquid pumped up the blades may be converted to electrical energy. This can be done in a variety of ways.

The means for allowing draining of the liquid may include nozzle jets adapted to expel the liquid under pressure in suitable vectored directions to thereby impart a turning force to the rotor assembly. This will supplement, or for a time replace, the power of the wind or water flow to allow the rotor to keep turning and hence generating electricity. The liquid may instead pass through an impeller or like device of a secondary generator adapted to generate electricity from this liquid flow as it drains from the blades. The pump adapted to pump the liquid into the blades may also act as a generator when liquid flows in the opposite direction. The pump may be driven by rotation of the main rotor assembly or from power derived therefrom.

The rotor assembly may preferably have only two blades, but it may also have three or more similar blades symmetrically provided thereon. The blades are each preferably shaped like a curved wing, with a rounded leading edge and a tapered trailing edge. Each blade may be curved to match a part of the circumference of a notional circle, upon which circumference the or each other blade is also aligned. The turbine blades may be of the form generally known as a turbine.

The hollow interior of the blades may be separated into individual vertically arranged chambers one on top of each other. The flow of liquid to and from each chamber may be independently controlled both with respect to each other and or with respect to the liquid source.

Each blade may comprise a single section, or may comprise a plurality of separate vertically stacked hollow blade sections that together define the blade. An appropriate number of these blade sections may be connected to one another to assemble a blade for a rotor assembly of a desired height.

The operation of the turbine may be controlled to ensure efficient operation. This control may depend amongst other factors on the fluid speed, electrical power demand, and amount of liquid held in the blades. The turbine may be provided with sensors to monitor these parameters and other parameters and these may provide feed back to control the flow of liquid and the speed of the rotor assembly's rotation. Valves may be provided to control the flow of liquid into and out of the blades, chambers and/or blade sections.

S These valves, sensors and other constituent parts may be controlled by a control system. The control system may be an electronic control system integrating the function of the turbine.

The liquid source may be a storage tank from which liquid is pumped to the blades and to which it drains therefrom. The nature of the storage tank and the piping that allows that flow to and from the blades depends on the nature of the liquid and the design of the rotor assembly. Preferably the liquid is water.

The liquid may contain suitable additives depending on its nature and the operating parameters of the turbine. Preferably the liquid, especially where it is water, contains an anti-freeze component. Alternatively it could be a fuel oil such as diesel. Such liquid fuel could also be used to run generators if required.

The main rotor assembly may be rotatably supported in a base with a mercury bearing as this provides a low friction bearing. The base may be mounted in the ground or below a surface.

The turbine may be adapted to be driven by flow of any fluid flowing in any direction generally perpendicular to the axis of the rotor. The fluid is preferably wind or water.

The turbine of the present invention may be constructed in a range of different sizes. At present however, it is generally anticipated that the turbine could be constructed up to a height of lOOm or so, a width (diametric) in suitable proportion of up to about 35m and a fluid content capacity of up to about 2000 tons.

The force of the fluid flowing past the turbine may at times be significant therefore, the blades must be securely fixed to the rotor assembly which in turn should be well mounted to the base. This could be achieved using any form of strong securing means.

By way of example only, one specific embodiment of this invention will now be described in detail, reference being made to the accompanying drawings in which:-Figure 1 is a somewhat stylised view of wind turbine according to an embodiment of the present invention; Figure 2 is a side view of the turbine of Figure 1; and Figure 3 is a plan view of the blades of the turbine.

Referring first to Figures I and 2 there is shown an embodiment of the present invention, being a wind driven vertical shaft turbine generally indicated 10. The turbine 10 comprises a rotor assembly having a main column 11, and two hollow blades 12, each blade comprising a plurality of vertically stacked blade sections 13. At the top of the rotor assembly there is a top plate 15 and at the lower end of the rotor assembly there is a bottom plate 16. The main column 11 is coupled to a generator 14 which coverts the rotation of that column into electricity. A plurality of generators could be used with each being selective coupled and uncoupled depending on the loading of the rotor assembly and the electrical power required. The main column 11 is supported on a base 24 with a mercury bearing to minimise friction. Everything except the rotor assembly is usually mounted below a surface such as the ground.

There are two tanks 18 that store water to be pumped into the chambers in the hollow blade sections 13. As required, the water is pumped through pipes 19 to a central pipe (shown in dotted line) running up the inside of the main column 11 by two fluid pumps 32 one associated with each fluid tank. The pipe is suitably coupled to the tanks so that it can handle the rotation of main column. The water enters the lowermost blade section 22 and, when this is full, the next one up and so on. A section isolating valve 21 is contained at the base of each blade section which can be shut to prevent flow of liquid down to the section below.

Water is pumped to the blades when wind is strong and there is surplus energy. This adds mass which stabilises the rotor assembly, controls the rotational speed and allows more of the wind energy to be caught. The pumps 32 pump the water up as required. At lower wind speeds, the water is not required and is allowed to flow under gravity back to the tanks. This causes a reverse flow which is used to generate electricity. Alternatively the blades may be drained by jetting pressurised water from directional nozzles on the blades, which cause a rotational force to be applied to the rotor assembly to keep it rotating -and hence generating via generator 14.

Each blade 12 may have a reserve of stored water that is not used as described above but instead is used to assist in restart of rotation after a rotor assembly has completely stopped. This reserve would be released to generate power to restart movement and overcome initial resistance at low air speeds.

A wind measuring device 26 is connected to the uppermost part of the turbine 10.

An electronic control system 28 is linked to the wind speed measuring device 26, the pumps 32 and the generator 14 (at least). It monitors the required power and power output at all times. If the power output is greater than required then this surplus power may be used to pump water from the fluid tanks 18 to the blades 12. The introduction of water into the blades 12 increases the weight of the rotor assembly. This causes the rotor assembly to decrease in rotational speed. However, additional water in the blades 12 increases the momentum of the turbine and therefore increases the torque. At this point additional generators if present can be turned on to make use of the extra torque developed. If the power output still exceeds the required amount and the blades 13 are full of liquid, it may be necessary to provide additional safety braking means or wind spilling means until the wind speed has decreased sufficiently.

If the wind and rotational speed drop below the optimum level, the electronic control system 28 activates the draining of water from the blades and the generation of power from this flow. The electricity generated can be used to power initial movement of the rotor assembly and overcome initial resistance to movement. As soon as the wind is maintaining sufficient speed and power output from the rotor assembly the electronic control system 28 prevents further draining and will refill the blades as required. The electronic control system 28 checks to monitor the amount of liquid released.

If the wind is sufficiently weak that the blades stop, a reserve of water is held. As soon as the wind speed is sufficient to rotate the rotor assembly 10 the electronic control system 28 starts to release the reserve water. The wind speed is sensed by the sensor 26 to trigger automatic restart before the wind could on its own cause that restart.

Figure 3 shows a cross section through the rotor assembly. The blades are shaped to provide a continuous rotational force whatever the wind direction. Each blade has a rounded leading edge 30 and a tapered trailing edge 31, and a plenum space 32 is defined between the two blades. Wind flow in the direction of arrow A passes trough the plenum as indicated causing increased torque.

Claims

1. A fluid driven vertical axis turbine for the generation of power comprising: * a base; * a main rotor assembly rotatably mounted on the base and having two vertically extending hollow blades; * a main generator coupled to the rotor assembly to generate electricity from the rotation thereof; and * at least one source of liquid and means for pumping that liquid into the hollow blades and allowing it to drain therefrom, dependent on the rate of fluid flow across the rotor assembly.

2. A fluid driven turbine as claimed in claim 1, wherein the means for allowing draining of the liquid includes nozzle jets adapted to expel the liquid under pressure and to thereby impart a turning force on the rotor assembly.

3. A fluid driven turbine as claimed in claim 1, wherein there is further provided a secondary generator adapted to generate electricity from liquid as it drains from the blades.

4. A fluid driven turbine as claimed in any of the preceding claims, wherein three or more similar blades are provided on the rotor assembly.

5. A fluid driven turbine as claimed in any of the preceding claims, wherein the hollow interior of the blades are separated into separate vertically arranged chambers.

6. A fluid driven turbine as claimed in claim 5, wherein the flow of liquid to and from each chamber may be independently controlled.

7. A fluid driven turbine as claimed in any of the preceding claims, wherein the blades comprise a plurality of vertically stacked hollow blade sections.

8. A fluid driven turbine as claimed in any of the preceding claims, wherein valves are provided to control the flow of liquid into and out of the blades, chambers or blade sections.

9. A fluid driven turbine as claimed in any of the preceding claims, wherein the source of liquid is a storage tank from which the liquid is pumped and to which it drains.

10. A fluid driven turbine as claimed in any of the preceding claims, wherein the rotor assembly is supported on a mercury bearing in the base.

II. A fluid driven turbine as claimed in any of the preceding claims, wherein operation of the turbine is controlled by an electronic control system.

12. A fluid driven turbine as claimed in any of the preceding claims, wherein a fluid speed measuring device is provided to assist in control of liquid flow to and from the blades.

13. A fluid driven turbine as claimed in any of the preceding claims, wherein the liquid is water.

14. A fluid driven turbine as claimed in any of the preceding claims, which is adapted to be driven by wind or water flow, in any direction across the axis of the rotor assembly.

15. A water or wind driven vertical turbine for the generation of power as claimed in claim I and substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 3 of the accompanying drawings.