GB2506133A

GB2506133A - Electrical energy storage and generating unit with suspended weight

Info

Publication number: GB2506133A
Application number: GB1216816.7A
Authority: GB
Inventors: Warwick John Bergland
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-09-20
Filing date: 2012-09-20
Publication date: 2014-03-26
Also published as: GB201216816D0

Abstract

An electrical energy storage and generating unit includes a large weight 1 suspended on a strong cable or chain 2 in a deep hole 3, eg a disused mine shaft, in the ground. The cable or chain passes over a pulley wheel 4 supÂported over the top of the hole and is connected to and wound round a nearby winding drum 5 which can be engaged to and disengaged from an electric motor 6 and an electric generator 7 via gearboxes 8. Under low demand power is taken from an external primary source of electricÂity to drive the motor to wind up the weight. During high demand on the primary source the weight descends under gravity, turning the generator to provide a secondary supply of power to supplement the primary source. The weight may be of streamlined shape to work in a flooded hole 3. In a modification (figs. 3,4), a combined motor-generator (12 is used instead of separate machines and the weight 1 is suspended using a block and tackle (10,11). Two winding drums 5 may be connected to one weight (fig.5).

Description

TITLE

Electrical energy storage and generating unit.

BACKGROUND

Almost all high powered electricity is generated and supplieq at the same time that it is used. Because the amount of electrical power used at different times varies greatly much of the generating capacity needed to supply peak demand lies idle during low demand. If some of this what I here call primary source of generating capacity" which is not being used during low demand could be used to economically -.

build up a store of energy during these periods of low demand, to be used later to generate what I call here a "secondary suply" during high demand then the total primary source of generating capacity needed to áope with peak demand could be considerably reduced. This would save considerable capital cost provided the capital cost of energy storage and secondary generation was significantly cheaper per unit of power than generation: of the primary supply. This invention relates to this purpose.

Wind wave and solar power are being used more and more for Drimary generation to reduce reliance on fuel and to reduce carbon dioxide and other emissions. A major problem with these "renewable" sources of electrical power is that they are intermittent and un- predictable so that they must he backed up with fuel burning goner--ation which is on standby ready to take over at short notice when t-he wind drops or the sun ceases to shine. As these back up fuel burning power stations take some time to start up from cold some of them on standby must be fired up and burning fuel when they are not actually supplying electricity in order to be ready to do so at short notice. If wind and solar generation could build up a store of energy when the wind was strong and the sun was shining brightly but demand was low to be used later preferably at short notice when demand was high but the wind was weak and sun had ceased to shine then less fuel burning standby capacity would be needed saving capital cost and fuel.

Rechargable batteries are the commonest method of storing electrical energy for later use and these work well for small amounts of power but theyare too inefficient and expensive for the larger amounts of power used for heavier domestic and commercial uses and supplying power grids which serve huge numbers of homes and businesses.

Pumped storage hydroelectricity fulfils the same purpose as this invention but it is quite different in detail and construction to this invention and much more expensive to build.

STATEMENT OF INVENTION

This invention comprises the following: a large weight suspended on a strong cable in a deep hole in the ground. The cable passes over a pulley wheel supported above the hole and is connected to a nearby winding drum. The winding drum is able to be engaged and disengaged through gear boxes to both an electric motor and an electric generator.

The motor and generator are able to be connected and disconnected to an external primary source of electric power. When there is surplus generating capacity on this primary source power is taken from it to drive the electric motor which is now engaged to the winding drum to raise the weight against gravity. When there is *a shortage of generat-ing capacity on-the primary source the winding drum is disengaged from the motor and engaged to the generator which is now turned by the weight as it descends under gravity to return power to the primar source.

ADVANTAGES

The main advantage of this invention is its ability to store electrical -energy from fuel burning generation when demand is low and release it later for use when demand is high at much lower capital and running costs than the extra fuel burning capicity which would be necessary without it.It can likewise store energy from wind and solar generation during high output and low demand and release it later for use during high demahd and lovt output thus reducing the amount of more expensive fuel burning back up necessary for these renewables.

A big advantage of this invention is that it could utilize existing large holes in the ground including redundant mine shafts and this would greatly reduce its capital cost.In many parts of the world where there are numerous old disused mine shafts (as in the British coal fields)these could be brought back into use to accomniodat this invention to reduce the cost of electricity and by making better use of renewables reduce carbon dioxide einmissions.

This invention has the same function-. as pumped storage hydro-electricity installations but wouldbe much cheaper to build per unit of electricity stored and generated especially if redundant mine shafts were used.

This invention could generate full power at very short notice This invention would not impose large eyesores on. the environ- ment as much of it is undergrotind.-

INTRODUCTION TO DRAWINGS

The invention will be described and explained refering to the accompawy-ing, drawings which are simplified schematic views of three possible versions. Mai1 more variations and configurations are possible and they will be described in the text.A drawing of each one would-be superfluous.

Sheet 1/3 shows two views of one version.Figure 1 is a side view i,yjth some of the components removed for clarity and fiiure 2 is a -view of the same thing at right angles to figure 1. Components 6,? & 8;showh on-figure -2 are removed for clarity on figure l.Figure 2 is Viewed from the right of figure 1.

Sheet 2/3 shows another version of the invention.Again there are two views at right angles to each other and the side view figure 3 has some components removed for clarity but they are included in figure 4 which is viewed from the right of figure 3.

Sheet 3/3 figure 4 shows a side-view of a third version of the invention

DETAILED DESCRIPTION

Referring to figure 1 and figure 2 a large weight 1 is suspended from a cable 2 in a deep hole in the ground 3.A pulley wheel 4 is supported on strong frame over the top of the hole. The cable 2 passes over the pul-.

ly wheel to be connected to and wound round a nearby winding drum 5 which is also supported On a strong frame. The winding drum can be en-gaged.and disengaged to an electric motor 6 and an electric generator 7 through gear boxes 8.The' gearing is such that slow revolutions of the winding drum accompany fast revolutions of the motor or generator.The motor and generator can be connected and disconnected to an external source of electric power here called the primary source. When there is spare capacity during low demand on the primary source the motor-6 is engaged to winding drum 5 and power: is taken from the primary source to turn the motor which turns the winding drum to wind the weight up the hole against gravity. When the weight reaches the top of the hole or When surplus power no longer available -the winding drum is locked to maintain the weight in its elevated position,Nhen there is high demand on the primary source the motor is disenflged from the winding" drum and the generator engaged to it,the generator is connected to the primary source and the drum unlocked to allow the weight to descend by gravity to turn the drum in the opposite direction to drive the generator to generate a secondary supply of electric power to sup-plement the supply: from the primary source.

In the unlikely but possible event of the cable breaking the weight would free fall and if it hit a hard bottom of the hole it may cause a minor earth tremor.As a precaution against this a deep layer of soft wet mud 9 would be kept in the bottom of the hole and the bot-tom of the weight would be pointed so that if it fell the impact would' be reduced to a safe level.

In most locations deep holes in the ground fill with ground water.A. small amount of the costs saved by this invention could be used to supply enough power to pump it dry. Alternatively the hole could be allowed to flood and the weight.could rise and descend in -.

water,In this case the weight would need to be as denOe a: material as practicable for example cast iron, then the upward force of the water's buoyancy would be small compared to the downward gravitational force on the weight. As the gearing is such that fast revolutions of the motor and generator accompany slow revolut±ons of tho winding drum and slow movement of the weight hydrodynamic drag would be small and could be minirriised by making the weight a streamlined shape, if the weight worked in water the danger of it falling if the Lable broke would be elihinatéd.In the case of the weight working in water the cable would need to be made rust resistant in some way for example: being made of stainless steel, being made of steel strands which are plated with rust resistant metal before being twisted together into a cable, being greased automatically as it rose above water level. As an alternative to a cable a chain could be used, this may be easier to make rust resistant. -As an alternative to separate motor and generator a dual purpose motor-generator can be used, this is a single unit which can function as either a motor or a generator changing from one to the other by redirecting the electric current through it.

In place of a single winding drum being engageáble to one:motor and one generator or one motor-generator the winding drum could be engageable to more than one motor and more-than one generator or more-.

than one motor-generator. - Pefer now to figure 3 nd figure 4 these show a different vers-ion of the invention.Instead of a separate motor and generator a dual purpose motor-generator 12 is used,Instead of a single length of cable supporting the weight it is suspended on a block and tackle. There i's still only one cable but more than one length of it supports-the weight so a thinner cable could be used. The advantage of this is that a thin----ncr cable is more flexible than a thicker one and bends more easily over pulley wheels and winding drum wasting la-se energy and losing less strength when it is ben't, Figures 3 and 4 show three lengths of cable supporting the weight. The too block 10 has two pulley wheels side by side and the, bottom block llhas-oxtejtre pulley wheels could be added tO 1)0th blocks so that the optimum number could be used for each install-';.

ation. The more pulley wheels used the less the gear ratic-between wind-ing drum and motor and generator or motor-generator. Itwould be poss'..

ible with enough pulley wheels to reduce the gear ratio to one to one and the gears would only be used to en-gage and disengage the d,nding drum with the motor and generator or motor-generator. In the case of the motor-generator if the required velocity ratio could be achiev?d by enough pulley wheels in the blocks then the gears ou1d be d:i.spen-.

ed with to simplify and reduce the cost of the whole mechaniomwith a direct drivebétween thewtlidtrig drwnañd' the' niotdrigenerator.

Refer. now to figure 5 this is a side view of a version with two wind1n drums connected to one weight. There coild be two pu:Lley wheels in the top blOck and one in the bottom with the weight supported by two lengths of cable or more pulley wheels in each block and and more lengths of cable could be used to increase the velocity ratio.

Motors and generators or motor-generators are to be connected, to each winding drum in any of the ways reviously described on other version but they are deleted from this dral.ving for clarity Normally both wind-ing drums with their attached motor and generating capacity would work in unison both lifting the weight at the same time and both generating power at the same time as the weight descended. However if' the lifting and / or generatiag caàcity.attadhed to one winding drum"hàd to be stopped for' repair ot thaintenance then that drum could be locked but theother with its attached motor and generating function could still work but at a reduced rate Cothàted.to both working.

Claims

CLAIMS1. An electrical energy storage and generating unit which can be con-nected to an external primary source of electrical generation and store energy from it when there is low demand on it and use most of this energy later to generate a secondary supply of electricity to supplement the primary source hen there is high demand on it,the storage of energy being accomplished by using slectricity from the primary source to raise aganst gravity a hcvy veight suspended on a cable or chain in a deep hole in the ground and the rsleae of this energy to be accomplished by the weight descending undor the influ-ence of gravity to drive electrical generation.
2. An electrical energy storage and generatinc unit according to claim 1, with a pulley wheel supported over the top of the hole in the ground and the cable or chain passing over it be connected to and wound round a nearby winding drum which can be engaged to an electric motor or motors and an electric generator or generators in such a way that when the otor or motors are engaged the generator or generators are disengaged and when the generator or generators are engaged the motor or motors are disengaged,to raise the weight for energy storage the motor or motors are engaged to the winding drum to-:.wihd on cable or chain ànd to releasel ehergy the generator, or generators are engaged to the winding drum so that as the cable or chain unwinds due to gravity pulling the weight downwards electricity is generated.
3. An: electrical energy storage and generating unit according to claims 1 and 2 in which the winding drum is engaged to electric motor or motors and electric generator or generators through gearing which is such that fast revolutions of the motor or motors cause slow revolu-tions of the winding drun and slow revolutions of the winding drum cause fast revolutions of the generator or generators.
4. An electrical energy storage and generating unit according to claim 1, with the cable or chain acting through multiple pulley wheels to form a block and tackle with at least two pulley wheels in the top block which is supported over the top of the hole and at least one pulley wheel in the bottom block which is fastened to the weight, the cable or chain to be fastened and wound round a nearby Windingdrum which can be engaged to a motor or motors nd a generator or generators as in claim 2 and the number of pulley wheels in the blocks to be the optimum for maximum efficiency.
5. An electrical energy storage and. generating unit according to clairal, with a block and tackle as in claim 4 and the winding drum isengaged to'u motor ormotors and generator or generators through gearing as in claim 3,in this version the:.èarratios will. be:lbwet than in clairit'3' becauâe the block and tatkleincreases' the number of revolutions of the wiitding drum.:for.a given speed of the weight.
6. An electrical energy storage and generating unit according to clainl, in which the cable or chain acts through multiple pulley wheels to forma block and tackle in which each end of the cable or chain leaves the top block with one end going to a winding drum on one side of the unit and the other end going to a winding drum at the opposite side, * -eath winding drum' engaged to a motor or motors-and generator or gener ators:itieithen of the ways described in CiaiIfts.4.and.2and claims 5 and 3,, One purpose of this version is to allow one winding block to be stopped for repait, and maintenance while the other continued to * function',normally both would work together in unison.
7 An electrical energy storage and generatin.unit according to any of the preceding claims,whlch instead of using one or more separ- ate discrete motors and one or more separate and discrete generat-on uses, one or more combination motor-generators permanently en_ gaged to the winding drum (or winding drums in claim 6) and in-stead of disengaging motor or motors and engaging generator or generators and vice versa the motor-generator *or motor generat-ors are changed from motor function to generating function and vice versa by redirecting the electric current through it or them.
8. An electrical energy storage.and generating unit accordihg to any of the preceding claims,which can use an existing deep hole in the ground,incjuding a redundant mine shaft,or a newly dug or drilled hole.
9, An electrical energy storage and generating unit according to any of the preceding claims,in which the deep hole in the ground has the ground water pumped out and a depth of sort wet mud is kept in the bottom of the hole and the bottom of the weight is pointed, these two latter measures are to reduce the impact if the cable or chain broke and the weight fell.
10. An elecrical energy storage and generating unit according to any of the preceding claircsexcept.:olaim9; .in tvhich't.he deep hole in the ground is allowed to flood with ground water and the weight is of a streamlined shape and made of a dense material,for example &äst iron and the cable or chain (and lower pulley block in claimth.,5, arid 6)'uade rust resistant in some way for example: being nade Yof stainless steel, bein made of steel plated with rustproof non ferrous metal,being greased automatically as it or they rise above water level.