Energy capture from gravity

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Background of technology, including the basic science foundation

Gravity is a ubiqutous force on earth, which has been tapped since ancient times. When considering the use of gravity as an energy source, there seem to be several themes / classes of technologies. In most of these cases, gravity is not technically the primary energy source, but rather the mass involved has gained potential energy from other energy sources.

  • Tapping into the natural water cycle (hydropower - see the "Other Technologies" page on this wiki). In all its forms, hydropower is an established technology deriving its ultimate energy from the continuous heat of the sun evaporating the world's oceans and lifting water molecules high up in the atmosphere. The amount of potential energy thus created is huge, but practical extraction of this energy typically only takes place where nature has created favourable topology. Most of the world's hydropower potential is already being used and represents a sizeable chunk of global power use. (2.4% according to latest IEA figures[1], half of the total contribution from nuclear energy at 4.8%)
  • Creating artificial water cycles would be another way of capturing energy from gravity, one such idea is described as drilling a deep hole in the bottom of the ocean towards an area where the heat of the earth would evaporate the water in the form of steam[2]. Placing a turbine would tap into the energy delivered from the falling water. The ultimate source of energy in this case is not gravity, but the heat of the earth's core.
  • Using gravity as energy storage. Several mechanisms exist to temporarily store energy using gravity, to be released at a later stage. These systems do not represent abundant clean energy sources, as they do not generate net energy. An example of this is pumped storage hydroelectric dams, where water is pumped uphill (using external energy), only to be released at a later stage. Another example is the regenerative drive technology elevator described below, where lifts are used to store energy.

Finally, there are those classes of technologies that claim net energy generation self-contained systems without external energy inputs. These concepts seem to defy the laws of physics, and no such generator has been proven to work to date. Key subclasses of such technologies are:

  • Mechanical systems, typically in the form of rotational devices or pendulums
  • Buoyancy systems, where certain objects' tendency to float in water is allegedly tapped as an energy source. According to one editor, "buoyancy machines are by far the most abundant species of perpetual motion machines. Unfortunately abundance is no guarantee for workability."[3] Another researcher attributes this abundance to the fact that "perpetual motion machine inventors are fascinated by buoyancy, supposing that buoyancy has some "magical" ability to produce motion against gravity without expenditure of energy."[4] Both sites provide a fascinating overview of the most common types of buoyancies machines, and their flaws.

The current state of technology

In order to generate electricity using gravity force you must find a source where gravity causes movement. Movement is kinetic energy, and you need to convert that into electricity. A stream that flows downhill, a waterfall, rain pouring out of a downspout all of these are considered movement caused by gravity.

Some devices are know to exist which convert gravitational energy into kinetic energy or movement to generate energy[5].GravityLight is a Mechanically powered flashlight designed by the company Deciwatt for use in Developing world nations, as a replacement for /Kerosene lamps[6].

Required inputs for energy generation

The inputs for any energy generation process can be represented as shown in the System Representation. [7] The efficiency of the system is represented by the output energy divided by the input energy. Note that all energy inputs should be accounted for. Gravity is an unusual entry in the energy wiki, because gravity is not a form of energy: gravity is a force, or as Einstein might have said a curvature of space-time! As with any force it has a role in "doing work": a force acting on an object and displacing it over a distance does work, which is energy.

So for example, a lot of work has to be done to launch a rocket to a high altitude; that requires a lot of (chemical) energy, which turns into potential energy as the rocket increases in altitude. Dropping a mass from a altitude gives it kinetic energy; as its altitude (and potential energy) lowers its speed (and kinetic energy) increases until it reaches terminal velocity, or hits the ground. This cycle demonstrates that energy is [always] conserved, it just changes from one form to another.

It is theoretically possible to use gravity to collect energy, shall we say for "free". For example, directing an asteroid to Earth (with a little rerouting energy) and then collecting the energy as it falls to Earth. [Risks and practicalities over looked here.] In this scenario, the energy input is that required to direct it to Earth. (That might be obtained in space via solar power perhaps.) No doubt life-time energy inputs would be required to build the energy collection structure, and to operate and decommission it.

So some gravity proposals might make sense, and some might not.

All known system of energy generation from Gravity is a result of movement caused due to gravity, usually the movement is used to rotate a generator to produce energy[8].

Energy is also needed to move the falling mass to a higher level, where it has the potential energy converted into kinetic energy by the downward motion. This may be done by e.g. the sun in evaporating water, moving it, and depositing it on mountains or high land in the form of precipitation, or by another energy source (e.g. a human winding a grandfather clock).

Organizations/researchers working with this technology

The following is a list of companies, inventors and research groups investigating in this space[8].

Veljko Milković

"VEMIRC Pendulum Lab (a subsidiary of Veljko Milkovic Research & Development Center) is a scientific and research institution dedicated to the exploration of new boundaries in science and promotion and development of new clean technologies and their application in every day life. VEMIRC Pendulum Lab realizes its goals in the field of energetics, mechanical engineering, ecology and other connected fields, by having for the goal of its scientific, expert and practical work scientific and expert research, development, improvement, affirmation and realization of practical application of Veljko Milkovic's scientific and research work, of his inventions, innovations, patents and other technical discoveries in the field of oscillations of the pendulum drive."[9]

According to a test report of the Serbian Academy of Inventors and Scientists, "It is estimated that the input of gravity in the performance of the Biphase Oscillator is around 80%... "[10]

Sjack Abeling

Dutch inventor Sjack Abeling of the Abeling Economy Group, states on his website "In the past few years it seemed quiet around our project. But we have certainly not been idle: We made another important discovery at the end of 2015. Thanks to this discovery it is now our objective to bring a functional system, powered by gravitation, to the market, possibly in 2016.

With several unique transport systems masses are kept in balance and their centrifugal force is converted into potential gravitation; This is transformed into kinetic energy to drive, for example, a generator. The provided return is expected to be over 80% for driving secondary systems. On customer demand these can be low-, medium- or high-voltage, 50 or 60 Hz, 4 to 24 poles, and from 5 MW to 25 MW. Such generators are currently used in power plants and can be powered by the gravitational systems of Abeling Economy Group."[11]

Mr. Abeling holds one patent, his website seems to shows recent activity.

Sandip Institute of Technology and Research Centre, India - Pin Wheel Mechanism

A recent paper[12] from the International Journal of Advanced Research in Science and Engineering, explains the Pin Wheel Mechanism, an experimental methodology to generate power from gravitational forces. The Pin Wheel Mechanism can independently generate electricity and can be parallel connected to wind power and solar power generation systems to generate electricity. However, no information was provided on the real world application of this technology, nor could I Identify any patents related to this technology.

KDK College of Engineering, India - Pendulum power generator

One recent scientific paper[13] from the International Research Journal of Engineering and Technology, provides an explanation of how this technology works. "In this paper we designed a methodology wherein gravitational energy is further amplified in terms of its magnitude by using Perpetual Motion Mechanism and hence can be successfully transformed into usable electrical energy. The basic concept of a gravity power generating mechanism is simple. When a body moves down from a higher altitude to a lower one its potential energy is converted into kinetic energy. This motion is converted into circular motion and is then converted into electricity using a generator.

Rosch Innovation, Switzerland

"The Kinetic Power Plant (KPP®) uses - amongst other things - the Archimedes´ principle of buoyancy and produces continuous 24/365 total green, emission-free electricity without adding fossil fuels or any other fuel for its effectiveness. The power plants offered by ROSCH INNOVATIONS® are modular scalable in size and are supplied from a power output of 200 kW to what ever the need may be."[14] There seems to be quite some controversy around the company and its partners, as illustrated by a current law suit (in German)[15] and a statement on their website reading : "Due to massive hacker attacks on our computer network, the Internet and databases, we hold back with the release of new and interesting articles for an indefinite period."

KPP has been tested by TUV, who have produced a report which concludes "The Kinetics machine examinated can generate about 180 W"[16]. It is not completely clear from the report whether that means that TUV is confirming net energy generation from the device. If so, the report seems remarkably light for such a ground-shaking conclusion. Further comments on the use of test certificates from DEKRA and TUV can be found on-line in a discussion forum (in German)[17], where a DEKRA spokesperson is quoted as writing: "The report applies only to individual measurements on a system and is not to be understood as a confirmation of the functioning or the operating principle of the system."

This episode is perhaps a good example of the difficulty for companies in this space to get their technology externally validated.

RAR energia, Brazil

The company seems to have at least two patents (see IP section[18][19]), and has claimed working prototypes as per this on-line article[20]. The company's website is now dysfunctional[21].

Reasons why the science and technology has not moved forward

The energy generated from gravity is on a very small scale and hence scientific community is unable to explain and see the potential in this field of research. However hydroelectric power is an indirect method of extracting energy from gravity using dams where water falls from a height on the turbine here potential energy of water is converted into kinetic energy to run the turbine.

Costs of facilities, production, now and projected future costs with improvements

Intellectual Property surrounding technology

Mechanical systems

  • (Cayubit, 2014) WO 2014178734 A3[22] Machine and method for gravitational-magnetic electricity production The invention is a machine for electricity production and other day-to-day uses that may apply, that does not use fossil fuels and renewable energies but rather gravitational and magnetic energies to function or operate. The invention as a prime mover includes its major parts comprising a shaft attached to the bearings mounted on stands, a spinner attached or welded to the said shaft, a magnetic spinner attached to the said shaft, said shaft being made such that it is capable of rotating and resisting or carrying the load of the spinner including the other parts and accessories attached to the said shaft, said spinner is being made to spin together with the said shaft, said magnetic spinner is being made so as to function and make a rotation or spinning when switch on, aside from the main parts, a dynamo is also included along other parts, accessories, operating and controlling means provided in the system such that capable of starting, operating, insulating and stopping the function or operation of the invention machine.
  • (Rajagopal, 2014) WO 2015177804 A1[23] A leverage assembly for energy generation The present invention relates to various aspects of leverage assembly for energy generation. According to one aspect, the leverage assembly comprises at least one first order lever having an effort arm and a load arm, where at least one weighted body is fitted to the extreme end of the effort arm and positioned in opposite to the end of the load arm. At least one mounting table has a fulcrum on its top side and a slot to pass-through the lever load arm into it, where the table is mounted on a base plate for being reciprocally actuated in back and forth movement. Power receiver assemblies are positioned adjacent to the mounting table to be in operative contact with the end of the lever load arm at the time of lever oscillation. The first order lever is pivotably mounted onto the table through its fulcrum in a frictionless manner in such a way that when the table is being reciprocated, the lever effort arm along with its weighted body is oscillated on the fulcrum at a desired oscillating angle, which simultaneously generates a multiplied force, at the end of the lever load arm, that is directed to operate the power receiver assemblies for energy generation. Thus, such leverage assembly generates efficient energy with the oscillating first order lever arrangement in an easy, reliable and cost effective manner.
  • (Maleksaeedi, 2014) CA 2839273 A1[24] GRAVITATIONAL ENERGY CONVERSION TURBINES Inventor Ghasraldashti Seyedjalal Maleksaeedi was awarded a patent on Jul 20, 2015 (filed Jan 2014) for his invention that "provides devices that convert the gravitational force to work and energy, the name of the Gravitational Energy Conversion turbines with a concise name of GECturbines is selected for it. They include heavy rollers or blocks, levers, inclined rails, central arms, gears, etc. On a side of the lever arms, the heavy rollers come down under the gravitational force and on the other side of the levers axel the lever arms push upward other heavy rollers on the inclined rails.  The difference of the forces and torques that the rollers or blocks create on the two sides of levers makes a powerful gyration for them that in a closed circle can give useful energy to another device such as a generator."
  • (Ribeiro Bastos, 2013) WO 2013144757 A1[18] Mechanical motion system for energy generation The objective of the present invention is to create a system to produce energy as well as the equipment necessary only using the planet's gravity as source of energy. To achieve the objective above, we developed a conception of different types of motions made up of a crankshaft and mechanical bars making up assemblies. Furthermore, these assemblies were placed side by side. In this case there is a 45 degrees lag between them. The movements of each assembly are combined and synchronized. Finally, each assembly has a bar on which a fixed weight is supported. This bar is supported on the positive or neutral bars through mobile locks that are placed or removed at the appropriate time.
  • (Maillot, 2012) FR 2989431 A1[25] Quasi-automatic electrical energy production device for producing electrical energy The device has an unbalanced wheel fixed at a primary shaft and moved in rotation around the shaft. An alternator is pulled by the shaft and adapted to convert mechanical rotation energy of the shaft into electrical energy. A motor is placed in top of the wheel, and includes an end shaft i.e. secondary shaft, coupled to the wheel by a coupling system. The wheel is unbalanced by a weight placed in a portion of the wheel and a counterweight placed in another portion of the wheel opposite to the former portion by the primary shaft.
  • (Hu, 2011) US 20120292133 A1[26] Zero-Carbon Clean Energy Generator and Operating Method Thereof A zero-carbon clean generator has a rotating rod, multiple swings, a sleeve and multiple pendulums. The rotating rod acts as a spindle pole and a fulcrum. The swings are mounted around the rotating rod and each swing has a structure of two flywheels to rotate clockwise and counter-clockwise. The sleeve is connected with the rotating rod. The pendulums respectively are connected with the swings and the sleeve. Each pendulum has an inner space filled with fluid. Accordingly, the pendulums are swung back and forth reciprocatingly, make the rotating rod rotate continuously in a fixed direction and eternally generate power.
  • (Hong, 2011) US 20130037352 A1[27] Power-generating apparatus using gravity and magnetic force The present invention relates to a power-generating apparatus using gravity and magnetic force. Rotors are fixed at either side of a main shaft, and heavy weighted bodies are arranged at a plurality of levers which are deployed during a descending operation and folded up during an ascending operation performed in the course of rotation of the rotor, such that the weighted bodies are unbalanced in a horizontal direction. An arch-shaped magnetic levitation unit is arranged adjacent to and above the rotors. The heavy weighted body located at the position of mechanical energy is levitated by means of the magnetic force from the magnetic levitation unit at a starting point of the magnetic force, such that a wheel is brought into contact with and rolls on a rail of a magnetic support, and the heavy weighted body levitates in the air at the position of mechanical energy. Then, the weighted body moves at a speed faster than the rotating speed of the rotors by means of a rotational propulsion member of a driving motor, such that the folded lever can be deployed and the heavy weighted body falls downward by itself at an ending point of the magnetic force, at which the magnetic force is weakened. Thus, the weight arranged at the edge of the rotor increases power and torque in the direction of gravity at the position of maximum gravity, and converts gravity-based kinetic energy into mechanical energy so as to rotate the rotors and the main shaft and thus generate power.
  • (Condric, 2011) US 20130047754 A1[28] Mechanical advantage machine A method for power generation comprising: mobilizing a weight about a circumference of an elliptical track comprising a fulcrum point disposed at a vertex of the circumference of the elliptical track, the mobilization pivoting the elliptical track at the fulcrum point in response to the weight traversing the elliptical track, while at least one actuation rod coupled to at least one cam at one end and coupled to the elliptical track as an opposite end of the actuation rod moves responsively to the mobilization as one portion of the elliptical track moves downwardly in response to the weight passing above the one portion, while concurrently a portion of elliptical track opposite the one portion across the fulcrum point moves upwardly, where the movement of the actuation rod causes the rotation of the cam.
  • (Rosace International co., 2009) US 20100253091 A1[29] Physical energy-converting rotor, rotating method of the same and generating set using the same A physical energy-converting rotor has a rotor body and multiple weights. When the rotor body is rotated, an inner virtual orbit and an outer virtual orbit are formed and the weights are rotated. The weights are moved back and forth between the inner and outer virtual orbits to form non-balances to keep the rotor body rotating. The physical energy-converting rotor may operate alone, or may cooperate with non-pollution generators such as wind generators and water generators to enhance power-generating effect.
  • (Soncin, 2009) WO 2009127445 A1[30] Gravity motor An energy generator comprising a primary shaft rotating around its own longitudinal axis and at least two rod elements radially associated with the primary shaft and having a concentrated mass associated with the free end of the rods, the at least two rod elements being cyclically rotationally moveable around the end associated with the primary shaft between a raised position and a lowered position separated by an angle of less than 180°, the at least two rod elements during the upward run being free to rotate with respect to the primary shaft, and, during the descent, being integral with the primary shaft, there also being raising means of the at least two rod elements, control means of the descent of the at least two rod elements, and means for the switching on and off of the energy generator.
  • (Cieslak, 2008) US 20090243305 A1[31] Gravity motor and method A gravity motor wherein a beam is pivotally mounted intermediate its opposite ends for oscillation in a vertical plane about a pivot point on a support structure. A moveable weight is slidably connected to the beam for reciprocal movement between the opposite ends of the beam past the pivot point. A drive unit is mounted and engaged for driving the weight back and forth between opposite ends of the beam thereby causing reciprocation of the beam about the pivot point by gravity to rotate a shaft in order to generate electricity or to provide other motor functions.
  • (Schmoll, 2008) WO 2008135248 A2[32] Device for driving a shaft by means of a pendulum and a crank drive The invention relates to a device for driving a work shaft, said device comprising a pendulum and a crank, the pendulum and crank being mounted on axles which are arranged parallel to each other...Invention-wise, a gravitational unit is proposed. By means of a gravitational unit, an advantageous use of energy of a gravitational force can be obtained.
  • (Asirvatham, 2008) WO 2009157002 A1[33] A device for conversion of gravitational energy into electrical energy This invention relates to a device for conversion of gravitational energy into electrical energy. using pendulums drive turbine. The invention also relates to a method of conversion of gravitational energy into electrical energy using the device. The device and the method is useful for various purposes such as for the operation of electric appliances and industrial machines. The freely available gravitational force in nature can thus be converted to electrical energy and can be utilized for the daily life of mankind.
  • (Wang, 2007) US 20090115195 A1[34] GRAVITY POWER GENERATION MECHANISM Another similar mechanism has been developed by Chun Chan Wang which generates energy using gravity conversion units that produce positive torques by adopting outward spreading single directional swing arms and reduces the negative torques by cooperating with a folding action of single directional swing arms. Inventors Chun-Chao WANG and Yuh-Suiang Wang earned a patent on the gravity power generation mechanism in May 2009 (Filed in Nov 2007).  According to the abstract "the gravity energy conversion unit produces positive torques by adopting outward-spreading single directional swing arms and reduces the negative torques by cooperating with the folding action of the single directional swing arms, so as to perform a long-time, effective and  continuous energy conversion of converting gravity potential energy into the kinetic energy....the kinetic energy will be transmitted to a power generating unit to perform another energy conversion, converting the kinetic energy into  the electric energy. And finally, a power supply system is used to transmit the electric energy out. By such arrangements, the gravity power generation mechanism not only has the advantages, such as: more  simplified in structure, higher conversion ratio, and more environment-friendly but only needs a little of starting energy to perform a long-time energy conversion."
  • (Abeling, 2007) NL 1034252 C1[35] Perpetua mobilia machine, comprises weights on rotary support which cooperate with radial guide system to convert gravitational energy into kinetic energy Gravitational energy is converted into kinetic energy using a machine comprising at least one support rotatable about a horizontal axis and having at least one weight mounted on it which can be moved in a radial direction relative to this axis; and a radial guide system for the weight.
  • (La Perle, 2007) US 20080011552 A1 Gravity powered rotational machine and method A gravity powered rotational machine for rotating an output shaft to power a generator, pump or the like. The machine comprises a frame mounted pivot bar, a plurality of first swingarms rotatably attached to a center section of the pivot bar, a weight member slidably mounted on the first swingarms, a stationary railing defining a path around the center section, a rotational structure rotatably mounted on end sections of the pivot bar, second swingarms interconnecting the rotational structure and the first swingarms, and a driving mechanism interconnecting the rotational structure and output shaft. The center section of the pivot bar is off-set from its end sections. The stationary railing guides the first swingarms around the center section and directs the weight members inwardly and outwardly on the first swingarms while they group in a drop zone and spread in a lift zone of the path to rotate the output shaft.
  • (Barksdale, 2006) US 20070090648 A1 Energy Generation Device A machine containing many moveable parts that outputs more energy than it takes to make it operate is provided. In operation, a plurality of heavy, preferably metal, balls are arranged to roll from a first location on a level platform down an inclined tube to a first stop gate located below the platform. A large drive wheel, centered on a horizontal shaft and arranged normal thereto, is adapted to rotate in a vertical plane and comprises a plurality of arms extending radially outward from a rotatable center. Each arm includes a channel or ball-supporting surface extending from between the wheel center and the end of the arm. The balls are introduced, through the first stop, to the channel of each arm when the arm passes downward, through the horizon, and are arranged to move in plurality to the end of the arm for resting on the ball-supporting surface. The weight of the balls on the arm force the arm to rotate downward, about the center of the wheel, thereby giving the wheel its driving force to rotate about its center. As the arms reach their lowest point in rotation, they are freed from the arm and directed to an elevator, driven by the wheel, and are raised upward to the platform in preparation of their journey onto the arms of the wheel.
  • (Reyes-Florido, 2006) US 20080315590 A1[36] System for Harnessing the Force of Gravity The invention relates to a system for harnessing the force of gravity. The purpose of the present invention refers to the combined or separate production of energy and/or the pumping of fluid or gases, using a system including a support point on which a long surface can pivot by mean of hinges or bolts. The aforementioned surface is characterized in that it comprises surfaces which are joined at each end by means of hinges such that they can move vertically, the vertical position thereof being maintained under the action of the force exerted by one or more weights which can be moved from one surface to the other and vice versa by means of mechanisms using motors of any type. In this way, when one end surface is lowered, the other surface is raised, thereby actuating the pistons which move inside cylinders which are joined by rods to the end surfaces and which can generate a pneumatic or hydraulic pressure system.
  • (Willis, 2007) GB2442585 A[37] Oscillating pendulum prime mover A prime mover comprises an oscillating pendulum carrying a mass and magnets, the magnets interacting with switched electromagnets to maintain the oscillation. The pendulum couples via a length compensator with a crank mechanism which may drive a generator, a hydraulic pump or a pneumatic pump. Alternatively the pendulum rotates the pinion of rack and pinion arrangement to provide an oscillating linear output which may drive a pair of pumps. A wind turbine or solar power supplies power to the battery energizing the electromagnets via timing circuit. A double pendulum system swinging in opposition is disclosed driving a shaft though freewheel sprockets. The construction of the compensator is shown. Basic hydraulic circuits are disclosed... Broadly, according to a first aspect of the invention, there is provided a method for for producing usable energy serving as a primary means of producing usable power by converting oscillatory motion into rotation, in conjunction with a secondary means for producing additional energy for maintaining the oscillatory motion.
  • (Willis et al, 2005) WO 2005100787 A1[38] Electric pulse pendulum power generator A method for producing usable energy characterised by utilising oscillatory movement of an oscillatory element/pendulum in combination with at least one of a number of different means for producing usable output energy at such a level that at least a portion of this output energy may be utilised to maintain oscillatory movement of the element pendulum in such manner that adequate output energy remains available as said usable energy. Said energy producing means are selectable from a group thereof comprising, hydraulic means, pneumatic means, electromagnetic means, and/or mechanical means.
  • (Gomez-Nacer, 2005) US 20070012518 A1[39] GRAVITY GENERATOR ELECTRICITY OR HOW TO USE GRAVITY TO GENERATE ELECTRICITY BY MEANS OF PENDULUMS Maximo Gomez-Nacer designed a system of obtaining electricity from the forces of gravity by incorporating pendulums whose weight and velocity provide energy for electricity generation. Although minimal information was available from authoritative sources, I did find the patent for this technology. Maximo Gomez-Nacer obtained a patent in Jan 2007 (filed Jul 2005) for his system and method of "obtaining electricity by means of the use of the force of gravity by incorporating pendulums, which weight and velocity provide energy for electricity generation while a weight storage from any additional source or structure provide the additional force to overcome  resistance by using hydraulic high-pressure chambers or gears in order to power turbine to power pendulums to power an electricity generation or by the use of any weight to power gears to power pendulums to  generate electricity."
  • (Stanciu, 2005) US 20060220385 A1[40] GRAVITY/ENERGY TRANSFORMER Inventor Iacob Stanciu gained a patent in 2007 (filed 2005) for a "gravity/energy transformer [that] includes a housing. First and second rotational shafts are mounted in the housing, each shaft having ends. First and third wheels are mounted proximate the ends of the first shaft on either side of a generator mounted on the first shaft, each wheel having an axis and halves on either side of the axis. Second and fourth wheels are mounted proximate the ends of the second shaft on either side of a generator mounted on the second shaft. A pair of weights are mounted on halves of  the first and second wheels on the same side of their axes, and a pair of weights are mounted on halves of the third and fourth on the same side of their axes, the positioning of the weights on the first and  second wheels counteracting the positioning of the weights on the third and fourth wheels."
  • (Seoane, 2004) US 20050248159 A1[41] System and method for converting potential energy into electrical energy In a system and method for converting potential energy into electrical energy, a force is applied to a force receiving end of a pendulum arm of a pendulum. The pendulum arm is connected to a periphery of a wheel. The wheel is rotated using the force applied through the pendulum arm and the connection between the pendulum arm and the periphery of the wheel. A rotational force produced by the wheel is then transferred to a generator through a gear mechanism. Electricity is generated by a generator using the rotational force produced by the wheel. A portion of the electrical energy generated by the electrical generator can be fed back to the piston or other force producing device to power the device to continue rotation of the wheel and electricity generation.
  • (Shimshi, 2004) US 7080509 B2[42] System for obtaining rotational energy from ambient forces The intended purpose of my invention is to create a point of origin in system from which driving thrusts could evolve. In this system, vacuum can be developed with less force than it naturally is required to create said vacuum. By posting a cylinder, containing two pistons in each cylinder, on each side of the axis of rotation and having gas flow in an out the cylinders under controlled pressures, the system could create such vacuum. As a result, said vacuum can lift more mass than the mass creating said vacuum and, thus, imbalance could be achieved that rolls the system in one direction.
  • (Clinch, 2003) US 20030155770 A1[43] Gravity motor and method A gravity motor has an output shaft, a support structure for rotatably supporting the output shaft, a rotor having a hub and a plurality of radial arms secured to the output shaft, a plurality of movable weights where at least one weight is slidably connected to each of the radial arms, a first guide surface positioned to be contactable by each of the movable weights where the first guide surface causes each of the movable weights to move from a distal end of the radial arm toward the hub as the rotor rotates, and a second guide surface positioned to be contactable by each of the movable weights where the second guide surface causes each of the movable weights to move away from the hub to the distal end of the radial arm as the rotor rotates.
  • (Dutta, 2003) US 6981376 B2[44] Apparatus for converting gravitational energy to electrical energy The present invention discloses an apparatus of converting gravitational energy to electrical energy. The apparatus includes a reciprocating drive mechanism for lifting liquid from a bottom reservoir to an upper reservoir and turbines between the upper and lower reservoirs which are turned by liquid falling down a flow path from the top reservoir through the turbines to the bottom reservoir. The reciprocating drive mechanism includes a large circular ring or wheel pivotally attached at its hub or center to a support frame and a cable over the upper periphery of the ring with two pipes attached one at each end of the cable. The ring pivots back and forth lifting one pipe and lowering the other pipe and vice versa. As a pipe moves down liquid enters the bottom of the pipe while liquid drains out the top of the pipe into the upper reservoir. One of the turbines is connected to the reciprocating drive mechanism and the other to a generator for producing electricity.
  • (Love, 2002) US 6694844 B2[45] Apparatus to recover energy through gravitational force A gravity apparatus having a wheel-like, connected, encircling surface, includes an axially horizontal track which has an interior surface which weighted objects contact and are carried around the interior surface. The interior surface is a connected, encircling, wheel-like surface, is not a round circle or a cylinder, but has an offset center of rotation closest to a side which approaches perpendicular, the weighted objects are carried by spokes attached to a support hub through the offset center of rotation. A plurality of spokes extend diametrally of the track in axially and circumferentially spaced array. Weighted objects are mounted on opposite ends of each spoke. The offset center causes the spokes to move axially diametrally of the track and extend the weights to rise and lower as the weights traverse the path of the interior surface. Optional bearings on the weights, wheel, and at the hub-spoke interface minimize friction.
  • (Ganimian, 2002) US 20030132635 A1[46] Gravity driven electric power generator An electric power generator harvesting the gravitational pull of the Earth, having a platform member, an electric generator housing slidably positioned on the platform member, the electric generator housing coupled to an axle having a rotor gear, an endless belt having tread members, a drive wheel, and an idler wheel, wherein the rotor gear is in mating contact with the tread member of the endless belt. Change of orientation of the platform member along a horizontal longitudinal axis causes the electric generator housing to slide on the platform member while the counter motion of the rotating endless belt maintains position of the electric generator housing on the platform member. As a result of rotation of the axle, electric power is generated by turbine generator located inside of the electric generator housing. Some of the generated electric power could be utilized to supply the needed power for rotation of the drive wheel rotating the endless belt. Hence, the electric power generator is capable of being self-sustaining.
  • (Hurford, 2000) US 6237342 B1[47] Gravity motor A gravity motor which is formed of at least one motor unit which has at least one motor member fixed to an output shaft. The output shaft is rotationally mounted on a housing. The housing includes a guide surface. The motor member is low frictionally longitudinally movable relative to an output shaft. Each end of the motor member includes a weighted follower which is low frictionally movable relative to a guide surface. The rotation of the motor unit will cause one weighted follower to be moved toward the output shaft by the guide surface with the opposite weighted follower of the motor member being moved away from the output shaft. The result is gravity produces an overall clockwise torque on the motor member which causes rotation of the output shaft.
  • (Sen, 1988) US 4980572 A[48] GRAVITY POWER GENERATION MECHANISM "This invention relates to a scheme for generating electricity using gravitational energy. The scheme uses a set of massive underground spinning wheels, each wheel being fitted with a mechanism to receive and transmit gravitational torque pulses from a passing vehicle to keep the wheels in motion."

Buoyancy systems

A wealth of patents seems to exist around buoyancy devices, many of them related to systems that simply transform compressed air into motion, through buoyancy, not claiming to be primary energy sources. The following list, however, contains only patents that actually claim to allow net power generation.

  • (Mahadevan, 2014) WO 2014128729 A2[49] Hydro buoyancy weight power generation Weight Assembly is launched from launching chamber which is located at the lower part of the water tank. Weight assembly moves upwards due to buoyancy force. Once the weight assembly reached top level of water tank it is lifted from the water by Pulling Unit and arrived at the falling tower. Pulling unit also acts as connecting bridge between falling tower and water tank. Weight is dropped from the falling tower by pulling unit through iron rope which connected with main rotor shaft of generator. Now the weight assembly falls down due to gravity. Falling weight makes Kinetic Energy which is transferred to operate main generator. Once the weight fallen from the top it has also high impact force. Here big water bag is used to convert impact force to Kinetic Energy High impact force weight pushes the water bag water is compressed and flow in a tank where the second additional generator is operated water returns downwards to water bag. The weight assembly falls down and finally compress the pistons of water exhausting unit which has water from launching chamber when water comes downwards to exhausting unit it has high force due to gravity this force is also utilized to operate the third additional generator. Finally after pushing the water exhausting unit weight assembly once again comes to launching chamber through inclined rails and enters through vertical gate now the vertical gate is closed and upper horizontal gate is opened water fills in all sides of launching chamber. Now the weight assembly once again moves upwards due to buoyancy force. All the above process are continued again and again thus 3 generators generate electricity.
  • (Manoj V, 2013) WO 2013128466 A2[50] GRAVITY-BUOYANCY OBJECT TURBINE Manoj V obtained a patent in Sep 2013 (filed Jul 2013) for a Gravity-Buoyancy Object Turbine (GBOT) generates "kinetic energy using gravitational force and buoyancy force [that]exist in the nature. The turbine of the invention has a gravity (air) chamber and a buoyancy (liquid) chamber, arranged side-by-side in such a way that both gravity and buoyancy exerts force directly and continuously on the shaft/drum/belt to cause the rotation of the turbine. The turbine blades (objects) forms the shape of a wheel, which enables leak-proof and resistance-free transfer between air and liquid chambers. The objects could be cylindrical and rotating by its own. The material, size and shape of key components and related control mechanisms of GBOT are optimized to deliver maximum performance."
  • (Bastos, 2008) WO 2008129515 A3[19] Apparatus and associated methods to generate useable energy The present disclosure relates to an apparatus and associated methods for generating energy by capturing and taking benefit of the energy generated by any quantity of air surfacing inside water. In exemplary embodiments, the apparatus comprises compressing a lower density gas in a liquid medium, allowing the gas to naturally rise to the surface of the liquid medium and then capturing the energy generated by the surfacing gas. An apparatus and method is disclosed to provide a low energy technique to compress air into water. In exemplary embodiments, air is introduced into water by simultaneously providing a low pressure area in the medium and compressing the air into the low pressure area. By compressing the air into water in low pressure areas, the energy required to compress the air is greatly reduced. The amount of energy generated by the rising air is less than amount of energy required to compress air underneath the water.
  • (Velchez Lopez, 2008) US 20080216472 A1[51] Buoyancy engine apparatus A buoyancy engine and compression device having a plurality of rotating flexible chains formed of individual segments, each having a plurality of compressible flotation members engaged thereon. The chains rotate around axises at upper and lower frames. The flotation members are alternately compressed and expanded during rotation around the upper and lower frames during passage through an angled pathway defined by paired planar members in an angled engagement which rotate in time with the chain and engaged flotation members. Expanded flotation members circumventing the lower frame produce upward thrust as a function of their dimension and displacement of water. Mechanical energy from the system may be harnessed by conventional mechanical engagement of the rotating flexible chains or segments forming the upper and lower frames.
  • (Marion, 2007) US 20080289324 A1[52] Clean energy generator An affordable system for the production of clean energy comprises a plurality of tubular columns, each sealed at the bottom, to contain water in most of its inner volume. A buoy having an opening at the very bottom and a mechanical valve at its top thereby becomes inflatable and deflatable at preset times in a cycle. Once made buoyant by letting air in the bottom opening—forcing most of the water out of the buoy—it thereby elevates to the very top of the column until it reached the top of the column where the column lid depresses the valve stem deflating the buoy thus lowering the buoy to the bottom to begin the cycle again. A chain and gears engage with a rotary alternator for the generation of electricity.
  • (Souris, 2005) US 20060272327 A1[53] Power tower Means to use a water column in conjunction with a number of containers, being filled with air, when at the bottom of the column and thus forced to travel to the top of the water column, due to the buoyancy principle and said containers being attached to a motor chain or other means to control their perpetual travel in a sequential travel within the column of water in the process of rising to the top, thus causing energy suitable to be used. Then provide means to transfer said energy so produced by the rotating motor chain caused by the container's function, being forced to the top of the water column every time they are filled with air. By being able to maintain said operating conditions in said equipment at all times, a continuous energy is produced and so transferred through the chain and holding gears to a desired use.
  • (Rios-Vega, 2003) US 6914339 B2[54] Kinetic energy powered motor (KineMot) system A new approach to use energy of a compressed air in combination with the moving rotational masses for generation of an electrical power is provided. A system has a tower with rotating masses driving an electrical generator where a compressed air with its reservoir and air compressor provides power for generation.
  • (Arel, 2002) US 20020108369 A1[55] Gravity-actuated motor apparatus A gravity-actuated motor apparatus includes a frame rotatably supporting a horizontal shaft connected to a power generator. A plurality of circumferentially equally spaced apart elongated supports extend radially away from and connect to the shaft. Each support carries a weight that radially moves relative to the shaft along a closed path, thereby providing variable torque to the shaft under gravity and induce its rotation. A track member guides the displacement of the weights relative to the shaft along at least a tracking portion of the closed path. The track member is releasably engaged by the weights. An active guiding means mounted on the track member actively guides the weights along the tracking portion of the closed path. The weights could also have a low density, such as floats, and be displaced by buoyancy while being immersed within a denser soaking medium inside an enclosure.
  • (Scharfenberg, 2002) US 6769253 B1[56] Turbine power plant utilizing buoyant force This invention relates generally to a turbine power plant powered by buoyant force and an associated method of operation. The introduction of a gas, e.g., air, underwater can be a powerful force that can produce a significant amount of lift that can propel vanes in a turbine to produce electricity. This present invention provides a desperately needed alternative energy source that is usable in any part of the world that can be manufactured in large numbers.
  • (Mizuki, 1999) US 6305165 B1[57] Methods and apparatus for acquiring free energy using buoyancy technology A generic buoyancy engine is first defined, and its refinements are subsequently identified in this specification. Comprehensive math models are discussed for the first time in this field of application. Potential methods for acquiring free energy, thus boosting output/input power ratio above unity, are discussed in detail.
  • (Alkhamis, 1998) US 6009707 A[58] Buoyancy driven energy producing device An apparatus and method are provided for generating energy from a source of pressurized fluid by harnessing buoyancy and/or gravitational forces. The apparatus includes at least one container having an inlet port on a top side for receiving the pressurized fluid while the container is at the top of a tank or stand and an a drainage port on a bottom side for draining the pressurized fluid while the container is at the bottom of the tank or stand; a chain belt attached to the container such that the chain belt rotates as the container travels; and a shaft connected to the chain belt for producing rotational energy.(Binford, 1995) WO 1996002747 A1[59] Energy generating system and method A method of generating energy by employing a first body of water having a surface and defining a depth, the method comprising steps of: disposing a buoyant body at a depth below the surface of the first body of water such that the buoyant body moves toward the surface; and converting the buoyant energy associated with the buoyant body into another form of energy by harnessing the movement of the buoyant body.
  • (Kim, 1986) US 4674281 A[60] Method of power generation and its apparatus utilizing gravitation force and buoyancy The present invention relates to a method of power generation and its apparatus utilizing gravitation force and buoyancy, wherein a bigger out-put force than in-put can be obtained by adding to the in-put power the force generated by the action of gravity and buoyancy. Previously, many methods and/or apparatus utilizing gravity and buoyancy principles have been developed which claim that they can be utilized to generate a larger out-put than in-put. However, such devices have proven to be only theoretical and thus do not have practical use for the claimed purpose. The present invention provides a method and apparatus which is practically utilizable as a separate source of power generation.

Ability to be scaled

The energy generation process can be represented as shown in the System Representation. For this technology to be scaled up consideration needs to be given to the logistics of scaling up of the input energy and/or input materials, and to the environmental impact arising from pollutants, waste, and land use.

The ability to scale up depends on which specific approach is adopted. Taking the asteroid harvesting approach described in the Required inputs section, it would be dependent on the space systems available, and their capabilities, at the time.

Of course, a far easier gravity assisted energy source is hydroelectric power, which currently represents the dominant form of renewable power. [61] [62] However, the extensive amount of land use, the displacement of people and wildlife, and other impacts can be controversial. [63]

The Sandip paper[12] outlines the advantages of this method:

  • It is available all the time, 24/7
  • It can be used at any place on earth.
  • It requires small energy input to perform a long-time energy conversion.
  • It is eco-friendly and pollution free.
  • This energy source will remain forever

Whereas the KDK paper[13] adds:

  • It can be used in remote areas where power supply is not available.
  • It does not require any fuel to run.
  • Compared to solar and wind, it can be installed in any place quickly.
  • It is portable; it can be used as portable power generator.
  • It is simple to construct.
  • It requires only a small area for installation
  • It requires less maintenance than other power plants.

Environmental impact

If some form of gravity engines were to be developed, their impact on the environment would likely be limited. Or perhaps not...

The long-term environmental impact of a prospective energy technology should be considered and compared with alternative technologies. One way to do this is to use a Sustainability Scale [64] Depending on the specific solution adopted, there could be significant environmental impacts.

Hydroelectric power dams have an initial impact associated with the huge construction projects. Also, the extensive amount of land use, the displacement of people and wildlife, and other impacts can be controversial. [65] Although a dam does not burn fuel, it is associated with carbon dioxide emissions, and methane emissions, both of which drive climate change [66].

Risks associated with a prize in this space

Care needs to be taken to understand that gravity is a force, not a source of energy. It can however be used to provide some indirect forms of energy, most notably hydro-electric power (as mentioned above).

Risks are associated with all radical innovations, and that can be due to several factors. A good technology might not succeed in the marketplace due to poor marketing and promotion. The perceived safety and environmental impact of a technology is also important to successful adoption. [67] [68] [69] Poor implementation of a technology can also prevent successful adoption of a good technology. These are risks that come into effect after the awarding of an energy technology prize, but perhaps the associated challenge can provide post award support to ensure that these risks are reduced. In addition, of course, there can be risks associated with the technical efficacy of the technology itself, and the logistics surrounding its development, operation and decommissioning.

The are a diverse range of possible solutions under this category, and so a variety of potential risks. However, hydroelectric power has achieved a notable role in being a major supplier of renewable energy, so success can be achieved in this area.

Positive energy tests to evaluate this technology

This is especially crucial for technologies that are as yet untested or have not yet generated large amounts of verifiable performance data. What conditions would need to be met for this technology to be considered unequivocally “verified” or “validated”?

Care needs to be taken where solutions look like perpetual motion machines, because the law of the conservation of energy still holds true, as highlighted on the discussion page: Talk:Energy capture from gravity[70].

The inputs and outputs for any energy generation process can be represented as shown in the System Representation. The efficiency of the system is represented by the output energy divided by the input energy. Note that all energy inputs should be accounted for. There are a diverse range of proposed technologies under this category so each would need to be judged on its own merits. A good place to start is by asking where is the energy source coming from? Does energy have to be put in to the system? If the originating energy source is external to the Earth then it might have potential.

Technologies that use gravity, but not as primary energy source

There is often confusion about which technologies claim to tap into a new energy source, and which technologies use gravity in smart ways without claiming net energy production. For reference, the technologies below are included as examples of technologies that use of gravity, but which are not claiming net energy production.

Power Generation through Gravity and Kinetic Energy

Gravity alone is not found to generate a lot of energy for now but gravity when coupled with kinetic energy, that is in combination with other sources of energy is found to improve the efficiency significantly. A few gravity based devices which works in combination with kinetic energy and other sources of energy input are known to exist.

Principle: This machine is based on the simple principle i.e., when an object is placed on a higher level ground then due to the gravitational force it experiences a pull towards the lower level and gains kinetic energy. This kinetic energy can be utilized in a précised manner in which it can be transformed into electrical energy. However this technology requires hydraulic energy input for working[5].

Another device uses mechanical components like Spur gears, chain and mass provide input to an electrical circuit through a generator motor. Every time you lift the weight, gravitational potential energy is converted into electrical energy for 68 seconds in this model. Power generation from gravity is cheaper and bio-efficient as compared to solar and other renewable energy sources.However this device can produce only energy for a small duration[71].


GravityLight is a Mechanically powered flashlight designed by the company Deciwatt for use in Developing world nations, as a replacement for /Kerosene lamps. It uses a bag filled with rocks or earth, attached to a cord, which slowly descends similar to the weight drive in a cuckoo clock. This action powers the light for up to thirty minutes[6][72].

The Feltenberger Pendulum

Introducing the Feltenberger Pendulum; a patented technology as easy to use as pushing a child on a swing. Stunning in its simplicity, this technology uses the always present force of gravity to assist with work. Its mechanical advantage allows the use of Gravity Assisted Power (GAP) anytime, anywhere[73].

Regenerative Drive Technology Elevator

In regenerative drive technology[74] electricity is generated by the gravitational pull of elevator cabs and counterweights in traction elevator systems. In 2011, two companies, Energy Investment Systems (EIS) and the C.V. Starr Research Foundation, petitioned the New York State Public Service Commission (PSC) to establish regenerative drives as a renewable resource, eligible for incentives in the customer-sited tier.

The PSC did no approve[75] the regenerative elevator drive as a renewable energy because the technology could not generate electricity by itself. It requires electricity to create the motion that is recaptured through regeneration from the relative weights and positions of the elevator and the counterweight. So while it is environmentally beneficial, it is not renewable but a technology that recaptures other energy already being expended.

Gravity Power Module

  • Organizations/Researchers Working With This Technology

Gravity Power, LLC[76], a spin-off of LaunchPoint Technologies, Inc., is developing a revolutionary grid-scale electricity storage system. The company’s new Gravity Power Module (GPM) exploits the established principles of pumped storage hydropower but extends the concept.

  • How Does It Work?

The GPM[77] relies on two water-filled shafts, one wider than the other,  which are connected at both ends.  Water is pumped down through the smaller shaft to raise a piston in the larger shaft containing a high-weight piston; reversing such a process forces the water to flow back through the pump to generate electricity. The GPM[78] stores energy and grid power drives the motor/generator in reverse, spinning the pump to force water down the return pipe and into the shaft, lifting the piston.  Hundreds of megawatt-hours per shaft can be stored with high efficiency,  since pump-turbines have low losses and friction is negligible at modest piston speeds.

This 2014 Paper[77] compares Electrical Energy Storage Systems and describes how the Gravity Power Module (GPM) works (p2300), referring to it as a "promising cutting-edge technology."

  • How The Technology Compares?

The peaking power market, simple cycle combustion gas turbines are the primary competition[79]. Being much more flexibly suited than Pumped storage hydropower  (PSH) or Compressed Air, GPMs are more attractive than conventional gas combustion turbine peakers on a levelized cost of electricity (LCOE) basis.

PSH is the only large-scale electricity storage technology widely used today, with over 120,000 megawatts of capacity[79] worldwide. However, a  new PSH installation typically takes 11 to 15 years[79] to develop and an investment exceeding one billion dollars before a single watt of power is produced. It also has severe siting limitations due to the need for two large reservoirs at different elevations and the resulting environmental disruption. In contrast, a GPM can be quickly be installed underground with virtually no adverse environmental impacts.

Gravity Power is collaborating with Robbins Co.[80], the inventor of the mole machine to adapt their technology to vertical tunneling capable of digging 100 meters deep in 24 hours.  The speed, low cost, and construction from readily available cheap materials expect the investment costs to reduce by at least half and the time between decision and implementation in terms of a few years instead of a decade.

  • Implementing GPM Technology

The cost issue[78][/ .] Economic operation of the GPM system depends heavily[81] on the construction cost of the shaft, which is surprisingly low. This is because the GPM system will require less excavation per storage capacity than many existing pumped storage hydro facilities and because that excavation can be automated. A small footprint and unobtrusive operation will allow multi-shaft installations to be constructed even in dense urban areas. GPM technology can satisfy the world’s growing utility-scale energy storage needs because it can:

  1. Provide[81] hundreds of megawatts for several hours, per installation, with the dynamic operating characteristics required by the grid
  2. Can achieve a competitive[81] cost
  3. Can be deployed on a truly gargantuan scale[81]

Advantages[81] include modularity; use of existing technology; environmental compatibility; flexible siting; fast permitting; rapid construction; low cost per megawatt-hour; long lifetime; high efficiency; and a short time from project start to revenue.

  • Environmental Impact

GPMs[78] will have no stack and no noise problems, lower land use,  burn no fuel and can be installed where most needed on the grid.

  • Intellectual Property


James Fiske, the founder of Gravity Power LLC obtained a Patent in Feb 2015 (Filed Aug 2014) for the GPM system for "storing energy that includes a body and a shaft having walls defining an  internal volume for containing a fluid, a seal member disposed between the body and the walls of the shaft, and a fluid passage in fluid communication with the shaft. The body is disposed within the internal volume of the shaft for movement with gravity from a first elevation position to a second elevation position within the internal volume of the shaft. The seal member divides the internal volume into a first portion located below the body and a second portion located above the body. The fluid passage communicates fluid with the first portion of the interior volume of the shaft. The system further includes a pump/turbine operatively coupled with the fluid passage to drive a motor/generator to generate electricity upon movement of the body from the first elevation position to the second elevation position."


  5. 5.0 5.1 Power Generation through Gravity and Kinetic Energy Md.Muqtar Ahmed, Heena Naaz
  6. 6.0 6.1 "How does it work?". Gravity Light Foundation. Retrieved 2016-08-28.
  7. Bostock A. (2017). System Representation, Energy Wiki
  8. 8.0 8.1
  12. 12.0 12.1 Gravity Power Generation[1]
  13. 13.0 13.1 Electrical Energy Harvesting By Using Pendulum Power Generator[2]
  18. 18.0 18.1
  19. 19.0 19.1
  24. Gravitational energy conversion turbines gecturbines[3]
  40. Gravity/energy transformer[4]
  47. Gravity motor
  50. Gravity-buoyancy object turbine[5]
  61. Hydroelectric power water use, The USGS Water Science School, U.S. Geological Survey
  62. Hydropower, International Energy Agency
  63. News: Dam Construction Objections
  64. Bostock A. (2017). Sustainability Scale, Innovation Future Specialist, (UK).
  65. Environmental impact of reservoirs, Wikipedia
  66. Duncan Graham-Rowe (2005). Hydroelectric power’s dirty secret revealed New Scientist, Daily News
  67. Slovic and Weber (2013). Perception of Risk Posed by Extreme Events, Regulation of Toxic Substances and Hazardous Waste (2nd edition) (Applegate, Gabba, Laitos, and Sachs, Editors), Foundation Press, Forthcoming
  68. Michael Siegrist, Heinz Gutscher & Timothy C. Earle (2006). Perception of risk: the influence of general trust, and general confidence, Journal of Risk Research: Volume 8, 2005 - Issue 2
  69. Linda Steg and Inge Sievers (2016). Cultural Theory and Individual Perceptions of Environmental Risks, Environment and Behavior: Vol 32, Issue 2, pp. 250 - 269, First published date: July-26-2016
  70. Discussion of the need to be careful with perpetual motion type methods.
  71. GENERATION OF ELECTRICITY USING GRAVITY Prathamesh Natu, Sameer Nadkar and Abhishek Badgujar
  72. "Soon, lamps powered by gravity - The Times of India". The Times of India. Retrieved 2012-12-22.
  73. The Feltenberger Pendulum
  74. Promoting Elevators as Renewable Resource[6]
  75. Dark Day for Elevators in Big Apple[7]
  77. 77.0 77.1 Electrical Energy Storage Systems: Technologies’ State-of-the-Art, Techno-Economic Benefits and Applications Analysis[9]
  78. 78.0 78.1 78.2 GRID SCALE ENERGY STORAGE:Technology[10]
  79. 79.0 79.1 79.2 THE NEED FOR ENERGY STORAGE[11]
  80. Gravity Power Electricity Storage[12]
  81. 81.0 81.1 81.2 81.3 81.4 A New Energy Storage Option: Gravity Power[13]
  82. System and method for storing energy[14]