gravity battery
   HOME

TheInfoList



OR:

A gravity battery is a type of energy storage device that stores
gravitational energy Gravitational energy or gravitational potential energy is the potential energy a massive object has in relation to another massive object due to gravity. It is the potential energy associated with the gravitational field, which is released (conver ...
, the energy stored in an object resulting from a change in height due to
gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
, also called potential energy. A gravity battery works by using excess energy from the grid to raise a mass to generate gravitational potential energy, which is then dropped to convert potential energy into electricity through an
electric generator In electricity generation, a generator is a device that converts motive power (mechanical energy) or fuel-based power (chemical energy) into electric power for use in an external circuit. Sources of mechanical energy include steam turbines, gas ...
. Energy generated from a gravity battery is a form of
sustainable energy Energy is sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs". Most definitions of sustainable energy include considerations of environmental aspects such as greenh ...
. One form of a gravity battery is one that lowers a mass, such as a block of concrete, to generate electricity. The most common gravity battery is used in
pumped-storage hydroelectricity Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential ...
, where water is pumped to higher elevations to store energy and released through water turbines to generate electricity.


Development

The earliest form of a device that used gravity to power mechanical movement was the
pendulum clock A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. The advantage of a pendulum for timekeeping is that it is a harmonic oscillator: It swings back and forth in a precise time interval dependent on it ...
, invented in 1656 by
Christiaan Huygens Christiaan Huygens, Lord of Zeelhem, ( , , ; also spelled Huyghens; la, Hugenius; 14 April 1629 – 8 July 1695) was a Dutch mathematician, physicist, engineer, astronomer, and inventor, who is regarded as one of the greatest scientists of ...
. The clock was powered by the force of gravity using an
escapement An escapement is a mechanical linkage in mechanical watches and clocks that gives impulses to the timekeeping element and periodically releases the gear train to move forward, advancing the clock's hands. The impulse action transfers energy to ...
mechanism, that made a pendulum move back and forth. Since then, gravity batteries have advanced into systems that can harness the power of gravity and turn it into electricity for large scale energy storage. The first gravity based
pumped-storage hydroelectricity Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential ...
(PSH) system was developed in 1907 in Switzerland. In 1930, pumped-storage came to the United States by the Connecticut Electric and Power Company. As of 2019, the total world capacity for PSH is 168 GW (gigawatts). The United States has 23 GW capacity from PSH, accounting for nearly 2% of the energy supply system and 95% of utility-scale energy storage in the US. Gravity based pumped-storage electricity is currently the largest form of grid energy storage in the world. In 2012, Martin Riddiford and Jim Reeves developed the first functioning prototype of GravityLight, a small-scale gravity battery that is now commercially available in certain countries. Energy Vault, a Swiss company founded in 2017, stores electricity using a crane that raises and lowers blocks of concrete. In late 2020, a prototype built in
Arbedo-Castione Arbedo-Castione is a municipality in the district of Bellinzona in the canton of Ticino in Switzerland. Geography Arbedo-Castione has an area, , of . Of this area, or 6.0% is used for agricultural purposes, while or 77.6% is forested. Of t ...
used six cranes on a 110-meter-high tower to move 35-ton concrete blocks with a capacity of 80 megawatt hours. Cascadia Carbon Inc., a
Portland, Oregon Portland (, ) is a port city in the Pacific Northwest and the largest city in the U.S. state of Oregon. Situated at the confluence of the Willamette and Columbia rivers, Portland is the county seat of Multnomah County, the most populous co ...
company, is developing a potential energy battery with the
University of British Columbia The University of British Columbia (UBC) is a public university, public research university with campuses near Vancouver and in Kelowna, British Columbia. Established in 1908, it is British Columbia's oldest university. The university ranks a ...
. Gravitricity, founded in 2011 by Peter Fraenkel, built a 15-meter 250-kilowatt gravity battery prototype near
Edinburgh Edinburgh ( ; gd, Dùn Èideann ) is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. Historically part of the county of Midlothian (interchangeably Edinburghshire before 1921), it is located in Lothian ...
, Scotland that started trial operations and grid-connection in April 2021.


Mechanisms and parts

Gravity batteries can have different designs and structures, but all gravity batteries use the same properties of physics to generate energy. Gravitational potential energy is the work required to move an object in the opposite direction of Earth's gravity, expressed by the equation U = mgh where U is gravitational potential energy, m is the mass of the object, g is the acceleration of the object due to gravity (9.8 m/s2 on earth), and h is the height of the object. Using the work-energy principle, the total amount of energy generated can be expressed by the equation \Delta E=mg(h_1- h_2) where E is the total amount of energy generated and h1 and h2 represent the initial and final heights of an object. The change of energy directly correlates to the vertical displacement of a mass; the higher a mass is lifted, the more gravitational potential energy is stored. The change in energy also directly correlates to the mass of an object; the heavier the mass, the bigger the change in energy. In a gravity battery, a mass is displaced, or lifted, to generate gravitational potential energy that is transformed into electricity. Gravity batteries store gravitational potential energy by lifting a mass to a certain height using a pump, crane, or motor. After the mass is lifted, it now stores a certain gravitational potential energy based on the mass of the object and how high it was lifted. The stored gravitational potential energy is then transferred into electricity. The mass is lowered to fall back to its original height, which causes a generator to spin and create electricity.


Types of gravity batteries


Large scale

Pumped-storage hydroelectricity (PSH) is the most widely used and highest-capacity form of grid-energy storage. In PSH, water is pumped from a lower reservoir to a higher reservoir, which can then be released through turbines to create energy. An alternative PSH proposal uses a proprietary high-density liquid, times denser than water, which requires a smaller
head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...
(elevation) and thus decreases the size and cost of the necessary infrastructure. Energy-storage-by-rail is a concept where excess renewable energy is used to run heavy trains cars uphill during times of low energy demand. The potential energy is released later by using
regenerative braking Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy into a form that can be either used immediately or stored until needed. In this mechanism, the electric traction mo ...
as they roll downhill, acting as a gravity battery. A utility-scale (50 MW) facility called GravityLine began construction in October 2020 by Advanced Rail Energy Storage, located at the Gamebird Pit gravel mine in the
Pahrump Valley Pahrump Valley is a Mojave Desert valley west of Las Vegas and the Spring Mountains massif in southern Nye County, Nevada, and eastern San Bernardino County, California. Pahrump, Nevada, is in the valley's center and the Tecopa and Chicago Valley ...
,
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
, and is planned to deliver up to 15 minutes of service at full capacity. Lift Renewable Energy uses a form of gravity battery. To store energy, buoyant gas containers are pulled down into water by a winch, water is in effect lifted hundreds of meters. The cycle is then reversed and electricity is generated as the gas containers rise. Relatively little infrastructure is required, the batteries can be sited near major population centers, round trip efficiency is 85+%, and the system can be built at a GWh scale. Lifted Weight Storage (LWS) technology uses surplus energy to mechanically lift solid weights vertically, typically on a pulley system. When extra energy is needed, the mass is lowered, and the pulley turns a generator. EnergyVault is designing a LWS system using a tower built from 32-ton concrete blocks, stacked with 120-meter cranes. One commercial unit is expected to store 20 MWh or energy, or enough to power 2,000 Swiss homes a day. Gravitricity's LWS system in an underground shaft uses an electric winch to lift a 500-to-5000-tonne weight, which when lowered turns the winch motor as a generator. The system generates 10 MWh, enough to power 13,000 homes for two hours. The weight can also be dropped quickly for a small burst of power.


Small scale

GravityLight is a small gravity-powered light that operates by manually lifting a bag of rocks or sand up and then letting it fall by itself to generate energy. It is designed as an alternative for those who do not have access to electricity and typically rely on
kerosene lamp A kerosene lamp (also known as a paraffin lamp in some countries) is a type of lighting device that uses kerosene as a fuel. Kerosene lamps have a wick or mantle as light source, protected by a glass chimney or globe; lamps may be used on a t ...
s, which are expensive, dangerous, and polluting.


Economics and efficiency

Cost of gravity batteries varies by design. Pumped storage hydropower costs $165/kWh to operate, with a
levelized cost of storage Different methods of electricity generation can incur a variety of different costs, which can be divided into three general categories: 1) wholesale costs, or all costs paid by utilities associated with acquiring and distributing electricity to ...
(LCOS), of $0.17/kWh. The pumps and turbines of PSH systems operate at up to 90% efficiency. Gravitricity's 250 kW demonstrator is expected to be $1.25 million, promising a 50-year lifespan and efficiency of 80–90%. A 2018 comparative review of the proposition was favorable considering the extended lifespan and power-to-energy cost ratio. Gravity batteries can make solar and wind more viable as they can store the excess energy they make during peak hours and distribute it later when needed.


Environmental impacts

Gravity batteries are designed to be paired with
renewable energy Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
solutions whose sources (sunlight, wind, etc) are frequently variable and do not necessarily coincide with demand. It is hoped that they will have a better long term cost than chemical batteries, while having fewer environmental issues than other traditional storage solutions such as pumped-water storage. It is anticipated that gravity battery systems will be able to quickly provide power during peak consumption which may allow them to supplement or replace fossil fuel
peaking power plant Peaking power plants, also known as peaker plants, and occasionally just "peakers", are power plants that generally run only when there is a high demand, known as peak demand, for electricity. Because they supply power only occasionally, the power ...
s. Single weight systems are expected to be able to achieve full power generation in less than a second. Among low-carbon long-duration energy storage methods, pumped storage hydropower had the lowest current energy cost, though lithium-ion batteries are expected to overtake it in the future. Pumped storage hydropower and other long-duration storage methods are considered to have low environmental and security risks compared to battery technology, with the only limiting factor being geology.


Gravity (chemical) battery

From 1870 to 1930, the term "gravity battery" was used to describe a collection of popular battery types where gravity was used to keep the chemical constituents separate based on their respective densities.


See also

*
Energy storage Energy storage is the capture of energy produced at one time for use at a later time to reduce imbalances between energy demand and energy production. A device that stores energy is generally called an accumulator or battery. Energy comes in ...
*
Pumped-storage hydroelectricity Pumped-storage hydroelectricity (PSH), or pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing. The method stores energy in the form of gravitational potential ...


References

{{Reflist Energy storage Swiss inventions Scottish inventions