Gravity energy storage is not a source of power. It is a battery that uses weight to store electricity. When you have extra energy from sources like wind or solar, you use it to lift heavy blocks or weights. When you need power later, you lower them. The falling mass drives a generator, turning potential energy back into electricity, and you always get back less than you put in.
This process is often called a “gravity battery”. It addresses one of the main problems with renewables: intermittency. The sun does not always shine, and the wind does not always blow. Gravity storage captures surplus energy and releases it when the grid needs it. It is a mechanical solution to an electrical problem.
How it works
The physics are straightforward. The energy stored depends on three things: the mass of the object, the acceleration due to gravity, and the height you lift it. The formula is Energy = mass × gravity × height. To put this in perspective, physicist Tom Murphy calculated in 2011 that lifting 100 kilograms by 10 metres stores roughly the same energy as one AA battery (about 3 watt-hours). Lifting 1 tonne by 100 metres stores only about 0.27 kWh.
This low energy density is why these systems need to be massive. You need thousands of tonnes of material or hundreds of metres of height to store useful amounts of power. This is why gravity storage schemes use deep mine shafts, tall towers, or long sloping tracks.
The cycle has two parts. First, charging. Excess electricity powers motors that winch the weights up. Second, discharging. The weights are lowered. As they descend, the motor acts as a generator, creating electricity that feeds back into the grid. The system is purely mechanical, relying on cables, winches, and tracks rather than chemical reactions.
Real-world examples
The landscape of gravity storage is small. While pumped storage hydropower is the dominant form of gravity storage globally, using water as the mass, solid-mass systems are still in their infancy.
Energy Vault: Towers and blocks
Energy Vault, founded in 2017, designs towers and buildings that move large composite blocks. In 2020, the company erected a demonstration tower about 70 metres tall in Arbedo-Castione, Switzerland, using 35-tonne blocks. A round-trip efficiency of around 75% has been reported for it, but this figure is not independently verified.
The commercial reality is more limited. In May 2022, construction began on a plant in Rudong, Jiangsu, China, next to a wind farm. This 25-megawatt, 100-megawatt-hour facility was commissioned in 2023–24, and Energy Vault lists it as “Built & Transferred” and operating for State Grid. It is the only commercial solid-gravity plant we could verify as operating anywhere in the world. Further Chinese projects have been announced but remain in development.
Energy Vault’s own focus has since shifted. In October 2026, 12 of the 13 projects on the company’s list were batteries or hybrid systems, and its homepage did not mention gravity. Its remaining gravity work includes a battery-plus-gravity hybrid in Sardinia, which is still in development. Gravity now looks like a niche product for the company rather than its core business.
Gravitricity: Weights in mine shafts
Gravitricity, based in Edinburgh, takes a different approach: it plans to hang weights in deep mine shafts. In April 2021, the company’s 250-kilowatt demonstrator in Leith, Edinburgh, delivered its first power to the grid. The rig used two 25-tonne weights on a 15-metre lattice tower and completed a three-month test programme. The company says the system went from zero to full power in less than a second.
Gravitricity plans to scale this up using disused mines. In February 2024 it announced an agreement with Callio Pyhäjärvi in Finland to turn a 530-metre-deep shaft at the Pyhäsalmi zinc and copper mine into a full-scale prototype of up to 2 MW. However, as of October 2026, there is no evidence this project has moved beyond the agreement and planning stage. The company has received government grants and has partnered with ABB and signed a memorandum of understanding with Baker Hughes, but no full-scale commercial deployment has been confirmed.
ARES: Rail cars on a slope
Advanced Rail Energy Storage (ARES) uses a different mechanism entirely. Instead of vertical lifts, it uses rail cars on a slope. In Pahrump, Nevada, a 50-megawatt system was designed to provide regulation services to the California grid. The project involved 210 mass cars on 10 tracks.
Groundbreaking took place in October 2020, with Potelco as contractor. However, there is no evidence that the Nevada plant was completed or is currently operating. The company’s website still shows only news from 2020. The project’s status remains unverified.
What the numbers say
When comparing these technologies, the numbers tell a cautious story.
Efficiency: Gravitricity claims an 80% round-trip efficiency. Energy Vault’s demo tower has been reported at about 75%. For context, the US pumped hydro fleet averaged 79% in 2019, while utility-scale batteries averaged 82%. The solid-gravity claims are in the same range as pumped hydro and slightly below batteries. However, no independently published efficiency data exists for a commercial solid-gravity plant.
Cost: There is no verified cost per kilowatt-hour for any operating solid-gravity plant. Gravitricity states its levelised cost is below lithium-ion, but provides no figures. ARES claims lower costs than batteries but publishes no data.
Scale: By our calculation, the Rudong plant in China (100 MWh) stores about 1% of the energy of the Dinorwig pumped storage station (about 9.1 GWh). Global pumped storage capacity exceeded 200 GW in 2025. Solid gravity storage is currently a drop in the ocean compared with established hydro or battery storage.
Longevity: The claimed advantage of gravity storage is durability. Gravitricity claims a life of more than 50 years with over 50,000 cycles and no degradation, and ARES claims a 40-year service life. Developers contrast this with battery degradation and argue it makes gravity storage attractive for long-duration storage, but these lifetimes have not been demonstrated in commercial operation.
Limitations and honest assessment
Gravity energy storage is not a silver bullet. It has significant physical and economic constraints.
The primary limitation is energy density. You need enormous mass or height to store meaningful energy. This makes the systems bulky and expensive to build from scratch. Energy Vault’s EV1 concept required roughly 7,000 blocks weighing 35 tonnes each. Building a tower of that size is a civil engineering challenge in itself.
Location is also critical. You need either a tall structure or a deep hole. This limits where these systems can be built. Pumped hydro already uses the same principle with water, which can simply be pumped and passed through turbines. Solid gravity systems try to achieve the same result without the water, which needs more moving machinery.
There is also the issue of verification. Most claims about efficiency, cost, and lifespan come from the developers themselves. The industry is young, and independent data is scarce. The unclear fate of ARES in Nevada shows how far announcements can run ahead of operating plants.
The UK angle
Gravitricity is based in Edinburgh, but its stated pipeline of mine sites is largely abroad, including more than 30 sites identified in Poland and the Czech Republic and feasibility work in Germany.
In June 2026, Ofgem’s provisional list for the long duration energy storage (LDES) cap-and-floor scheme, covering 16 projects, included pumped hydro, lithium-ion, compressed air, and a flow battery. No solid gravity storage project was on it.
Gravitricity has received government funding, including a £640,000 Innovate UK grant towards its Leith demonstrator and a £912,000 grant from the government’s LDES competition in 2022. However, without a commercial deployment in the UK, the technology remains unproven in the British market. Researchers have also warned that mine-shaft schemes can face hidden costs, such as structural repairs and environmental liabilities at old mines.
Frequently asked questions
Can you generate electricity from gravity?
No. Gravity is not a source of energy; it is a force. You cannot “generate” energy from it. You store energy by using electricity to lift a weight against gravity. When you lower the weight, you recover some of that energy. You always get less out than you put in.
How does gravity energy storage work?
The system uses excess electricity to power motors that lift heavy masses (concrete blocks, steel weights, or rail cars). When electricity is needed, the masses are lowered. The descent drives a generator, converting the potential energy back into electricity. The principle is similar to hydropower but uses solid masses instead of water.
How efficient is gravity energy storage?
Developers claim efficiencies of around 75% to 80%. This is comparable to the US pumped hydro fleet (79% in 2019) but slightly lower than utility-scale lithium-ion batteries (82%). However, these figures are based on demos or company claims, not independent data from large commercial plants.
Is there a working gravity battery?
Yes, but only one commercial plant could be verified. The Energy Vault plant in Rudong, China (25 MW/100 MWh) is listed as operating. Gravitricity completed a 250 kW demonstrator in Edinburgh in 2021. Other projects, like ARES in Nevada, remain unverified.
Is gravity storage better than lithium-ion batteries or pumped hydro?
It depends on the use case. Developers claim a longer lifespan and no fire risk, which they say suits long-duration storage. However, gravity storage has low energy density and high civil engineering requirements. Lithium-ion batteries are more efficient and compact. Pumped hydro is far more mature and deployed at much larger scale.
Is gravity storage being used in the UK?
Not commercially. Gravitricity ran a demonstrator in Edinburgh in 2021 and plans mine-shaft systems, but no full-scale plant is operating. No solid gravity project was included in Ofgem’s provisional June 2026 LDES list.