Fast, Versatile Energy Storage

As the world generates more and more electricity from intermittent renewable energy sources, there is a growing need for technologies which can capture and store energy during periods of low demand and release it rapidly when required.

At Gravitricity we are developing a novel storage technology which offers some of the best characteristics of lithium batteries and pumped storage.

Ideally suited to network-constrained users and operators, distribution networks and major power users, the technology operates in the 1MW to 20 MW power range and enables existing grid infrastructure to go further in a renewable energy world.

Our patented technology is based on a simple principle: raising and lowering a heavy weight to store energy. In practice, it has similar advantages to pumped storage for networks up to 33kV, without the need for a nearby mountain with a lake or loch at the top.

Our Gravitricity™ technology has a unique combination of characteristics:

  • 50-year design life – with no cycle limit or degradation
  • Response time – zero to full power in less than one second
  • Efficiency – between 80 and 90 percent
  • Versatile – can run slowly at low power or fast at high power
  • Simple – easy to construct near networks
  • Cost effective – levelised costs well below lithium batteries

Each unit can be configured to produce between 1 and 20MW peak power, with output duration from 15 minutes to 8 hours. 

semi-rural mockup Jan18

The Technology

Essentially, the Gravitricity system is a huge ‘clock weight’. A cylindrical weight of up to 3000 tonnes is suspended in a deep shaft by a number of synthetic ropes each of which is engaged with a winch capable of lifting its share of the weight. Electrical power is then absorbed or generated by raising or lowering the weight. The weight is guided by a system of tensioned guide wires (patents applied for) to prevent it from swinging and damaging the shaft. The winch system can be accurately controlled through the electrical drives to keep the weight stable in the hole.

The key requirement is a deep hole in the ground; it can be a disused mineshaft brought back into use, or a purpose-sunk shaft. Shaft depths can be from 150m for new shafts down to 1500m for existing mines.

The biggest single cost is the hole, and initially we will prove the technology using existing mine shafts. As our technology costs decrease, the costs of drilling will reduce significantly, opening the opportunity for purpose-built shafts.

Over the 12 months from January 2018 we will be undertaking sub-system design and deploying a 250kW concept demonstrator.  We aim to trial our first full-scale prototype in 2019 or 2020 at a disused mine in the UK.

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The grid connection is through modern power electronics to permit rapid switching between generation and absorption of power and the system can deliver reactive as well as resistive power to help with grid stability.

While the weight system can be used on its own, the energy storage capacity of the overall system can be much increased when the shaft is used as a pressure vessel for compressed air (patent applied for.)  This involves adding a pressure-tight “lid” to the top of the shaft and lining the shaft to prevent leakage. The ground provides the bursting resistance other than at the very top of the shaft. The winches and generators are normally contained in the pressurized space so that only electrical cables need to penetrate the pressure vessel walls. 

Gravitricity Ltd has several patents in process dating back to 2011.

Market Potential

Energy storage is a vital requirement for making best use of intermittent renewable energy resources such as wind, solar and marine renewables, and to incorporate clean electric vehicles onto the grid. 

The International Energy Agency estimates that in order to limit global warming to below 2°C, the capacity of storage connected to the grid worldwide should increase from 140 GW in 2014 to 450 GW by 2050.

Bloomberg New Energy Finance [Global Energy Outlook 2016] has forecast over $100 billion of global spend on energy storage to 2030. 

Our technology will provide balancing services on transmission grids as well as appealing to network-constrained users and generators, distribution networks and major power users seeking a reliable, fast response, and long-term means of storing power.

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The Gravitricity technology is inherently durable and flexible. Where ever it is deployed it will provide balancing services such as Frequency Response and Reserve to the  high voltage transmission grid in the region.  It can also be sited at locations where energy storage is particularly required: on constrained distribution grids, behind customer meters, and on micro-grids where the technology can provide long-term system balancing.

On existing grids Gravitricity installations can be considered as long term infrastructure assets that maximise the utility of existing grid hardware.  In many situations they can be deployed to minimise or remove altogether the requirement for expensive distribution grid upgrades as demand and supply patterns change.

On emerging grids, Gravitricity systems will significantly reduce the requirement for redundancy in grid hardware. There is very significant opportunity to reduce the cost of rural electrification across the developing world by deploying long-life storage technologies.


Charlie Blair, Managing Director, joined Gravitricity in 2015 having been Head of Marine Energy in the Carbon Trust's Innovation Team. He is an experienced commercial leader, delivering millions of pounds of innovation funding, and has 14 years’ experience in clean energy technology innovation. He has supported numerous early-stage technology start-ups ranging from electric vehicles through to biomass heating. 

Martin Wright, Chairman, has a background in entrepreneurial company development (eg. MCT) Venture Capital, oil and gas and, earlier, as a Seaman Officer in the Royal Navy. Today he is Chairman of both the UK Renewable Energy Association (the main UK trade association for renewable energy) and of Mojo Maritime Ltd, a leading marine installation and operations company focused on marine Renewable Energy.

Peter Fraenkel, Technical Director and inventor, is a chartered mechanical engineer with a background in international energy consultancy and technology development R&D, and he is also a visiting professor at the University of Edinburgh.  He was the inventor and Technical Director of Marine Current Turbines, which deployed the world's most successful tidal turbine in Northern Ireland. In 2013 Peter received an MBE for services to Marine Energy. 

Miles Franklin, Lead Engineer, is a chartered mechanical engineer with 5 years experience in new technology innovation from a number of fields, including novel borehole drilling machines in West Africa and new product development at Dyson.  Miles leads the engineering team in Edinburgh, which also works with the Edinburgh University Institute for Energy Systems and various external contractors.

Sarah Dreuilhe, Analyst, is a generalist engineer from French school Arts et Metiers Paristech with a background in industrial and mechanical engineering. She did her MSc in Renewable Energy Systems Technology at the CREST laboratory at Loughborough University and her PhD in Experimental Mechanics as part of the Photodyn project at the University of Southampton.



Company Reg. No: 7827384 England


21 March 2018 (press release): 

Gravitricity teams up with worldwide lifting, drilling and subsea specialists Huisman to build prototype energy store

  • Partners plan to build 250kW energy storage prototype this year
  • Plans for long-term partnership to bring gravity-fed technology to market
  • Technology will contribute to grid stabilisation and fast frequency response


Energy storage start-up Gravitricity has teamed up with worldwide lifting, drilling and subsea specialists Huisman to develop a scale demonstrator of their innovative gravity-fed energy storage system.

The Edinburgh green tech firm has signed an R&D agreement with the Dutch multi-national to develop a 250kW concept demonstrator and test it in the Netherlands and Scotland early next year. Following this they plan to scale up to fully commercial 20 MW systems.

Gravitricity technology uses a massive weight suspended in mine shafts to capture power, and then release it in seconds (pictured below). In February they received a £650,000 grant from Innovate UK, the UK Government’s innovation agency, to build their prototype.

The project partners believe Gravitricity can be a strong competitor in the frequency response market, where there is a requirement from grid operators for large, fast and frequent bursts of power to stabilise increasing amounts of renewables on the grid.

Huisman is a global operating company delivering innovative technical solutions to leading companies in the oil & gas, renewables, leisure and civil industries.

“This 250kW prototype will help us validate our simulations about how the technology works in practice and will give us the opportunity to utilise Huisman’s enormous experience in winches and cranes,” says Gravitricity Managing Director Charlie Blair.

“At the same time Huisman and our engineers will begin detailed design of the winch drive modules for our full-size 4MW demonstrator, which will be deployed in a UK mine shaft in 2020.

“Huisman are now a core partner in our industrial consortium, which will enable us to quickly take this technology to market,” Blair says.

Commenting on the agreement, Peter Berting, Business Development Manager at Huisman says:

“Gravitricity’s low power cost and high cyclability sets it apart from other technologies. The recent global growth of renewable energy means there is a growing need for grid stabilisation, and their energy storage system plays directly into this market.

“The technology is scalable, easy to install and comes with a long lifetime. Huisman is a very innovative company and we see a great fit between our expertise and this exciting new concept.

“Our ambition is to work with Gravitricity to develop an innovative commercial solution which will make a substantial contribution to grid stabilisation and safe future power supply to all its users,” Berting concludes.

It’s planned the Dutch specialist will build the test module in Holland before shipping it to Scotland where it will be put through its paces at the Power Networks Demonstrator Centre (PNDC) in Cumbernauld.

“We have been working with the PNDC in the design of our test regime, and they will give us vital data on how our technology can provide grid balancing and rapid frequency response services to grid operators,” says Gravitricity lead engineer Miles Franklin.

Gravitricity is also working with Glasgow firm Industrial Systems and Control (ISC) on dynamic simulations and control mechanisms for the Gravitricity system.

07 February 2017: 

Gravitricity awarded £650,000 funding from Innovate UK's Infrastructure Systems Innovation competition

19 December 2017:

Gravitricity selected to present at CleanTech Innovate Showcase

10 December 2017: 

Levelised cost of Storage in the spotlight. Lazards publish Version 3 Analysis. 

27 November 2017: 

Charlie Blair will be speaking at Energy Storage & Connected Systems, Feb 2018

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07 February 2018: 

Gravitricity awarded £650,000 funding from Innovate UK's Infrastructure Systems Innovation competition.

This innovation funding will be used to design and build our 250kW concept demonstrator, ready for testing in late 2018.  The project will be completed in collaboration with our international winch partner and with controls engineers Industrial Systems & Controls in Glasgow.  It will confirm Gravitricity's commercial characteristics, validate our simulations, and provide a physical proof-of-concept demonstration.     During 2018 the company will also develop the site and engineering designs for the full-scale prototype, planned for a UK mineshaft in 2019-20. 

Gravitricity is now raising seed funding to match the grant and would like to speak to potential investors, particularly those with power systems or mining experience.  

Plenty of press pick up: 

Times Headline Thursday 8 Feb 18

19 December 2017:

Gravitricity selected to present at CleanTech Innovate Showcase

Gravitricity ltd has been selected for the prestigious Cleantech Innovate Investor Showcase in March 2018.  Charlie Blair will be presenting details of the 250kW Concept Demonstrator and the associated investment proposition. This adds to a list of showcasing and pitching events that Gravitricity has attended in 2017, including the Greentech Challenge, Clean & Cool, and Rushlight.

See https://www.cleantechinnovate.... for a list of 2018 finalists.

10 December 2017: 

Levelised cost of Storage in the spotlight

Lazards have published Version 3 of their Levelised Cost of Storage benchmarking analysis.  This time the financial advisory firm have included capex and operating data from numerous new Lithium Ion batteries deployed since Version 1 in 2015.

The report can be accessed directly at . Lazards report various use-cases where Energy Storage projects are now cost effective, primarily behind-the-meter industrial applications and grid-support applications such as Dynamic or ‘Enhanced’ Frequency Response. Both of these require high-power and rapid response and are of interest to Gravitricity.

Gravitricity has worked with experts from Imperial College London to understand how our storage costs compare.  Our fast-response, multi-cycle technology is exceptionally well suited for any application requiring a high c-rate and several daily cycles.  As expected, our levelized cost of energy is lower than lithium ion and any other technology in the Lazard’s report for the applications we are targeting. 

Commentators have taken the opportunity to read between the lines of Lazard’s report.  Greentech Media’s observations on lithium-ion round trip efficiency are well worth a read.

Gravitricity is working with Imperial College Storage Labs to understand how our costs compare to other technologies. Results are very encouraging.

27 November 2017: 

Charlie Blair will be speaking at Energy Storage & Connected Systems in London, February 2018

Gravitricity will be presenting at the REA supported conference at London's Oplympia on 6th February 2018. He'll be speaking in the late morning session fittingly titled 'Scaling to GW; It's not just Lithium' along with speakers from flow-battery, CAES and electrolyser technology developers. 

Conference programme is available here

25 May 2017: 

Charlie Blair has been selected as one of Britain's leading cleantech entrepreneurs and will be traveling to Silicon Valley as part of the Clean&Cool mission.

Clean & Cool is a UK Government supported mission for British CleanTech innovators to San Fransisco.  Gravitricity has been selected as one of the most exciting clean technology innovations coming out of the UK and will be showcased to investors and potential partners in America's capital of innovation from 10th - 17th June 2017.

See and and for updates