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 – capital costs comparable to lithium ion batteries.
Each unit can be configured to produce between 1 and 10MW peak power, over a period of one to ten hours.
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 aim to develop our technology utilising existing mine shafts. As our technology costs decrease, the costs of drilling will reduce significantly, opening the opportunity for purpose-built shafts.
Over the next 12 months we will be undertaking sub-system design and testing at an existing mine site in the UK, and aim to trial our first full-scale prototype in 2019.
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.
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 the value of the global energy storage market at $250 billion annually by 2040.
Our technology will provide balancing services on transmission grids as well as appealing to network-constrained users and operators, distribution networks and major power users seeking a reliable, fast response, and long-term means of storing power.
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.
People
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, 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.
Charlie Blair, Managing Director, joined Gravitricity in 2014 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 ranging from electric vehicles through to biomass heating.
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.
Contact
4th Floor, Alrick Building
King's Buildings
Edinburgh
EH9 3BF
Company Reg. No: 7827384 England
News
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 https://cleanandcool.org and and https://twitter.com/cleanandcool?lang=en for updates