Our patented technology is based on a simple principle: raising and lowering a heavy weight to store and release energy.
The Gravitricity system uses weight configurations totalling up to 12,000 tonnes in a deep shaft, suspended by a number of cables, each of which is engaged with an electric winch capable of lifting its share of the weight. Electricity is stored in the form of potential energy by raising the weights. Power is then generated by lowering the weights to turn a generator. The technology has been proven to reach full power in less than one second and has a predicted full scale efficiency of between 80% and 90%.
Gravitricity is able to store excess energy ready to be released whenever required – either in very rapid, short bursts or over a long period of time. This can deliver vital services needed to balance the grid at a local or national level as well as providing behind the meter services in Industrial use cases. In addition, the technology’s long lifespan offers strong synergy with new grid infrastructure projects by facilitating a vast reduction in materials required to achieve desired peak power transmission capability.
Analysis carried out by Imperial College London calculates our system – which can operate for up to 50 years – can store energy at half the cost of lithium-ion batteries.
In our first full-scale system our technology will utilise decommissioned mine shafts – in Europe and Africa – whilst in the longer term we will also sink purpose-built shafts, allowing the technology to be deployed wherever it is required
Each unit can be configured to produce between 1 and 20MW peak power, with output duration from 15 minutes to eight hours. For example a 10 MW, 25 MWh system could deliver full power (10MW) for 2.5hrs, or 5MW over five hours.
The Gravitricity system will go from zero to full power in less than a second – which can be extremely valuable in the frequency response and back-up power markets.
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
- Shaft depth – for existing shafts, those with depths of over 300m can be suitable for Gravitricity projects.
- Size of weights – up to 24 weights of 500 tonnes. So a total 12,000 tonnes per system.
- 20MWp system could power 63,000 homes for every hour that it discharges.
- Gravitricity has submitted seven patent applications; four have been accepted for grant and three are in examination.