Generate energy from old mineshafts: Gravitricity gets funding boost

Mine shaft energy generation innovator, Gravitricity, has been awarded £650,000 funding from Innovate UK’s Infrastructure Systems Innovation competition. “This innovation funding will be used to design and build our 250 kW 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.”

The company adds: “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.”

Essentially, the Gravitricity system is a huge ‘clock weight’. A cylindrical weight of up to 3,000 t 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 150 m for new shafts down to 1,500 m 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.”