Results from Prototype Testing and Feasibility Studies of a Cryogenic Energy Storage System with the Capacity to Provide Co-generation of Electrical Power and Chilling, Compressed air and Chilling and Motive Force with Chilling.

2019

Daniel Cluff, CanMIND Associates; Douglas Morrison, Centre for Excellence in Mining Innovation (CEMI)

Chilling an underground mining project becomes more costly as the depth increases. The increase in the temperature of the air as it descends due to the adiabatic lapse rate (auto-compression) and the heat flux from the host rock are inevitable and although a move to battery powered vehicles may allow for less air flow, legislation changes pending, the susceptibility to any further additional heat is enhanced. Battery powered vehicles liberate heat and so does the charging process so for a reduced air flow the amount of heat needed to raise the temperature to unacceptable levels may only require the operation of a few 500 kW units. This paper discusses results from a prototype and a feasibility study that provides a comparison between a bulk air chiller and a cryogenic chilling system. The cryogenic system stores energy in the cryogenic liquid (cogeneration of electricity and chilling) effectively the heat from the mine is converted to electricity with extra chilling over and above the amount of electricity produced (5 MWe electrical power absorbs 8 MWr of chilling). Furthermore compressed air can be produced whilst simultaneously chilling (5000 cfm produces 1.2 MW chilling) and motive force, engines for equipment (a vehicle would produce cool clean air for exhaust with about 1/3 motive power to 2/3 chilling). Results obtained from a prototype system, approximately the size of a small spot chilling system, demonstrates conclusively the rapid response of the air flow to chilling on demand while simultaneously producing electricity. Since the chilling is delivered by a cryogenic fluid a deeper mine only requires a longer pipe and the system can provide chilling where it is needed; thus, in the same way that ventilation on demand is cost effective so also chilling on demand is economic. This project is funded by the UDMN, CEMI, Glencore and CanMIND Associates.

Keywords: Chilling, refrigeration, cryogenics, energy storage, electricity arbitrage, mine thermodynamics