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  BiMBy Power Company, LLC

Mine Overburden/Waste Rock/Tailings as a Renewable Energy Storage Play

The future US and worldwide renewable energy storage market will demand assets costing billions or even trillions of dollars. Innovative assets for electricity-grid-scale energy storage must be developed to supply this demand.


The mission of BiMBy Power Company is to design large porous medium pressure vessels using mine overburden/waste rock/tailings to serve as compressed gas reservoirs for renewable energy storage. The gas stored in the reservoirs may be compressed air which has a low energy density by volume, or a clean burning gas such as H2 which has a high energy density by volume. A single device containing such a porous medium pressure vessel is referred to as a BiMBy (Big Mass Battery).


In the US, 3-4 giga-tonnes of mine overburden/waste rock/tailings associated with coal mining and 1-2 giga-tonnes associated with metals mining are moved annually. The worldwide totals are perhaps 5-10 times the US amounts. Globally, mines - needed to satisfy the demand for earthen raw materials - are big and getting bigger.


Wide-scale re-purposing of mine overburden/waste rock/tailings for several decades in the US would provide enough energy storage capacity to replace a significant fraction of the fossil fuels currently burned to generate electricity: 10-20% replaced for BiMBy devices storing compressed air, and 100% replaced with capacity to spare for BiMBy devices storing hydrogen A BiMBy pressure vessel is built using on-site, recycled mine overburden/waste rock/tailings and is designed to last 50-100+ years.


The BiMBy Device

A familiar home compressed air storage system is compared to a BiMBy pressure vessel in Fig. 1: porous waste rock is encapsulated by a liner forming a pressure vessel and overlain by additional waste rock forming a pressurizing layer; a compressor pumps air into the pressure vessel via air in piping when renewable energy source (wind or solar power) is available; compressed air is released via air out piping to run a turbine to generate electricity upon demand. This beneficial use of mine waste rock adds economic value to the waste rock, is potentially transformative for the mining and renewable energy economies, and could positively affect regulatory acceptance by offering alternative reclamation options.

                         Home                                                                 BiMBy

Fig. 1. A home compressed air energy storage system (left) compared to a BiMBy device (right).


Company History

BiMBy Power Company, LLC (BPC) was organized in Nevada in December 2015. During the 2015-2016 academic year, BPC enlisted student engineers from Harvey Mudd College to study the lifting and lowering of mine waste rock using a variable volume pressure vessel. BPC settled upon a fixed volume, porous medium pressure vessel (US Patent Pending). Work to date has so far affirmed the feasibility of constructing BiMBy pressure vessels using materials on hand at most mine sites, materials such as relatively impermeable bedrock and silt/clay earthen materials and relatively permeable sand/pebble/boulder earthen materials. To prove, demonstrate, and advance its technology, BPC is presently seeking to build a Proof-of-Concept BiMBy device, preferably at an active mine site where costs are lowest and learning opportunities greatest.


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Yerington Pit, Anaconda Mine (inactive open-pit metal mine), Yerington, NV from Weed Heights looking east (R. Donelick, 9 August 2016).