New Mexico regulations on mining do not authorize the state Mining and Minerals Division (MMD) to regulate electrical usage at mines. However, in considering permitting a mine, the MMD is charged to consider all the impacts of the project, and that includes the impacts of using a very large amount of electricity.
Generating electricity takes very costly constructions, and it consumes large amounts of coal, gas, and nuclear power as well as water (boiled to make steam to power the generators). While new technology can reduce the amount of water used, thermoelectric generation constitutes about 40% of all water withdrawals in the US, the majority from fresh water sources. See https://watercalculator.org/footprint/the-water-footprint-of-energy/ #:~:text=Because%20of%20the%20large%20amount,all%20withdrawals%20for%20thermoelectric%2 0power.
The problem in writing an article about the mine’s electrical needs is that we generally do not understand electricity. Experts can calculate energy, power, and loads, but even they have a very foggy notion of how it works, partly because electrical calculations were invented in the 19th century, long before the discovery of electrons and atoms, which is where the action takes place. The terminology of electricity is misleading because it was based on an analogy with water flow. For example, we talk about electrical “current.” Electricians calculate the “current” of positive charges in an electrical circuit, but in reality, it’s the negative charges which move through the circuit, so the “current” actually backwards backwards.
Still, the electrical needs of the mine are very great, and its use will impact all other electrical users in the grid that allows it to draw electricity from that grid. That needs to be thought about and considered by the MMD and by the public in their deliberations on permitting.
I will not bore you with the calculations, but by using the filtered tailings method of recycling water, NMCC increases its consumption of electrical energy from about 236 million kWh per year to about 306 million kWh per year, a 30% annual increase. One can expect, therefore, that this increase in energy consumption will increase proportionally the impacts of fuel and water consumption to generate that electrical energy.
Here is the tricky part about electricity. Annual usage is a kind of generalizing, averaging way to look at electricity. Its use (and generation) is not constant. The generating machines put out energy according to the use. Those machines and their connected transmission equipment have a capacity, and when that capacity is over-demanded by use you get a blackout. The system breaks down.
To deal with this overload situation, electrical engineers use the concept of “peak demand.” The BLM’s 2019 Final Environmental Impact Statement calculated Copper Flat Mine’s peak demand to be about 35 Megawatts (MW), but that is without the added electrical demands of the large filtering plant to produce filtered tailings. Adding that load would make a peak demand as high as 48 MW.
To put that into understandable perspective, consider that El Paso had a blackout during a heat wave in July, 2023, when El Paso Electric’s system hit a record demand of 2,384 MW. Copper Flat’s demand would be the equivalent of 2% of that demand from El Paso Electric’s 460,000 customers, residential, commercial, and industrial during a heat wave. And, Copper Flat Mine’s demand is 24/7.
Recently, NMCC has turned away from El Paso Electric as its electrical source and turned to Tri-State, the energy supplier for Sierra Electric Coop. Tri-State’s peak demand capacity is similar to El Paso Electrics, about 2,500 MW. Either way, a 2% increase in peak demand on either grid is significant.
Sierra Electric, who is part owner of Tri-State, has said that it will make certain that if Copper Flat Mine is allowed onto its grid, it would ensure that generative capacity will be sufficient not to harm its present clients. However, its decision will have to balance the risk of increasing surges of peak demand against the $24 million (at $0.08 per kWh) annual income from selling its excess capacity.
The fact that we are facing higher temperatures makes the issue of electrical usage at Copper Flat Mine important for everyone in Sierra County. Someone at the Hearing in Hillsboro this Thursday should be asking MMD what the impacts of this energy use will be on us all.