Flooding a mine is a closure strategy that mining companies often use as part of a rehabilitation plan usually decided at the beginning of a mine’s operating life.
Once the tunnels are flooded, the mine and its workings become submerged, not just in a physical sense but in the minds of the public, who then regard that mine as finished, and the lake that fills the former pit probably assigned a recreational use.
An abandoned mine in New York state seemed to be destined to a similar, ignominious fate, but for a group of engineers who saw the historically-significant iron ore mine serving a more useful purpose.
The engineers are “pitching a plan to circulate some of the millions of gallons of groundwater that have flooded the mine shafts over the years to power an array of 100 hydroelectric turbines a half-mile underground,” reads a story about the centuries-old mine, located in the Adirondacks mountains of upstate New York, carried by Associated Press.
The mine which closed in 1971 apparently notched its mark on history for contributing iron for one of the first naval battles of the Revolutionary War on nearby Lake Champlain. According to Wikipedia, the Battle of Valcour Island, also known as the Battle of Valcour Bay, took place on October 11, 1776, on Lake Champlain. Some more colour is provided by the Lake Champlain Maritime Museum, which sets the stage for the battle on its website:
The American fleet, commanded by Arnold, consisted of eight gondolas, three row galleys, two schooners, one sloop, one cutter and bateaux. The vessels in the British fleet were not only larger with better sailing characteristics, but they were also crewed by professional sailors under the command of skilled naval officers.
Electricity produced from the turbines would feed into current solar and wind producers, who lack a source of uninterrupted power, according to AP:
Engineers would drain roughly half of the water from the shafts and pump the remainder into an upper chamber. The water would then be released into a lower chamber, powering turbines and creating electricity. The turbines would be reversed to pump the water back up to repeat the process.
The project is basically an underground version of big outdoor projects that rely on the same principle. The New York Power Authority’s Blenheim-Gilboa Pumped Storage Project in the Catskills and the proposed Eagle Mountain project in southern California, for example, use outdoor, hilltop lakes as the upper reservoirs.
While pumped hydro power has been used for decades in the United States as the primary source of energy storage used to meet periods of peak electricity demand, mines are not typically used as reservoirs. If approved by federal authorities, the Mineville Pumped Storage Project would be one the first of its kind in America. AP points out that a similar project has been proposed for an abandoned mine and quarry in Elmhurst, Illinois.
North of the border, Northland Power is considering a pumped power project involving a decommissioned open-pit iron ore mine on the former Bethlehem Steel site between Ottawa and Toronto. The Marmora Pumped Storage facility would produce 400 megawatts of electricity for five hours, and create a waterfall nearly five times the height of Niagara Falls, Clean Technica reported in 2013.