The Heritage of Hydro

The Heritage of Hydro. . , The hydroelectric plant built at the end of the dam in the 1890s had large arched windows for light and ventilation. The dam today is downstream from the railroad truss bridge that towered above the plant; only piers from the bridge survive today., Two companies controlled the rights to the Mississippi's waterpower with a dam at Saint Anthony Falls. They sold or leased these rights to mill owners and other industrialists, who used waterwheels and turbines to run factory equipment. With few sources of power, waterpower was very valuable., William De la Barre, a brilliant engineer, wanted to get even more power from the river. Between 1895 and 1897, he oversaw construction of the Lower Dam, which raised the water level in an area of rapids below the falls. The massive dam, called "De la Barre's Folly," cost nearly $1 million, an incredible sum when a horse cost about $32. A plant on the river's east bank used the drop ("head") from the dam to generate electricity for the city's streetcar system., The Lower Dam Today , The Lower Dam was rebuilt in the 1950s with a 56'-wide lock and three gates controlling the spillway. Another lock was built at Saint Anthony Falls. These locks allowed boats to travel above the falls, a long-time goal of some Minneapolis leaders. The bay adjacent to the Lower Lock held another gate intended to be converted into a second lock when river traffic increased. This increase never happened. Half a century later, plans were launched to install a hydroelectric matrix turbine-generator system in the bay., Looking upstream at the lock and dam during construction (1954) and today (2011). The bay next to the lock was to be developed as a lock at a later date. Instead, it now holds a matrix turbine unit to produce electricity., The U.S. Army Corps of Engineers finished building the Lower Lock and Dam in 1956 and opened the Upper Lock in 1963. Part of the Great Northern Railway's Stone Arch Bridge was modified so boats could reach the Upper Lock., The 1897 hydroelectric plant at the dam's east end operated until its foundation failed in 1987, forcing its removal. Today, there is an earthen embankment where the plant stood., Hydro Revival , Hydroelectricity was an important early source of electricity in Minnesota, with 35 plants operating by 1910. The Mississippi plants, though, were dependent on the river's erratic flow, which ranged from flooding to frozen., As steam and other sources of electricity became more economical and reliable, dependence on hydropower dropped. One writer concluded in 1962: "Although Minnesota could develop nearly 50 percent more hydro power than at present, it is unlikely that new developments will be constructed because of various economic factors.", A contemporary observed, though, that "changes in cost and availability of fuels, in values of lands and waters, and in costs and methods of construction may alter this situation in the future." The future has arrived, thanks to increasing fuel costs and innovations in technology., The generators inside the Lower Dam hydroelectric plant (above) had horizontal shafts connected to large turbines. Only the turbines were submerged. The Hydromatrix® unit (below) has the turbine and generator combined in a single mechanism., Sixteen Hydromatrix® units were installed at the Lower Dam in April 2011., Cross-section of Lock Chamber , A - Gate swings open to let in water. , B - Turbine-generator units. , C - Matrix frame. , D - Hoist that can raise units for maintenance., Operated by Brookfield