Current capacity is 1.651 GW and includes major developments such as the 120 MW Breadalbane scheme and the 245 MW Tummel system. Several of Scotland's hydro-electric plants were built to power the aluminium smelting industry. These were built in several "schemes" of linked stations, each covering a catchment area, whereby the same water may generate power several times as it descends. Numerous remote straths were flooded by these schemes, many of the largest of which involved tunnelling through mountains as well as damming rivers. Emma Wood, the author of a study of these pioneers, described the men who risked their lives in these ventures as “tunnel tigers”.