New England's electric generating capacity has grown by nearly a third since the wholesale markets opened in 1999, but the transmission system hasn't been able to keep up with the progress. As a result, the aging transmission system is in need of significant expansion, says Gordon Van Welie, president and chief executive of ISO New England. ISO, which operates the New England power grid, recently approved a multi-billion dollar program that includes 250 proposed transmission upgrades. Some reliability projects are already underway in southwest Connecticut, northwest Vermont, and Boston. A combination of increased power demand and power plant closings heightened the need for transmission upgrades in the Boston area. Customers in Boston, as well as in other areas of New England, often pay higher electricity bills and suffer more service interruptions because they aren't always able to access power from the regional grid.