? Co-op City plans to power itself into the future by producing its own electricity, which managers say will lower costs for tenants.

Co-op City is building a generator that will use steam to produce electricity, heat and air conditioning for the 35-building complex. Management company Riverbay says that will lead to $15 million saved annually on electricity alone. Riverbay also expects to sell some electricity to Con Edison for a profit of $5 million each year. Co-op City officials plan to pass on the savings to tenants in the form of lower rent and lower bills.

The housing complex expects to have its own power system running by summer 2007.