Technical Feasibility and Economics of Retrofitting an Existing Nuclear Power Plant to Cogeneration Operation for Hot Water District Heating

摘要

This paper presents the results of a study of the hypothetical conversion of two 560-MW(t) PWR plant turbines to cogeneration operation to supply a future hot water district heating system load in the Twin Cities of Minneapolis-St. Paul. The conceptual design of the nuclear turbine retrofitted for cogeneration and of a hot water transmission system has been performed, and the capital investment and annual owning and operating costs have been estimated for thermal energy capacities of 600 and 1200 MW(t). Unit cost of thermal energy for cogenerated hot water at the nuclear plant gate has been estimated to be competitive with the cost from a coal-fired cogeneration plant. The unit cost of delivered thermal energy was based on a 36-mile-long (57.9-km) transmission route between the Twin Cities and the Prairie Island Nuclear Plant. Major variables considered in this study include: (1) inclusion of back-pressure turbines in the retrofitted nuclear steam system to maximize cycle efficiency; (2) transmission system delivery capacities of 600 MW(t) and 1200 MW(t) corresponding with a retrofit of one or two nuclear turbines; (3) reduced transmission distances from the 36-mile system design basis; (4) the effect of fixed charge rates on the capital investment costs ranging from 15 to 21% per year; and (5) effect of firm vs oil-interruptible service modes on the annual unit cost of delivered thermal energy. (ERA citation 09:048091)