Separating Nuclear Reactors from the Power Block with Heat Storage to Improve Economics with Dispatchable Heat and Electricity

Abstract

Markets are changing as the result of (1) the addition of variable wind and solar that causes highly volatile electricity prices and (2) the goal of a low-carbon economy. These changes require economic low-carbon dispatchable electricity, which is now provided by natural gas turbines, and dispatchable heat for industry and commerce. Moreover, nuclear plant requirements have changed in the last 50 years with high capital costs in western countries. An alternative plant design is described with the nuclear island separated from a nonnuclear power block by large-scale heat storage. All heat from the reactor is sent to heat storage. The nuclear reactor operates at base load and is sized to meet average energy demand over a period of days. Heat storage provides variable heat to industry and/or the power block. The nonnuclear power block is sized to provide peak electricity capacity (kilowatts) several times the nuclear reactor base-load power output to maximize revenue by sale of electricity at times of high prices. The power block capital cost (heat exchanger, turbine, and generator) per unit of generating capacity (kilowatt) is less than a conventional gas turbine that includes heat generation (compressor and burner) and the power block (turbine and generator). Nuclear reactor capital cost is reduced by fewer requirements on the nuclear system (not connected to the grid) and nuclear-quality construction for only the reactor. Operating costs (security, maintenance, etc.) are minimized by separation of the nuclear reactor plant from balance of plant. Low-cost heat storage provides a competitive economic advantage to heat-generating technologies (nuclear, concentrated solar power) over electricity-generating technologies (wind, solar, photovoltaic) with more-expensive battery or other electricity storage systems in providing dispatchable electricity to the grid.

A perspective on high‐temperature heat storage using liquid metal as heat transfer fluid

“…16 In 2012, a single-tank concept with a floating barrier between the hot and the cold Na was proposed by Hering et al 17 For the use as thermal energy storage systems in nuclear power plants, hexagononal steel structures were suggested to be used with Na as the heat transfer fluid by Forsberg. 18,19 A previous evaluation of the author regarding different storage solutions showed that, when using Na, a packed-bed thermal energy storage is a promising solution based on five evaluation parameters (storage medium cost, storage density, cycling behavior, technology readiness level, and suitability for Na). 20 In a subsequent comparative study, it was concluded that, besides small filler diameters and large tank height to tank diameter ratios, low porosities are advantageous, as they minimize the axial thermal diffusion processes in the packed bed.…”

Nuclear Energy Drop-In Replacements for Gas Turbines, Natural Gas and Fossil Liquid Fuels

“…2). A recent workshop examined this option [1]. For higher-temperature reactors the heat storage material is a sodium potassium nitrate salt-the same solar salt used in Concentrated Solar Power (CSP) plants for heat storage.…”

“…The heat-storage capital costs are $20-30/kWh of heat-an order of magnitude less than battery or pumped hydro storage. Advanced heat storage systems are being developed that may lower costs to a few dollars per kWh of heat [1,3].…”

What is the Demand for Low-Carbon Liquid Hydrocarbon Fuels and Feedstocks?

“…The heat source for storage can be nuclear, concentrated solar power or low-price electricity converted to heat. Systems [19] have been developed (Fig. 2) that integrate heat storage, liquid hydrocarbons, and hydrogen with electricity generation.…”