Holtec unveils hybrid nuclear-solar power plant design

02 February 2024

Holtec International has announced a new power plant design which combines the benefits of nuclear with those of solar. The Combined Nuclear/Solar Plant (CNSP) features the company's SMR-300 small modular reactor, its HI-THERM HSP solar thermal system, together with its Green Boiler energy storage system.

An SMR-300 plant (Image: Holtec)

The plant can "provide base load or on-demand power while eliminating the intermittency drawback of solar plants", according to Holtec.

Holtec has been developing its small modular reactor (SMR) unit since 2011. The SMR-300 is a pressurised water reactor producing about 300 MW of electrical power or 1050 MW of thermal power for process applications, and the company says it has undergone several design evolutions, the most recent of which is the incorporation of forced flow capability overlayed on gravity-driven flow in the plant's primary system.

With the combined plant, the energy contribution of the Sun to the power plant will occur through the HI-THERM HSP hybrid solar plant.

The nuclear reactor's steam supply system and the heat from the solar thermal plant are conjugated in the Green Boiler which is a heavily insulated thermal energy storage device with integral steam generators. Holtec says the Green Boiler is a three-in-one device that: can store vast amounts of heat; receives high temperature heat conveyed to it from the solar collector; and  can make motive steam at the required pressure and superheat to power the turbine.

"The CNSP will have a much higher thermodynamic efficiency than the nuclear plant alone and would make solar power an integral part of base load supply," the company said. "It should be noted that the CNSP does not use any batteries, which have been the Achilles heel of the renewable energy industry. In fact, CNSP contains no fragile parts or materials that may limit its service life, which is expected to exceed 60 years."

Holtec believes the most immediate application of the CNSP technology is to repower coal-fired power plants, which typically have sufficient land area to house the CNSP, which would use the coal plant's existing power block, thereby minimising the cost of transition. The steam production portion of the coal plant will be decommissioned, it said, freeing up most of the plant's land area where the solar plant would reside.

While it says the CNSP is adaptable for deployment in any country, the company plans to offer the technology principally in those regions of the world where "solar radiation level is adequate to be harvestable".

"We believe that an adroit combination of nuclear and solar embodied in the CNSP provides a compelling solution for nations seeking to move past fossil fuels," said Holtec President and CEO Kris Singh.

In December 2019, California-based Oklo Inc launched its Aurora energy plant which is powered by a small reactor with integrated solar panels. The company describes Aurora as an "advanced fission clean energy plant design developed to power communities with affordable, reliable, clean power." The Aurora "powerhouse" includes a "fission battery" which uses metallic fuel. Its sloped roof serves as the support for solar photovoltaic panels. It can produce about 1.5 MW of electrical power and can also produce usable heat.

Researched and written by World Nuclear News