Holtec International has completed the design and computer simulation phases for its HI-HEAT district heating system, which has been underway since May 2020. The system design is complete and digitally verified. Certain miscellaneous laboratory tests to re-confirm the critical characteristics of the thermal capacitor material, Feorite, are underway to complete the quality documentation on the development programme.
HI-HEAT is intended to provide a carbon-free solution for district heating in countries facing a cut-off of Russian fuel supplies as well as countries aiming to shrink the footprint of fossil fuels in their national economies, Holtec said. It is the low-pressure steam supply version of Holtec’s Green Boiler which is characterised by harnessing an external heat source such as surplus electrical energy available during off-peak hours or a co-located nuclear reactor (for example Holtec’s SMR-160) or the molten salt from a proximate solar power plant. The external thermal source is used to heat the HI-HEAT thermal capacitor, called Feorite, to elevated temperatures reaching 700 degrees C. A single shop-manufactured HI-HEAT module stores over 300 million BTUs of thermal energy in its Feorite capacitor which is enough to produce 300,000 pounds of steam.
There is no limit on the number of modules that can be arrayed in parallel to achieve the rate of steam generation needed for a district.
Holtec noted that the raw materials needed to manufacture the district heating system are typically available in every region of the world, which will facilitate their manufacture to occur locally under Holtec’s technical guidance. Even the thermal capacitor material, Feorite, can be sourced locally in most parts of the world.
HI-HEAT is entirely based on the Green Boiler design platform and is configured to produce steam at a relatively low pressure. The Green Boiler design platform enables the system to be designed to produce steam at any pressure level and any level of superheat. The ability to produce high pressure/high superheat steam in the Green Boiler affords the opportunity to repurpose coal fired plants which would otherwise be completely dismantled. The high-pressure variant of the Green Boiler can be used to power the turbogenerators of existing coal fired boilers, which can be retired along with their coal and ash handling facilities. Thus, by installing the Green Boiler, much of the existing infrastructure of the coal plant can be saved and re-used.
Holtec is now focused on integrating its Green Boiler technology with an innovative solar energy collection technology to provide a clean source of high pressure/high temperature steam to support the production of hydrogen fuel, generation of electricity, as well as supply of process steam to proximate industries. We believe that the classical heliostat/receiver-based technology can be optimised to make it commercially competitive and practically viable.
Image: Holtec's HI-HEAT district heating system (courtesy of Holtec International)
