David Milner
Department of Civil, Environmental, and Architectural Engineering, Boulder, CO, 80309, USA
Kathryn Hinkelman
Department of Civil and Environmental Engineering, University of Vermont, Burlington, VT, 05405, USA
Jeffery Gifford
National Laboratory of the Rockies, Golden, CO, 80401, USA
Wangda Zuo
Department of Architectural Engineering, Pennsylvania State University, University Park, PA, 16802, USA
Zhiwen Ma
National Laboratory of the Rockies, Golden, CO, 80401, USA
Keywords: Case study, District heating, Electrification, Modelica, Silica-sand, Thermal storage
Abstract
Buildings account for 40% of global energy consumption and contribute to 30% of global carbon emissions. As energy from renewable sources increases in availability and building designers push for increased electrification, thermal energy storage (TES) systems will play a crucial role in extending the usable time horizon of renewable energy. While water, molten salt, and phase change materials are typically used for building TES heating applications, silica-sand has emerged as an alternative medium for concentrated solar power applications due to its low cost, wide availability, and comparable system efficiency. This paper proposes a new silica-sand particle-based TES system for building heating applications. In this work, a novel steam plant for district heating applications is first designed to utilize silica-sand TES, which can be used for different district energy systems. To demonstrate the silica-sand TES plant performance, the design is modelled in Modelica based on a case study on the University of Colorado Boulder’s campus. The simulation results show that the sand TES plant is more costly to operate than a gas-boiler based plant due to the low cost of natural gas, while the site EUI and carbon intensity can be improved. This novel system shows initial promise as a low-carbon alternative to conventional natural gas steam boilers but will require further modelling and follow-up research to improve its energy efficiency. An eventual rise in natural gas prices, and reduction of electricity prices, could improve the economic viability of this system.
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