Search

Geothermal energy storage provides opportunities to store renewable energy underground during summer for utilization in winter. Vertically oriented systems have been the standard when employing boreholes as the means to charge and discharge the underground. Horizontally oriented borehole storage systems provide an application range with specific advantages over vertically oriented systems. They are not limited to the surface requirements needed for installation with vertical systems and have the potential to limit storage losses. Horizontal systems can be incorporated into the built environment and utilize underground storage sites below existing infrastructure. An experimental study examines configurations using a mix of renewable energy (photovoltaic panels) and grid energy to charge a storage system during summer for use during winter. A comparison of five different borehole configurations at three different loading temperatures was composed using an experimentally validated numerical model. The horizontal systems studied and analyzed in this work showed improved performance with scale and charging temperature. This paper supports further exploration into specific use cases for horizontal borehole thermal energy storage systems and suggests applications which would take advantage of better performance at scale.

Nuclear fusion is the gateway to a whole new paradigm of energy and is a strong candidate for the decarbonization of electricity generation on a global scale. With recent developments in high-temperature super-conducting magnets, the race is on to develop sub-systems which will support a commercially viable fusion reactor for use as a thermal power plant. The fusion of lighter elements creates an enormous amount of heat which must be transferred away from the reactor core. These intense conditions require novel approaches to efficiently transfer very high heat loads into useable thermal energy without compromising the structural integrity of the reactor core and the surrounding components. This report outlines the concept of a fundamental approach to solve the heat transfer problem as proposed by Commonwealth Fusion System’s design for a fusion reactor. A literature review was conducted for other applications that could serve as inspirations, as well as material properties and machining methods for the proposed power exhaust system. A dive into the theoretical thermodynamic and fluid dynamic characteristics of plate heat exchangers and finned surfaces was conducted from a fundamental perspective. A laminar flow regime was studied for the purpose of setting the floor for energy needed to pump coolant while simultaneously representing the least favorable heat transfer regime between a solid surface and a fluid. The results served as a basis for dimensioning and executing numerical simulations as a means for a first look into a solution of this heat transfer problem. The results were compared with the theoretical conclusions and judged based on constraints of the system. Recommendations were made for the continued development of a corresponding system.

This study investigates a measurement method of thermal diffusivity for samples with arbitrary geometries and unknown material properties. The aim is to curve fit the thermal diffusivity with the use of a numerical simulation and transient temperature measurement inside the object of interest. This approach is designed to assess bulk material properties of an object that has a composite material structure such as underground soil. The method creates the boundary conditions necessary to apply analytical theory found in the literature. It was found that measurements best correlated with theory and simulation at positions between the center and surface of an object.