The Thermoelectric Generator Using Hot Sand To Store and Generate Electricity

Overview

In modern times, our planet has plunged into a crisis of energy, one where "clean" energy systems rely on Lithium-Ion Batteries, or LIBs to store electricity. Due to the Lithium, Cobalt, and other rare metals in these batteries, LIBs are extremely expensive, limited in supply, and dangerous. These issues, (along with ties to child labor and pollution), make Lithium-Ion batteries unsuited to store large quantities of energy. This leads to curtailment, brownouts, and blackouts in "clean" energy grids that rely on LIBs. My solution to the energy crisis is The Thermoelectric Generator Using Hot Sand To Store and Generate Electricity. This project uses sand's low heat transfer ratio to store energy in the form of heat for long periods of time. After that, thermocouples use the Seebeck Effect to convert the thermal difference between hot sand and a colder, outside temperature into electricity. In the past, I have proven that this concept can not only store and generate electricity, but do it in a way that both lasts longer and is cheaper than using Lithium-Ion Batteries. New developments of this project include the improvement of the thermocouples, sand, heating system, and insulation used in this project. By using a nitinol-and-copper-based thermocouple, I have been able to achieve more than a 100% increase in my system's power output, reaching 6.52 volts and 5.901 watts from a 255 degree Fahrenheit temperature difference. Additionally, at about $.50 per piece and only taking up a one mm^2 area, I can implement hundreds more of these thermocouples into my design while still being a cost effective and smaller alternative to the thermocouples that I have used in the past. This also greatly increases the timeframe at which energy can be produced, as less heat is dissipating through the smaller (in surface area) but longer thermocouples. The time at which over 1 watt of electricity can be produced after sunset is just under 5 hours. The insulation system for this project consists of an all-foam (with an R6 insulation rating) box. By using a gravity-fed heating system, I funneled layers of sand that were half an inch thick to where a concave mirror could quickly heat up each layer hours quicker than what had been previously achieved. All of these components result in a cheaper design that uses less time and thermal energy to achieve a greater power output over time.

Competition history

• CSEF 2026 Environmental Engineering (Track 2) (Senior Division) · Entry S-12-04

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