Problem Statement

TEG modules mounted on the flue stack surface convert the heat from the exhaust gases directly into DC electricity using the Seebeck effect. The generated power is regulated and used to run auxiliary loads or charge a battery.

Solution

TEG modules mounted on the flue stack surface convert the heat from the exhaust gases directly into DC electricity using the Seebeck effect. The generated power is regulated and used to run auxiliary loads or charge a battery.

In Detail

Proposed Solution The proposed solution is to install thermoelectric generator (TEG) modules on the outer walls of flue stacks, where exhaust gases continuously carry away large amounts of heat. Each TEG module has a hot side in contact with the stack wall and a cold side cooled by a heat sink or water jacket. The temperature difference across the module generates DC electricity through the Seebeck effect. Because flue stacks run for as long as the furnace or kiln operates, the heat supply is steady, and the modules convert it into electricity without interruption. Many modules are connected in series and parallel to reach the required voltage and current. A DC-DC converter or MPPT controller regulates the output, and an inverter converts it to AC where needed. This turns the flue stack from a source of wasted heat into an independent electricity generator for the industry. Application in Steel and Cement Industries Steel plants release high-temperature flue gases from furnaces, reheating furnaces, and foundry units, while cement plants release them from rotary kilns, preheaters, and clinker coolers. The project focuses mainly on small-scale industries, especially the ancillary units that manufacture components and products for large steel and cement companies. Examples include small foundries, forging units, re-rolling mills, and brick or lime kilns. These units usually cannot afford large waste heat recovery systems such as steam turbines or organic Rankine cycle plants, so a compact, modular TEG system suits them well. Modules can be added or removed as the stack size and exhaust temperature require, so the system scales from a few watts to several kilowatts. Energy Storage and Utilization Each industry can use its own space and equipment to store the generated power, such as a battery bank with a charge controller. The stored energy can run auxiliary loads such as lighting, control panels, sensors, fans, and pumps, reducing dependence on grid power. If the industry has no space or facility for storage, the generated electricity is transferred directly to the government grid through net metering, with no battery needed. The units supplied to the grid are recorded by the electricity board and deducted from the industry's monthly or yearly electricity bill, so the power is never wasted. The plant therefore gains a reliable power source, lower energy costs, and some protection against power cuts. Advantages TEGs have no moving parts, so wear, vibration, and noise are minimal. Maintenance is low, usually limited to cleaning the surfaces and checking the cooling system and electrical connections. Little labour is needed, because the system runs automatically once installed and needs no dedicated operator. The system is simple and compact. It needs no boiler, turbine, or working fluid, and it does not interfere with the existing process. The generation is clean and silent and produces no additional emissions. Recovering waste heat also reduces the thermal load released into the environment. The setup is modular, so small industries can start with a small investment and expand later. Expected Outcomes Lower electricity bills and a faster return on investment through reduced grid consumption and export credits. Better overall energy efficiency, since heat that would otherwise be lost is put to use. A smaller carbon footprint, supporting sustainability goals and energy-saving norms. A practical, low-cost waste heat recovery option for small-scale steel and cement supply industries, which have so far had few affordable alternatives.