Introduction

Large amounts of thermal energy are dispersed in industrial processes (metal melting furnaces, cement synthesis, furnaces for glass production, refineries, etc), which is often first converted into mechanical and then electrical energy. This process thou successful for high energy dissipation processes, is not at effective for lower energy ones, where conventionally the excess heat in disposed into the environment. Energy harvesting from extremely low enthalpy sources, however, can play an important role in increasing the sustainability of future energy applications: low temperature differences are common and abundant, available both in the natural environment and as the result of a many industrial processes, waiting for be exploited.

Technical features

The use of thermomagnetic machines, which undergo rapid changes in the magnetisation state can be used to convert low yields of thermal energy into electricity. Proposed here is an energy generator which, by producing a thermal gradient in a ferrofluid contained in a volume and applying a magnetic field, is able to produce electromagnetic energy that can be harvested as electric power. The generator consists of a hollow toric vessel delimited by a wall containing a ferrofluid, comprising of magnetic nanoparticles (minimum saturation value of 10 mT and preferably of 100 mT) dispersed or suspended in a fluid carrier. This invention offers the opportunity to be captured waste heat recovered from, for example, energy-intensive industrial processes, below 250 °C, such as steam for cooling industrial processes, hot gases from internal combustion engines, low-enthalpy geothermal sources, photovoltaics for cooling modules, wind power used for cooling operations of rotating components, as well as human body radiant heat, and produce electricity.

Possible Applications

• Low electrical power generation;
• Industrial processes to capture waste heat;
• IoT in remote locations.

Advantages

• Direct conversion of waste heat into electricity;
• Manufacturing and installation costs are such as to allow large-scale production;
• Small complexity and small impact on raw materials if compared to existing solutions
• Sustainable energy generations.