Thermoelectrics is one of the emerging technologies for effective recovery of waste heat from power plants, factories, motor vehicles, computers or even human bodies and conversion of this into useful electricity. This technology can greatly contribute to the enhancement of energy efficiency, the reduction of global reliance on fossil fuels as well as greenhouse gas emissions, and promotes the sustainable development. The many advantages of the thermoelectric energy-conversion technology include solid-state operation, absence of toxic residuals, vast scalability, maintenance-free operation, lack of moving parts or chemical reactions, production of negligible direct emissions of greenhouse gases over lifetime, and a long life span of reliable operation. Current thermoelectric energy converters can be categorized into two main categories, low (for smartphones, MP3 players and iPods) and high power generation (waste heat recovery).
The application of the thermoelectric modules in the industrial higher-grade waste heat recovery sector is gaining increasing attention due to the tremendous economic and environmental benefits. Regarding maritime applications, TEGs can offer a suitable solution for clean energy from waste heat for shipboard operations. However, their implementation is still limited, due to the technology cost and the lack of a holistic approach to design such systems, integrating them into existing ship components.
Regarding thermoelectric materials, Half-Heusler materials (especially the n-type TiNiSn and the p-type TiCoSb based compounds) were recently identified as highly potential, cost effective and environmentally friendly thermoelectric compositions. The substitution of Ti/Hf/Zr elements to form (Ti,Hf,Zr)NiSn alloys is confirmed to be an effective way to enhance the thermoelectric properties of this system. An interesting summary of the state of the art n- and p- type HH compositions exhibiting the highest reported ZT values, is shown below.
Fig.: Literature survey summary of the current state of the art n-type (a) and p-type (b) HH TE alloys.
MarTEnergy Project aims to develop new energy-harvesting TE materials and converters, based on bulk n- and p- type HH TE materials with carefully controlled structure and properties. Attention is focused on the extensive need of relatively cheap, widely available, non-toxic, lightweight, and scalable for industry TE materials and converters. Such technology can contribute to the increase of the energy efficiency in the energy transportation sector (i.e. maritime shipping industry) via TE conversion. Analysis on the performance prediction of converters in specific waste energy harvesting applications will also give to the industry a clear direction for the use of this technology.
The methodology in materials synthesis/processing as well as characterization is: