TEGMATIC – ThermoElectric Generator Magnesium-based mATerials for application in Internet Connected devices.

Thermoelectric materials are capable of converting waste heat into electricity. It is forecast that there will be ~20bn connected devices by 2020\. Postulating 50% are battery powered, with 1-year battery lifetime, this would create demand for an additional 5bn batteries/year. Thereby, the use of thermoelectric generators for powering IoT devices is becoming very attractive. In addition, the use of Li-batteries is not recommended in some industries such as Oil&Gas Industry (OGI) due to their risk of explosion and their inefficiency over 80C. Thereby, OGI is moving towards thermoelectric energy harvesting to replace batteries in a wide range of sensing applications.

The thermoelectric materials market is dominated by Bismuth Telluride (Bi3Te2) which exhibits the greatest figure of merit, zT up to 200C leading to it mainly being used for waste heat recovery within this range. Above this temperature, its zT dramatically reduces therefore becoming prohibitively inefficient. The current solutions to address the efficiency is the use of lead telluride (PbTe) at medium temperatures or silicon-germanium (SiGe) for \>500C. Other disadvantages are the toxicity and the high price of Tellurium due to its scarcity.

The market therefore requires the following

1)more effective energy harvesters for applications at medium temperature (200-350C) ideal for the Oil&Gas Industry temperatures, and

2)Generating more power in smaller and more cost-effective devices for sensor applications.

TEGMATIC will address these needs by developing magnesium-antimonide (Mg3Sb2)-based materials and their commercialisation. This cutting-edge material offers:

1)More efficiency, since MgSb-based materials outperforms the current state-of-the-art - Mg3Sb2 achieves a zT = 1.4, in comparison to 0.2 for Bi3Te2 at 300-350C. Also, MgSb-materials has significantly superior mechanical toughness (_KIC_ = 3.0 MPa\*m1/2) than the State-of-the-art.

2)Less space and cost-effective: MgSb-based materials possess low thermal conductivity, so the leg length will be reduced by 40% decreasing the cost per module by 12-20%. Moreover, the raw material cost is cheaper for MgSb estimated at 9.5-11 $/Kg than BiTe 44.1 $/Kg.

3)Environmentally friendly: Magnesium and Antimony are non-toxic and abundant in the Earth.

TEGMATIC is a collaboration between ETL and Avalon Sciences. ETL, a worldwide recognised innovative SME leader in the thermoelectric market, currently supplying ~2% of the global thermoelectric modules due in part to their in-house automated manufacturing. Avalon Sciences (ASL) is a manufacturer of borehole seismic equipment.