MIT Discovers New Material: To Harness Energy, Generate Electricity With Water, Without Waste
If there’s one thing most people can agree on, it’s that the world needs to embrace renewable energy to reduce environmental pollution. As of 2018, renewable energy only accounted for 11% of all the power consumed in the U.S.Yet 77% of Americans wanted more investment in renewable energy (1).
A couple of guys over at MIT discovered a way to harness the energy and generate electricity with water without waste.
How It Works
Scientists have been researching thermoelectric devices — devices that generate electricity when there is a difference in temperature on either side of the machine (2). Research shows that heat produces power in such devices without external inputs.
However, the guys at MIT have gone the extra mile with their research. Instead of using thermoelectric devices, they use a thermal resonator to generate electricity from fluctuations in temperature. Instead of using two separate temperature inputs, the thermal resonator uses the swing in ambient temperature throughout the day-night cycle to generate power.
This new project could eliminate the need to charge remote sensing systems by providing uninterrupted electric power for years. External power sources, such as batteries or grid connections, would be redundant.
The research has been undertaken by Anton Cottrill and Carbon P. Dubbs Professor of Chemical Engineering Michael Strano plus seven more from MIT’s chemical engineering department.
One of the key advantages of using a thermal resonator is that it can draw power from waste heat, such as solar panels or batteries. It is also not affected by small environmental changes such as cloud cover or wind conditions (3).
The team established that the thermal resonator far outshines the commercial pyroelectric alternatives by a factor of three. The thermal resonator generates more power per area.
Besides Strano and his team, another team from Stanford and MIT has been working on a battery that utilizes the thermo galvanic effect. Yi Cui and Seok Woo Lee from Stanford and Yuan Yang and Gang Chen from MIT have developed a thermoelectric system that takes advantage of the thermo galvanic effect to charge batteries. The thermogalvanic effect states that a rechargeable battery’s voltage is dependent on temperature (4).
The MIT-Stanford team utilizes heat waste to generate electricity through heating a battery, charging, cooling the battery, and discharging. Once the battery has heated, a voltage is applied to it as the battery cools down, the voltage increases because of the thermogalvanic effect.
While this method of generating power using a battery was advanced in the 1950s, it was not as efficient as today. The heat-charge-cool process has significantly improved thanks to the improvements in technology and electrodes in batteries.
Although efficient compared to thermoelectric devices, the thermogalvanic effect generates a smaller amount of power per weight.
One of the challenges of storing thermal energy has been a high need for insulation. However, thanks to another research study by MIT’s postdocs Grace Han and Huashan Li as well as Professor Jeffery Grossman, thermal heat can be efficiently stored in thermal batteries and later on be used for cooking or for light.
Whereas the popular direction has been to use Phase Change Material (PCM), PCM loses heat fast without proper insulation. PCM is where a material changes form while storing from solid to liquid and releases the heat once it cools down to solid (5).
The new system is a hybrid of PCM and molecule switches that react to light by changing shape. The hybrid systems allow the phase to change the new material to maintain thermal energy beyond the melting point of the standard material.
This new system can be used not just with solar but with other sources of heat. Lots of industries and processes generate waste heat.
Thermoelectric devices have proved to be an incredible source of clean energy. The research by the MIT and Stanford teams shows that the thermoelectric power can be taken a step further.
Once harnessed, the applications are limitless. The energy generated can not only be used for cooking or lighting in less developed countries, the thermogalvanic effect can be used to power sensor systems as well as rovers and individual rover components.
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