NOV 24

I'm assuming that the conversion of the waste heat to electricity also helps cool the device - leading to further benefits.

I am planning on buying a new cell phone but I'm in the middle of my 2-year plan, so I want a phone that will cost the same so I'm not really at a disadvantage. thanks..

Any way that we can conserve energy and produce more for our effort is worth investigating. Thanks for the informative article!

Could it be used in air-conditioning technology?

Solar wastes 85% of the energy it gets as heat. If this turns out to be real and feasible, would be great for solar.

The idea that engineers could achieve upwards of 90% of the Carnot efficiency is fantastic, but we need to frame this a bit better.

A thermodynamic cycle requires two thermal bodies at different temperatures to get work out (electricity in this case). The greater the temperature difference, the higher the efficiency. The Carnot cycle, theoretically the most efficient thermodynamic cycle operates as follows:
efficiency = 1 - Temp_Cold/Temp_Hot
The temperatures cold and hot are the temperatures of the two thermal bodies that the Carnot cycle is in contact with and are based on absolute temperature scales (Kelvin and Rankin not Celsius or Fahrenheit).

As an example, a computer processor is measured at 80 degrees Celsius (353 Kelvin) and is producing 100 Watts of waste heat. Assuming the room where this processor is located is at 20 degrees Celsius (293 Kelvin), we have established our two thermal bodies.

eff = 1 - T_c/T_h = 1-293/373 = 17% Efficient Theoretical

Waste heat * Eff = Recovered Power

100 Watts * 17% = 17 Watts Theoretical Recovered Electricity

The MIT scientists are aiming to recover upwards of 90% of the Carnot Efficiency, or 90%*17% = 15% or 15 Watts recovered out of 100 Watts.

Presently they have recovered 40%*17% = 7% or 7 Watts out of 100 Watts, which is an enormous improvement over 10% of Carnot.

However, we mustn't get ahead of ourselves, if this team can get achieve 90% of Carnot Efficiency, that will be a big step, but be aware that this is still a relatively small return on the heat used - the teams' success will not yield 90% of all waste heat being converted to electricity, but 90% of the Carnot Efficiency being recovered. Its fascinating work and I very much hope they succeed, but this is one of many things needed to improve our energy efficiency, the likelihood that it alone will double battery life is not accurate.

For those curious, part of the reason why car engines run so hot is to increase their efficiency. Power recovery is excellent when dealing with very hot or very cold devices, but the closer each device is to the same temperature, the less efficiency the process can be.

What a wonderful idea!

It is good to know that everything even down to our cell phones gives off heat! if there is a true way to change things i hope it comes quick enough! I dont want much to change though!

It would be of great benefit to the eco-friendly movements around the world if the powered their campaigns could be powered with The greenest power possible. Spread the word!