> The new study revisits Landauer's principle for cases when the values of the bits to be deleted may be known. When the memory content is known, it should be possible to delete the bits in such a manner that it is theoretically possible to re-create them. It has previously been shown that such reversible deletion would generate no heat. In the new paper, the researchers go a step further. They show that when the bits to be deleted are quantum-mechanically entangled with the state of an observer, then the observer could even withdraw heat from the system while deleting the bits. Entanglement links the observer's state to that of the computer in such a way that they know more about the memory than is possible in classical physics.
"The thermodynamic meaning of negative entropy" (2011) https://www.nature.com/articles/nature10123
Landauer's principle: https://en.wikipedia.org/wiki/Landauer%27s_principle
> This study reports new records for pyroelectric energy conversion energy density (1.06 Joules per cubic centimeter), power density (526 Watts per cubic centimeter) and efficiency (19 percent of Carnot efficiency, which is the standard unit of measurement for the efficiency of a heat engine).
"Pyroelectric energy conversion with large energy and power density in relaxor ferroelectric thin films" (2018) https://www.nature.com/articles/s41563-018-0059-8
Carnot heat engine > Carnot cycle, Carnot's theorem, "Real heat engines": https://en.wikipedia.org/wiki/Carnot_heat_engine
Carnot's theorem > Applicability to fuel cells and batteries: https://en.wikipedia.org/wiki/Carnot%27s_theorem_(thermodyna...
> Since fuel cells and batteries can generate useful power when all components of the system are at the same temperature [...], they are clearly not limited by Carnot's theorem, which states that no power can be generated when [...]. This is because Carnot's theorem applies to engines converting thermal energy to work, whereas fuel cells and batteries instead convert chemical energy to work.[6] Nevertheless, the second law of thermodynamics still provides restrictions on fuel cell and battery energy conversion
"How to Reuse Waste Heat from Data Centers Intelligently" (2016) https://www.datacenterknowledge.com/archives/2016/05/10/how-...
> There are two big issues with data center waste heat reuse: the relatively low temperatures involved and the difficulty of transporting heat. Many of the reuse applications to date have used the low-grade server exhaust heat in an application physically adjacent to the data center, such as a greenhouse or swimming pool in the building next door. This is reasonable given the relatively low temperatures of data center return air, usually between 28° and 35°C (80-95°F), and the difficulty in moving heat around. Moving heat energy frequently requires insulated ducting or plumbing instead of cheap, convenient electrical cables. Trenching and installation to run a hot water pipe from a data center to a heat user may cost as much as $600 per linear foot. Just the piping to share heat with a facility one-quarter mile away might add $750,000 or more to a data center construction project. There’s currently not much that can be done to reduce this cost.
> To address the low-temperature issue, some data center operators have started using heat pumps to increase the temperature of waste heat, making the thermal energy much more valuable, and marketable. Waste heat coming out of heat pumps at temperatures in the range of 55° to 70°C (130-160°F) can be transferred to a liquid medium for easier transport and can be used in district heating, commercial laundry, industrial process heat, and many more. There are even High Temperature (HT) and Very High Temperature (VHT) heat pumps capable of moving low-grade data center heat up to 140°C.
Heat Pump: https://en.wikipedia.org/wiki/Heat_pump
"Data Centers That Recycle Waste Heat" https://www.datacenterknowledge.com/data-centers-that-recycl...