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People seem to be misinterpreting this a lot. This is not about solar cells. This is about thermophotovoltalics, and the application here is using a burning fu
by IanCal 7y ago
People seem to be misinterpreting this a lot.
This is not about solar cells. This is about thermophotovoltalics, and the application here is using a burning fuel source to generate electricity.
The "drone" the paper talks about seems to be a reference to another paper on unmanned sea vehicles though. Edit - to be fair the flying drone part is from the corresponding author.
- clouddrover 7y ago> This is not about solar cells. There's wasted thermal energy when using solar cells. If you can capture some of it you'd be able to increase the efficiency of the cell.
- pjc50 7y agoExactly. The paper is here: https://www.pnas.org/content/early/2019/07/15/1903001116 https://www.pnas.org/content/early/2019/07/15/1903001116 The context of thermophotovoltalics is very interesting - conventional heat-to-electricity engines are limited by Carnot efficiency, which relies on a "cold side" and generally has low theoretical maximum efficiencies. This approach takes any hot emitter heated by any process - fuel burning, solar concentration, nuclear - and extracts electricity directly from the mostly IR photons it emits. > Here, we present experimental results on a thermophotovoltaic cell with 29.1 ± 0.4% power conversion efficiency at an emitter temperature of 1,207 °C. This is a record for thermophotovoltaic efficiency.
- jacobush 7y agoI sense a new kind of nuclear power plant?!
- StreamBright 7y agoThat would be amazing to get rid of the traditional boiling water part of nuclear power plants. Is this what you are thinking about?
- jcfrei 7y agoSo (one of) the advantages compared to a Peltier element is that you no longer need a cold side?
- Diggsey 7y agoYou still need to keep the thermophotovoltaic cells cool, it doesn't violate thermodynamics (energy can only be extracted from a temperature differential).
- pjc50 7y agoWhile it looks like you still do, the other advantage is that these are far more efficient than Peltier devices, which tend to be single-digit percentage efficiency.
- k__ 7y agoIsn't Carnot efficiency higher than 29%?
- Retric 7y agoPhotovoltaic’s are also limited by Carnot efficiency. The theory is you can increase the hot side more as you are less limited by mechanical stresses and moving parts. However, the sun’s surface is 5,505°C, so these are always going to have lower efficiency than traditional solar panels. Which are still less efficient than the bets thermal engines.
- lightedman 7y agoTHERMOphotovoltaics are limited by Carnot's efficiency. This does not apply to basic pure-photon non-thermal photovoltaics.
- skykooler 7y agoThis also relies on a "cold side" - the thermophotovoltaic cell has to be colder than the IR source or it will emit photons faster than it can absorb them.
- spuz 7y ago> According to Yablonovitch, this finding builds on work that he and students published in 2011, which found that the key to boosting solar cell efficiency was not by absorbing more photons (light) but emitting them. By adding a highly reflective mirror on the back of a photovoltaic cell, they broke efficiency records > "What the mirror does is create a dense infrared luminescent photon gas within the solar cell, a phenomenon that adds voltage," said Yablonovitch > Recently, his team recognized that this mirror could serve double duty. In fact, it solves one of the biggest challenges in thermophotovoltaics: how to exploit the thermal (heat) photons that have too little energy to produce electricity. It turns out that the mirror can reflect those small photons to reheat the thermal source, providing a second chance for a high energy photon to be created and generate electricity. This phenomenon leads to unprecedented efficiency. Given these paragraphs and the name "thermophotovoltalics", that this is about solar power seems like a reasonable conclusion to draw. Also, googling around I am seeing figures for steam turbine efficiency of between 40 and 80%. How sure are you this is not about solar cells?
- arijun 7y agoYour quotes seem to very clearly support the idea its a an onboard heat source as claimed by gp. Specifically >>the mirror can reflect those small photons to reheat the thermal source I'm pretty sure holding a mirror up to the sun is not going to change the sun's temperature much. > I am seeing figures for steam turbine efficiency of between 40 and 80% There's more that goes into choosing an engine for a drone than just efficiency. Particularly important would be power/weight. A Carnot engine would get much higher efficiency for sure, but would not put out nearly enough power per weight for a drone to fly. (It's so low power we don't even use it for cars!)
- IanCal 7y ago> Given these paragraphs and the name "thermophotovoltalics", that this is about solar power seems like a reasonable conclusion to draw. Also, googling around I am seeing figures for steam turbine efficiency of between 40 and 80%. How sure are you this is not about solar cells? That it's not about the solar cells people in the comments mean? Very, the paper and citations talk about furnaces, and the temperature this operates at is 1200C. This isn't something you'd stick on your roof.
- raducu 7y agoWhy couldn't this be used in cars -- 50% seems better than traditional internal combustion engines?
- baking 7y agoHybrid cars are potentially their biggest market. Ten times solar PV. https://www.youtube.com/watch?v=lDxJsa8miNQ&feature=youtu.be&t=3437 https://www.youtube.com/watch?v=lDxJsa8miNQ&feature=youtu.be...