# “Hot” coffee cup **URL:** \ **Category:** Factual Questions\ **Created:** [January 20, 2024, 7:45pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406 "2024-01-20T19:45:03Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [January 20, 2024, 8:50pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/21 "2024-01-20T20:50:51Z")
A sane solution would be a mug with a small resistive heating element in the base that would work off a Qi wireless charging pad. Could even have thermostatic control to maintain precisely your preferred temperature. Actually, this seems so obvious that I bet this product already exists. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [January 20, 2024, 8:52pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/22 "2024-01-20T20:52:54Z")
Maybe you could get a variation on this sane, practical idea. > **[China’s nuclear battery powers your smartphone for 50 years straight](https://interestingengineering.com/innovation/chinas-nuclear-battery-power-smartphone)** > > Chinese startup Betavolt announced it has successfully developed a micro atomic energy battery that can juice a smartphone for 50 years. ---
**Author:** ![Common\_Tater](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/common_tater/32/13846_2.png) [@Common\_Tater](https://boards.straightdope.com/u/Common_Tater)\ **Post date:** [January 20, 2024, 8:53pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/23 "2024-01-20T20:53:57Z")
Surely, but it is just something else to be charged. More cables, reduced performance over time. Batteries just lack that engineering _elegance_ of a decaying isotope. We are stardust, man! We got to get ourselve back to the Garden! ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [January 20, 2024, 8:58pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/24 "2024-01-20T20:58:07Z")
I take it the OP wants a closed container, and not an actual open-topped cup? ---
**Author:** ![Common\_Tater](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/common_tater/32/13846_2.png) [@Common\_Tater](https://boards.straightdope.com/u/Common_Tater)\ **Post date:** [January 20, 2024, 8:59pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/25 "2024-01-20T20:59:28Z")
No, just a coffee cup. Though a travel cup that doesn’t spill would be a boon to humanity. Let’s do that too, while we’re at it. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [January 20, 2024, 9:03pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/26 "2024-01-20T21:03:27Z")
Coffee is made up of water and ground coffee beans. Even if you found a safe and simple way to keep the coffee at a constant hot temperature, you still have the problem of steam escaping and turning what is left to sludge. ---
**Author:** ![Common\_Tater](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/common_tater/32/13846_2.png) [@Common\_Tater](https://boards.straightdope.com/u/Common_Tater)\ **Post date:** [January 20, 2024, 9:05pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/27 "2024-01-20T21:05:11Z")
Why? It just needs to be kept “warm” or to “hot”. This happens to take 52 seconds on my microwave. I then drink it. The coffee isn’t permanent, the heat would be, or near enough. Can we make control rods small enough? Maybe a Teapot that could be nuclear powered. Or coffee pot. That would be useful. Hammacher-Schlemmer - “World’s Best Nuclear Powered Coffee Pot”! (Can be found on pg. 42) ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [January 20, 2024, 9:06pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/28 "2024-01-20T21:06:42Z")
Getting it hot is not the problem. What happens if you _keep_ it hot is the actual problem. ---
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [January 20, 2024, 9:06pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/29 "2024-01-20T21:06:48Z")
> [@Common\_Tater](#): > > We are stardust, man! We got to get ourselve back to the Garden! Have you considered a geothermal solution? ---
**Author:** ![Common\_Tater](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/common_tater/32/13846_2.png) [@Common\_Tater](https://boards.straightdope.com/u/Common_Tater)\ **Post date:** [January 20, 2024, 9:08pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/30 "2024-01-20T21:08:33Z")
Nuclear is geothermal, kinda. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [January 20, 2024, 9:10pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/31 "2024-01-20T21:10:49Z")
In what way? ---
**Author:** ![Beckdawrek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beckdawrek/32/3647_2.png) [@Beckdawrek](https://boards.straightdope.com/u/Beckdawrek)\ **Post date:** [January 20, 2024, 9:15pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/32 "2024-01-20T21:15:52Z")
Wait. My Daddy had something like that. It was electric but I could see it being wireless, solar, or nuclear. I suppose. He sat his mug on it at his desk. I guess it worked. He never complained. I imagine he got it at Harriet Carter. Neiman Marcus wasn’t in his mindset. Maybe one of those airline catalogs. Hey, the airline cup rears it’s head again. Nice. ---
**Author:** ![Common\_Tater](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/common_tater/32/13846_2.png) [@Common\_Tater](https://boards.straightdope.com/u/Common_Tater)\ **Post date:** [January 20, 2024, 9:20pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/33 "2024-01-20T21:20:41Z")
Admittedly that sounds dangerous. The old “FiestaWare” was mildly hot on a geiger counter. We can name the new line “SiestaWare” - permanent, that is. ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [January 20, 2024, 9:50pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/34 "2024-01-20T21:50:44Z")
No, not something that can be charged. Something with a heating element driven directly by the charging pad. Build the charging pad into your desktop or whatever and Bob’s your uncle. ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [January 20, 2024, 10:10pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/35 "2024-01-20T22:10:37Z")
**Beck** may be a lot of things, but a dude she ain’t. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [January 20, 2024, 10:12pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/36 "2024-01-20T22:12:50Z")
Beck is Dudette. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 20, 2024, 10:18pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/37 "2024-01-20T22:18:38Z")
Getting back to the OP after the recent unpleasantness … In the real world there are electric coffee cup keeper-hotters that’re essentially a hotplate sized for a standard ceramic mug. I’ve had one for each desk for years. They don’t put out enough energy to heat coffee from room temp, but they reduce the cooling rate to near zero. Yes, it very slowly cooks your coffee. But it keeps a standard cup drinkably warm much longer than you’re likely to be interested in it. Here’s a typical example of the breed; they are legion: **[Amazon.com: Coffee Mug Warmer](https://www.amazon.com/dp/B0872JLFN4)**. My point is _not_ that the OP should buy one. It’s that now we have access to the specs, so we can size our RTG, dilithium crystal, flux capacitor, anti-matter annhilator or whatever. This warmer runs on 18W. A few others I checked have similar specs. A resistive heating element is nearly 100% efficient. So what we need is a) an 18W radioactive heat source, and b) (ref @Chronos above) a way to turn the heat off, or dissipate it safely so the empty cup doesn’t self heat to the point of singing your desk or thermally burning your hand. Google informs me Strontium-90 puts out 0.95W/g. So we need about 20g of pure Strontium-90. That’s a lump of metal about the size of 4 or 5 US 5 cent coins. So the volume is not a problem. The half-life is ~29 years, so it seems we could count on decent coffee warming performance for 5, maybe 10 years. The hard part is turning it off. I suppose we could deliver it with a heat-sink / scrub brush like thing that you put into the empty cup that has enough surface area to passively radiate and conduct 18W into room temp air indefinitely while maintaining the cup at a safe-to-touch temperature. Whew, that was kinda easy. These nice folks will sell you some. Really: **[Radioactive Sources; Isotopes (imagesco.com)](https://www.imagesco.com/geiger/radioactive-sources.html)**. It’s $90 per 0.1 microcurie, and I was unable to locate a good conversion factor so I can’t say how many of these little beauties you’ll need per cup. Anyone? The nice thing about Strontium-90 is it’s a beta emitter. So it should be practical to keep the radiation inside the cup structure, net of whatever daughter rays are created as the ceramic absorbs the betas. As mentioned above, gamma would be environmentally unfortunate. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [January 20, 2024, 10:19pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/38 "2024-01-20T22:19:48Z")
I have not had good luck with those USB-powered coffee warmers; however, if you get one that is not a cheap piece of shit, or, better, one where the cup itself contains a heating element, then it should do what you want. ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [January 20, 2024, 10:21pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/39 "2024-01-20T22:21:11Z")
My wife has an Ember self-heating mug for her tea. Expensive as shit but works as advertised. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [January 20, 2024, 10:57pm UTC](https://boards.straightdope.com/t/hot-coffee-cup/996406/40 "2024-01-20T22:57:12Z")
> [@John\_DiFool](#): > > **Beck** may be a lot of things, but a dude she ain’t. > In the early 1960s, dude became prominent in [surfer culture](https://en.m.wikipedia.org/wiki/Surf_culture) as a synonym of _guy_ or _fella_. The female equivalent was “dudette” or “dudess”, but these have both fallen into disuse and “dude” is now also used as a [unisex](https://en.m.wikipedia.org/wiki/Unisex) term. > **[Dude](https://en.wikipedia.org/wiki/Dude)** > > Dude is American slang for an individual, typically male. From the 1870s to the 1960s, dude primarily meant a male person who dressed in an extremely fashionable manner (a dandy) or a conspicuous citified person who was visiting a rural location, a "city slicker". In the 1960s, dude evolved to mean any male person, a meaning that slipped into mainstream American slang in the 1970s. Current slang retains at least some use of all three of these common meanings. > The etymology of the term "dude"... [Previous page](https://boards.straightdope.com/t/hot-coffee-cup/996406.md?page=1) [Next page](https://boards.straightdope.com/t/hot-coffee-cup/996406.md?page=3)