# Ways of harvesting heat energy besides steam? **URL:** \ **Category:** Factual Questions\ **Created:** [October 26, 2002, 11:05pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037 "2002-10-26T23:05:57Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Mushono](https://avatars.discourse-cdn.com/v4/letter/m/cdc98d/32.png) [@Mushono](https://boards.straightdope.com/u/Mushono)\ **Post date:** [October 26, 2002, 11:05pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/1 "2002-10-26T23:05:57Z")
Are there any methods of turning that turbine besides using steam power? I really can’t think of any gathering heat-energy besides this. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [October 26, 2002, 11:27pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/2 "2002-10-26T23:27:15Z")
gas turbines/ diseal & gasoline engines ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [October 26, 2002, 11:29pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/3 "2002-10-26T23:29:06Z")
actually the IC engine doesn’t typically turn a turbine (but it could) but gas turbines do. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [October 26, 2002, 11:30pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/4 "2002-10-26T23:30:38Z")
For that matter hydroelectric uses liquid water at lake tempature to turn turbines, windmills could also be thought of as turbines. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [October 27, 2002, 1:38am UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/5 "2002-10-27T01:38:38Z")
You can generate current from heat directly without any mechanical parts using [Peltier’s Principle](http://www.nanothermel.org/public_main.htm). You can also use it to make a heat pump if you provide the current. ---
**Author:** ![AndrewL](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@AndrewL](https://boards.straightdope.com/u/AndrewL)\ **Post date:** [October 27, 2002, 1:45am UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/6 "2002-10-27T01:45:33Z")
A Stirling cycle motor will convert a heat difference directly into mechanical energy, with high efficiency. ---
**Author:** ![Wikkit](https://avatars.discourse-cdn.com/v4/letter/w/c0e974/32.png) [@Wikkit](https://boards.straightdope.com/u/Wikkit)\ **Post date:** [October 27, 2002, 7:48am UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/7 "2002-10-27T07:48:34Z")
> [@](#): > > \*Originally posted by Mushono \* > \*\*Are there any methods of turning that turbine besides using steam power? I really can’t think of any gathering heat-energy besides this. \*\* To specifically answer your question, not really. In a situation where you have heat, and you want to generate rotational energy with a turbine, steam is pretty much the only thing that’s used. You could use some chemical other than water, but there’s been more research done on steam, steam engines, and steam turbines than anything else, so steam is still popular. Expanding your question, so that you just have a heat source that you want to get some energy from (and saying nothing about turning turbines), the aforementioned Peltier and Stirling come in. With Peltier you get electricity, with Stirling you get energy that can be converted to electricity with a generator. There are other ways, but those are probably the two most efficient. You could, for example, have a closed vessel full of air at ambient temp and pressure. You could then heat it using your heat source, raising the temperature and pressure. Then you could use the pressure to drive a turbine or piston, then refill the chamber will air at ambient and start over. Using steam instead of air is just more efficient. ---
**Author:** ![starfish](https://avatars.discourse-cdn.com/v4/letter/s/87869e/32.png) [@starfish](https://boards.straightdope.com/u/starfish)\ **Post date:** [October 27, 2002, 7:55am UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/8 "2002-10-27T07:55:47Z")
Think airplane. The engines, and many other comercial engines, run turbines from fuel, not steam. ---
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [October 27, 2002, 12:48pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/9 "2002-10-27T12:48:23Z")
> [@](#): > > \*Originally posted by starfish \* > \*\*Think airplane. The engines, and many other comercial engines, run turbines from fuel, not steam. \*\* That was my first reaction upon reading **Wikkit** ’s post, along with a lot of “What the hell?” 's. But he is correct if you are talking about using _heat_ to turn a turbine, and not _fuel_. If you are trying to convert fuel to turn a turbine, a gas turbine might be (depending on the fuel) the best option. But if you are talking heat, well, steam is a good way to go. You could use ammonia or freon too, I suppose. ---
**Author:** ![Agback](https://avatars.discourse-cdn.com/v4/letter/a/977dab/32.png) [@Agback](https://boards.straightdope.com/u/Agback)\ **Post date:** [October 27, 2002, 1:58pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/10 "2002-10-27T13:58:56Z")
> [@](#): > > \*Originally posted by Mushono \* > \*\*Are there any methods of turning that turbine besides using steam power? I really can’t think of any gathering heat-energy besides this. \*\* Yes. There’s a pilot plant in Spain that uses (essentially) a giant greenhouse to warm air, and then lets it pass up a tall chimney. Turbines in the chimney extract energy from the draught. Full-scale construction is being considered for Australia. Regards, Agback ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [October 27, 2002, 2:07pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/11 "2002-10-27T14:07:31Z")
[Here](http://www.enviromission.com.au) is the link for that solar tower. Fascinating project. ---
**Author:** ![bunyip](https://avatars.discourse-cdn.com/v4/letter/b/e19b73/32.png) [@bunyip](https://boards.straightdope.com/u/bunyip)\ **Post date:** [October 27, 2002, 8:14pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/12 "2002-10-27T20:14:51Z")
You could turn heat into electricity using Thermocouples, as in RTG generators on Apollo Alsep; and deep space probes(Pioneer,Voyager, Galileo, etc). ---
**Author:** ![Huerta88](https://avatars.discourse-cdn.com/v4/letter/h/82dd89/32.png) [@Huerta88](https://boards.straightdope.com/u/Huerta88)\ **Post date:** [October 27, 2002, 10:25pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/13 "2002-10-27T22:25:52Z")
I seem to recall an alternative expression of the Second Law to the effect that "A quantity of heat cannot be converted directly to work without some loss of energy or some external input. " Did I just make that up? The prof. illustrated this by reference to a vat of 85 degree C water – plenty of energy, not too practical as a power source. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [October 27, 2002, 11:41pm UTC](https://boards.straightdope.com/t/ways-of-harvesting-heat-energy-besides-steam/134037/14 "2002-10-27T23:41:17Z")
> [@](#): > > Did I just make that up? Nah. Any time you convert one kind of energy to another (heat to motion in these cases) you’re going to loose some of it to the inefficiencies in the system. No energy transforming systems known to man are 100% efficient.