Will Stirling engines ever be a viable, efficient power source? Steam engine revival?

I learned about Stirling engines while watching a documentary several years ago, and this guy had a fairly large one outside his home that he could run on either wood, liquid fuel, etc. For those of you who might not know what a Stirling engine is, there are several companies that make different working desktop models, and here's a few:

Here's one of the coolest small Stirlings I've ever seen. Its a really well built, but fairly simple double cylinder alcohol burning Stirling engine you can buy. Scroll slightly down and you'll see a video icon you can click on to see it running:

http://www.ministeam.com/acatalog/Double-Cylinder.html

^^Scroll down that page to see many other double cylinder Stirlings made by the same company, but more complex with more cams, etc.

Here is another different type of Stirling engine from the same site that runs on the heat from a cup of hot water. Scroll down to find video icon to see them in action:
http://www.ministeam.com/acatalog/Low-Temperature.html

**BTW: ^the site where I got those links from has some really interesting stuff including small steam engines, as well as single, double, triple and quad cylinder Stirlings and a whole lot of other well made and interesting stuff. Check it out!

Here's an overly expensive model from another seller that runs off the heat from your hand:
http://www.youtube.com/watch?v=zCGTNArwJ0s

***Here's a small-mid sized Stirling a guy made for himself, which runs off the heat from his wood burning stove in his cabin, so that stove would already be a necessity for heat, but he is also essentially recycling that heat and using it to run the Stirling engine to perform other tasks:

http://www.youtube.com/watch?v=pPVCLpnTnvI


Having shown those examples, I have read that Stirlings arent extremely efficient, and they dont scale up to larger sizes without losing some efficiency in the process. But I also read that it might be possible to make them more efficient. What do you think? I would think that inefficiency wouldnt be a factor for the guy who's running one off a pre-existing energy source which is already in use to make heat, such as a wood burning stove or a furnace, or a radiator, because that energy is being recycled, so its almost free, redundant energy because its already there serving another purpose(am I explaining that idea clearly?)


What about steam engines? Do you think that steam engines could be re-introduced, but in more efficient designs. They already use steam engines in nuclear reactors......

Probably a principle not fully utilized...but thermoelectric devices have these beat for many applications.

I do love a good sterling engine.

See Biolite Stove.

obi

Love stirling engines. ( have made quite a few, people are amazed when they start moving off the heat of their hands.

As glassblowers (and physics profs) know, an open tube heated at one end can get EAR-SHATTERINGLY loud! That's a Stirling engine doing work!

If you could do that work as something other than sound it could be useful!

[I have a buddy enthralled with thermoacoustic engines, which use audible-frequency-range sound energy to move gas molecules around a chamber of varying temperatures (very similar to Stirling's use of heat from flame to get gas molecules to push pistons around a cylinder of varying temp). :thinking: ]

Wicked thing seems to be, there can't be too huge a gap between the characteristics of your internal fluid, and the working environment (in the screaming Rijke tube example above, both are air-filled).

REALLY efficient mechanical linkages could (in theory) bridge huge fluid gaps, but we haven't invented them yet.

Stirling engines are good for places where you have available heat and require long maintenance intervals. High-radiation areas especially prohibit 'solid state' heat engines (made from semiconductors) from durable operation. So NASA is looking into them for space bases.

But like all thermodynamic engines, their efficiency is limited by the temperature difference available, and their working volume by size. One of the more interesting related technologies I've seen are:

Jerker lines

Power tower (Cover ten thousand acres with greenhouse material. Build a chimney in the center. Install an wind turbine at the top).

If i'm not wrong, some researchers were also toying with the idea of using stirling engines to produce electricity using sun rays as the heat source, ie, you have a parabolic reflector that converges light rays towards a sterling engine which in turn runs an alternator to produce electrical energy during the day. haven't really followed up on that so idk if it's viable even if it should work.

N10 said:

If i'm not wrong, some researchers were also toying with the idea of using sterling engines to produce electricity using sun rays as the heat source, ie, you have a parabolic reflector that converges light rays towards a sterling engine which in turn runs an alternator to produce electrical energy during the day. haven't really followed up on that so idk if it's viable even if it should work.

Click to expand...

The main issues would be cost and efficiency compared to photovoltaic cells. All other things being equal, a solid-state solution with no moving parts is always better. Stirling would have to be significantly better than photovoltaic in some way to make this commercially viable.

N10 said:

If i'm not wrong, some researchers were also toying with the idea of using sterling engines to produce electricity using sun rays as the heat source, ie, you have a parabolic reflector that converges light rays towards a sterling engine which in turn runs an alternator to produce electrical energy during the day. haven't really followed up on that so idk if it's viable even if it should work.

Click to expand...

There were two compelling styles of application. The first uses teleostats (mirrors on wheels LOL) to focus acres' worth of light on a HOT TOWER.
Issue: Gotta pump water all the way up there.

I have seen this in operation, and it looks like the ANGELS are LANDING!!

The other paradigm uses thousands of meters of partial-tube reflectors focused on a long tube of fluid:

Both styles are working today in Almeria, Spain. The second was also sold to investors in Nevada, but has yet to make a go (see Solar Millennium Corp.): official line is that farmers restricted the water supply. :thinking:

^But even if the farmers did limit or prevent them from using the water, it seems to me you could just truck in the water to begin with in a few 18 wheeler tanker trucks, and design a solar system with a condenser that recycles the water. Problem solved. Plus, as was eventually understood back in the late 1800's and early 1900's, you dont have to use the steam just once. As long as its still hot(which it would be if its still steam), you can cycle that steam through another part of the system and continue using it to create energy/electricity til its cooled down(condensed), then re-heat it into steam again. Back in the day, they eventually created steam engines that would cycle the steam through 2 or even 3 pistons, one after another, to get as much use out of that heat energy as possible.