Renewable Energy Concept - Stirling Engine Composting

Click For Summary

Discussion Overview

The discussion revolves around the concept of utilizing heat generated from anaerobic composting to power a Stirling Engine. Participants explore the feasibility of this idea, including potential configurations and efficiency considerations, as well as the practical aspects of measuring power output and heat generation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes using heat from anaerobic composting to power a Stirling Engine, suggesting a gamma configuration with compressed helium as the working gas to increase efficiency.
  • Another participant suggests measuring the power output from a compost heap by running water through copper pipes and calculating the energy based on specific heat capacity, flow rate, and temperature difference.
  • A third participant mentions that compost generates heat at approximately 275 watts per cubic meter and notes that methane production is already utilized in industrial applications, emphasizing the need for insulation to maintain temperature for microbial activity.

Areas of Agreement / Disagreement

Participants express varying views on the practicality and efficiency of using compost heat for a Stirling Engine, with no consensus reached on the best approach or the feasibility of the proposed idea.

Contextual Notes

Participants acknowledge the complexity of calculations required for the Stirling Engine design, including gas equations and torque requirements, which remain unresolved in the discussion.

Who May Find This Useful

Individuals interested in renewable energy concepts, composting technologies, and Stirling Engine applications may find this discussion relevant.

Waggles
Messages
2
Reaction score
0
So I've got this crazy idea. To put it simply, to use the heat from anaerobic composting to power hot-air engine, specifically a Stirling Engine.

Based solely on my own reading, the center of a closed composting heap can reach anywhere from 120-160 degrees without killing the microorganisms required to produce methane. By water cooling the cold side of an engine, a temperature differential of >100F.

I imagine a gamma configuration with opposed/linear cylinders: hot cylinder down, cold cylinder up out of the heap. Compressed helium as the working gas will increase efficiency. And a properly built Stirling Engine requires a regenerator to further increase efficiency.

I'm the guy with the ideas, but I don't know how to do the complex gas equations, cylinder computations, electrical computations and etc. required to calculate the dimensions. As well as the necessary torque to run, say, an alternator.

Trying to upload concept sketches.
Any help would be much appreciated!
 

Attachments

  • 1495964304293790199471.jpg
    1495964304293790199471.jpg
    33.5 KB · Views: 809
  • 14959643371551813675428.jpg
    14959643371551813675428.jpg
    28.9 KB · Views: 733
Engineering news on Phys.org
Try working out how much power you can extract from a compost heap first. The simplest way would be to push some copper pipe through it and run some water through. You would need to know the flow rate and the temperature of the water going in and out. Leave it going for a few days to check you are measuring the long term rate.

Power = SHC * flow rate * (Tout - Tin)
where SHC is the specific heat capacity of water.

It might be better to use the hot water directly to heat your house/shower. Perhaps see..
https://www.hindawi.com/journals/ijce/2010/627930/
 
According to Google, compost generates heat at about 275 watts per cubic meter.

The other thing it generates is methane, which is already done on an industrial scale in landfills and sewage treatment plants. Usually, they just use the reactor heat to keep the waste warm for the microbes to do their jobs. If you cool it, you will at least need to insulate it to keep it warm.
 
Last edited:
Thanks for the replies, y'all. I'll extrapolate and ask a few more things when I can. Thanks again.
 

Similar threads

Will curved heat pipes improve Stirling engine efficiency?
  • · Replies 3 ·
Replies
3
Views
6K
Undergrad Ideal working gas for a Stirling engine
  • · Replies 1 ·
Replies
1
Views
3K
High School Can a Heat Pump and Stirling Engine Create a Perpetual Energy Cycle?
  • · Replies 6 ·
Replies
6
Views
4K
Will this be more efficient than the Sterling engine?
  • · Replies 47 ·
2
Replies
47
Views
9K
Using gas engine's residual heat to power a Stirling engine.
  • · Replies 3 ·
Replies
3
Views
3K
How Does Heat Affect the Motion of a DIY Stirling Engine's Wheel?
  • · Replies 6 ·
Replies
6
Views
3K
A Carnot engine between the Earth's poles and equator
  • · Replies 67 ·
3
Replies
67
Views
7K
Stirling Engine Design Considerations
  • · Replies 15 ·
Replies
15
Views
6K
Thermodynamics - Stirling Engine
  • · Replies 10 ·
Replies
10
Views
6K
Efficiency Calculation for a Stirling Engine Cycle
  • · Replies 3 ·
Replies
3
Views
3K