Science Buddies: "Ask an Expert"

Hi I would like to make a methane digester using cow manure. I understand I must seal the methane and have tubing run through buckets,but what I'm having trouble with is how am I going to make the methane burn from a flame and make energy for a light bulb

Hi Nicho397 and welcome!
I think your project idea is interesting and useful and very timely. I don't know a great deal about methane digestors. But I do have some thoughts for you to consider.

1. Burning the flame to power a light bulb would probably require energy capture and storage. Specifically, the burning would cause energy from expanding and heat, which would need to be captured in an electromagnetic turbine of some sort. An example description may be found here:
http://www.edfenergy.com/energyfuture/generation-gas
As you may be aware, the problem is that at the smaller scale of a demonstration project, the amount of heat energy produced from burning may be inefficient for motoring a small scale turbine. This is one of the interesting challenges. I did a google search for the words "science project electromagnetic turbine" and turned up the following interesting link (and others):
http://www.super-science-fair-projects. ... bines.html

2. Another approach that you could consider would be to try to measure the amount (volume) and composition of methane or other gas produced by the digestor. Then, making some assumptions you could estimate the amount of power that could be produced per unit volume of methane.

3. There are potentially some safety concerns from accumulating highly flammable gas like methane. So I'm wondering when working with developing the digestor if you are able to use a well ventilated location like an open garage - this way the methane released does not present a potential health hazard. Of course, if the digestor is very small, the hazard is reduced.

Others may have other useful ideas, but hopefully this question will get you thinking.

Cheers
Ben

This helped a lot! Thank you for the website reference they have information that will be very useful.

Thanks, I'm glad to hear it!
Feel free to keep us posted as your project continues to develop, and you want help refining your questions, methods, etc. We'll be interested to hear how its going...
Ben

Hi Ben,
I think I'm going with the idea of only producing small amounts of methane and measuring how much the manure produces gas. I decided this because of concerns from the flammability of methane. MY next problem is how to measure the volume of the methane.

Thank you

Hi Again
Looking on the web, I found that a method of measuring gas volumes is by water displacement:
http://www.ehow.com/how_7912117_measure ... ement.html

But a big question is whether this method would be sensitive enough to detect the amount of gas that would be produced by you compost system. I do not know if it would or not. Maybe you can research this method further and see if it may be appropriate? Maybe also discuss with a chemistry teacher at your school, and even try setting it up in the lab?

Anyways, just something to think about - There may be better ideas out there.

Feel free to keep us posted on your progress

Ben