A perfect complement to yesterday's solar powered automatic chicken coop opener would be this portable hyrdogen generator.

Kristie Lu Stout has an interesting post about this exciting new product that will allow everybody to generate their own hydrogen from water and store it in a safe, low pressure battery-like container. No word yet on how much it might cost, but plans are to have a tabletop model available by the end of 2010.

Getting off the grid with solar or wind has always come back to battery storage. If this technology improves, it could replace most of those expensive and toxic chemical batteries and bring alternative energy within the reach of the common homesteader.

Everett commented on my mention of planting clover to say:

I don't know why inoculant is so hard to spell, but I struggle with it too and seem to have to look it up every few weeks.  Anyway, back to the point....

If you're not a gardener, you may not realize that nitrogen is usually the limiting ingredient in many plants' growth, and is thus one of the big three components of chemical fertilizers.  Organic gardeners often add nitrogen to the soil with compost or manure, but others take advantage of nitrogen-fixing bacteria to turn the copious nitrogen in the atmosphere into nitrogen their plants can use.  This week's lunchtime series will explore how this symbiosis can be worked to your advantage in the garden.

As part of  my continued obsession with lower-energy cooking, I decided to try to make a haybox to cook my chicken carcass down into stock Sunday.  Someone (Heather?) had emailed me in response to my Dutch oven post, telling me that you can bring a pot of incipient soup to a boil, wrap it in towels, and leave it alone for the afternoon.  The cast iron and towels will hold in the heat, and the soup will cook itself.

While researching rocket stoves, I stumbled across a mention of hayboxes, which seem to work on a very similar principle to Heather's idea.  You fill up a box with hay (or other insulation), put in your boiling pot, and leave it alone for several hours.  I've seen figures suggesting that using a haybox with long-cooking recipes like chicken stock will save 80% of the energy you would use to simmer the stock on the stove.  You should leave the pot in the haybox somewhere between once and twice as long as you would have left it on the stove.  If you're worried about bacteria, bring the whole thing back to a boil for a few minutes on the stove before serving.

So how did my experiment go?  I brought my carcass and water to a boil and tucked it into an old comforter in a cardboard box.  (The image on the left shows the pot before I bundled the rest of the comforter over the top.)  Our house temperature was low on Sunday --- 50 degrees Fahrenheit --- but when I peeked in six hours later, the pot was still steaming and the stock was a lovely yellow.  Success!

What do you do if you want to install an automatic chicken coop door but you don't have electricity running to your coop?

Chicken coop door.com has recently come out with a new solar powered option that will save you the chore of letting your girls out in the morning and remembering to lock them back up at night.

The price is 324 dollars and maybe worth it if you don't have the skill and time to build an automatic chicken coop door yourself.

A few of you were as intrigued by the rocket stove concept as I was, and Roland's comments sent me searching the web for more information.  Basically, I wanted to know if I could design a slightly modified rocket stove made out of found/bought materials to simplify construction.  I was also interested in any updates to the design that might maximize efficiency.


Preheating the combustion air

The drawing shown here is Roland's suggestion for preheating the combustion air to increase efficiency, in much the way that efficient space-heating wood stoves work.  A search of the web turns up contradictory pages --- folks who have tried similar methods are split on whether it increases efficiency or not.  Many sites suggest that the conventional design already preheats the combustion air by passing the air intake underneath the burning fire, so I think I'll stick with that.


Insulation

Insulating the burning chamber is another important factor in rocket stove efficiency.  The official Aprovecho design calls for making your own fire bricks, which are rated at about R10 when fully assembled.  Roland's suggestion --- perlite --- has an R-value of 2.7 per inch, so four inches of loose-filled perlite placed between an inner and an outer wall could be a much easier option than making our own fire brick.  (For future reference, other folks mention using materials such as vermiculite (R2.08 per inch) and pumice (R2 per inch).)


Body materials

I've seen various DIY rocket stove options using found or bought materials, and the ones that caught my eye used nested stove pipe.  The image shown here is my revised version of the official design made out of one big stove pipe, two pieces of smaller stovepipe, and an elbow to connect the smaller stovepipe pieces together.  As Roland mentioned, the bigger stovepipe might be replaced by a metal bucket --- otherwise, I'd have to add some kind of cap to keep the perlite from coming out the bottom.  I'm envisioning the pot sitting on pieces of rebar stuck through the exterior walls rather than welding anything together.

There's a bit of math involved in deciding how high the interior chamber should be and how much air space should be left between the pot and the skirt -- more on that later!