Yes, Virginia, There is Free lunch: It's Called the Solar Greenhouse!

Enlarge Image Image Gallery Southwest and southeast views of Bill Yanda's add-on greenhouse, with some notes on materials and construction.

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The basic drive behind alternative energy research is to achieve maximum output of energy from the least possible input (and consequently the least possible drain on the environment). Although the law of entropy tells us that there can be no gain without a certain percentage of loss, th.e primary aim of the experimenter with natural power sources is to shave that percentage down to its irreducible minimum. Therefore, while we know that there aren't any "free" lunches, we also know that some lunches are a heck of a lot cheaper than others.

That "free lunch" metaphor is more than just a figure of speech. When one reflects on the fact that current agribusiness practices in this country require about twenty calories of energy in the form of petroleum to produce only one calorie of energy in the form of food, it becomes obvious that the connection between Exxon and Safeway is a lot closer than it might appear at first glance. The entire process would be considerably more efficient if we could learn to drink our meals directly from the gasoline pump!

It follows that those of us who don't relish the idea of some ex-camel drover or corporation fat cat having virtual control over our victuals would do well to start cultivating our own gardens. Unfortunately, in most sections of this country, a vegetable patch is strictly a seasonal affair. Animal protein can generally be raised in any season, but the majority of food plants won't grow during the winter unless you happen to live in the tropics.

Enter the solar greenhouse . . . an invention so simple and productive that I regard it as the single most effective alternative energy device anyone can possess. Wind electric systems, methane digesters, and solar collectors might well be added later in your progress toward self-sufficiency, but a sunwarmed growing area built onto the south wall of your dwelling will probably yield more immediate benefits at less cost than all the other equipment combined.

First of all, just what do we mean when we refer to a "solar" greenhouse? Don't all such gardening structures fit into that category (since they all make use of the sun's energy)? The answer, of course, is "yes". Generally speaking, though, a "solar" greenhouse differs from others by receiving all its warmth from the sun and using no auxiliary heater as backup. (Actually, I feel that the adjective "solar" is redundant . . . but since the term "solar greenhouse" is now part of our language, I'll use it.)

Readers of my "Build Your Own Ecosystem" series in MOTHER NOS. 28 through 31 will recall that the system I'm working with is based on the concept of the "growhole" or pit greenhouse, which is a gardening structure built below ground level to take advantage of the insulating properties of the earth itself.

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