Under The Microscope

THE EARTH GARDEN BOOK OF ALTERNATIVE ENERGY, by Alan T. Gray. University of Otago Press, 1997; 176 pages; $29.95

This book is not about double glazing your windows or adding a few more batts in the attic. Its major theme is complete self sufficiency in energy production.

It is a book for the dedicated lifestyler. Not the one who commutes into the city each day from the hobby farm/vineyard/orchard and whose home has all the comfort, convenience and expense that connection to the electricity grid can bring. The person this book is targeting is already convinced that we cannot go on burning vast amounts of fossil fuels to generate electricity to heat, light and cool our homes, provide hot water or drive our machines. He or she will also be prepared to pay much more attention to the supply and consumption of energy in their home than do most grid connected dwellers, although perhaps not as much as one contributor who gives helpful hints for efficient refrigerator use:

Try not to open the fridge door too often, or for as long. In our house we keep often used items in agreed, readily accessible places in the fridge. It is one person's job at the beginning and end of each meal to get the fridge things together and put them all away at the same time.

So what does the buyer get for her money? A glossy eye-catching cover holds 170 pages of recyclable paper from environmentally sound sources. The text is neatly structured into three parts: 1, Generate; 2, Store, Regulate and Invert; and 3, Consume. Within each of these sections are chapters on topics such as photovoltaic arrays, batteries and energy efficient appliances. There is also a chapter on steam power. The generating chapters are meant to be "stand alone", so that it is not necessary to read the chapter on micro-hydro power, for example, if you have no access to a head of water.

Much of the text is made up of articles contributed by people who either live with or supply and fit alternative energy systems. Little or no knowledge of physics by the reader is assumed but as I read I began to wonder if anyone with a basic knowledge of the subject had proofread some of the articles. The common but unhelpful description of voltage as electrical pressure is used, and there are many examples of confusion over terminology. For example: "900 watts at 12 volts is equal to 450 watts at 24 volts". There are so many that it comes as a relief when someone gets it right.

As a resource for teaching physics these could be used as "Explain what's wrong with..." exercises, but they are not helpful for the reader with no expertise in this area.

The book is published in New Zealand by University of Otago Press, but is unashamedly Australian. Of the thirty or so contributions from people other than the editor, there are only two from New Zealand. While some parts of Australia have similar climactic conditions to New Zealand, most do not, and New Zealand readers thinking of installing alternative energy systems might do better to spend their money on a book with more emphasis on the New Zealand energy environment. The Earth Garden Book of Alternative Energy is a useful introduction to the principles of small scale energy systems. It spells out what can be achieved with sufficient effort and motivation. However, as one of the writers points out, there is no substitute for the experience and expertise of people who have been involved with alternative energy systems for many years. If you're a novice, seek them out. If not, you probably don't need this book.

Peter Sadd teaches Physics and Electronics at Burnside High School, Christchurch