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Our book today, Doable Renewables:  16 Alternative Energy Projects for Young Scientists by Mike Rigsby, is full of creative new ideas and information. Do you remember in our post about smart materials (the materials that respond to the environment), we were looking for a source of nitinol (nickel-titanium alloy) wire? This book not only lists a source, but also uses nitinol springs in projects.

Mike Rigsby is a professional electrical engineer and he has a noble cause for writing this book. He has come up with projects to investigate various forms of renewable energy in the hope at least one of them will spark a young person to discover something that will change the world. His projects include making engines that use heat as a source of energy (including one with nitinol springs), solar energy, wind energy and wave energy. Each project is explained clearly, with a detailed list of supplies and numerous black and white photographs showing the assembly, as well as the finished project.

Before we get too excited, though, let's do the reality check. Safety is one concern. Some of these projects have steps that could potentially cause injuries, especially those that involve cutting. Unlike many of the activities found in children's science books, some of these projects are not made from items lying around the house. Many will require the purchase of specialized pieces of equipment or supplies from science and technology suppliers. For example, the nitinol springs are available from Jameco Electronics, part number 357835. As of today, they cost $45.95 for a 4 pack. The bottom line is that this book is for serious older children or young adults who enjoy engineering and inventing, and who preferably have an experienced adult mentor.

That said, do you have a science fair coming up soon? Doable Renewables: 16 Alternative Energy Projects for Young Scientists is a wonderful resource sure to generate innovative science fair projects.

In fact, the book inspired us to do some of our own investigations:

1. Stirling tin can engine

In chapter 4, Mike Rigsby suggests purchasing a Stirling engine to explore this technology investigated by Reverend Dr. Robert Stirling way back in 1816 (see our Amazon suggestions below). The Stirling engine uses heat to do work, and is known to be very quiet in comparison to the internal combustion engine.

Rigsby also mentions that there are instructions for building your own on the Internet, so of course we had to look. We found quite a few examples of Stirling engines you can make at home plus numerous videos of the engines in action. Here is one example of a fan Stirling engine (note: there is a pop-up ad).

The instructions can be found at Easy to build Stirling engine

There is more about how Stirling engines work at How Stuff Works.

2. Radiometer

We already had a radiometer, so we dusted it off and tried it out. A radiometer is a glass bulb that looks like a light bulb. Inside are 4 tabs suspended from wires. Those tabs are reflective on one side and black on the other. When placed in sunlight, the tabs rotate like crazy.

The Crookes radiometer caused quite a stir in its time, because no one was quite sure how it worked. Several hypotheses were proposed and shot down. Eventually the idea of thermal transpiration was found to be the one most generally accepted. It involves the movement of gases from the warmer side of the tab (the black side) to the cooler, reflective side. In any case, the only energy supplied is that from the sun.

3. We have a previous post on Windmills and wind power that also relates to this topic.

We hope this inspires you to try a few new projects with renewable energy. Be sure to let us know how they turn out.

Reading level: Ages 9-12 (Amazon)
Paperback: 224 pages
Publisher: Chicago Review Press; Original edition (October 1, 2010)
ISBN-10: 1569763437
ISBN-13: 978-1569763438

This book was provided for review.

Stirling Engines at Amazon

Other scientific supplies suggested in the book:

Have you been over to visit the Cybils nomination lists yet? cybils2010

What are Cybils? The acronym stands for children's and young adult bloggers literary awards. Bloggers who specialize in children’s and young adult books have developed the Cybils awards to highlight some of the best books published in the previous year. Back in September people nominated their favorite books by genre. Now the judges are reading and reviewing all the books to pick one winner from each category.  Although there is a lot of excitement about which books will be chosen as the best, going through the nomination lists is also a great way to find interesting new things to read.

To save you some time, I went through the list of nominated nonfiction books in the picture book category and selected some science and nature books that you might find useful. (By the way, once again I am a round II judge for nonfiction picture book category.) Soon I'll tackle the middle grade/young adult books.

Nonfiction Picture Books - Science and Nature
(The titles are linked to take you to Amazon for more information)

 Pop!: The Invention of Bubble Gum by Meghan McCarthy
Never Smile at a Monkey: And 17 Other Important Things to Remember

By Steve Jenkins

Moon Bear by Brenda Z. Guiberson
Hurricanes! by Gail Gibbons

We love Gail Gibbons, see my brief bio for more about her.

Bugs and Bugsicles: Insects in the Winter by Amy S. Hansen

See my review

Astro: The Steller Sea Lion by Jeanne Walker Harvey

See my review

Little Black Ant on Park Street (Smithsonian's Backyard Collection)

by Janet Halfmann

See my review

Growing Patterns
by Sarah Campbell
 Little Red Bat by Carole Gerber
Insect Detective by Steve Voake
A Place for Frogs
by Melissa Stewart
Bones by Steve Jenkins
Kingdom: Savage Safari
by Nam Nguyen
Meet the Howlers! by April Pulley Sayre
Mammoths and Mastodons: Titans of the Ice Age by Cheryl Bardoe

See my review

Changing of the Guard: The Yellowstone Chronicles by Ted Rechlin
Come See the Earth Turn By Lori Mortensen

The Story of Leon Foucault

Dinosaur Mountain: Digging into the Jurassic Age by Deborah Kogan Ray
EcoMazes: 12 Earth Adventures
by Roxie Munro
The Shocking Truth About Energy
By Loreen Leedy
The Life of Rice: From Seedling to Supper (Traveling Photographer)

By Richard Sobol

The Buzz on Bees: Why Are They Disappearing?
by Shelley Rotner
Summer Birds: The Butterflies of Maria Merian by Margarita Engle

Maria Merian was an incredible woman.

Yucky Worms by Vivian French

More Cybils nominees about science and nature:

Have you read any of these books? Do you have any suggestions?


I am excited to report that the experiment for this week are inspired by a new book, You Can't Wear These Genes by my friend Shirley Duke, who blogs at SimplyScience. Be sure to look for my interview with Shirley and more about the book over at Wrapped In Foil. Shirley will be celebrating her 100th blog post this week at SimplyScience, so you might want to stop over and say hello.

About the book:
You Can't Wear These Genes is an easy-to-understand overview of genetics for children in grades 4-7. Reading this book is a perfect way to introduce a lesson on genes and DNA.

Shirley starts out with an idea a child can relate to, how we inherit traits from our parents. Further inside are explanations of common terms, like chromosomes, alleles, and what a genome is. The crisp clear, illustrations of the structure of DNA, for example, complement the text. Not only does Shirley review the background of what we know so far in the field of genetics, but she also gives us a glimpse of the future by looking at the Human Genome Project, genetic engineering and cloning.

I know I will be using this book when I present the following activity to a group of children next month.

Activity: DNA Extraction From Strawberries and/or Bananas

Believe it or not, these days you can extract DNA from common fruits and vegetables right in your own home.

You'll need:

  • strawberries, bananas or both (these fruit contain extra copies of DNA making extraction easier)
  • plastic bags that seal (or something to mash the fruit in)
  • water, preferably distilled
  • a device to measure liquids in ml (optional for a single test, see 1 below)
  • dish detergent
  • table salt and measuring spoon
  • a container to mix the extraction buffer in
  • isopropyl alcohol and a way to keep it cold. Most recipes call for 90%, but 70% is acceptable.
  • glass container, like a beaker
  • funnel (optional)
  • filter material such as cheesecloth, coffee filter, paper towel or any old piece of cloth
  • test tube or spice jar, and some type of holder to keep it upright
  • A medicine dropper (optional)
  • wooden stick that will fit in the test tube, such as a craft stick or wooden skewer


Before you start, put the isopropyl alcohol in the fridge or on ice so that it is cold when you need to use it. Note:  you can use ethanol, but isopropyl (rubbing) alcohol is cheaper and easier to obtain.

1. If you are working with a group you will need to make the extraction buffer, which is the solution that helps break down the strawberry cells and release the DNA. The basic ingredients are water, dish detergent (or shampoo) and table salt. One common formula is 300 ml water, 25 ml dish detergent, and 1 Tablespoon table salt. Note:  Stir this mixture gently. Excessive bubbles will interfere with the extraction process later on.

If you are doing a single test on one strawberry or one piece of banana, there's no need to make up a big container of buffer. Try 2 tsp water, 1 tsp soap, and 1 pinch salt for each berry.

2. Place a single strawberry or 1/2 a banana in the plastic bag, seal and mash it up. You can do one kind of fruit, or do both separately and then compare your results. The plastic bags works well if you are doing this with a group of children because each child can mash his or her own. You can simply mash the fruit in a bowl, too. This should only take a minute or two. If the banana is somewhat green, you can add a bit of water to make it easier to mash.

3. Add up to 10 ml of the extraction buffer to the bag, and mash some more. Again, try not to create excessive bubbles. Remind small children not to taste the fruit after this step.

4. Set up some sort of filtration system. This can be a simple as a coffee filter over a cup or cheesecloth over a funnel. The idea is to separate the fruit juice from the pulpy material. The DNA should now be in the juice that passes through the filter. You can throw away the pulpy remains. The videos have more details about filtering if you have never done it before.

5. Pour your juice into the test tube or spice jar. If you have a lot of bubbles on top, remove these with a medicine dropper. Now slowly pour in 8 to 10 ml of the cold isopropyl alcohol. It should form a layer on the top of the juice.

6. With the wooden stick, stir at the interface of the alcohol and juice. A thick, globby material should form on the stick, which is your DNA. If it doesn't appear right away, give it a minute or two and try again.

There's nothing like being able to watch someone do a demonstration to help you figure out what to do. Here are two videos that show how to extract DNA, each using slightly different techniques.

DNA Extraction from Strawberry Video

DNA Extraction from a Banana Video

These are sure to give you some ideas for further experiments. What happens when you add the alcohol to the test tube first versus second. Does the order change the amount of DNA you obtain?

Once you are confident of your technique, go ahead and try other fruit or vegetables, such as kiwi or onions. You can also compare room temperature versus cold alcohol to see whether it really needs to be cold. Have fun and I'd love to hear what you find out.

For more information about genetics online, try Learn Genetics at The University of Utah.

You Can't Wear These Genes

Reading level: Ages 9-12
Paperback: 48 pages
Publisher: Rourke Publishing (FL) (August 2010)
Language: English
ISBN-10: 1615905634
ISBN-13: 978-1615905638