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Solar Fire in a Nutshell

November 23, 2010

Today, Solar Fire Technologies stand out among the most versatile and effective solar concentrators and will play a key part in reducing deforestation, desertification and poverty… if things go according to plan.

Reading the following post will aquaint you with this project/movement/vision.

After visiting India 20 years ago, my father challenged my grandfather to design a machine that would enable people around the world to harness solar energy. He set three design parameters that he thought would, if met, encourage grass roots popularization. Those three parameters were:

1) That no advanced construction techniques be needed to build it

2) That the materials necessary be available in every major city

3)That it be simple enough that a child can operate it

The working principle is ‘solar concentration’.

As a magnifying glass can start a fire by concentrating sunlight so too can an array of mirrors, when properly arranged. Lenses of sufficient size to gather enough sunlight to cook are prohibitively expensive, but steel and mirrors are relatively cheap and available worldwide.

After a few prototypes my grandfather, Fraser Symington, developed the Helios seen here:

The Helios is a steel structure supporting 54 foot square mirrors which are bent slightly giving them parabola like characteristics. I will soon post a technical brief about how bend mirrors using what we call ‘spiders’. When 54 square feet of sunlight are focused to a 6 inch circle we have achieved temperatures of 900C. The first application we developed was a baking oven. Rated at between 3000 and 3500 Watts, a Helios oven is as powerful or more than most conventional kitchen ovens.

Most people around the world, however, are not accustomed to baking. 2 billion people or so depend on biomass (wood, charcoal, dung) as fuel and cook over a fire. Bending mirrors won’t work for focal points under 10 feet so we developed a new method for creating faceted parabolas… stay tuned for a discussion on how to make them yourself. This lead to the creation of the Vesta domestic cooker.

Domestic scale solar cooker

The Vesta can boil a pot as if the pot were over an open flame (hence Solar Fire) or on a gas or electric stove top. It can also be fitted with an oven. Rated at ~1800W the Vesta is roughly equivalent to the large electric burner on many kitchen stoves. It will boil a liter of water in 6 minutes.

Taking the techniques like the Spider and the faceted parabola, we can build solar concentrators of just about any size and adapt them to accomplish essentially any task requiring heat.

Roasting coffee in Chiapas, Mexico.

Prometheus 100

100 sq. ft. array called the Prometheus 100. Semi industrial scale steam or hot air.

Billions of people depend on biomass as cooking fuel and this has adverse effects on their health, their income and the environment. As I mentioned in my post on Haiti, many families spend between 25 and 40 percent of their daily income on cooking fuel. In other cases, children don’t get to go to school because it is their responsibility to go out and find wood. Getting a good solar cooker would essentially amount to getting a 25% raise. Additionally, many cheaper solar cooking techs (box ovens, cardboard and tinfoil light funnels) have encountered resistence because of the dissimilarity between a slow cooker and cooking over a fire (recipes and schedules have to be changed). Solar Fire techs cook like fire and so have one less barrier to market.

My goal is to spread awareness of Solar Fire and share my knowledge of how to build the machines so that their adoption becomes viral and as many people as possible start using them asap.

Check back soon and I will have completed each of the tech profiles which you can find in the navigation bar. In the meantime, for further info you can visit http://www.solarfire.org

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2 Comments leave one →
  1. December 29, 2010 1:37 pm

    This is fascinating – even for a non-scientific reader like me. Solar Fire sounds like a viable alternative to OPEC dependency and environmentally friendly. I’m going to tweet the link to this post because I believe it’s worth sharing with as many people as possible. Jackie in Colorado

  2. July 19, 2011 11:21 am

    Fantastic projects!!!

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