Decent Democracy
About | Acknowledgements | Contact | | Follow site activity RSS 2.0

Solar Fire Technique

First published May-2010
last update 5-April-2016

There are many solar concentration techniques that are easy to build but low temperature, and so are limited in use. There are also techniques that are high temperature but complicated to build, and so have many uses but are not economically possible in most of the world.

The "Solar Fire Technology" was developed by going to poor regions and developing a technology with what’s available locally and so the high-costs of complicated technologies and the high cost of importing, setting up and maintaining complicated technologies is avoided.

Solar Fire Technique

At the heart of the Solar Fire Technique there are small parabolic reflectors mounted on straight rows, using a method that can be accomplished almost anywhere. To build a larger machine is straightforward: we simply multiply the small reflectors, add and lengthening the rows as required. What’s more, even after the limit is reached, since the focal point is fixed, many machines can be easily coupled together in the same steam system.

The Solar Fire Technique is a method of building high power solar concentrators locally, without any special materials, tools or skills. We understand this to mean construction possible with only wood or bamboo, steel, mirrors and resin/fibre, with no parabolic bending of material, no measuring instruments more precise than measuring tape, and no math skills more advanced than arithmetic.

With these qualities the SFT can be built in any economy in the world, and especially in economies that are poor in consumption but rich in sunlight.

The platform has been created to try to make this rural-viral vision of solar technology a reality (update: currently the first true-rural pilots are underway!).

Pay back period
The main advantage of the "Sol" series of concentrators for agricultural processing is that the payback time can be well under a year if fully utilized (2 - 9 months depending on the fuel being replaced). The small capital, high temperature and power enabling commercial activity that creates real income that pays off the initial investment in a radically short period is what can enable this technology to go truly viral. In order for people to invest in developing countries and rural places the investment must be low enough and payback short enough for people to take the risk. This is really the only criteria that matters, determining every other criteria.

No parabolic construction
The main thing we have observed as the key to getting costs down, is the to use no material cut or bent into a parabolic shape. The parabolic shape results from the calibration of the reflectors by simply watching the reflection and adjusting flat mirror surfaces with screws. The rows our Final Reflectors rest on are completely straight, mounted on a frame also made of straight lengths. This significantly decreases either the tools or the time required to make the machine.

Vertical and horizontal
The technique can be used to make both a vertical and horizontal concentrator, which will be seen more clearly in the applications. The advantage of horizontal reflection is that the focal point can be at ground level for easy access, which is ideal for an oven type application. Vertical reflection on the other hand produces a focal point off the ground and above the machine, but it becomes simpler and more efficient to capture the energy, since heat rises; this is more suited for energy intensive applications like steam production.

All the construction guides in the appendixes are based on steel and mirror, because these materials are widely available and easy to work with. There are of course plenty of other construction, reflective and adhesive substitutes which may be better depending on the situation.

However, the material that has the most promise of significantly reducing cost is bamboo, which is typically 50 times cheaper than steel, if not freely available locally, and will continue to grow under essentially any economic condition, such as the increase in the price of fossil fuels.

At least the rows in the Solar Fire Technique should be relatively easy to construct with bamboo. The rows represent the majority of the steel in the machine and are simply straight members holding the relatively light Final Reflectors. Though with bamboo rows may bend out of shape and it would be necessary to re-tune the machine more often, the time tuning would still be fairly minimal compared to the operation of the machine (and the machine can continue to operate while individual reflectors are tuned to the focal point).

To provide as much rigidity as possible, my design proposal is three bamboo lengths in a triangle configuration, with periodic pieces of flat steel, placed through the triangle, which can serve as the connecting base for the reflectors. A single larger piece of bamboo should work as well, but may be heavier. Development and experimentation is needed.

Written by Eerik Wissenz.

Table of Contents

*Chapters in grey are in progress.

About | Acknowledgements | Contact |
Built with | template | | Follow site activity RSS 2.0