Fresnel mirrors is a technology to concentrate light on a focus point. Then the concentrated rays of the sun can be used for different energy purposes. Lytefire is a solar oven freely inspired by Fresnel mirrors.
Fresnel mirrors[edit | edit source]
Technology[edit | edit source]
The technology of Fresnel mirrors is inspired from Fresnel lenses. “The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design.”
Advantages[edit | edit source]
The first advantage is economical. Flat mirrors are cheaper and easier to find than curved mirrors. Flat mirrors are also easier to maintain and replace if needed. Moreover, the overall structure can be more compact in the same way that a Fresnel lens is more compact than a traditional lens. It can be useful to deal with wind troubles and space limitation.
Limits[edit | edit source]
The approximation of a parabolic mirror leads to a less precise focus point. Depending on how the concentrated light is used after, a second reflector may be necessary.
History[edit | edit source]
In the 19th century, the Italian Allessandro Battaglia did pioneering work on solar concentrators. He did not make practical implementation, but his work is considered as the origin of Fresnel linear concentration technique. In the 20th century, another Italian named Giovanni Francia developed a Linear Reflection Fresnel Concentrator system and he built the first prototypes in Genova (Italy) in 1963 and in Marseille (France) in 1964. Francia’s belief was that solar energy could develop only with economic efficiency and a simple technology, hence the flat mirrors importance. Since then, the Linear Reflection Fresnel Concentrators have developed slowly around the world. An increasing interest in this technology is emerging in the context of climate emergency. The Solar Fire Concentration Ltd technology is close to LFR geometry. It is simpler and adapted for small-scale application (oven) for a wide dissemination of the system, particularly in poor countries.
Lytefire[edit | edit source]
Technical specification[edit | edit source]
The Lytefire is the solar oven inspired by Fresnel mirrors and developed by Solar Fire Concentration Ltd. It has 5 m2 of mirrors made of small-size flat mirrors oriented differently. These mirrors reflect the sun rays in a second collector which is directly linked to an oven. Thanks to the high power of this oven, professional bakers can rely on this technology for their business.
Pilot projects[edit | edit source]
Multiple pilot projects were developed: three in Africa Kenya and one in France. These pilot projects confirmed that a professional activity can rely on sun power. A bigger Lytefire was built for the French project with 11 m2 of mirrors and it proved that a professional baker could rely on the sun even under European latitudes (in Normandy).
Impact[edit | edit source]
The impact of these solar ovens on the pilot projects were measured and calculated. The impact on climate is obvious as the sun power replace fuels which emit greenhouse gas. On a normal baking year (i.e. around 25 tons of bread for one oven), one Lytefire can save few tons of CO2eq, depending on which oven it replaces (electric, gas or wood-fired).
The social impact is also high as it allows people to start an entrepreneurial activity relying on sustainable and autonomous source of energy. Due to the simplicity of the design, the solar oven can easily be built and maintained locally everywhere in the world. In addition, solar cooking prevents bakers from inhaling toxic fumes from wood or coal combustion and thus it is better for health. All in all, the Lytefire fights for 7 of the 17 United Nation Sustainable Development Goals: No poverty (1/7), Gender equality (5/17), Affordable clean energy (7/17), Decent work and economic growth (8/17), Reduced inequalities (10/17), Sustainable cities and communities (11/17), Climate action (13/17).
The oven is no lack of economic benefits. The simplicity of its design allows local craftsmen to build it for an affordable price locally in developing countries. Then, the use of this solar oven has no fuel costs and maintenance costs are not higher that traditional ovens. Pilot projects showed that solar bakers tend to augment their profit (due to reduced costs) and to augment their production (due to easy and free energy). The Lytefire allows communities to develop and thrive thanks to sustainable and economic activity.
[edit | edit source]
- Cogénération héliothermodynamique avec concentrateur linéaire de Fresnel: modélisation de l'ensemble du procédé, F.Veynandt, déc. 2011
- Arnaud Crétot is a French baker using a Lytefire. His website: https://neoloco.fr