Solar cooking

Position: autonomous/ project owner


Roughly one third of the world population cook their meals over a wood fire. Idyllic somehow, but not without a downside*. Social economic, environmental and health issues require the search for alternative cooking fuels. One of them is just provided by the sun; clean, abundant and free!


Since the first time I saw it working, in Uganda, the idea refused to let me go: somewhere out there must be a hidden solution, the ultimate concept that once and for all outrights the question: if solar cooking works, why would not everybody use it?  

     * Downsides of wood fire

  • Firewood collection, often done by women and children, is heavy and can take hours a day; time that could otherwise spent on income generation and schooling. If not collected by themselves, a great part of the income is often spent on charcoal or firewood, obviously at the cost of other primary needs.

  • Wood is becoming scarce in many places. It is predicted to affect more and more people across the world who depend on this cooking fuel.

  • Intensive wood logging can cause disasters as landslides and floods and local climate change. Droughts or just too much rain (in the wrong season) often result in failed crops.

  • Smoke inhalation (especially when cooking inside) causes respiratory illnesses; it's estimated that millions of people die from it yearly. 

Research and pilot
I read all I found on the subject, gathered solar cookers of the common types - box, panel, parabolic collector - and tested them intensively. This gave me a more practical understanding of the capacities and (dis)advantages of each type. I gave a demonstration in a village and organised a user pilot, providing a family with a box cooker, instructions in Luganda (central Ugandan language) and enough food to try the cooker for about a week. During the pilot however, the weather was (un)luckily not on our hand; it was too cloudy to fully convince the testers of the benefits the oven could bring on the many sunny days.


Hybrid solar-biomass
Based on the experiences in Uganda I developed a 'hybrid solar-biomass oven', in order to make the cooker useful under a wider range of weather conditions. I built a prototype with an oil drum, insulated with glass wool and covered with plywood, closed with a double glass lid. The idea is simple: when clouds appear during cooking, you can burn some small branches or charcoal in a compartment below the drum in order to keep the temperature steady. In this way only a fraction of the normal amount of firewood will be used. Besides, the burner will be efficient and cause hardly smoke.


Wageningen University
When the first tests showed promising results, I commissioned an assignment for students of Wageningen University. For their course 'Cutting Edge Issues' they conducted a study: 'A Social Sciences Approach to the Hybrid Solar-Wood Oven'. They focused on the chances of this concept for acceptance and spreading in rural India. Besides we cooked popular Indian dishes with the prototype. An interesting report was delivered, containing many aspects to consider for further development.


Purify drinking water
Back in Uganda I bought a good parabolic solar cooker; we used it daily to boil drinking water for ourselves and the visitors of our guesthouse. This way we saved costs on the expensive bottled gas. The only disadvantage was that you had to see the water actually boiling to know if it was safe to drink. I started working on a concept that solved this issue. In the same period I had three interns (industrial design engineering and food technology) helping me with the search for the ideal solar cooking device.


Innovation directions
'So if solar cooking works, why would not everybody use it?'
- 'Because it's hardly known by potential users!'
True, but not a fair excuse, given the fact that its extension has been tried for decades. Instead we better recognize that the ultimate solar cooker is not among the current solutions. So either it doesn't exist, or it is still hiding out there. I feel that some innovation directions may eventually lead to a trace:

• Differentiate for specific applications and target groups
• Ideal: solar cooker with extensive heat storage
• For drinking water purification (and tea) 'only'
• Hybrid devices: combinations with other technologies


Indeed, a real good solution would spread itself like wildfire.

Research and pilot

Hybrid solar-biomass oven

Water purification