Sub-Saharan Africa has abundant sunlight, yet many residents still rely on wood and coal for their energy needs. In response, NTNU is spearheading research to explore new ways of harnessing solar power in the region.
Replacing Wood and Coal With Solar Energy
In sub-Saharan Africa, many people still cook with wood or coal, leading to serious health issues from smoke and soot. According to a study from the KTH Royal Institute of Technology, replacing these traditional fuels with cleaner alternatives could save up to half a million lives each year.
Solar ovens in Africa provide a cleaner, healthier alternative to traditional cooking methods.
In Uganda, for example, residents often cite the short lifespan and high cost of batteries as barriers to adopting small solar panels. This lack of effective storage makes using solar and wind power for cooking difficult. To address this, NTNU professor Ole Jørgen Nydal—in collaboration with African universities and as part of Norad programs—is developing new technologies for solar cooking.
Solar Panels Preferred to Direct Solar Heating
Writing in the journal Energies, Nydal reviewed various solar cooking concepts, such as can cookers and solar concentrators, noting their limited adoption despite a long history. A key challenge is that solar energy must be available when people need to cook.
Nydal proposes using heat storage systems, or “heat batteries,” to capture solar energy during the day for use in the evening, particularly in combination with solar panels.
Nydal and his team tested heat storage concepts at temperatures up to 220°C, using materials like vegetable oil, rock beds, and solar salt. They compared direct solar heating with solar panel systems and found that while direct systems are more efficient, solar panels are often preferred for their simplicity, durability, and ability to capture diffuse sunlight.
The team evaluated several factors, including safety for indoor operation, feasibility of local production and maintenance, overall robustness, and the speed of heat transfer to food. As Nydal’s article points out, some systems are better for frying, while others are more suitable for oven baking.
Nydal also notes significant activity among African partners in Ethiopia, Tanzania, Uganda, and Mozambique. More recently, interest has grown to include Malawi and South Sudan, with universities in South Africa and Namibia also expressing interest.
For instance, Jimmy Chaciga—a PhD student at Makerere University in Uganda—published an article on solar cookers in the Journal of Energy Storage. He developed a small-scale solar cooker with an 18-litre sunflower oil tank, a heating element, and three solar panels, achieving promising energy efficiency.
Combining Wind and Solar Energy
According to Nydal, while many concepts have been tested, the main challenge is now implementation. This requires moving beyond university settings to engage with external producers and testers.
Researchers and students are also exploring new ideas, like converting wind energy into heat storage. Nydal emphasizes the benefits of combining wind and solar energy, with the ultimate goal for partner universities to play an active role in developing these new cooking solutions.
The solar oven research at NTNU has captured public attention over the years. During tests of various concepts under the weak Trondheim sun, onlookers would often stop to take photos.
As part of their master’s projects, students have travelled to Tanzania in partnership with Engineers Without Borders. A group of entrepreneurial students even developed a solar grill to test a similar solution in Europe. The project’s influence extends further, with some of Nydal’s research now featured at the Norwegian Museum of Science and Technology in Oslo.
The museum’s permanent energy exhibition traces the history of Norwegian energy, from steam and hydropower to modern sources like solar and hydrogen. In the solar energy section, alongside early Norwegian solar panels and current technology, visitors can see a prototype from the NTNU solar oven project developed by Nydal.
The efforts led by NTNU and its partners in sub-Saharan Africa represent significant strides in harnessing solar energy for cooking. While challenges like storage limitations and implementation hurdles remain, ongoing research and innovation promise to transform energy access and improve health outcomes across the region.
