Studies indicate that despite the plentiful sunlight in sub-Saharan Africa, residents continue to rely on wood and coal for energy. NTNU is spearheading research to explore methods for harnessing solar energy in the area.
Replacing Wood and Coal With Solar Energy
Despite the potential for solar ovens in sub-Saharan Africa, many still use wood or coal for cooking, leading to health issues from smoke and soot. A study from the KTH Royal Institute of Technology suggests that replacing wood and coal could save up to half a million lives annually.
Solar ovens in Africa provide a cleaner, healthier alternative to traditional cooking methods.
In Uganda, residents often cite the short lifespan and high cost of batteries as reasons for the lack of small solar panels in houses. This lack of storage solutions makes it difficult to use solar and wind energy for cooking. NTNU professor Ole Jørgen Nydal — in collaboration with African universities and as part of Norad programs — is developing technological solutions to develop solar energy for cooking.
Solar Panels Preferred to Direct Solar Heating
In an article in the Energies journal, Nydal reviewed solar cooking concepts like can cookers and solar concentrators, noting their limited adoption despite a long history. The main challenge is the need for solar energy at cooking times. Nydal proposes using heat storage systems, or heat batteries, to store solar energy during the day for evening use, especially in combination with solar panels.
Nydal and team tested heat storage concepts up to 220°C, using materials like vegetable oil, rock beds, and solar salt. They compared direct solar heating with solar panel systems. Despite direct systems being more efficient, solar panels were preferred for their simplicity, durability, and ability to capture diffuse sunlight.
The team evaluated several factors: including the safety and cleanliness of indoor operation, local production and maintenance feasibility, robustness, and the speed of heat transfer to food. Nydal's article notes that some systems are better for frying, while others are more suitable for oven baking.
Nydal notes significant activity among African partners in Ethiopia, Tanzania, Uganda, Mozambique, and more recently in Malawi and South Sudan, with universities in South Africa and Namibia also showing interest.
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
Nydal highlights that while many concepts have been tested, the main challenge now is implementation, which requires moving beyond university settings to engage with external producers and testers. Researchers and students continue to test new ideas such as converting wind energy into heat storage, with Nydal emphasizing the benefits of combining wind and solar energy. The goal is for partner universities to play an active role in developing new cooking energy solutions.
The solar oven research at NTNU has captivated many people over the years. When various concepts were tested under the weak Trondheim sun at NTNU, numerous onlookers stopped to take photos.
Students have also travelled to Tanzania in partnership with Engineers Without Borders as part of their master's projects. Additionally, a group of entrepreneurial students developed a solar grill to test a similar solution in Europe. Some of Nydal's solar oven research is now featured at the Norwegian Museum of Science and Technology in Oslo.
The permanent energy exhibition at the Norwegian Museum of Science and Technology in Oslo traces the history of Norwegian energy from steam power and hydropower to modern sources like solar and hydrogen power. In the solar energy section — alongside early Norwegian solar panels and modern technology — a prototype from NTNU's solar oven project developed by Nydal is displayed.
The efforts led by NTNU and its partners in sub-Saharan Africa highlight significant strides towards harnessing solar energy for cooking. Despite challenges such as storage limitations and implementation hurdles, ongoing research and innovation promise to transform energy access and improve health outcomes across the region.