Ararsa Derese Seboka’s PhD shows that combining different types of organic waste can boost biogas production by up to 40 percent, while turning residual materials into new bioenergy products and reducing dependence on traditional fuels.
In many developing regions, energy systems still rely heavily on traditional fuels such as firewood and charcoal, while large amounts of organic waste are poorly managed and contribute to environmental pollution and loss of forest resources.
In his PhD research at the Norwegian University of Life Sciences (NMBU), Ararsa Derese Seboka shows how this challenge can be turned into an opportunity by using natural biological processes to produce biogas. He further demonstrates how these processes can be integrated into a circular system that also converts biogas residual materials into bio‑briquettes.
An overlooked source of energy
Seboka’s research shows that significant quantities of biodegradable waste remain underutilized despite their high energy potential.
By combining biological conversion for biogas production with the mechanical processing of digestion residues into solid bio‑briquettes, organic waste can be used for cooking and heating, replacing traditional fuels and improving local energy access.
A key contribution of the study is the experimental validation of an integrated waste-to-energy system that improves both energy recovery and resource efficiency.
“Combining different organic waste streams can increase biogas production by up to 40%,” says Seboka.
“It also enables the reuse of digestion residues as bio‑briquettes and soil amendments.”
Where waste and energy needs meet
The thesis also provides detailed evidence from both field studies and laboratory experiments. In Southern Ethiopia, hotels and university campuses were identified as important ‘decentralized hubs’ where organic waste and energy demand occur in the same place.
“These sites generate substantial amounts of biodegradable waste, Seboka explains.
“Up to around 1,450 tonnes per year at the campus level, while still relying partly on fuelwood and fossil fuels for cooking and heating.”
Experimental digestion trials showed that co‑digesting agricultural residues such as coffee husk with avocado and flower waste improves process stability and methane yield, while the remaining digestate can be densified into bio‑briquettes with energy values comparable to conventional solid fuels and potential organic fertilizer.
Lower emissions, better energy use
Overall, Seboka’s findings demonstrate that decentralized circular bioenergy systems can reduce greenhouse gas emissions, limit environmental pollution, and decrease reliance on charcoal and fuelwood, thereby contributing to reduced waste, deforestation, and more sustainable energy use.
The results are relevant not only for Ethiopia but also for other low‑ and middle-income regions facing similar energy and waste management challenges.
Ararsa Derese Seboka will defend his PhD thesis “Integrated Circular Valorization of Lignocellulosic Biomass into Biogas and Bio-briquettes with Environmental Implications in Southern Ethiopia”, Monday 18 May 2026. Trial lecture and public defense are open to all.