New bio digester designs - Why?

New bio digester designs - Why?

In Ethiopia cooking is mostly done using biomass (wood and dung) in traditional stoves as access to modern energy is limited.

Since 1979 the country has been promoting the biogas technology. During that period, Ethiopia has constructed around 1,000 biogas plants in various parts of the country. However, I observed that most of the plants are not functional due to:

  • Lack of effective management and follow-up.

  • Adoption of a project-based stand-alone approach without follow-up structure in place.

  • Absence of design and quality standard.

  • Technical problems such as poor workmanship and loss of interest.

  • Users’ lack of capacity in terms of operations and minor maintenance etc.

On the other hand, the demand for alternative energy sources keep on growing. To address the issue, the country has established the National Biogas Programme of Ethiopia (NBPE) in 2008 - a joint effort of Ethiopian Rural Energy Promotion and Development Centre (EREDPC) and SNV Ethiopia.

The programme began implementation in Amhara, Oromia, Southern Nations Nationalities and Peoples Region and Tigray regions promoting Nepal’s GGC2047 fixed dome bio-digester which was locally called SINIDU. Through the use of household digesters, the families and friends of the long term bio-digester users like Shume Deyas and Tesfanesh Bekele have benefited from the light, energy and the co-product bio-slurry. But they keep asking for improved but cost effective technology to address their energy needs. For example, Welde Kidanu Nereay, a farmer in Tigray region Hintalo Wajirat woreda, wishes to have a water efficient bio-digester technology as he is living in a water scarce area.

The National Biogas Programme of Ethiopia - one of the responsible structures to support the country achieve its plan to give affordable, clean and modern energy for all citizens by 2025 - started to introduce and promote bio-digester designs which are less costly, more efficient and adjustable to different soil conditions and moisture. Consequently, the programme is rolling out bio-digester designs called SINIDU2008 in all regions, piloting Solid State Digester (SSD) and Black cotton Soil Digesters (BSD) in Oromia region and planning to launch non-domestic large size bio-digester to create market-based sector development.

New bio digester designs - Why?

SINIDU2008 constructed by trainee masons (January 2018)

The SSD is suitable for all regions and more specifically for water scare regions as it uses 75% less water as compared to the conventional SINIDU 2008. Users need water with full ratio only for mixing dung for the first initial feeding. Gradually the amount of water used for mixing decreases and finally only a quarter volume of water per total volume of daily feeding will be needed as its inlet pipe is modified to allow stiff materials to enter in to the digester.

New bio digester designs - Why?

Soid State biodigester has concrete inlet unlike the SINIDU2008 which has PVC

New bio digester designs - Why?

The Black Cotton Soil Digester (BSD) is more suitable for areas where black cotton soil predominates as its strong structure enables the digester to withstand the contractions and relaxations of the soil in different weather conditions.

New bio digester designs - Why?

Black cotton Soil Digesters with curvature at the bottom

Taking an active role in the process, has given me the opportunity to learn that - compared to the masonry stone construction - the new designs are less costly, easy to construct and more compact in terms of surface area to volume ratio. This will address some of the main repelling factors the prospective users raise – space and cost.

Before rolling out large size bio-digester by mid 2018, SNV has made an inventory of non-domestic larger size bio-digesters in pre-identified establishments such as public institutions (prisons, religious settings, elderly houses) and commercial entities (dairy farms, feedlots and abattoirs) in Oromia, SNNPR and peripheries of Addis Ababa.

Messele Kada, Senior Expert - Product and Quality Development, SNV, said, _“_NBPE+ has made quick a inventory in terms of existing larger bio-digester designs in Ethiopia, identified targets and potential threats affecting the dissemination of the technology. We have learnt that most of the larger size bio-digesters built for the last three decades in Ethiopia are very few in number and most of them are not functional due to technical, maintenance and other follow up problems”. I’m sure these problems will be given due attention and addressed when the After Sales Service Guideline is fully implemented.

Along with the promotion of the new products, SNV is enhancing capacity to make the technology market based. Biogas masons/biogas construction enterprises together with technical personnel from national and regional biogas programme coordination units, regional mines and energy offices, have taken a ToT which aimed to build the skill and knowledge of constructing the new SSD and BSD digesters. SNV will keep documenting the lessons on the performance and suitability of new products accessories/appliances.

Currently**,** more than 18,481 domestic bio digesters are constructed. Biogas Dissemination Scale-Up Programme (NBPE+), a five year (2017-2022) EU funded programme, is designed to play a key role in promoting alternative designs for improved bio-digester market with options for different products suiting specific segments or conditions.