Our factory in Murang’a, Kenya is on the cutting edge of sustainable practices thanks to the Olivado Biogas Project.
This project was created to find a responsible and sustainable solution for dealing with the waste the factory produces.
Biogas is a perfect solution for treating the organic waste from the factory, as it not only offers a renewable substitute to costly and unreliable grid electricity, but it is also an alternative to the environmentally damaging vehicle fuel that is currently used.
On top of that, a by-product from this process comes in the form of a bio-fertiliser from digester effluent, adding further value to this treatment process.
Early on in this project, it was clear that there was great potential for duplicating this system in the region. Various other food processors were facing similar challenges in waste management and energy supply, and this led to the establishment of Olivado Biogas Africa Limited.
The goal was set to develop and showcase a system that is technically and economically viable in this environment, helping local communities, businesses, and the environment.
The 4 key elements of the Olivado Biogas Project
The project can be broken down into the following 4 key aspects:
The capital investment of our system is 25%-50% that of other, similar systems installed in the region. It is safe to say, that future systems will only be more favourable in this regard, due to the experience gained from this pilot project – and this makes for a very viable solution for dissemination of this technology in Africa.
Development of local capacity
Our approach of taking the time to source and develop local capacity will enable us to provide installations that can be reliably and sustainably operated and maintained, even in remote locations.
Simplicity of design
With this again the focus has been on developing a product that can easily and reliably be sustained in developing countries. The concept was developed in Germany and lends itself perfectly to operation in this environment.
Locally-sourced materials wherever possible
Due to the nature of the location of many agri-industries in the region, we felt it was necessary to use readily available materials wherever possible. This allows for installation in remote locations and offers the opportunity to establish operations close to the product.
Challenges faced during the project
From very early on in this project our mandate was not solely to install a system to serve the Olivado factory in Kenya, but also to offer a viable option for our facility in Tanzania, and further as a pilot project to demonstrate a very real solution for duplication across Africa.
Looking at the bigger picture meant we were prepared to spend time on the design, material, equipment and skills sourcing/refinement with the aim of developing a product with great potential.
From our past experience in operating in this region, we knew that something as new as this would come with challenges, but we also felt confident that they could be overcome and by the end of it, we would be able to do it all over again with much more efficiency.
We certainly did have significant challenges along the way and it has taken 3 years longer than we planned for, but the finish line is in sight.
With the digesters operational and all the end-user equipment in place, we now look forward to the final commissioning this year, which will allow us time to fine-tune the operation and maximise the potential in the following avocado season early next year.
We found many challenges to this enormous project, most of which can be broken down into the following 4 categories.
Availability of materials
Wherever possible we used construction materials that we knew, from experience, would be readily available locally. Over time we managed to build up a good network of suppliers, locally and abroad, and a clear picture of which materials should be considered for purchasing from abroad in future.
Extreme weather event damage to gasholder membrane
We suffered a major setback due to damage caused by an extreme weather event. This caused delays in completion as we needed to make repairs.
Two separate equipment orders, one from India and one from Germany, were delayed during the project, resulting in the entire process taking much longer than planned.
Local financial Institutions
From the start, finding local banks that were interested in providing finance for projects like this, was a challenge. Funding assistance offered by DEG was invaluable and together with having to dig deep into our own resources, we managed to keep moving forward.
These delays and financial difficulties were completely out of our control and added to project costs significantly.
However, we took so many lessons from this experience and in the end, we have managed to achieve our goal of developing a technically and economically viable solution for industrial-scale anaerobic digestion in Africa.
With all our experience gained, we are confident and very excited about effectively launching Olivado Biogas Africa Ltd as a leading provider of commercial biogas plants in Africa.
Although the metres which measure gas flow arrived late from India, we can still predict that for 4,000 tonnes of avocado fruit processed per year, the bio-fertiliser produced annually will have a value of €450,000.
The automated digester feeding process starts at the back of the factory where 3 waste streams consisting of avocado seeds (stones), avocado pulp, and green process water exits the avocado oil production process.
A chopper is used to crush the seeds and a conveyor combines the crushed seeds with the pulp coming from the decanter before depositing it into a 24m³ mixing tank together with the green processing wastewater which is separately pumped in.
Sensors indicate when mixing pumps are switched on and off, with the feedstock pH and temperature measured on a regular basis to monitor the characteristics of the feed.
This automated process replaces the labour-intensive waste-handling that was in place before embarking on this project.
The plant consists of two underground anaerobic digesters, each with 1,400m³ substrate capacity.
A giant circular wall surrounds the tanks, which also has viewing ports so we can see what’s going on inside.
The two digesters can operate in series or in parallel and this is manually controlled via a selection of valves in the feeding lines. This setup allows us to optimise the process at different times of the year depending on waste quantity.
Digester mixing is achieved with two high flow pumps offering completely external installation and easy maintenance, so if things break, they can be easily fixed without shutting down the entire system.
Each tank has a large gas holder which looks like a giant tent. They can both store 1,400m³ of biogas each at low pressure, and are built from two separate membranes, with the outer one protecting the inner one from the elements.
Digester effluent flows into the tanks via gravity, while at the bottom the same volume simply flows out. This simple design feature makes feeding very straight forward, yet is incredibly efficient, both in terms of gas production and waste treatment.
Biogas bottling plant
The Biogas bottling plant consists of two main components; biogas purification and the compression/bottling of biomethane.
Despite severe delays in equipment arriving from India, we finally managed to get all the equipment on site, and once that happened, we were able to move forward successfully.
In September 2018 the installation was completed, tested and we produced our first purified biomethane with a methane content of 97%.
This purified biomethane will serve to supply our two natural gas CHP generators, with any excess gas compressed and bottled for use as a vehicle fuel and substitute for petrol.
CHP generators (electricity & heat)
The CHP system was designed by Jurgen Schwarz from Schwarz Electrics, Germany , who is also our lead consultant for all matters relating to the two CHP generators and the new electricity distribution system.
The design of the new system allows us to choose which generator to operate and for what purpose. In off season we can cut down on our electricity use, while during peak season, we have the option to run the bigger generator, or even both at the same time.
The extensive design came at a significant cost in cabling and electrical components, but we now have a commissioned/operational CHP system successfully providing all electricity and hot water requirements for the site.
Through this process, we have developed a biofertiliser called Avogrow, which has been certified by the KEBS (Kenya Bureau of Standards). After the solid/liquid separation of the effluent from the digesters, the solid portion remaining is enriched with crushed rock phosphate.
Trials and analysis have shown very good results for use of this by-product as a bio-fertiliser and soil conditioner, and we now plan to market/sell both solid and liquid fertiliser.
Analysis of our pulp and process water waste has also shown high quantities of boron and zinc, both of which are lacking in soils in central Kenya and Tanzania, offering further potential as a source for farmers in this region.
Much of the liquid proportion, after separation, can be recycled back to the mixing chamber where it can be used to water down the feedstock to facilitate ease of pumping.
On top of that, the active bacteria in the effluent water also continuously re-inoculates the digesters and thus enhances the stability and efficiency of the anaerobic digestion process. Any portion of the liquid effluent not recycled runs through a planted wetland system for further filtering and removal of nutrients, whilst being utilised for crop/biomass production.
Utilising the digester effluent in this way completes the cycle and therefore maximizes the potential from our avocado oil production process.
Training of personnel
One of the benefits of the extended duration of this project is that it provided us with the opportunity to offer extensive on-the-job training to a number of staff members, resulting in a reliable and capable team to maintain and operate the plant efficiently.
Two of our team members, Stephen Kageche and John Chege, have been part of this project from the very beginning and know this biogas plant inside out.
Stephen Bwoga has joined us more recently and comes with very good technical background. He has been employed to operate and maintain the bottling plant and CHP generators, as well as offering technical support on site. He has been completely involved in every step of the installation of all the equipment relating to his role and worked very closely with the engineers from India and Germany during installation.
Though not currently part of our team anymore, Geophrey Oyugi, engineer and former employee during this project, deserves being mentioned. He left us only to pursue a wonderful opportunity to complete his Masters’ degree at the University of Edinburgh.
The hands-on experience gained in designing and realising this project, including all the challenges faced and overcome, for the most part, by ourselves, has also given our staff the necessary skills to confidently undertake new projects by Olivado Biogas Africa Limited. This gives us great confidence in our ability to efficiently deliver this service to prospective clients.
We strongly believe that the Olivado biogas team is the most qualified and most experienced outfit for installing and operating industrial biogas plants in East Africa, if not further afield.
Staff training continues on a daily basis and new challenges always bring with them more experience, constantly improving the skill-sets of all our staff and our team as a whole!
Economic assessment of the Biogas project
Based on actual project expenses and confirmed results, it’s estimated that the Biogas project will pay for itself in only 3.2 years!
And as mentioned earlier, Avogrow, our Bio-fertiliser can add additional value of €450,000 each year to the project.
Factoring in this, the project would pay for itself in only 1.3 years!
For future projects, we will also reduce the investment cost further by implementing changes based on our experience. This will result in an even shorter payback period making this a very viable solution for agri-industries to handle their waste.
Working towards a future of sustainability
With all work complete and a full season behind us, we can safely say the Biogas project was a success, despite the many set-backs we suffered.
Olivado have designed and successfully installed a system that costs a fraction of other similar systems in the region, while having developed the local skills required to implement and operate such a facility.
With both digesters fully operational, CHP generators installed, and fertiliser product developed and certified, we strongly believe the future of sustainability for the agri-industry is in Biogas.
Contact us today if you have any questions about our biogas plant in Kenya or about Olivado. We will be happy to answer any questions you may have.