Green Processing Company · Ngagara, Bujumbura · Burundi

L’Avocat d’AfrikaL’Avocat des Barundi Virtual tourTour

Energy and the loop

The stone becomes fuel. The skin becomes gas. The cake becomes soil.

An avocado-oil plant is first a residue plant: 8 to 15% of the fruit leaves as oil, the rest is stone, skin, fibre and water. We are turning that into an energy programme — for the plant, for Bujumbura’s households and, next, for the grid. What is in place, what is in preparation and what is still only an estimate is written as such.

The material

One tonne of fruit, in five streams.

1 000 kg Oil · 100–180 kg Stones · ≈ 160 kg Skins · ≈ 120 kg Cake · 100–150 kg Process water · ≈ 500 L
  1. Oil100–180 kgThe product.
  2. Stones≈ 160 kgTwo-thirds starch. Dried, a stone burns at 19 MJ/kg — like firewood; torrefied, 23 to 24 MJ/kg, close to charcoal.
  3. Skins≈ 120 kgCompost; slow biogas (79 mL CH₄/g) — polyphenols slow digestion, pretreatment matters.
  4. Cake100–150 kgThe best solid substrate: 204 mL CH₄/g of volatile solids from a cold-press line.
  5. Process water≈ 500 LRich in phenols and in methane (173–247 mL CH₄/g). It is not discharged: it is digested.

Sources: Alfa Laval; Food Chemistry 2020; Waste and Biomass Valorization 2021; MDPI Applied Sciences 2020.

Five routes

What we do with 92% of the fruit.

01 In preparation

Biogas: a battery you fill with avocado stones.

Anaerobic digestion of cake, skins and process water, co-digested with brewery spent grain and livestock manure to bring the carbon-to-nitrogen ratio from 56 to 26–34. One cubic metre of methane is worth about 10 kWh; a biogas engine converts 43% of it to electricity and recovers the rest as heat for the malaxers. The gas holder is a reserve: filled all day, burned at the evening peak when the grid falls short. In Germany a biogas plant earns its premium only if it installs twice the engine capacity it needs on average — the flexibility rule.

22,000–35,000 m³of methane per peak day, estimate for 1,000 t of fruit
1–2 MWeengine class for a 10,000 to 15,000 m³ digester (estimate)
6 hof evening-peak support with ≈ 5,000 m³ of storage (estimate)
02 In progress

Briquettes: the stone against charcoal.

Stones dried and compacted, or torrefied to approach charcoal’s calorific value. In Bujumbura a sack of charcoal went from BIF 35,000 to 50,000 between 2022 and 2024; a family of eight spends BIF 4,000 to 5,000 a day on it; making one kilo of charcoal in a traditional kiln consumes up to 10 kg of wood and emits 7 to 9 kg of CO₂e. Schools, barracks and institutions are the first customers: the army already buys some 10,000 tonnes of peat fuel a year.

19 MJ/kgdried stone; 23–24 MJ/kg torrefied; charcoal ≈ 30
BIF 50,000a sack of charcoal in Bujumbura in 2024
2,000–6,000 t/yrof briquettes, estimate depending on the share of stones kept for biogas
03 In progress

Compost: the soil of the hills goes back to the hills.

Cake and skins are composted with spent grain from Bujumbura’s brewery and manure from livestock farms: carbon, nitrogen, structure. The digestate from the biogas, next, brings 4 to 5 kg of nitrogen per tonne. The compost goes back on the same trucks that brought the fruit, to the cooperatives that delivered it. Target: every truck that comes up full goes back down full.

4,000–6,000 t/yrof finished compost, estimate
4–5 kg Nper tonne of fresh digestate
0empty trucks on the return trip, target
04 In preparation

Process water: screening, flotation, digestion, reed bed.

An oil mill’s effluent is acidic, loaded with organic matter and phenols. The treatment train we aim for: screening, oil recovery by flotation, anaerobic digestion (where the methane is made), aerobic polishing in a planted reed bed, then reuse for irrigation. Anaerobic digestion removes 62 to 94% of chemical oxygen demand; a reed bed takes out 80 to 90% of what remains. Zero discharge is an aspiration; effluent analyses will be published.

62–94%of COD removed by anaerobic digestion
80–90%of COD removed in a reed bed
≈ 500 Lof effluent per tonne of fruit
05 In preparation

Electric collection: the fruit goes up, the compost comes down.

Burundi has lived through cyclical fuel shortages since 2022; in August 2026 a litre of petrol cost BIF 4,000 at the official price and close to 13,000 on the black market. An East-African-built electric motorcycle carries 220 kg for 180 km and recharges in four hours from a socket; a tricycle, up to 500 kg. Solar charging stations every 30 km — Zembo’s model in Uganda — cover a 100 km radius around the plant. The national rural-energy programme supplies the station network; the plant supplies the return load.

220 kg / 180 kmpayload and range of a regionally built electric motorcycle
BIF 13,000a litre of petrol on the black market, August 2026
30 kmbetween two solar charging stations, the Ugandan model

Estimate

How much energy in a day of fruit?

The calculator applies published yields — residue mass, measured methane potential, 10 kWh per cubic metre of methane, 40% electrical efficiency, 19 MJ/kg for briquettes — to a fruit tonnage. These are orders of magnitude, not plant measurements; methane-potential tests on Ngagara’s residues are the programme’s first step.

Drag the slider: tonnes of fruit per day. Every value is an estimate built on published yields (Alfa Laval; IEA Bioenergy; peer-reviewed journals), not a plant measurement.

Oil— t/day
Methane— m³/day
Electricity— MWh/day
Households that could be supplied— households
Seed briquettes— t/day
Charcoal displaced— t/day
Compost— t/day
CO₂e avoided— t/day

Estimate.

It has been done

Two plants that prove the loop.

Olivado, Murang’a (Kenya)

Two buried 1,400 m³ digesters, designed for up to 5,000 m³ of biogas a day at 66% methane, upgraded to 94–97%: first biomethane in September 2018, for the pickers’ trucks, field cars and staff buses. Certified biofertiliser sold for EUR 450,000 a year. Payback: 3.2 years on the gas, 1.3 years with the fertiliser. 2,200 smallholders.

Gorge Farm, Naivasha (Kenya)

150 tonnes a day of vegetable residue into Africa’s first grid-connected biogas plant (2015): 2.4 MW, USD 6.5 million, payback under six years, 35,000 tonnes of digestate a year returned to the fields, about 6 million litres of diesel displaced.

The national programme

One plant, one pillar of a national waste-to-energy programme.

GPC puts its residue stream, its site and its laboratory at the service of a national waste-to-energy and rural-energy programme, carried by PURE Power Burundi and presented as such to the ministries responsible for agriculture and energy. The programme rests on the Rusi polytechnic campus as national base and training academy, on the continental AAIN network of agribusiness incubators to deploy, and on cooperation with FAO for agro-processing and productive-use energy. For the plant it means: residue digestion co-fed by other Bujumbura manufacturers, a network of solar charging stations for electric collection, operator training, and stored biogas that supports the grid at peak hours.

Programme in preparation; agreements and their scope are specified as they are signed. The programme is promoted by Gigawatt Burundi S.A. under the PURE Power Burundi brand. PURE Power Africa · PURE Power Burundi

Join the energy programmeCo-product availability and terms
Operator in front of the plant boiler
One fruit, four products: oil, compost, livestock feed, briquettes — and biogas in preparation. Whole avocado pressed in Ngagara Oil to industry Compost back to the soil Livestock feed pigs, on trials Briquettes cooking Compost goes back to the fields · biogas and water treatment in preparation

  1. Oil

    To refiners and manufacturers in food, cosmetics and pharmaceuticals. Analyses on every lot.

  2. Compost

    Cake and skins composted with brewery spent grain and manure, then returned to growers’ fields.

  3. Livestock feed

    Dried, milled stone, up to 10% of pigs’ rations according to published trials; never for ruminants or poultry.

  4. Briquettes

    Dried, compacted stones, an alternative to charcoal for households and institutions.

Avocado oil

Main product

Avocado oil

To refiners and manufacturers in food, cosmetics and pharmaceuticals.

See the oil

Compost and biofertiliser

Co-product · being set up

Compost and biofertiliser

Cake and skins are composted with spent grain and manure and go back to the fields of partner growers and cooperatives.

Livestock feed

Co-product · in development

Livestock feed

Dried, milled stone, up to 10% of growing pigs’ rations according to published trials; never for ruminants, poultry, rabbits or horses, which are sensitive to persin.

Briquettes

Co-product · in development

Briquettes

Dried, compacted stones: an alternative to charcoal for Bujumbura’s households and institutions.