Did you know?

1.3 billion people in the world live without electricity, which makes energy access a crucial world problem that urgently needs a solution. This situation has created extra environmental, economic and social pressure.
It is estimated that rural communities generate 25% of global CO2 emissions. That is more than emissions from all the cars, trains and planes in the world combined.
The use of biomass as a fuel for cooking, along with forest degradation and deforestation, creates around 18% of all GHG emissions.
Household air pollution as a result of burning fuels is responsible for 12% of air pollution in the world.
More than 4 million people die prematurely every year because of inhaling the smoke produced by burning fuels for cooking.
Household air pollution causes lung cancer, chronic lung disease and cataracts. Exposure to excessive smoke is the main risk factor for these diseases.
The use of rudimentary stoves and open fires can cause carbon monoxide to be inhaled at levels 100x higher than those recommended by the WHO.
Undifferentiated and improper depositing of waste in inadequate locations, often close to communities, has consequences for soil and water contamination.
90% of diarrhoeal diseases recorded in Africa are linked to environmental pollution, lack of drinking water and poor sanitation.
It is estimated that 1.8 billion people use sources of drinking water that are contaminated by human or animal faeces.
In Africa, timber harvesting for household firewood or to make coal amounts to around 66,000 hectares per year.
In Sub-Saharan Africa, 200% more wood is used for cooking than the annual tree growth rate.
85-90% of wood’s energy content is lost in the form of heat in traditional cooking methods. Low efficiency increases the use of natural resources.
Women and children spend up to three hours a day looking for, obtaining and transporting wood to meet their daily needs.
Many children cannot go to school full-time because they need to help look for firewood.
The cost of fuel for cooking can represent more than 30% of a household’s annual income.

The Solution

Applying the anaerobic digestion process by building and installing small-scale anaerobic digesters is a simple, practical and effective solution with an environmental, economic and social impact.
For the same energy access, the emission of pollutants related to climate change could fall by 0.4-0.9 billion tonnes of CO2 by 2020 as the result of adopting clean fuels such as biogas.
Reducing the emission of air pollutants means adopting clean fuels, such as biogas, together with more efficient stoves.
Studies on biogas stoves show reductions in household air pollution of up to 90%, which has a significant impact on health.
The use of stoves suitable for burning biogas reduces smoke inhalation, especially among women, caused by cooking.
Using stoves designed for burning biogas favours complete combustion, which reduces the smoke generated and the danger this poses to human health.
Properly disposing of organic waste, especially if latrines are connected to the digester, minimises the spread of parasites, diarrhoeal diseases, etc.
Proper depositing of waste, instead close to communities, minimizes soil contamination.
Stopping waste from being deposited next to watercourses helps increase the quality of water resources around communities.
Anaerobic digestion produces a solid fraction sanitized - digested which can be used as an organic fertilizer.
Anaerobic digestion is a viable alternative for materials that at first glance would not appear to have any added value because they can be used as replacements for biomass and/or fossil fuels.
A small-scale anaerobic digester may avoid the consumption of around 0.25 hectares of forest every year.
Stoves adapted for use with biogas halve the need for fuel (firewood) for the same use.
Replacing firewood, with the resulting reduction in the amount of time spent collecting it, will allow women and children to carry out other activities – literacy.
Waste can be used as fuel, which reduces dependence on buying fuel and variations in price.
Recovering waste could mean a saving of more than 30% of a household’s annual income.

The Project

Anaerobic digestion is a biological process witch breakdown the organic matter in the absence of oxygen. Anaerobic digestion produces two main outputs: biogas which can be used in adapted stoves or for lighting and digest, a solid fraction that can be used as fertilizer.
The project its financed by Fundo Português de Carbono with the support of Cooperação Portuguesa, trough Camões - Instituto da Cooperação e da Língua e da Agência Portuguesa de Ambiente.
The overall aim of Bio&Energy is to reduce vulnerability to the impact of climate change in Sao Tome and Principe.
Ecovisao and the Sao Tome and Principe Directorate-General for the Environment have drawn up a work plan in order to properly implement the BIOENERGY project. The plan is based around four main actions.
To provide technicians and people with the tools they need to implement anaerobic digestion solutions.


The selection of the communities was made based on a set of technical, economic and social criteria, namely:
- Size and number of households.
- The absence of electric energy provided by the network of the Water and Electricity Company of São Tomé and Príncipe (EMAE) and the absence of a medium/long-term expansion prediction.
- Mixed farming potential.
- Access to the community and organization of the houses.
- Proximity to the Natural Park of Obô of São Tomé and the relevant Buffer Zone.
Based on systematized results of the surveys and the campaigns, a plan was drafted and five anaerobic digesters were installed in rural communities of the districts Mé-Zóchi, Cantagalo and Lembá, respectively: Novo Destino, Mendes da Silva and Santa Jenny.

In Santa Jenny and Novo Destino, the work carried out consisted of:
  1. digging of the trench for placing the digesters
  2. installing the digesters and the gas network
  3. landfilling and outside arrangements.
In Mendes da Silva, the work carried out consisted of:
  1. defining the most functional layout in the terrain
  2. making support foundations for the upcoming constructions
  3. building
  4. installing the gas network
  5. landfilling and outside arrangements.
In order to mobilize the different parties involved – Government, District Councils, Sector Entities and the Communities – to support the activities of the project, 3 official ceremonies were held to celebrate the beginning of the project, symbolised with the throwing of the first stone.
The communities‘ involvement in the daily operation of the digester, through the preparation of the residues and the water to be placed in the digester.
These elements are fundamental for the correct operation of the digesters and to assure the production of biogas.
Currently, 18 families, of a total of approximately 70 people, use biogas to cook, in replacement of wood, which is a deforestation precursor.
Training initiatives, development of leaflets and awareness-raising panels, and information exchange between target communities of the project were some of the means used to empower and raise awareness in the communities.


Maria João Martins
General Coordinator

Arlindo Carvalho
Directorate-General for the Environment
Sao Tome and Principe Coordinator

Ana Justo
Project Management

Débora Carneiro
Technical Coordinator

Gordon Ayres
Technical Assistant

Abnilde Lima
Directorate-General for the Environment
Senior Member of Staff, Sao Tome and Principe

Antónia Júnior
Directorate-General for the Environment
Senior Member of Staff, Sao Tome and Principe

Constantina Oliveira
Directorate-General for the Environment
Senior Member of Staff, Sao Tome and Principe

Elisângela Lima
Directorate-General for the Environment
Senior Member of Staff, Sao Tome and Principe

Mayra Baía
Directorate-General for the Environment
Senior Member of Staff, Sao Tome and Principe

Leonardo do Rosário
Directorate-General for the Environment
Member of Staff, Sao Tome and Principe


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