Weeds to Wealth – Brazil

December 2004

In the coastal state of Ceará in Brazil, the cultivation, drying and selling of seaweed has been an integral part of daily life for over 30 years. The over-collection of seaweed has now, however, begun to threaten the coastal environment and ecosystem. The B-REED (Brazil Rural Energy Enterprise Development) programme has been introduced to assist a village co-operative, which has begun to cultivate seaweed in a more sustainable way. The programme has also helped improve the drying process, thereby increasing productivity and creating a final product of higher quality.

Seaweed Cultivation

Seaweed is a marine alga that is generally classified as a plant. Most seaweed species are red (6000 species), brown (2000 species) or green (1200 species). Seaweed is found throughout the world’s oceans and seas – many are eaten* and considered to be a delicacy. There are many other uses, with seaweed extract appearing in many foods and cosmetics.

The development of seaweed cultivation is generally market-driven. If demand is low and natural resources are adequate, artificial cultivation is unnecessary. As demand increases, however, attempts may be made to increase production using resource management techniques. Improvements can be made to harvesting methods and artificial habitats, competing species can be removed and cleared areas seeded.

Should management prove to be inadequate, the use of artificial structures to grow seaweeds becomes inevitable. The techniques used to cultivate seaweed depend on the species being farmed, the life cycle, and biogeographical factors. In general, fragments of adult plants, juvenile plants, or sporelings are seeded onto ropes in nurseries and then the plants are grown to maturity at sea. The complex life cycles of many types of seaweed means that detailed knowledge of the species being cultivated is critical, especially at nursery/hatchery stages. For example, kelps cannot be grown from fragments of adults as fragments do not regenerate. For red seaweed, on the other hand, this is easily possible.


Flecheiras is located in the Municipal district of Trairi, about 150 km from Ceara’s capital city, Fortaleza. The main economic interests in the district are fishing, agriculture and tourism. The Flecheiras region has about 40,000 inhabitants, 75 per cent of them in rural areas. About half the population is considered to live in poverty, without adequate access to health services, sources of nutrition and education.

Conditions in the fishing industry are poor, with little reward coming from long, arduous hours at sea, and there has been a growing interest in what else the sea can offer. The marine flora provide plentiful resources that can be used for the benefit of the local people. Seaweed cultivation has the potential of benefiting many women, who are the most likely to adopt the practice.

In Flecheiras, seaweed cultivators adopt the following method. A rope structure is attached to the sea bed and to buoys near the beach, and seaweed plants are cultivated in the rope. Planting is therefore carried out in shallow waters, and caring for the crop is done through frequent visits by boat. After approximately 3½ months, the plants can be harvested, cleaned and dried for retail. In general, seaweed loses about 80 per cent of its weight after drying. It is possible to cultivate several tonnes of seaweed in each location and studies have been made into the possibility of reducing the growing period. This would have the combined benefit of increasing income and reducing the seasonality of production. In areas such as Flecheiras and Guajiru, harvest periods as low as two months have been achieved.

Where cultivation in the sea is not successful or efficient, the plant can be grown in artificial beds on land. This involves the use of either tanks or ponds into which seawater is pumped and the seaweed is grown at very high densities. This requires the careful study of the growth parameters of the seaweeds involved and the development of special strains adapted to the artificial conditions.

Uses of seaweed

Seaweeds are used in many countries as a source of food, for industrial applications and as a fertiliser. Seaweeds may be used as:

  • A stabiliser and/or emulsifier for many food products, such as chocolate.
  • An additive in instant food drinks.
  • An emulsifier, to bind certain foods together and give them a smooth consistency.
  • Medicinal ingredients in the preparation of surgical jellies, soothing ointments (demulcents), and antacid tablets.
  • Natural latex creaming and thickening for rubber.
  • Adhesive for paper bags and gummed tapes.
  • Coating for food packages and milk containers, ceramic glazes, leather finishes, and emulsions.
  • Additives in the preparation of fertiliser and pesticides.

A Clean Reed

In Flecheiras, seaweed is mostly harvested by simply ripping off the plants from their growing place. This process soon leads to over-harvesting and loss of productivity. To address this problem a partnership venture has been established between IDER (Instituto de Desenvolvimento Sustentável e Energias Renováveis – Institute for Sustainable Development and Renewable Energy), B-REED (Brazil Rural Energy Enterprise Development), E+Co, and APAFG(Association of Producers of Algae of Flecheiras and Guajiru) in the municipality of Trairi.

In a broad sense, the programme seeks to develop new sustainable energy enterprises that use clean, efficient and renewable energy technologies to meet the energy needs of under-served populations. The aim is to reduce the environmental and health consequences of existing energy-use patterns. In the municipality of Trairi, the programme offers rural entrepreneurs a chance to establish a sustainable and profitable small-scale business approach to seaweed cultivation.


The B-REED approach offers rural energy entrepreneurs a combination of enterprise development services and start-up finance. This enables them to develop from business plan to small companies capable of accessing mainstream loans. B-REED provides this assistance by helping build successful businesses that can promote clean energy technologies to rural Brazilian customers. B-REED’s services includes training, hands-on business development services and, for the most promising businesses, early-stage investment and assistance in securing later stage commercial financing.

B-REED offers:

  • Training and tools to help entrepreneurs start and develop energy businesses.
  • Enterprise start-up support in areas such as business planning, structuring and financing.
  • Seed capital for early stage enterprise development.
  • Partnerships with banks and Brazilian organisations involved in rural energy development.

The objective is to help prepare Brazilian organisations to identify potential energy projects and to provide follow-up business support services to entrepreneurs. For these purposes, resource tools that focus on business planning, management structuring and financial planning for the rural energy sector are prepared and disseminated.

A particular element of the programme focuses on the process of drying the seaweed. In Flecheiras, the process traditionally involves placing the seaweed on racks to dry, and does not enhance the final product quality. B-REED identified that adding a solar drier to the process would reduce the drying time, increase productivity, and improve the quality of the plant being cultivated.

Solar-drying Seaweed

Solar drying refers to methods of using the sun’s energy for drying, but excludes open air ‘sun-drying’. Solar driers are more effective than sun-drying, but have lower operating costs than mechanised driers.

The objective of drying is to reduce the moisture content of the product to a specified value, thereby increasing the product’s shelf-life. Moisture content is expressed as the weight of water as a proportion of total weight. The heat required to evaporate water is 2.26 kJ/kg. Approximately 250 MJ (70 kWh) of energy would be required to vaporise 100 kg water. However, there is no fixed requirement for solar heat input to the drier. This is because the incoming air can give up some of its internal energy to vaporise the water (becoming colder in the process). Indeed, if the air is dry enough, no heat input is essential.

Nevertheless, extra heat is useful for two reasons. First, if the air is warmer then less of it is needed. Second, the temperature of the seaweed may be an important factor, especially in the later stages of drying, when moisture has to be ‘drawn’ from the seaweed to its outer surfaces. This temperature will depend mainly on the air temperature but also on the amount of solar radiation received directly by the seaweed.

In a natural convection system, the flow of air is caused by the fact that the warm air inside the drier is lighter than the cooler air outside. This difference in density creates a small pressure difference across the bed of seaweed, which forces the air through the drier. The higher the bed of seaweed is above the air inlet and outlet, the greater this effect will be.

‘Before, we used to place the seaweed in a simple drier and it used to take two days to dry. Sometimes when it rained and got wet we had to start again. But with this new drier we put it in and after an hour and a half it is already dry.’
Raimundo Nonato Nunes, seaweed producer

In Brazil a more advanced drier is used. The ‘tunnel drier’ was developed to dry lemongrass in Thailand and different kinds of fruit around the world. The drier is easily adaptable to the specific plant or fruit and its demands of temperature and drying time. The product to be dried is distributed on a mesh grid of appropriate size. The sun passing through a transparent plastic roof heats up the seaweed. Air flows through the tunnel by means of small fans powered by a solar photovoltaic panel. The temperature and the airflow are adjusted according to the necessities of the seaweed. This requires knowledge of the appropriate values, which is provided by the training services offered by B-REED.

Solar Tunnel Dryer
Solar Tunnel Dryer

The drier is easily constructed and can be constructed locally without any sophisticated materials. Essential items are plastic sheets, wood, and a handy carpenter. The cost of the unit, completely installed with the solar panel and fan, is R$4000 (4000 Reais = US$1,400). Prices paid for seaweed products in the area are normally about R$0.4 per kilogram. The community’s experience of drying seaweed, without drying technology, increased the retail price to R$1.2. With a solar drier, the end product could fetch a price of R$1.7.

Research by IDER has showed that the help from B-REED and other project members, in the form of essential equipment, training for administration, operation and maintenance, and in marketing the products, could provide a turning point for the community. The results showed the required investment levels were low, making the project feasible for local producers. The process does not require permanent attention and the people involved can work elsewhere.

The enterprise has the potential to add more value to the end product by producing blends with simple additional technology. The production of algae, known as Gracilaria, on the Northeast coast is already a reality. Products such as agar-agar and carragena are extracted from Gracilaria, which can be used in industry as fillers, gel and stabilisers. They are also used in the cosmetics industry as moisturisers and antioxidants.

Training Workshops

‘If we can produce good quality seaweed and introduce it into the market, then the whole community gains. This achievement belongs to everyone in the community.’
Edivan Santos Viana, community leader

The project does not simply give the community the driers and then leave them to work out how best to use these. The partners involved have established a series of training modules to cover the needs and wants of the local people. The aim is not just to teach renewable energy use, but to concentrate on creating a complete production chain where renewable energy is a tool to enhance the produce quality and sustainability. Local people, nearby communities and institutions are invited to acquire and disseminate knowledge.

The training begins with a broad scope, covering personnel information, enterprise management, and accountancy. The specific technical training then covers all steps from cultivating the raw product, through the processing, to the marketing of the final product. The productive use of renewable energy is taught as integral to this process.

The training workshops not only encourage the use of sustainable drying technologies amongst those who participate, they also help to spread a community-wide consciousness of the importance of sustainable techniques. Seaweed cultivators in Brazil can now increase their profits, while spending little extra on the production process and conserving the locally available seaweed.

Most seaweeds are safe for consumption, but care should be taken as a few have been found to be poisonous.

Further Information


Anhalt, J-D. (2003). “The use of renewable energy in the production of goods: seaweed.” World Climate and Energy Event. Ceará, Brazil: IDER.

Participating Organisations

Brazil Rural Energy Enterprise Development (B-REED) www.b-reed.org


Institute for Sustainable Development and Renewable Energy – Instituto de Desenvolvimento Sustentável e Energias Renováveis (IDER)

UNEP DTIE www.unep.org/energy

Donor and Supporting Organisations

Department for International Development (DFID) www.dfid.gov.uk

USAID www.usaid.gov

World Bank www.worldbank.org


ITDG Technical Briefs answers.practicalaction.org

Relevant Hands On case studies

Green Gold – Saint Lucia
Kelp! – Ireland
Weed to the Rescue – Madagascar
Mango Mountains – Burkina Faso
Pollen Power – Brazil
Rise and Shine – Mali