Toxic algae could fuel power plants

BRETON farmers have taken it into their own hands to try to stop the toxic green algae which has killed up to 30 wild boar on the region's beaches.

After the Agence Nationale de Sécurité Sanitaire confirmed hydrogen sulphide fumes from rotting algae was responsible for the deaths, farmers were blamed because of their heavy use of fertilisers. These chemicals are washed off the land and into rivers where they feed the giant algal blooms that wash up on to the beaches.

Now groups of pig farmers are looking at cutting the pollution that causes the blooms – and also at powering fuel plants with the algae. With 53,000 tonnes of rotting algae cleared from beaches in the Côtes d’Armor this year alone, it could be a major resource.

In the commune of Mené farmers recognised their small farms had no space to get rid of effluent and, being at the head of the Saint Brieuc bay where they boars died, any rainwater just washed the effluent into the bay to encourage more algal growth.

They have set up a gasification plant which mixes agricultural and other waste to produce biogas which they can use to power a steam turbine.

Called Géotexia, the plant is intended to produce 13MWh of energy including 4MWh for adjoining greenhouses and 6,000 tonnes of nitrogenrich fertiliser.

Bacteria-rich pig slurry can be used to produce biogas. The plant uses 35,000 tonnes of slurry mixed with 40,000 tonnes of food industry waste which is fermented in a vat at 35C to produce the gas.

This is burned to produce steam and power a steam turbine which produces electricity – and the waste by-product of the whole operation is nitrogen-rich dry compost which can be sold to other producers.

While the Mené plant is in production – and the commune gets 24% of its energy needs from renewable sources – farmers in Guernevez at Saint-Goazec are taking the next step and performing experiments to see if they can use algae for the gasification.

They mix the slurry with algae to produce biogas. If successful, the algae could power a planned 20 gasification plants near Saint Brieuc. Each 100kW plant costs €700,000 so farmers are grouping together to make it work.