Committed Harvesters The Algorythme Know-How

2014–2016 – CREATION OF ALGORYTHME IN ARS-EN-RÉ, ÎLE DE RÉ

Driven by their passion for the coastline and convinced of the largely untapped potential of French macroalgae, Hélène Jouannet and Tanguy Gauvin founded Algorythme.

Before launching the company, the founders spent two years conducting research and development on the seaweeds of the Île de Ré, laying the groundwork for their expertise.

In the same year, they secured their first harvesting rights in the northern canton of the island and defined their core values: selective manual harvesting, biodiversity preservation, low-tech processing, and ultra-short supply chains.


CONTINUOUS GROWTH

  • 2018–2019: Restoration of 6 hectares of salt marshes and first trials in integrated algal cultivation

  • 2020: Launch of an autonomous solar platform and installation of a second low-temperature dryer

  • 2022: Launch of the Alg4Ré collaborative project with La Rochelle University

  • 2025: Increased annual capacity to 100 tons of fresh algae thanks to marsh-based cultivation


LOW-TECH EXPERTISE

  • Selective manual harvesting – No motorized equipment; algae are hand-cut at low tide using knives, respecting natural crop rotation to encourage regrowth

  • Washed in controlled borehole water – Sand-filtered fresh water, chlorine-free, preserving pigment and enzyme integrity

  • Air-drying at < 40 °C – Ensures the stability of iodine, fibres and polyphenols; uses five times less electricity than standard industrial dryers

  • Custom grinding & sieving – 5 mm flakes for thalassotherapy, 80 μm powder for nutrition, raw material for R&D extraction; particle size certified by laser sieve

  • Regular quality control – Heavy metals, microbiology, and nutritional profiles are tested in partnership with COFRAC-accredited labs


VALUES & DECARBONIZATION

The more algae we produce, the more CO₂ we sequester and oxygen we generate: one tonne of fresh algae can capture up to 1.7 t CO₂‑eq and release around 1.4 t of O₂.
Per hectare, that’s three times the average carbon capture of a mature tropical forest.

Our low-tech process reduces embodied energy: no active heating, logistics limited to a 30 km radius, and solar energy autonomy.
We advocate for a regenerative coastal economy where production becomes an ecosystem service, not a threat.


OUR COMMITMENT

To provide R&D teams, formulators, and industrial partners with 100% French, responsible, and high-performance seaweed ingredients, while preserving the unique ecosystem of the Île de Ré and actively contributing to climate action.


SUPPORT & NETWORKS

  • Région Nouvelle-Aquitaine – Innovation and energy transition funding

  • France Relance – Low-carbon industrialization support

  • Initiative Charente-Maritime – Honor loan and entrepreneurial mentoring

  • CEVA – Technical support for cultivation and processing methods

  • EVALG (ANSES) – Continuous regulatory monitoring of heavy metal and contaminant levels in edible seaweed

  • La Rochelle Carbon Cooperative – Guidance in developing low-carbon strategies

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