Artificial barrier reefs: Boosting marine diversity and fish stocks

Exo Engineering, based at the University of East Anglia’s Enterprise Centre, is at the forefront of an innovative approach to enhancing marine life around offshore wind turbines and rigs. Their artificial barrier reefs, crafted from sustainable, low-carbon concrete, are designed to create new habitats that support the revival of marine biodiversity, particularly in the North Sea.

Client: Exo Engineering 

Photos of the installation & underwater shot courtesy of Exo Engineering

Solution

The reefs not only restore biodiversity but also support the local fishing industry. Cod, for instance, has seen declining numbers in the North Sea, partly due to the lack of suitable habitats. Exo Engineering’s artificial reefs are built with a focus on fostering conditions conducive to cod and other marine species, thereby supporting both ecological balance and commercial fisheries.

One of the standout features of Exo Engineering’s reefs is their sustainable design. Unlike traditional concrete, which has a high carbon footprint, these artificial reefs are made with low-carbon alternatives to cement and recycled aggregates. This makes the reefs an environmentally friendly option that not only supports marine life but also contributes to reducing greenhouse gas emissions.

How we helped

Concrete is made up of aggregates, water, cement and air. Of these four ingredients, aggregates make up the largest amount of volume and, fortunately, are low in embodied carbon. Cement has the highest embodied CO2, and this is where our focus has been to find alternatives to OPC (Ordinary Portland Cement), to reduce the carbon footprint of this important building material.

Using bespoke steel moulds and liners supplied by Exo Engineering, we cast 5 units, each weighing 4.5 tonnes, using a bespoke mix which had an increased percentage of GGBS (Ground granulated blast-furnace slag) as a replacement for OPC. In addition, we also used recycled aggregates including granite dust and crushed limestone in order to reduce the carbon footprint even further.

Ongoing trials

The artificial reefs are currently being trialled in collaboration with Total Energies in the Dutch North Sea. The project aims to monitor the impact of the reefs on marine biodiversity over the coming years. The results of the pilot project could provide valuable insights for future nature-inclusive designs of offshore wind farms and other energy infrastructure. By creating sheltered environments for marine species, these reefs encourage the growth of reef-building organisms and provide habitats for juvenile fish, which are essential for sustaining marine biodiversity.

As offshore wind farms expand, initiatives like those led by Exo Engineering offer a critical opportunity to balance renewable energy development with environmental sustainability. The artificial reefs are designed not just to coexist with offshore infrastructure but to enhance the ecosystem around it, promoting a symbiotic relationship between human innovation and nature.

The work being done by Exo Engineering represents a significant step forward in mitigating the ecological impact of offshore projects. By fostering marine biodiversity and supporting the historic fishing industry, the artificial reefs are paving the way for a more sustainable future for both energy and marine conservation.