The collaboration, alongside The Crown Estate, the Centre for Environment, Fisheries and Aquaculture Science (CEFAS), the Scottish Association for Marine Science (SAMS), Queen’s University Belfast and Newcastle University, aims to evaluate the viability of farming sugar kelp seaweed for bioenergy production by anaerobic digestion (AD).
Seaweed is already used in animal feed and dietary supplements, and is also becoming increasingly popular as a so-called superfood, owing to its high protein content, abundance of minerals, including calcium and iron, and high levels of Vitamin C.
It has, for centuries, been used as an organic fertiliser, though more recent applications have included processing to extract valuable chemicals.
There is now growing interest in the UK around the potential of seaweed as feed for anaerobic digestion (AD), to produce sustainable energy.
AD operations use crops such as maize and beet, as well as agricultural and food wastes.
However, there is a question of sustainability when growing land-based crops for energy production, rather than food production, and it is also anticipated that food waste volumes will continue to fall as will the gate fee, leading to availability and financial issues.
Seaweed could be a suitable feedstock replacement as it has the potential to be a sustainable source of biomass, which does not require fertiliser, fresh water or agricultural land for production. Furthermore, seaweeds have high productivity, fast growth rates and high polysaccharide content, all of which are important qualities for biofuel biomass.
Global seaweed production has grown exponentially.
Between 2000 and 2014, production more than doubled from 10.5 to 28.4 million tonnes.
Asia is responsible for 96.6 per cent, with China and India having the largest global markets for seaweed production.
Europe, meanwhile, is only responsible for one per cent.
The following objectives were set for the successful delivery of the SeaGas project:
- The farming and harvesting of Saccharina latissima at a previously untried scale, to support the practical AD work
- The development of an ensilage storage system to support 12-month AD operation and to counter seaweed availability and variability.
- To determine effective operating conditions for anaerobic digestion, including assessment of any inhibitory factors and applications for digestate
- Economic modelling of the supply chain, from seaweed growth to digestate usage, to test financial viability
- Assessments on the environmental impact of seaweed farming and civic society’s willingness to pay
The technical focus of the project is divided into three key areas: seaweed storage to ensure year-round supply; the potential for bio-methane production through AD optimisation and environmental and socio-economic impacts.
The economic case is being assessed through a financial model created for SeaGas, to include the specifics of seaweed cultivation, harvesting and storage.
The project consortium is working towards building a viable supply chain for farming and storage of seaweed, ultimately to enable the production of bio-methane from seaweed, through AD.
The project started in July 2015 and is on track for completion by June 2018.
The Crown Estate is one of the UK’s largest owners of coastal land, including marinas and mooring around half of the UK’s foreshore around England, Wales and Northern Ireland.
The company holds the licensing and rights to the UK coastline for 12 nautical miles out from the shore, therefore providing access and permission for developing seaweed farms in the UK.
CPI is project lead. As well as covering the project management functions, CPI’s AD specialists are responsible for all three work packages concerned with the performance of Saccharina in anaerobic digestion.
We are working across three different scales: small scale batch tests, 8 x 5L small scale reactors and 2 x 800L pilot scale reactors.
This enables us to assess scalability, through the data generated at each scale.
The application of computational fluid dynamics (CFD) modelling to determine heating and mixing efficiencies will aid this assessment. A programme of operational optimisation at pilot scale is underway. The team at SAMS offers expertise in suitable strains of seaweed to use and the optimal growing conditions.
In the first year of the project, SAMS developed the seaweed farms to produce Saccharina for the small-scale AD work.
SAMS is also developing the seaweed storage system for the project, based on the preservation of seaweed. AD requires feedstock 365 days a year and, as with any plant, seaweed has a growing season, so storage is important to ensure a constant supply.
Newcastle University is identifying and modelling the dynamic relationships between our seaweed-food waste AD operations and the reactor microbial communities, with a view to optimising operational conditions to promote safe, stable and efficient digestion.
They have also assessed the polyphenol content of the seaweed, which at elevated levels, can be inhibitory to the AD process.
Queen’s University Belfast has been responsible for growing seaweed for our pilot plant operations; in 2016 they delivered almost ten tonnes (wet weight) to CPI.
We will be digesting around 20 tonnes from the May 2017 Strangford Lough harvest, over the remaining year of the project. Queen’s University Belfast is also working with CEFAS, to look at the environmental and socioeconomic impacts of [pilot-scale] seaweed farming.
CEFAS looked at and selected seaweed farm locations around the UK and has been devising a model for inputting particular ecological, environmental or marine-type factors into the mapping study.
This ensures the best locations for seaweed farming are selected. CEFAS has also been investigating regulatory and legislative framework for the production of seaweed, as there is no current framework in place.
The lack of information on the potential environmental impact of seaweed farms and their management means regulators are unclear on how to interpret requirements under national and international law, and this has the potential to hold up seaweed production.
The SeaGas project is attempting to redress this by reviewing and reporting on the current legislation and licensing processes.
We also have two companies that are subcontracted on to the project to look after two important work packages.
ADAS has been analysing the digestate according to the PAS110 quality protocol and identifying possible market opportunities for its utilisation.
Eunomia has devised an economic model for SeaGas that we are just beginning to test with real data, generated from the project.
This model will enable us to understand the economics of the supply chain, from farming, planting and harvesting through to what happens with the digestate. Flexibility is designed in to the model to enable us to look at various scenarios of AD operation, seaweed farms and co-digestants.
To date, the project team has delivered data which supports the proposal to farm Saccharina latissima as an energy crop.
We have seen successful growth of 20 tonnes of seaweed, the UK’s largest seaweed farm to date and a significant milestone; the ensiling technique has yielded positive results regarding preservation and; the ensiled seaweed has proved itself as an effective feedstock for AD.
We are progressing through the scales and are now digesting at pilot scale, using Saccharina from the 20-tonne farm managed by Queen’s.
Efforts have been made to try and mechanise the harvest, to reduce the cost burden of manual harvesting, the results of which are being fed into the economic model.
By the end of the project, there will also be a better understanding of the environmental impact on the marine ecosystem and appreciation of the socio-economic impacts of seaweed farming for bioenergy production.
The SeaGas project brings together the necessary knowledge and expertise to enable the development of this underutilised marine resource at a commercial scale for the UK.
If the data continues to support commercial seaweed farming and the economics can be made to work, this project will help open up the supply chain to support commercial business opportunities, not only for bioenergy production but also for higher value biorefinery applications.
The next stage should be a small commercial demonstration project, to up-scale the whole process and further de-risk full-scale investment.
CPI are very keen to talk to any potential business partners, interested in taking up this opportunity.