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Description
Limpets are one of the most appreciated marine mollusks in the Macaronesian region. In the archipelago of Madeira alone, their consumption reaches up to 180 tons yearly. However, the edible part of the limpets corresponds to only 30% of the total weight while the remaining 70%, around 100 tons per year, relates to their shells which are considered waste and sent to landfills, even though they are potential sources of biomaterials for other industries. The CELS project, funded by EEA and Norway Grants, aims to address the under-usage of this valuable marine resource by creating a new value-chain to reuse this waste in other industries following a circular economy approach. To that end, GoLimpets and NOFIMA will engage in a collaborative effort to determine the quantity and quality of biomaterials that can be extracted from limpet shells, taking advantage of the recognized expertise of NOFIMA’s analytical services applied to the food industry.
The main goal of the CELS Project is to establish the reutilization of limpet shell waste to produce new value chains. This will be achieved by firstly addressing the legal, logistic and food safety aspects related to the collection of shell waste from restauranters, thus establishing a network of potential waste providers and the protocol for its adequate handling. Secondly, the technical aspects of the mineral extraction process will be addressed resulting in the installation of the required equipment for processing the shells, and the initial tests of the mineral extraction process according to industry (client) interests. Lastly, the extractable materials will be evaluated regarding yield and purity of the final product and a scalable business plan will be produced.
Overall, the CELS Project will contribute to a more environmentally friendly approach to waste management of limpet shells resulting in less waste being deposited in landfills, creating jobs, and promoting literacy on marine resources.
Summary of project results
The premise of the CELS project is that this “waste” can be reutilized providing a new added-value resource that can be used in different industries in a circular economy-based setting. To that end, we proposed to evaluate the mineral composition of the shells of the two commercially exploited limpet species (Patella aspera and Patella candei) and establish a business plan that identifies the major players, the sustainability and risk of such a venture.
During the execution of the project, we established that the chitin composition of the limpet’s shells is low, around 3% of the total dry weight of the shell and most of the shell is composed of calcium carbonate (93%). This meant that the potential use of these shells for the extraction of chitin for use in other industries is not viable, leading us to then evaluate the potential uses of calcium carbonate in different industries. This implied performing a market study, that showed that the cost of extraction of calcium carbonate from limpet shells is not competitive, since most calcium carbonate comes from the leftovers of limestone quarries. As such, it was evident that to improve the competitiveness of limpet shell-extracted calcium carbonate, it would be required to identify any potentially differentiating property that might render its extraction viable and profitable. One such property is the iodine content of the extracted calcium carbonate, however testing showed that these shells have residual amounts of iodine. Lastly, we identified a environment friendly and potentially viable alternative, which was to use ground limpet shells aggregated in cement for the construction industry.
Even though the project did not yield the expected results, it was nonetheless important as it represents a first approach to the possibility of implementing a circular economy approach to the exploration of these marine molluscs.
Summary of bilateral results
The development of the CELS project, resulted from the cooperation between the promoter, GoLimpets S.A., and the donor project partner, NOFIMA. This cooperation proved essential for the successful execution of the project and was based in a synergetic relationship between partners. Having a donor project partner such as NOFIMA benefited the project, since their previous expertise in the subject being tackled was greatly important in defining the used methodology. This cooperation resulted in the conjunction of data, acquired by both the promoter and the donor project partner, these shared results consolidated the project results leading to the improvement of the current knowledge and understanding of our approach to the set-up of a circular economy-based product, resulting from the extraction of biopolymers or minerals from the shell of highly exploited marine mollusc. This highly positive cooperative relationship resulted in the desire to continue collaboration in future endeavours.