Energy Performance of Saccharina latissima Production System where Biogas is Produced - Case Study of the Swedish West Coast
Background
Tthe European Union Commission’s call to develop bioeconomy strategies for Europe (EC, 2012), the Swedish Research Council (FORMAS) funded Seafarm project set out in 2014 to foster research around a cultivated Saccharina latissima (henceforth S. latissima) biorefinery supply-chain to develop and assess the viability of marine biomass based socio-economic utilization strategies for Sweden. A pilot scale kelp farm was established approximately 20km from the Norwegian border. Sheltered from storms, with adequate currents, salinity and suitable water depths for the cultivation infrastructure. This study therefore perform a systems analysis of a cultivated kelp to biogas and fertiliser biorefinery in the perspective of energy and greenhouse gasses (GHG) emission performances, in support of future decision making and to shed light on the viability of scaled up kelp cultivations and third generation biofuel biorefineries in a Swedish context.
Reference
EC, 2012. Innovating for sustainable growth: a bioeconomy for Europe, in: Directorate-General for Research Innovation (Ed.). Publications Office of the European Union, Brussels.
Findings
Using a conservative estimate for the biogas yield (40% of experimental yield), neither the 0.5 ha case nor the 10 ha estimates reached the target minimum EROI of 3. The EROI value for the 0.5 ha case was below 1, meaning that more energy was consumed than produced by the system, while the 10 ha estimate EROI value was slightly above 1, meaning that only a little less energy was consumed than produced by the system. An optimistic biogas yield (90% of experimental yield) however, at 10 ha revealed an EROI of 2.6 and GHG savings potential above the 60% target. Analysis of the scale up identified processes in need of improvements, such as anaerobic digestion and potential for economies of scale, such as in the at sea processes, both worthy of further investigation. For more detailed findings please see published material.
Reference