Environmental life cycle assessment of biogas production from marine macroalgal feedstock for the substitution of energy crops

The central objective of this paper is to evaluate the production of biogas by the substitution of energy crops with marine macroalgae: mixture of brown (20%) and red algae (80%) as feedstock in an industrial scale biogas plant. This plant operates with the co-digestion of maize (27%), grass (54%), rye (8%) and chicken manure (11) and produces 500 kWh energy. In order to assess environmental friendliness, a life cycle assessment was performed by using the software Simapro. Potential environmental impact categories under investigation were global warming, acidification, eutrophication and land transformation potential. Our results determine the affirmative impact of the codigestion of algae with chicken manure on the emission reductions: 52%, 83%, 41% and 8% lower global warming, acidification, eutrophication and land transformation potentials, respectively per 1 MJ of energy generation, moreover, 84% and 6% lower acidification and land transformation potentials per kg of feedstock.