Environmental assessment of bioethanol from onshore grown Ulva

PosterBesides biofuels from microalgae, an emerging interest in using macroalgae as feedstock for biofuel production is observable. Macroalgae have the advantage that they are much easier to harvest than microalgae so that the problem of low feedstock concentration does not arise. The environmental performance of bioethanol from onshore grown green algae is assessed using literature data and initial laboratory scale data. The optimized system model allows for producing an environmentally efficient biofuel in comparison to fossil fuel and bioethanol from sugar cane. Handling the co-product by substitution instead of energy allocation significantly reduced the environmental impacts of the system and resulted in environmental bonuses in several impact categories. Thus, the management of the co-product in the LCA model (energy allocation vs. substitution) is a key step in the LCA, as it highly influences the impact assessment results

Simulating management policies on stock supplied by multiple production units : Application to a pig slurry treatment plant

National audienceBecause of intensive animal farming, the problem of animal wastes disposal has become very acute in the Reunion Island, namely for liquid wastes such as pig slurry. In this paper we address the problem of determining efficient supply policies of a slurry treatment plant collectively managed by individual farmers. For this, we built a simulation model with a continuous part (i.e., slurry stocks modeled as ordinary differential equations) and a discrete part (i.e., transport allocation as a Linear Program). Simulations are carried out considering the specific constraints of farmers in a critical zone in the Reunion Island. The results emphasize the positive role of a closed-loop control, which means organizing slurry transportation according to the current states of individual stocks

Agrégation/abstraction de modèles pour l'analyse et l'organisation de réseaux de flux (application à la gestion des effluents d'élevage à La Réunion)

MONTPELLIER-SupAgro La Gaillarde (341722306) / SudocSudocFranceF

Use of fertilizing residues by agricultural activities in LCA studies

This work is a review of Life Cycle Assessment (LCA) studies dealing with agricultural use of fertilizing residues (FR). The majority of the studies were dedicated to LCA of waste and wastewater treatment systems and, in few cases, to agricultural productions. In most of the studies on LCA of waste and wastewater treatment, FR spreading induces toxicity due to heavy metals and global warming and atmospheric pollution because of emissions of nitrogen compounds. When a livestock is studied, FR spreading is generally a minor contributor to the impact compared to livestock building and animal manure stocks. The fertilizing effect of FR is taken into account by substitution of mineral fertilizers. Substitution of mineral fertilizers is the main driver of the environmental assessment result. Unfortunately, the substitution is not always explained or presented in the different studies, which makes interpretation of the results difficult. This variability of system boundaries also affects the results

Optimal integration of microalgae production with photovoltaic panels: environmental impacts and energy balance

Background Microalgae are 10 to 20 times more productive than the current agricultural biodiesel producing oleaginous crops. However, they require larger energy supplies, so that their environmental impacts remain uncertain, as illustrated by the contradictory results in the literature. Besides, solar radiation is often too high relative to the photosynthetic capacity of microalgae. This leads to photosaturation, photoinhibition, overheating and eventually induces mortality. Shadowing microalgae with solar panels would, therefore, be a promising solution for both increasing productivity during hotter periods and producing local electricity for the process. The main objective of this study is to measure, via LCA framework, the energy performance and environmental impact of microalgae biodiesel produced in a solar greenhouse, alternating optimal microalgae species and photovoltaic panel (PV) coverage. A mathematical model is simulated to investigate the microalgae productivity in raceways under meteorological conditions in Sophia Antipolis (south of France) at variable coverture percentages (0% to 90%) of CIGS solar panels on greenhouses constructed with low-emissivity (low-E) glass. Results A trade-off must be met between electricity and biomass production, as a larger photovoltaic coverture would limit microalgae production. From an energetic point of view, the optimal configuration lies between 10 and 20% of PV coverage. Nevertheless, from an environmental point of view, the best option is 50% PV coverage. However, the difference between impact assessments obtained for 20% and 50% PV is negligible, while the NER is 48% higher for 20% PV than for 50% PV coverage. Hence, a 20% coverture of photovoltaic panels is the best scenario from an energetic and environmental point of view. Conclusions In comparison with the cultivation of microalgae without PV, the use of photovoltaic panels triggers a synergetic effect, sourcing local electricity and reducing climate change impacts. Considering an economic approach, low photovoltaic panel coverage would probably be more attractive. However, even with a 10% area of photovoltaic panels, the environmental footprint would already significantly decrease. It is expected that significant improvements in microalgae productivity or more advanced production processes should rapidly enhance these performances