Liquid biofuel production from volatile fatty acids

The production of renewable fuels and chemicals reduces the dependency on fossil fuels and limits the increase of CO2 concentration in the atmosphere only if a sustainable feedstock and an energy efficient process are used. The thesis assesses the possibility to use municipal and industrial waste as biomass feedstock to have little of no competition with food production, and to save greenhouse gasses emissions. Waste is a complex substrate with a diverse composition and high water content. It can be homogenized without losing its initial energy value by anaerobic conversion to volatile fatty acids. Using VFA gives the opportunity to process cheap and abundantly present biomass residues to a fuel and chemical instead of sugar containing crops or vegetable oil. This thesis describes the feasibility to convert VFA to compounds with a higher energy content using mixed culture fermentations by eliminating of oxygen and/or increasing the carbon and hydrogen content. At high hydrogen pressure, protons and electrons release via the reduction of organic products such as VFA becomes thermodynamically more attractive. Three VFA reduction reactions were studied: hydrogenation to an alcohol with 1) hydrogen and 2) an electrode as electron donor, and 3) by chain elongation with hydrogen and ethanol. Based on concentration, production rate and efficiency, elongation of acetate with hydrogen and/or ethanol was the best technique to convert VFA into a fuel. In a continuous flow CSTR, 10.5 g L-1 caproic acid and 0.48 g L-1 caprylic acid were produced with ethanol and/or hydrogen at a specific MCFA production activity of 2.9 g caproate and 0.09 g caprylate per gram VSS d-1. The products were selectively removed by calcium precipitation and solvent extraction with ethyl hexanoate and petroleum ether. Microbial characterization revealed that the microbial populations were stable and dominated by relatives of Clostridium kluyveri. VFA could also be reduced to alcohols. Acetic, propionic and butyric acids were biohydrogenated with hydrogen and acetic acid also with an electrode. Observed alcohol concentrations were 0.62 g L-1 ethanol, 0.49 g L-1 propanol and 0.27 g L-1 n-butanol. Methanogenesis was successfully inhibited after thermal pre-treatment incubated at pH 6, while acetate reduction was enhanced. In the second study, ethanol (0.084 g L-1) was produced at the cathodic compartment of a bioelectrochemical system, in which the electron transport was mediated by methyl viologen. The ethanol production activity at the cathode was only of very short term, since the mediator irreversibly reacted at the surface of the cathode. Of the two VFA conversion processes, biohydrogenation and chain elongation, chain elongation was a more dominant process that consumes ethanol with acetate to medium chain fatty acids. With this technology, wet organic waste can be converted to biofuels carbon and energy efficient. The technology is promising due to the good fuel and separation properties of medium chain fatty acids, and the possibility to produce them at high concentrations and specific production rates comparable to other anaerobic conversions. <br/

Microbial solar cells: applying photosynthetic and electrochemically active organisms

Microbial solar cells (MSCs) are recently developed technologies utilizing solar energy to produce electricity or chemicals. MSCs use photoautotrophic microorganisms or higher plants to harvest solar energy, and use electrochemically active microorganisms in the bioelectrochemical system to generate electrical current. Here, we review the principles and performance of various MSCs, in an effort to identify the most promising systems as well as the bottlenecks and potential solutions towards „real life. MSC application. We give an outlook on future applications based on the intrinsic advantages of MSCs, showcasing specifically how these living energy systems can facilitate the development of an electricity-producing green roof.This is a "Post-Print" accepted manuscript, which has been published in "Trends in Biotechnology". This version is distributed under the Creative Commons Attribution 3.0 Netherlands License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Please cite this publication as follows: 2011 Trends in Biotechnology Microbial solar cells: applying photosynthetic and electrochemically active organisms. David P.B.T.B. Strik, Ruud A. Timmers, Marjolein Helder, Kirsten J.J. Steinbusch, Hubertus V.M. Hamelers, , Cees J.N. Buisman. Trends in Biotechnology 29 (1), 41-49 You can download the published version at: http://dx.doi.org/10.1016/j.tibtech.2010.10.00

From weak to strong coupling of localized surface plasmons to guided modes in a luminescent slab

We investigate a periodic array of aluminum nanoantennas embedded in a light-emitting slab waveguide. By varying the waveguide thickness we demonstrate the transition from weak to strong coupling between localized surface plasmons in the nanoantennas and refractive index guided modes in the waveguide. We experimentally observe a non-trivial relationship between extinction and emission dispersion diagrams across the weak to strong coupling transition. These results have implications for a broad class of photonic structures where sources are embedded within coupled resonators. For nanoantenna arrays, strong vs. weak coupling leads to drastic modifications of radiation patterns without modifying the nanoantennas themselves, thereby representing an unprecedented design strategy for nanoscale light sources

Sintra Eco Camping

Este trabalho foca-se no desenvolvimento de um projecto assente na sustentabilidade, tendo como base o ecoturismo, através da elaboração de um plano de negócios relativo a um eco parque de campismo no município de Sintra. O ecoturismo é uma forma de turismo responsável que se desenvolve em áreas naturais de forma a promover a preservação do ambiente e o bem-estar da população. Realizado algum enquadramento teórico sobre a sustentabilidade, o ecoturismo e o campismo, e explanada a metodologia utilizada, desenvolve-se posteriormente um plano de negócios para a criação de um eco parque de campismo na freguesia de Colares, próximo da Praia Grande. É objectivo deste parque a oferta de alojamento alternativo ao existente no município, em pleno contacto com a natureza, de modo a beneficiar, não só a economia e a população local, mas promovendo também actividades que incentivem e criem acções de conservação e preservação do ambiente. Pretende-se que as actividades propostas, que englobam passeios na região, amostras gastronómicas, workshops ecológicos, entre outros, beneficiem os visitantes e turistas, mas também a população residente. No âmbito do plano de negócios, após a apresentação do parque, realiza-se a análise dos principais mercados alvo e, de seguida, desenvolve-se o plano de marketing. No plano dos recursos humanos e no plano de operações que se seguem, aprofunda-se o conhecimento sobre o funcionamento do parque e suas actividades. Finaliza-se o estudo com o plano financeiro e as devidas conclusões, com base em todo o trabalho desenvolvido para este projecto de mestrado.This paper focuses on the development of a project based on sustainability, which centers on ecotourism, by drawing up a business plan for an eco-camping in the municipality of Sintra, in Portugal. Ecotourism is a responsible form of tourism that develops in natural areas in order to promote the preservation of the environment and the people's well-being. Once presented the theoretical framework on sustainability, ecotourism and camping, and explained the methodology employed, a business plan is elaborated for the creation of an eco-camping in Colares, near Praia Grande. The purpose of this camping park is to offer an alternative accommodation to those existing in Sintra, in plain contact with nature, in order to benefit the economy and local population, by also developing activities that promote and create actions for the preservation and conservation of the environment. It is intended that the proposed activities, which include, among others, tours in the region and environmental oriented workshops, will benefit visitors and tourists, as also the resident population. Under the business plan, following the presentation of the park, an analysis of the main target markets is carried out, giving rise to the development of a marketing plan. The human resources plan and the operations plan, which follow, deepen the knowledge of the workings of the park and its activities. The study finishes with the financial plan and the necessary conclusions based on all the work involved in this master degree project