tag:blogger.com,1999:blog-9127356769712307332024-02-22T08:41:55.493-08:00Energy for São ToméTeaching Renewable Energies and Sustainability in the School of Diogo Vaz (São Tomé, Africa)Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.comBlogger10125tag:blogger.com,1999:blog-912735676971230733.post-32869175979245110572009-09-15T12:01:00.000-07:002009-09-14T23:57:03.624-07:00Abstract<div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><br />
<span style="font-size: small;">This work aims to show how sustainability and renewable energies could benefit a rural area of Africa (in São Tomé) by means of using solar energy and biogas. Applying these technologies requires ingeniousness and little founding, the favourable outcomes are becoming less dependent of fossil fuels (wood, coal and gasoline) while saving time and, more importantly, the forest. We have taught how to design, build and operate systems for cooking, lighting and water-heating that use renewable sources of energy.</span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;"><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;">The Petri-dish where this study has been conducted is ‘Escola de Artes y Oficios Diogo Vaz’ (association Natcultura) located in the roça Diogo Vaz, 36 km away of São Tomé city. This roça is a rural area in where approximately five hundred people sustain their living from cacao cultivation. </span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;"><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;">Please feel free to use this information for your needs, but do not forget to refer your sources. I appreciate all the comments and suggestions.</span></div>Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.com3tag:blogger.com,1999:blog-912735676971230733.post-78521351531576381672009-09-15T11:00:00.000-07:002009-09-14T23:58:31.545-07:00Problem statement<div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><br />
<span lang="EN-US" style="font-size: small;">The increasing use of natural resources and the emission of higher amounts of contaminants to the atmosphere, rivers, seas and soils have sown, once more, the necessity of using our sources of energy in a sustainable way. That is, the sustainment and development of our civilization must be based on a responsible mode of consuming the raw materials, in a way that this will not induce to their extinction. In other words, the idea is to consume at the same rate nature can produce. Moreover, the emissions generated from the mentioned consumption should have the lesser impact on the environment and human beings in order to sustain life and progress. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">The upcoming depletion of fossil fuels (oil and gas) joins to the fact that the population of the world is constantly increasing. This population have equal right to use energy since it is one of the pillars to nourish the development, enhancing the quality of life of the society. In this manner, renewable or sustainable energies are gaining importance nowadays, to mention some; solar, wind, hydraulic, geothermic or tidal energy. Additionally there is a strong investment of money, time and ideas in order to produce gas and liquids from renewable sources as algae, plants-crops, wastes (forestall, agricultural, wooden, animal…), wood or coal. All of them to incorporate the term bio- to indicate the renewable source: biogas, biofuel, biodiesel, etc.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"> <o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">São Tomé and Principe is the second smallest country in Africa, situated in the gulf of Guinea, posses around 150,000 inhabitants from which ca. 60 % of them live from agriculture-fishing. The electricity is obtained both by hydroelectric plants and from fossil fuels as petroleum or gas. Interestingly, the immense majority of the kitchens operate by combusting wood and charcoal (made by rudimentary methods from wood) and therefore, representing a threat for the fragile ecosystem that exists in this country. The humid equatorial climate alternated with periods of strong solar radiation has leaded to a fauna and flora that has evolved separately from continental Africa, creating a rainforest which is unique in the world. It is hence important to propose initiatives for protecting this ecosystem. The source of energy in São Tomé cannot come from agricultural-land since the amount of crops produced from it is barely able to feed the population and exportation of cacao.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">The education of sustainability is the main point of concern, as long as this is the long-term road for giving the African people tools for developing their own ideas and technology. The approach is investing in their education first to further devote money for infrastructures of sustainable energy.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"> <o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">This work aimed to teach sustainability and renewable energies to the community of Diogo Vaz and particularly to the internal students of the school, and show at the same time how these technologies could benefit their life. We will set first the objectives of the work based on the limitations of founding and environment (temperature, solar radiation, access to raw materials...), selecting the appropriate technologies to develop in the area. We will explain the workshops undertaken, giving appropriate data for building replicas. Finally we will explain the results and what we all have learn. Additionally we will provide with some pictures of the devices built and useful references.</span></div>Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.com1tag:blogger.com,1999:blog-912735676971230733.post-21366358579313596382009-09-15T10:00:00.000-07:002009-09-14T23:59:07.132-07:00Objectives<div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><br />
<span lang="EN-US" style="font-size: small;">The main targets of the project can be divided in (i) educational and (ii) practical. The educational targets consist in teaching what sustainability is, what renewable energies are, raise the concern of the students on the peculiar ecosystem in where they live, how fragile it is and what actions, if any, are required to protect it. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">The practical objectives consist in a series of workshops in which we had built systems to use renewable sources of energy for cooking, lighting and the sanitarian showers. Although electrification is imperative in the area, due to the limited time and founding we decided to concentrate our efforts for saving wood in the kitchen, and among all the available technologies we selected a number of them based on the conditions of the area, that is, temperature, humidity, availability of raw materials (manure, clay, and solar radiation among others), etc. The selected sources of energy for the school of Diogo Vaz were solar and biogas.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Besides the educational targets above mentioned we described a little of the science behind the workshops. As we taught these principles the students, might be able to master the design-operation of the units for a given set of conditions.</span></div>Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.com0tag:blogger.com,1999:blog-912735676971230733.post-41258401960938981832009-09-15T09:00:00.000-07:002009-09-15T00:03:44.406-07:00Workshops<div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><br />
<span lang="EN-US" style="font-size: small;"><b>3.1. Education.</b> We started by broadcasting a video of the local television named ‘Floresta en peligro’. In this documentary it is explained and showed all the threats for the forest of São Tomé, being the use of wood and charcoal for cooking one of the most important ones. Then I explained what a ‘mass balance’ and ‘energy balance’ are, what enters, what goes out, what reacts… This enabled me to go a bit further into sustainability and what this term means. I used examples as places or people to sustain my hypothesis. We talked a bit of some sources of energy and why some are going or may go to depletion. I explained some sources of renewable energies.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">In terms of the workshops I briefly explained some of the concepts required to understand how the systems work; types of heat transmission (radiation, convection…), types of solar cookers using direct radiation (concentration of solar rays) or convection (ovens), fermentation and methane production with bacteria, short discussion of the law of ideal gasses (for building a barometer) and hydraulics (for building systems that contain liquid and gases and use this principles to pump one or the other). All of these concepts were explained in a way they can use them in their normal life, with accessible language, avoiding if possible technical words, playing games and putting them in real situations. The concepts of biogas production through bacteria-assisted-digestion were better understood from the basis of fermentation and wine production, which almost all of them knew. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">As for the general material requirements: screw-driver, hacksaw, rule(r), pens, drill, silicone-holder (syringe type) and hummer.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><b>3.2. Solar energy. </b>The systems that use solar radiation for heating-cooking can be divided attending to the main way they transfer the energy from the sun into the element (black-metallic-tube or -pan in, where we put the food or water): radiation, also called solar concentrators or panels; and radiation-convection, also called solar ovens. The materials required for the workshops are accessible in almost every country, proven that we were able find them here. Most part of the workshops do not require especial abilities except some carpentry, welding and mathematics (to design correctly) among others, in each case we will explain such requirements.</span><br />
<br />
<span lang="EN-US" style="font-size: small;">These workshops required little explanation for understanding the scientific principles in which they are based. As long as most people have experienced the difference from a sunny to a cloudy day, and how an oven works, it is straight forward to start designing and building. There is an exception nonetheless, which is the principle under the solar heater works: the water is warmed in the oven and then changes its density, therefore it is forced to flow upwards so that cold water (with lower density) flow downwards.</span><br />
<br />
<span lang="EN-US" style="font-size: small;">For solar cooking workshops it is required to have a black pan or one that can be painted in black.</span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"> </span><br />
<span lang="EN-US" style="font-size: small;"><i>3.2.1. Solar panel 1, </i>the first design of a collector was based on one design proposed in the literature named CooKit (<a href="http://solarcooking.wikia.com/wiki/CooKit%29">http://solarcooking.wikia.com/wiki/CooKit)</a>. The unit was easy to construct and use so as a starting point presented a number of benefits. </span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Materials: cardboard (130x100cm), aluminium foil, glue, cutter and metallic-wire. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Price: 120,000 dobras (€5.30).</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Skills: none.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Procedure: We first drew the lines (described in the reference previously cited) on one side of the cardboard. On the other side of the cardboard we glued the aluminium foil to the surface taking care that the surface is as flat as possible. Using the cutter and the ruler we cut the perimeter of the collector. For the folding parts we did a small incision in the first layer of the carton (on the side without aluminium foil). The metallic wire is twisted to give cylindrical shape with a diameter enough to sustain a pan at 5-10 cm from the bottom. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>3.2.2. Solar panel 2, </i>the second design was a parabolic collector of 1.6 m of diameter. It was important to emphasise with the students that the one we built is different from the antennas since the focus laid inside of the parabola. As a result the user needed to make much less rearmaments with the change in solar position (or shall I say the earth position?).</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Materials: metallic-frame, cardboard (300x100cm), aluminium foil or panels (10 panels of 70x50cm), glue (pattex), ruler, cutter, metallic-wire and stapler-staples (used for carpentry).</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Price: 1,000,000 dobras (€44.40)</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Skills: As we aimed a robust and relatively big panel, it was hence required the abilities to wield, twist and cut metal. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Procedure: A blacksmith built the metallic frame of the panel with the support for the pan. This structure is shown in Fig. 1. The outline of the panel was calculated using the following expression (Eq. (1)):</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><div style="text-align: left;"><span lang="EN-US" style="font-size: small;">x² =4·a·y<br />
</span></div><br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">where x and y are the horizontal and vertical position respectively while a is the focal length (a= 40 cm).</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Once received the structure, we installed the cardboard with triangular shapes along the panel, making small perforations and using metallic-wires to fix them to the frame. The dimensions of the aluminium panels available were smaller than the cardboard, so that the triangular shapes of aluminium were smaller. We fixed the panels to the cardboard using first glue (pattex) and then the stapler. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><br />
<a href="http://picasaweb.google.nl/lh/photo/GnzsLWuztQkvNriiv5puMg?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEho0UA6LK8cCfwlHVELKuWxsTnac2ijapX98lrlLudM3VGrhwosrzqsD2XZ_3QHrRLZZbhvDE48LMRRx7lINS6YUb6ApMGi0QdPdAV86IwgGN-qA57PMuqpaoEkx2b1zVOwhwrIkBaZWltn/s400/Solap%20panel.jpg" /></a><br />
<o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"> Fig. 1. Scheme of the solar panel 2.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>3.2.3. Solar oven. </i>The oven was specifically designed for cooking coconut biscuits. The shape and size of such wafers yielded the final dimensions of the oven, as described in Fig. 2. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Materials: cardboard (300x150cm or two boxes, one a bit smaller than the other), glass (dimensions in Fig. 2) aluminium foil, glue, ruler, metallic-panel painted in black, cutter, insulating material (hollow cardboard or some short of plastic), small rope (1.5 m) adhesive tape and silicone.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Price: 200,000 dobras (€8.90)</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Skills: none</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Procedure: I started by using a video of youtube to explain the procedure better to the students (<a href="http://www.youtube.com/watch?v=96qPRgmfbXc">http://www.youtube.com/watch?v=96qPRgmfbXc</a>). </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">We constructed the inner box, covering all its surfaces with aluminium foil, using glue. In the bottom we installed four bases of insulating material. Then we assembled the outer box making all of its faces except the bottom and the top of three layers; cardboard, insulating material and cardboard. The dimension of the hole of the outer box had to be such that the inner box (plus insulating material) was placed tight. Once placed both, we introduced the metallic-panel (it needn’t to be aluminium) and constructed the top of the box with cardboard, glass and silicone. We also assembled some extra reflectors made with cardboard, aluminium foil and rope on the top. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><br />
<a href="http://picasaweb.google.nl/lh/photo/2DBIg2H2E9YDDCwO2b0m4g?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4XqOIlmmX3-qnJNQ4h-pBP1_809DyD2qsMEU4XJeCkyKqwe4SsfIbGOvrIlcuTA5Uu6jvY4on0d2c7Vu6ZVIHgjfIIVYVQgAXchhdW7vlV-i7z6f2Bz6KkpYVHRq-blgV4nKojsQ_TZQO/s400/Solar%20oven.jpg" /></a><br />
<o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"> Fig. 2. Scheme of the solar oven.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>3.2.4. Solar water-heater.</i><b> </b>The designed unit was made for heating 50 L of water, that is, for the communitarian showers. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Materials: plastic container of 50 L, hose (id. 1 cm; length, 4 m), 2 clumps, cupper tube (id. 0.7 cm; length, 2 m), wood (30x2x200 cm), metallic-panel, insulator, studs, silicone, glass, ruler and pen. The dimensions of the metallic-panel and the glass are specified in Fig. 3. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><br />
<a href="http://picasaweb.google.nl/lh/photo/O2r7xs1Yjfx6H1BwuCjkCg?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgI2N2gUBaNUTZNWHMX9x1TBRhLk4wOrOSijf-Q8c0-O3CkZhVBqXFRKfmnaluq7wT77Yq8s5S37UEMRlbqkqIeebwixHgxhw2XRJVip9umJUGoBaLv1mNTvLue-hu72unJT0znIcBq3dpJ/s400/Solar%20heater.jpg" /></a><br />
<o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"> Fig. 3. Scheme of the heating element (solar heater).</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Price: 1,200,000 dobras (€53.30)</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Skills: none.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Procedure: We twisted the copper tube giving it an S-shape, we assembled the wooden box using the studs (some carpenter skills and gadgets were required) and then the isolator plus the metallic-panel. We set the tube inside the box, making two holes for inlet and outlet. We fixed the glass using some extra wooden pieces and studs, shielding all the holes with silicone. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">We perforate three times the plastic container: the lowest one for the inlet of the heating element, the outlet of the heating element (15 cm above) and the outlet of the container (1 cm above the second). By doing so we allowed filling the heating element while avoiding empting it during normal use. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">We connected the container with the heating element with the hose, shielding the connections using silicone (for the container and also for the third hole) and the clamps (for the heating element).</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><b>3.3. Biogas. </b>The principles of biogas production from manure are based on anaerobic digestion of bacteria. Although it has been investigated in detail previously we focused in the classes on explaining to the students the very concepts required to understand how it works. These concepts, as it was previously explained, were better understood talking about fermentation and human digestion. It is recommended for the introductory classes to put manure and water in a bottle (PET, 1.5 L) with a balloon on top prior the class (4 days in a tropical weather). This allows the teacher to show the gas expansion during the digestion of manure.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">The material used was accessible with the sole exception of the tubular polyethylene used for the biggest digester. The abilities for these workshops involve only bit of mathematics to do the calculation of the dimensions of the digester.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>3.3.1. Pilot-plant digester. </i>As a first step we tried to prove the concept by a small pilot plant of 50 L, the unit consisted in three sections; digestion chamber, barometer (pressure gauge) and burner. Materials: plastic container of 50 L, hose (id. 1 cm; length, 1.5 m), gas-hose (id. 0.5 cm; length, 1 m), wood (30x2x100 cm), studs and silicone. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Price: 500,000 dobras (€22.20)</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Skills: none.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Procedure: We made two holes on top of the container, introducing en each the hoses specified before and shielding the connections with silicone. We twisted one of the hoses and gave it a U-shape, fixing it to the wood using the studs and filling it with some water. The other hose was specific for natural-gas connections and it was just plugged to a burner.<o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>3.3.2. Kitchen-plant digester.</i> For a complete description of the materials and procedures it is advised to consult the literature (<a href="http://www.bioenergylists.org/files/guia_biodigestor_jmh_final.pdf">http://www.bioenergylists.org/files/guia_biodigestor_jmh_final.pdf</a>). The design scheme followed these criteria: We wanted to use 40 kg/day of manure, considering a dilution 1:3-4 in mass we had a total daily loading of 160-200 kg/day. In the literature there is not an agreement of the resident time, so the most conservative value was selected; 20 days for this tropical conditions. The total mass in the plant was calculated multiplying the daily loading by the residence time yielding 3200-4000 kg. Assuming that the volume of the liquid would be 75% of the total digester, the final volume was 4.3-5.3 m³. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Materials: instruments for digging, tubular polyethylene (id. ~1.9 m; length, 14 m), rubber (recycled tyres), PVC tube (id. 15 cm; length, 2 m), connection male-male for transposing the walls of the digester (PVC), elbow connection (PVC), tee connection (PVC), hose (id. 1.3 cm; length 10 m depending in the distance digester-kitchen), 10 clumps, 1 ball-valve (metallic), 1 bottle (5 L, PET) and 1 burner. No special skills required.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Price: 1,600,000 dobras (€71.10)</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Skills: some mathematics to calculate the dimensions of the hole and digester.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Procedure: the hole was made in first place (see Fig. 4), then we assembled the digester (see also Fig. 4); (1) make 2 layers of plastic, (2) make a hole for the exit of gases, (3) put the connection for crossing the walls of the digester plus the elbow and (4) tight the inlet and the outlet of manure-water using the rubber. We placed the digester in the hole and we leak-tested the unit using the exhaust gases of a car. Once leak-tight we introduced the mixture manure-water recollected several days in advance.</span><br />
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<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><br />
<a href="http://picasaweb.google.nl/lh/photo/uf5Gbx5hEgQ6lT7ffNUZpQ?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1MfOYvizVCcHGMowZJHsr59iH5_jHlLKCjBvACeR0-QOwV9AlBvIjSKBIZO79S8Lcplc9zVMxwdPyRGgX-osMet657EvbZxZ1wUBJZ-nK7welzKNcOac0Y-MjwkfiXbilXAP2ZP8XFfV1/s400/Digester.jpg" /></a><br />
<o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"> Fig. 4. Scheme of the digester.</span></div><div style="text-align: justify;"></div>Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.com2tag:blogger.com,1999:blog-912735676971230733.post-89689878851190458152009-09-15T08:00:00.000-07:002009-09-15T00:05:25.538-07:00Results and recommendations<div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><br />
<span lang="EN-US" style="font-size: small;"><b>4.1. Education. </b>The concepts (sustainability and renewable energies) were learnt easily. Sometimes it was extremely difficult to keep the students focused. I cope with that giving more practical examples, inventing some game, etc. The audiovisual material (videos and pictures) turned out to be of extreme importance, because they could visualize examples.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">Knowing until which extent they will use this knowledge in the future is at this point impossible. I tried to point many times that they have a huge responsibility, considering the fact that they live in a unique ecosystem of which they are responsible. Nevertheless the word ‘unique’ is not easily memorized if someone think it is ‘granted’.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><b>4.2. Solar energy.</b> Teaching how a solar panel, oven or heater works was successful. The solar radiation of São Tomé is powerful, especially in the rainy season, but also in the dry one called gravana. Due to the proximity of the area to the equator, the orientation of the day-trajectory of the sun is constant all year long. The main problem was that the radiation is scattered, as the weather is constantly alternating between sunny and cloudy. As a result we decided to use the solar panels and oven for preparing thinks that required long times of cooking (jams, biscuits, soups… ) or for frying when the radiation is strong (eggs or ‘fruta paõ’).</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>4.2.1. Solar panel 1.</i> The system was proved to be easy to assemble and the major benefit was that soon we were able to collect information in regard to solar panels. However, the panel was not able to boil water in any of the circumstances that we tested it. The maximum temperature reached by 1 L of water was about 70°C.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">It is of a severe importance that the cardboard is flat and dry from the beginning and maintained likewise during the working-life of the panel. Special care must me taking when gluing the aluminium foil to make it flat; it is recommended to cut it in small pieces (10x10 cm).</span><br />
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<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>4.2.2. Solar panel 2. </i>In São Tomé is almost impossible to find aluminium panels in the shops, and shipping would last too long. As a solution we first used aluminium foil and then we asked in the local printing house, in where the aluminium panels are used in the manufacture of the newspapers. The waste panels have one side reflective (still useful after cleaning with gasoline or organic solvent) and they are free of charge. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">In the first attempt we used aluminium foil, in which case the same recommendations that for the solar panel 1 are given. Using foil resulted in heating 1 L of water up to 80-90°C in the sunniest days, enabling cooking eggs for example.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">In the second attempt we used aluminium panels (as it has been described in the ‘workshops’ section), enhancing significantly the heating capacity of the unit, thus boiling water and frying was possible in about 20-30 min of exposure.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>4.2.3. Solar oven. </i>The unit was a success from the very beginning, enabling reaching temperatures above 120°C within 30 min of exposure. The most important parameter is insulation; special care must be taking avoiding holes. Although the easiest design looks like a box we recommend the use of reflectors close to the glass, as the radiation greatly increases.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>4.2.4. Solar water-heater.</i> Depending on the copper tube it must be required to have material to twist and turn tubing. The same requirements of insulation (as the solar oven) are required for the heating element. During the start-up of the unit care must be taken filling the heating element with water, avoiding the presence of bubbles of gas into it.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">The unit was able to heat 40 L of water up to 30°C in about 3 h of exposure.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><b>4.3. Biogas. </b>The tropical conditions of São Tomé made this land very attractive for developing biogas technologies. However the number of kettle in the country is relatively small so incrementing this number or exploring the digestion of other renewable sources can lead to a sustainable energy for the country.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>4.3.1. Pilot-plant digester. </i>The unit was able to build up pressure; however the resulted gas was not flammable (probably because of the burner). In this sense the system was a failure. Originally we built an additional system based on hydraulics in order to collect the gas, however as the number of connections (shielded with silicone) increased, so it did the chances of leakage. Minimizing these connections is therefore recommended.</span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;"><i>4.3.2. Kitchen-plant digester. </i>If tubular plastic is difficult to acquire, as in this case, new approaches are needed. In the literature it is advised to use a length:diameter ratio of 7 for the digester. As the only tubular plastic available had 1.9 m of diameter we rolled one side with a hose, fixing it with a rail on one side of the digester, resulting in a tube of 1.5 m of diameter. </span><br />
<br />
<span lang="EN-US" style="font-size: small;"><o:p></o:p></span></div><div class="MsoNormal" style="font-family: "Trebuchet MS",sans-serif; text-align: justify; text-indent: 0cm;"><span lang="EN-US" style="font-size: small;">The final volume of the digester was 5 m³.</span></div>Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.com0tag:blogger.com,1999:blog-912735676971230733.post-34673773825465432542009-09-14T23:40:00.000-07:002009-09-15T00:06:20.818-07:00Pictures<span style="font-family: "Trebuchet MS",sans-serif; font-size: small;"></span><br />
<div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;">Solar panel 1 – Construction:<br />
<a href="http://picasaweb.google.nl/lh/photo/MTneFA74fAmPMyrmv8HxhQ?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgQhGMyfjB1KzcGcdxx528kvkOawK_OyE0ihDYpLZOOS7FGuNP73pzUNB9PNnlN1CVy-gjD8-F4ZNOV5fE88dAgUBT2p4wP_96BbT_A-cVD77K-RSWGQUIIU2tqCax0OZ2IdMb8s8Rqoa_M/s288/a1.jpg" /></a><br />
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<span style="font-size: small;">Solar panel 1 – Final unit:<br />
<a href="http://picasaweb.google.nl/lh/photo/73sQ9sFYwYcIn8FwnoTAoA?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgHDrn0NDS3JiBXcunTtJkmrVZmfY5QT-exLI7Byx3pqTMt6ol2bP58JVypGvSvFkuxKN0WFdvBiTguWCwA7tigUBrOfZYiapqLntbYMiHr0kxFfUio0MWneHg9R7mf91YMevTK0sJrdu6B/s288/a2.jpg" /></a><br />
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<span style="font-size: small;">Solar panel 2 – Placing the cardboard: </span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/VdyLv1KdbqPblTJ_lijwUg?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjCxD5enYnQ8YkxuDLJaPxvqL6XhsF8zlKrWVGcgwbeUdBMIMZ8G-linI6rcSkgvstxssjCRbb28TNMV4ebY7Y5qsbTfTPyzdSlntKniBe6zEko733gCMkuTv7Kob2c2Hvuwg2EVYukCMLd/s288/b1.jpg" /></a><br />
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<span style="font-size: small;">Solar panel 2 – Detail of the unit:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/37VlHdjQaWXwV-8iurhQQw?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjEi6pPGO58I0hvYsjHqMvJQ3pK9nYjpAxwHD5PQAjIwHicPMfmcqjZqwUSqyFyl0XiR9ThmnNdIkaleRrXOYy5J0yDT_TIqsgfYVOweQM_8zS0fBR0KbGPgXqcJnY3Z5c9uDWcqi0j3Zkl/s288/b2.jpg" /></a><br />
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<span style="font-size: small;">Solar panel 2 – Cooking with sun in the jungle (stage 1; using aluminium foil):</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/eiS7akC_Yz7WkOqt7vbUmg?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2RWiKIM-aApQVjjgof3JdxyF5IO_2Wb8QQPsh1u93f7tMXD75vYR5n3UcLs6yD_EpAuM-k_5fkB_4RV3XQfwz1DJ0nM2Svvf6smniwny83_tWYBjoXI1DPtUzF4reQnNyldiqRQhyphenhyphenyq7h/s288/b3.jpg" /></a><br />
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<span style="font-size: small;">Solar panel 2 – Detail of the unit (stage 1)</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/-XeJD-DhPEgyJjyioVgVcw?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHfZvR77P2FylK3Uw6gUPqzsQB3fEj6_An7FRvEQzn1NjKapNXsrYz2nUA4ym1ro3o2XhegqOlxtky0ucQald9nHSj2DakPKgBRidY9Tr938bR05M-J3GPl8FjfGK1mmj1TSpLAMHzLPjy/s288/b4.jpg" /></a><br />
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<span style="font-size: small;">Solar panel 2 – Placing aluminium panels (stage 2):</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/vqNMxYHW54mKY6J7CbTPQw?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgo8fxct0HYxD2lzc9vP9q4gdsqI39CPs4ikWSvzJHOndYe9DXzWmCQK2cycw5nPO5QOmgm_KqZL9_oUtbyx5d9u2EHi3sQiOQImcaBPhbwkGIgYJjB8W1a-emx58euqZas2aHnyGSsaIv8/s288/b5.jpg" /></a><br />
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<span style="font-size: small;">Solar panel 2 – Detail of the unit (stage 2)</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/bBtj45H3Fffdb1xR0dF4Qw?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJVr84dzJEGMUNs4rfPjEFbjMAS7JkDtMUcCX9s75B4rWMdV9nTmtw8XQUMaZP5aGVnvW_6ibioU1jaDhYQlRrxCac1ZgpQ3tcR7vqI6kMLV0iW3Qj2R2RB0p9m-NgYMJN-L9c2elMiibN/s288/b6.jpg" /></a><br />
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<span style="font-size: small;">Solar panel 2 - Final unit:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/y2OidcGuzL-ptCybSOqRSw?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhh7SN5_Wi9ZeanmBQ-H63J6eCh86-yRkNLroFwWhxiyMvU-iNat2kgU_wbkTX5n_32MI87Dk1m7YtjT_FjR7-DOa2wjgCUGamuL6jknOdbC0U32w7-g04XOIxr4RE9p1fEKmZnJ0qB5uAa/s288/b7.jpg" /></a><br />
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<span style="font-size: small;">Solar oven – Detail of the unit: </span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/LT2bbXVojE-lx8aM4MTlcg?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnpm45Ym3Gbhghfgbkz9_RC_18Z-ZAnEXerIMSPbm3eEW9-Enl1GqKBX5OXjZkoNSssQF1VZY6FZumcWSPFsfudZueswjv-EI1ebYfezCbCif1bZiO6XyGjFUnv8CHd3k6x1hgqLNtYZBO/s288/c1.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Solar oven – Final unit:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/UnBeJU7mSies-5lhuCFs_w?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgkrvbnCfM8env9iVxO3IrS9nMolCTmrhj7ChvG7mgvVeUD9uozxWKGA7SFR9SMc2kJqnNvLFyqozlGUVkYcomICIpmjLGvzKf3j9Mtx0PgVPbTjc_pXPgMuPkdIUZfFjpx8NfhIQLNoNzT/s288/c2.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Solar oven – Final unit:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/r4oZjrlac53FcbkPneMx5A?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJsCreuhyArnA-S7173k42A4tUQLxnD4lLax2arQULrCrZaiLdta2kG9Sszt92CFBUXpL6C8eCbl9xoszz2eRLyEvKJjiaI0jzDYy9jvmCTUnK-IvDVzmZVk3ZT2b9ybJ54aBacXibey_o/s288/c3.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Solar heater – Detail of the heating element:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/xHPY1UXkm58X-84QzYk4ew?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhGJBcSLX_37rC-0gebZ3b494gk6quNDQeHA24aNtHWChpbp_hNqkD9m_Ks0GnXZD3TqiatZEcmVW68l7eVpkCApny8bUHut-T3zVEaCpc2V7L7bne-zbgPThq6PIX7yb3ODDIDMhKGS_jY/s288/d1.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Solar heater – Detail of the heating element:<br />
<a href="http://picasaweb.google.nl/lh/photo/-rgzHFB6yuECMhJLcAX9hQ?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEinLF_ybfzyBDJve7LLOp95Uf77gH2mYisfYFuAXmq0HatFAUxuOTv9hesp2urDVXj6Ni3YSMFfPBqp2ICsipLnkvWmsIrKJQJPvvx_8sOjZwzHl6Bte_ozQu2MDjCCCbPGeFcsAAXF4d_e/s288/d2.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Solar heater – Detail of the heating element:<br />
<a href="http://picasaweb.google.nl/lh/photo/BYk-_kRyr1FGI7DMHUfdVw?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-MZ8VSMCfq47BEnQZ4XR5lgLpPp8z96wsnvXsRz4kISDTREA7dt_bZGtY4NVXDSbXZa_mzRl6g2U6Chi0KGp2aAdYfM5DUlOdzpuyj5C2AwL3srcllOiZgJ3RyUT_E2baQq-xgBEmz2bV/s288/d3.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Solar heater – Final unit:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/BofnMrCvypG8aVY_Em14cg?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgGAxRv6YlYRjx3S2r_smY6QejuEvec7VX_NsETIx6nCsYWp4j5aGOftVoa30rz52MlizCajvSYTqcnrSUN03Q9zcyVnS6CY8CLuN_Div7LNLtAqARF2UX53s6xWAT1R3Iya6yaEji6wLf5/s288/d4.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Pilot plant digester – Detail of the unit, barometer:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/CIBzI0BjDy3lTMvrObdE8w?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLtDOIXzmPxuA4iAWhGamf-nuXIzlBpE60mIy4atvmZv69if8y-HEUoAYtD6KrLIe4IE8P5V_xOfCNddAu15atGCZuvDwVt4j52W-SGhbuaVV9Uyvs_ottkFTmz_vYoNs0OyctspydSI59/s288/e1.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Pilot plant digester – Final unit:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/2G3eIr095dpM-DS0N1oFVQ?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOuEn98yR1L4UyfN0t-0exrdx6LH8qX9KYBAJnmjiClrlBRA44lC9P-acOkEvkIBTdQ7TC85pRaiel89-amX0QpK6OO8HOWJ1Unb9AHe4RY1Lexq74WcAtjA7TCTt9RgOTW9XLUKlC2xjf/s288/e2.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Kitchen plant digester – Digging the hole:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/Dyws0PanC1b9tUjavouwaA?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiyBEvSVQ1mLurKfWl01I-aIQ2gLNkTxQROY0xA12iEyKiETdSqHLXNdBaUJc-WZkaPuMfkX8kYM01cFgt8IiJAa1jZyK_nTn7U-AKC5j00ZANbIzXee4lIpEAINsRb4_UvmPRiwbKBoZV-/s288/f1.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Kitchen plant digester – Securing the hole:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/WOYcL3pXgkMxPljQXkK49g?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgX8ayRtJIZvUwFxxArHH2U3SOI5-T8yzCJ7dkV7rTTH6GiOOmCc6L_kWRJylXNfjPXfdjFtlsOYaKZOoY7gJa5n7l52e5ysQB1DqfXlsdHDpUvGlVObjbbDet1_e9IkBY8WhNRi3b2b3r0/s288/f2.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Kitchen plant digester – Extending the plastics:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/iCodgvFVJJ0xv3Ux9xcNbg?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihEGKSPbGIl38R5WeOzWIZQx0GTDU7NKR3vePH92UonlosyP2zQKv5fwX4e7k_jJ-nx1LFXXV4MUTCwTredsIp56oHRiv8hsk3Gsf04BI3Bwoo2L1XJ5zz7x7aX_3yvK8NdA4Bl1r6P09e/s288/f3.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Kitchen plant digester – Making the digester:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://picasaweb.google.nl/lh/photo/9hcbgJ24GjO-60spgpGqMQ?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzURJI3n0cUqUGejPMegHOpMuPlOLbtK6k0jtgkQkd19vWE8bzKkyunTSQl-pSZ0mRjFV0TGtXlrAF1xZ-TGULUOjGE0XsumnjcN-Fhauk-ShwHd5tX95sLWVhWLXQLB4jgPL6yaL24H77/s288/f4.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Kitchen plant digester – Leak test 1:<br />
<a href="http://picasaweb.google.nl/lh/photo/yKRZc9q0rb2Baws2eQyeew?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdMGMMyGeJrXKCshT59_aG8OSboCydgNlKrbKeXbvysRmkg98vp7AFt3HzVLQaAhyphenhyphenbZxbC-lXctlOATC-Py1AdWaS-ubfqLSmQTQQoVTkPIAaikoJN7GaovFjIQmymYRQGg473gtcXASmG/s288/f5.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Kitchen plant digester – Leak test 2:<br />
<a href="http://picasaweb.google.nl/lh/photo/dtVtHKZf1ZJOyVBz1_XsHA?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIeQe9t32jVyNQq1uR1CFAsvc2B_kiqN0nUscE1fwZji2XmEmsOPwhpQyAJvu5g2B7WbuLpYmWlEHc_Kza12FbFP1gU4bLBvZF4AYInxmKfDqUxkJXWpeirXEOlYfTOSnG8C7LkeWjIOr3/s288/f6.jpg" /></a><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Kitchen plant digester – Ready for loading:<br />
<a href="http://picasaweb.google.nl/lh/photo/9XiZVU5NyMFRXNhH0irL5w?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgIcdSG03VJPanS3mkq_uIa-o_PUMjxYFjEBKKV2kj3qdZKnPWFyTeyAdRWdo7KwQwQIrMdeIDNVIfaxMBen74_ERu8srRPoV-Y_PHIo0RENB_-3OMhAF5Fc20O7uX-_XJHUFydETdc8dWq/s288/f7.jpg" /></a><br />
</span></div><br />
<div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;">Kitchen plant digester – Loading:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"></div><div style="font-family: "Trebuchet MS",sans-serif;"><a href="http://picasaweb.google.nl/lh/photo/-IQZ9gYuOKTj0o9iYezmWg?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhYvtRM2gEHWb1EPPfDzLN5OOH6dq7tB36XS1McQoKTx0PrO6YfibFwzWIdWXR9RhmMTnzHWlAjAz_E44Y_QQL3GvK8YPg1drXfNDA5VcCvyWZMa7jpr-NNGpXUXYwmIv_REfsI403w_oIp/s288/f8.jpg" /></a></div><div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">Kitchen plant digester – Final unit:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"> <a href="http://picasaweb.google.nl/lh/photo/XR5dlDKPDOgWMlBHJLwV9w?authkey=Gv1sRgCKb0geC508jB4QE&feat=embedwebsite"><img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6cmgXD2qW-oZGuFD37iFuYzqE4aH9E8cTdptbqieq57eBHaGP7IrQpO7M0cHsI4UrdfcLBkNElu1ShqE1w7kiSzoCBvgI3cKgNoGDtT5djl0JpfqlTYKBx9UT6_QTGA6G3BQntp1zcmpM/s288/f9.jpg" /></a><br />
</span></div>Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.com0tag:blogger.com,1999:blog-912735676971230733.post-13305691692837567012009-09-14T23:00:00.000-07:002009-09-15T00:13:55.747-07:00Conclusions<div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><br />
<span style="font-size: small;">Teaching sustainability and renewable sources of energy is one of the keys to enhance the quality of life of the habitants of rural Africa. We conducted this particular study in ‘Escola de Artes y Oficios Diogo Vaz’ (association <i>Natcultura</i>) located in the roça Diogo Vaz (São Tomé e Principe, Africa).</span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;"><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;">We developed an educational and practical program based on the use of two renewable sources of energy: solar and biogas. The selection of these technologies was based on the scope of time, founding and availability of raw materials.</span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;"><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;">We proved that the use of both solar energy and biogas can lead to save time (the users do not need to go to the forest to cut wood but taking the available manure) and more importantly the forest (the rainforest of São Tomé is unique in the world). The total expenditure was 4,620,000 dobras (€205.30).</span></div>Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.com0tag:blogger.com,1999:blog-912735676971230733.post-69283806850857190662009-09-14T22:00:00.000-07:002009-09-15T00:14:56.385-07:00Acknowledgments<div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><br />
<span style="font-size: small;">I would like to acknowledge<b> Nora</b> <b>Rizzo </b>for giving me the chance to come to São Tomé. The entire school (director <b>Gustavo</b>, students <b>Danny</b>, <b>Ney</b>, <b>Nuno</b>, <b>Odair</b>, <b>Wander</b>... and the cook <b>Teresa</b>) had been always supporting and encouraging me to give as much as I could. I thank <b>Christina Ploutoglou</b> for being the key to come here as well as my listener, confident and greek-personal-teacher. I would like to show my gratitude to <b>Manuel Tornador</b> for his constant-will to help and discuss fruitfully, <b>Sergio Garcia</b> for sending me exceptionally useful information in regard to the digester, and <b>Toñi Martos </b>for pointing me São Tomé in the world-map.</span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;"><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;">The financial support of ‘Ayuda Española para la Cooperación y el Desarrollo (AECID)’ is greatly acknowledged. </span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;"><br />
</span></div><div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><span style="font-size: small;"><b>I dedicate all this work to the people of São Tomé, who deserve all the energy of the world</b>.</span></div>Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.com0tag:blogger.com,1999:blog-912735676971230733.post-20359399448077416802009-09-14T21:00:00.000-07:002009-09-15T00:08:25.306-07:00Recommended literature<div style="font-family: "Trebuchet MS",sans-serif;"><br />
<span style="font-size: small;">The school and and São Tomé:</span><span style="font-family: "Cambria","serif"; font-size: 8.5pt; line-height: 105%;"></span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.natcultura.org/">http://www.natcultura.org/</a></span> </div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://uk.groups.yahoo.com/group/saotome/">http://uk.groups.yahoo.com/group/saotome/</a></span> </div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://stomepatrimonio.blogspot.com/">http://stomepatrimonio.blogspot.com</a></span> </div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;">Teaching sustainability and renewable energies:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.isf.es/menu_publicaciones">http://www.isf.es/menu_publicaciones</a></span> </div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.sustainabilityafrica.unny.org/">http://www.sustainabilityafrica.unny.org</a></span> </div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;">Solar energy:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.gaia.org.ar/">http://www.gaia.org.ar</a></span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.sitiosolar.com/">http://www.sitiosolar.com</a></span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.practicalaction.org/">http://www.practicalaction.org</a></span> </div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.ecomaipo.cl/">http://www.ecomaipo.cl</a></span> </div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.solarcooking.org/">http://www.solarcooking.org</a></span> </div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://solarcookers.ning.com/">http://solarcookers.ning.com</a></span> </div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.motherearthnews.com/">http://www.motherearthnews.com</a></span> </div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;">Biogas:</span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.bioenergylists.org/">http://www.bioenergylists.org</a></span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.practicalaction.org/">http://www.practicalaction.org</a> </span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.ganesha.co.uk/">http://www.ganesha.co.uk</a></span></div><div style="font-family: "Trebuchet MS",sans-serif;"><span style="font-size: small;"><a href="http://www.biogasafrica.org/documentlib.html">http://www.biogasafrica.org/documentlib.html</a></span></div>Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.com0tag:blogger.com,1999:blog-912735676971230733.post-13270790605499848522009-09-14T20:00:00.000-07:002009-09-29T01:20:37.834-07:00About the author<div style="font-family: "Trebuchet MS",sans-serif; text-align: justify;"><br />
<span style="font-size: small;">I graduated in chemical engineering in 2002, four years later I defended my PhD in the same field. During my entire professional career I had always been attracted to the ‘energy discipline’ to which I had been devoted. My academic vocation has taken me to work (in chronological order) in United States (Massachusetts Institute of Technology), Spain (University of the Basque Country and Institute of Catalysis and Petrochemistry), Canada (University of Western Ontario), the Netherlands (Delft</span><span style="font-size: small;"> University </span><span style="font-size: small;">of </span><span style="font-size: small;"> </span><span style="font-size: small;"> </span><span style="font-size: small;">Technology</span><span style="font-size: small;">)</span><span style="font-size: small;"> and now in São Tomé.</span><br />
</div>Guarahttp://www.blogger.com/profile/04806901441805932546noreply@blogger.com0