2.pdf

## Renewable Fuels and Biofuels ### 2. Relative density: * d densitygas/density air * **Ranges:** * d < 0.8 - light gas (e.g. natural gas CHA) * 0.8 < d < 1.2 - medium category (e.g. CO) * 1.2 < d - heavy gas (e.g. LPG-propane-butane) ### 3. Wobbe index * For assessment of gas exc...

## Renewable Fuels and Biofuels ### 2. Relative density: * d densitygas/density air * **Ranges:** * d < 0.8 - light gas (e.g. natural gas CHA) * 0.8 < d < 1.2 - medium category (e.g. CO) * 1.2 < d - heavy gas (e.g. LPG-propane-butane) ### 3. Wobbe index * For assessment of gas exchange ### 4. Flammability limits * Flammability limits, also called flammable limits, give the proportion of combustible gases in a mixture. * Between these limits the mixture is flammable * **LFL (Lower Flammable Limit):** describes the leanest mixture that is still flammable. * The mixture with the smallest fraction of combustible gas. * **UFL (Upper Flammable Limit):** gives the richest flammable mixture. ### Renewable Fuels * Renewable fuels (biomass) are formed in a year or a few years basis. * **Synthetic fuels** may come from fossil or from renewable sources. * **Gaseous:** biogas from anaerobic fermentation or gasogen gas from pyrolysis of biomass. * **Liquid:** alcohols, ethers (biopetrol), esters (biodiesel). * **Solid:** wood, charcoal, fuel pellets (from wood or vegetable residues). Agriculture residues, cattle manure, urban waste ### Comparison of Fossil Fuels and Renewable Fuels * Renewable fuels are more disperse than fossil fuels (oil and gas). * Renewable fuels have less energy content than fossil fuels. * Renewable fuels have more moisture and ash content. * Renewable fuels require more handling effort. * However, renewable fuels are more environmentally friendly. ### Biofuels * The terms **biofuels**, **biomass fuels** and **renewable fuels** may be used indistinctly if they refer to the same combustor. * Biofuels may refer to biomass derivatives directly substituting fossil fuels * Biomass may be restricted to unprocessed biomass (forest waste, crops, animal waste, domestic waste). * Renewable fuels may include fuels like hydrogen obtained by electrolysis and not from biomass. ### Disadvantages of Biofuels * Biomass fuels are mostly solid. * Pre-processing is needed (gasification, liquefaction) to produce fluid fuels, the kind of fuci best fitted to both engines and stationary combustors. * Biomass fuels are less energetic than fossil fuels. * Living matter is roughly a water suspension of oxygenated hydrocarbons, and fossil fuels were slowly cooked over the eons to separate water and most of the oxygen. * Biomass fuels have non-fuel components that must be separated. * Soil in forest-waste, metals in industrial waste. * Biomass fuels are contaminant. * Not contributing to global warming (because the CO2 produced compensates with that synthesized from the air during the biomass growth). * However, biomass fuels produce much more particulates and new chemical emissions (e. g.-dioxins) if not properly treated. ### Biofuels in The Phillipines * The Biofuels Act or Republic Act (RA) 9367 was signed in January 2007, making the Philippines the first country in Southeast Asia to have biofuels legislation in place. * Sugarcane and molasses are used in Philippine ethanol production. * Coconut oil (CNO), where coconut methyl ester (CME) is derived, is the preferred biodiesel feedstock. * The current blend mandates are 10 percent for ethanol, and two percent for biodiesel, respectively. ### Definitions of Biofuel Types * **Bioethanol:** refers to ethanol (C2H5OH) produced from feedstock and other biomass. * **Biodiesel:** refers to Fatty Acid Methyl Ester (FAME) or mono-alkyl esters derived vegetable oils or animal technically proven and approved by the DOE for use in diesel engines, with quality specifications in accordance with Philippine National standards (PNS). * **Bioethanol Fuel:** refers to hydrous or anhydrous bioethanol suitable denatured for use as motor fuel, with quality specifications in bioethanol suitable denatured. * **Biofuel:** refers to bioethanol and biodiesel and other fuels made from biomass and primarily used for motive, thermal and power generation with quality specifications in accordance with the PNS. * **Biofuel blends:** refer to gasoline or diesel that has been blended with biofuels (bioethanol and biodiesel). * **Biomass:** refers to any organic matter, particularly cellulosic or lignocellulosic matter, which is available on a renewable or recurring basis. * This includes trees, crops and associated residues, plant fiber, poultry litter and other animal wastes, industrial wastes, and the biodegradable component of solid waste. ### Biofuel Production Methods * **Ethanol:** by fermentation of biomass sugars, starch or cellulose by yeast or bacteria. * In Japan, a bacteria has been bred which produces ethanol from paper or rice-straw without any pre-treatment. * **Methane:** (actually a biogas mixture) by anaerobic digestion of biomass waste (manure, straw, sewage, municipal solid waste (MSW). * **Oils (biodiesel):** by reforming oleaginoseous plant seeds (eg. colza, sunflower, soya). * The marine microscopic algae Botryococeus Brauni has been shown to accumulate a quantity of hydrocarbons amounting to 75% of their dry weight. * **Methanol:** from wood-waste distillation. * **Hydrogen:** by reforming other biofuels (eg. ethanol or methane), or from water electrolysis by solar or wind energy.