1. Biofuel Biofuel (also called agro fuel) can be broadly defined as solid, liquid, or gas fuel consisting of, or derived from biomass. Wood and its byproducts can now be converted into biofuels such as woodgas, methanol or ethanol fuel Biofuel is considered by some as a means of reducing greenhouse gas emissions and increasing energy security by providing an alternative to fossil fuels. Biofuels are used globally. Biofuel industries are expanding in Europe, Asia and the Americas. The most common use for biofuels is automotive transport (for example E10 fuel). Increased American and European demand has led to clearing land for Palm Oil plantations. Biofuel can be theoretically produced from any (biological) carbon source. The most common by far is photosynthetic plants that capture solar energy. Many different plants and plant-derived materials are used for biofuel manufacture. The greatest technical challenge is to develop ways to convert biomass energy specifically to liquid fuels. To achieve this, the two most common strategies are: 1.To grow sugar crops (sugar cane, and sugar beet), or starch (corn/maize), and then use yeast fermentation to produce ethanol (ethyl alcohol). 2.To grow plants that (naturally) produce oils, such as algae, or jatropha. When these oils are heated, their viscosity is reduced, and they can be burned directly in a diesel engine. The oils can also be chemically processed to produce biodiesel. 2
2. Vegetable oil 3 Vegetable oil can be used for either food or fuel; the quality of the oil may be lower for fuel use. Vegetable oil can be used in many older diesel engines (equipped with indirect injection systems), but only in warm climates. In most cases, vegetable oil is used to manufacture biodiesel, which is compatible with most diesel engines when blended with conventional diesel fuel. MAN B&W Diesel, Wartsila and Deutz AG offer engines that are compatible with straight vegetable oil. Used vegetable oil is increasingly being processed into biodiesel, and at a smaller scale, cleaned of water and particulates and used as a fuel. Many vegetable oils have similar fuel properties to diesel fuel, except for higher viscosity and lower oxidative stability. If these differences can be overcome, vegetable oil may substitute for #2 Diesel fuel, most significantly as engine fuel or home heating oil. The main form of SVO/PPO used in the UK is rapeseed oil (also known as canola oil, primarily in the United States and Canada) which has a freezing point of -10°C. However the use of sunflower oil, which freezes at -17°C, is currently being investigated as a means of improving cold weather starting. Unfortunately oils with lower gelling points tend to be less saturated (leading to a higher iodine number) and polymerize more easily in the presence of atmospheric oxygen. Taxation on SVO/PPO as a road fuel varies from country to country, and it is possible the revenue departments in many countries are even unaware of its use, or feel it insufficiently significant to legislate. Germany offers 0% taxation, resulting in their leading on most developments of the fuel use. However SVO/PPO as a road fuel will be taxed with 0,09 /liter on January, the 1st of 2008 in Germany. From thereon it will rise up to 0,45 /liter until 2012.
2. Vegetable oil 4 Waste vegetable oil which has been filtered.
3. Biodiesel 5 Biodiesel refers to a non-petroleum-based diesel fuel consisting of short chain alkyl (methyl or ethyl) esters, typically made by transesterification of vegetable oils or animal fats, which can be used (alone, or blended with conventional petrodiesel) in unmodified diesel-engine vehicles. Biodiesel is biodegradable and non-toxic, and typically produces about 60% less net- lifecycle carbon dioxide emissions, as it is itself produced from atmospheric carbon dioxide via photosynthesis in plants. Its emissions of smog forming hydrocarbon are 65% less, although the Nitrogen Oxide emissions are about 10% greater than those from petroleum-based diesel. Net-lifetime carbon dioxide emissions can actually differ widely between fuels depending upon production methods of the source vegetable oils and processing methods employed in their creation. It is therefore debatable as to the extent that biodiesel reduces total carbon dioxide emissions currently contributing to anthropogenic global warming compared to those from petroleum-based diesel. Biodiesel is a better solvent than standard diesel, as it 'cleans' the engine, loosening petrodiesel deposits in the fuel lines, which can cause blockages downstream in engines that have previously run for some time on petroleum diesel. For this reason, car manufacturers recommendatation needed that the fuel filter be changed more frequently for a few months after switching to biodiesel. Most manufacturers release lists of the cars that will run on 100% biodiesel. Volkswagen, for example, may tell European customers that they have no problem with biodiesel, while dealers in the USA have posted notices that only blends above 95% petrodiesel are permitted.
6 3. Biodiesel Biodiesel sample
7 4. Bioalcohols Although fossil fuels have become the dominant energy resource for the modern world, Alcohol has been used as a fuel throughout history. The first four aliphatic alcohols (methanol, ethanol, propanol, and butanol) are of interest as fuels because they can be synthesized biologically, and they have characteristics which allow them to be used in current engines. One advantage shared by all four alcohols is octane rating. Biobutanol has the advantage that its energy density is closer to gasoline than the other alcohols (while still retaining over 25% higher octane rating) - however, these advantages are outweighed by disadvantages (compared to ethanol and methanol) concerning production, for instance. Generally speaking, the chemical formula for alcohol fuel is CnH2n+1OH. The larger n is, the higher the energy density. Alcohol fuels are usually of biological rather than petroleum sources. When obtained from biological sources, they are known as bioalcohols (e.g. bioethanol). It is important to note that there is no chemical difference between biologically produced alcohols and those obtained from other sources. However, ethanol that is derived from petroleum should not be considered safe for consumption as this alcohol contains about 5% methanol and may cause blindness or death. This mixture may also not be purified by simple distillation, as it forms an azeotropic mixture. Bioalcohols are still in developmental and research stages. Use of optimized crops with higher yields of energy, elimination of pesticides and fertilizers based on petroleum, and a more rigorous accounting process will help improve the feasibility of bioalcohols as fuels.
8 5. BioGas Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Biogas is comprised primarily of methane and carbon dioxide. Biogas originates from biogenic material and is a type of biofuel. Biogas is a product of the anaerobic digestion or fermentation of biodegradable materials such as manure or sewage, municipal waste, and energy crops. Other types of biogas include wood gas which is created by gasification of wood or other biomass. Depending on where it is produced, biogas can also be called swamp, marsh, landfill or digester gas. A biogas plant is the name often given to an anaerobic digester that treats farm wastes or energy crops. Biogas can be produced utilizing anaerobic digesters. These plants can be fed with energy crops such as maize silage or biodegradable wastes including sewage sludge and food waste. The composition of biogas varies depending upon the origin of the anaerobic digestion process. Landfill gas typically has methane concentrations around 50%. Advanced waste treatment technologies can produce biogas with 55-75%CH4. Biogas can be utilized for electricity production, space heating, water heating and process heating. If compressed, it can replace compressed natural gas for use in vehicles, where it can fuel an internal combustion engine or fuel cells.
10 6. SynGas Syngas is produced by the combined processes of pyrolysis, combustion, and gasification. Biofuel is converted into carbon monoxide and energy by pyrolysis. A limited supply of oxygen is introduced to support combustion. Gasification converts further organic material to hydrogen and additional carbon monoxide. The resulting gas mixture, syngas, is itself a fuel. Using the syngas is more efficient than direct combustion of the original biofuel; more of the energy contained in the fuel is extracted. Syngas may be burned directly in internal combustion engines, used to produce methanol and hydrogen, or converted via the Fischer-Tropsch process into synthetic fuel. Gasification can also begin with materials that are not otherwise useful fuels, such as biomass or organic waste. In addition, the high-temperature combustion refines out corrosive ash elements such as chloride and potassium, allowing clean gas production from otherwise problematic fuels. Industrial-scale gasification is currently mostly used to produce electricity from fossil fuels such as coal, where the syngas is burned in a gas turbine.
6. SynGas Gasification is also used industrially in the production of electricity, ammonia and liquid fuels (oil) using Integrated Gasification Combined Cycles (IGCC), with the possibility of producing methane and hydrogen for fuel cells. IGCC is also a more efficient method of CO2 capture as compared to conventional technologies. IGCC demonstration plants have been operating since the early 1970s and some of the plants constructed in the 1990s are now entering commercial service. Within the last few years, gasification technologies have been developed that use plastic- rich waste as a feed. In a plant in Germany such a technologyon large scaleconverts plastic waste via syngas into methanol. 11
7. Second generation biofuels Supporters of biofuels claim that a more viable solution is to increase political and industrial support for, and rapidity of, second-generation biofuel implementation from non food crops, including cellulosic biofuels. Second-generation biofuel production processes can use a variety of non food crops. These include waste biomass, the stalks of wheat, corn, wood, and special- energy-or-biomass crops (e.g. Miscanthus). Second generation (2G) biofuels use biomass to liquid technology, including cellulosic biofuels from non food crops. Many second generation biofuels are under development such as biohydrogen, biomethanol, DMF, Bio-DME, Fischer-Tropsch diesel, biohydrogen diesel, mixed alcohols and wood diesel. The following second generation biofuels are under development: Biohydrogen is the same as hydrogen except it is produced from a biomass feedstock. This is done using gasification of the biomass and then reforming the methane produced, or alternatively, this might be accomplished with some organisms that produce hydrogen directly under certain conditions. BioHydrogen can be used in fuel cells to produce electricity. Bio-DME, Fischer-Tropsch, BioHydrogen diesel, Biomethanol and Mixed Alcohols all use syngas for production. 12
Biomethanol is the same as methanol but it is produced from biomass. Biomethanol can be blended with petrol up to 10-20% without any infrastructure changes. DMF. Recent advances in producing DMF from fructose and glucose using catalytic biomass-to-liquid process have increased its attractiveness. HTU diesel. HTU diesel is produced from wet biomass. It can be mixed with fossil diesel in any percentage without need for infrastructure: Wood diesel, A new biofuel was developed by the University of Georgia from wood chips. The oil is extracted and then added to unmodified diesel engines. Either new plants are used or planted to replace the old plants. 7. Second generation biofuels 13
Algae fuel, also called oilgae or third generation biofuel, is a biofuel from algae. Algae are low-input/high-yield (30 times more energy per acre than land) feedstocks to produce biofuels and algae fuel are biodegradable: With the higher prices of oil, there is much interest in algaculture (farming algae). One advantage of many biofuels over most other fuel types is that they are biodegradable, and so relatively harmless to the environment if spilled. The United States Department of Energy estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles (38,849 square kilometers), which is a few thousand miles larger than Maryland. 8. Third generation biofuels 14