Biofuels are solid, liquid or gaseous fuel, that are derived from biomass. The biomass is usually processed or converted in some way into a more convenient form, which is the biofuel, principally to increase energy density. This may involve physical pre-processing simply to cut it into more manageable pieces or reduce the moisture content, or may involve thermal or chemical processing to convert it into a solid, liquid or gas. Biofuels are one of the green alternatives to fossil fuels.

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Biodiversity reflects the number, variety and variability of living organisms. It includes diversity within species, between species, and among ecosystems. The concept also covers how this diversity changes from one location to another and over time. The promotion of biofuel production might accelerate global species loss because it encourages the conversion of pasture, savanna and forests into new cropland.

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Biomass is biological material derived from living, or recently living organisms. In the context of biomass for energy this is often used to mean plant based material, but biomass can equally apply to both animal and vegetable derived material. Biomass is carbon based and is composed of a mixture of organic molecules containing hydrogen, oxygen, nitrogen and also small quantities of other atoms. Some examples for biomass for energy: wood, energy crops (high yield crops grown specifically for energy applications), agricultural residues, food waste.

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Catalytic material is a substance that will change the rate of a chemical reaction. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself (although it might be inhibited, deactivated, or destroyed by secondary processes).

Catalysts can be either heterogeneous or homogeneous, depending on whether a catalyst exists in the same phase as the substrate. Biocatalysts (enzymes) are often seen as a separate group.

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Also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol. Ethanol is widely used as fuel, especially in Brazil which has the largest national fuel ethanol industry. Ethanol as a fuel reduces harmful car motor emissions of carbon monoxide, particulate matter, oxides of nitrogen, and other ozone-forming pollutants. Ethanol is commercially produced from corn or sugar cane.

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The raw materials used for the production in an industrial process. The feedstock for ethanol fuel production is crops such as corn in the US, sugarcane in Brazil and cassava in tropical regions. In modern industrial processes, 0.42 liter of ethanol can be produced from a kilogram of corn.

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Fermentation is the process in which sugars are transferred to ethanol with the release of CO2. Ethanol fermentation occurs in the production of alcoholic beverages and ethanol fuel, and in the rising of bread dough. Yeast fermentation of various carbohydrate products is used to produce much of the ethanol used for fuel.

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Fossil fuels are formed from the fossilized remains of dead plants by exposure to heat and pressure in the Earth's crust (or by natural processes such as anaerobic decomposition) over millions of years. Thus fossil fuels are non-renewable resources.

Fossil fuels contain high percentages of carbon and include coal, petroleum, and natural gas. At present, most of the world's energy supply comes from fossil sources, although mankind is increasingly facing issues of resource limitation, environmental pollution and problems such as global warming.

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A series of individual chemical reactions in a living system/organism that combine to perform one or more important functions. The product of one reaction in a pathway serves as the substrate for the following reaction. The production of biofuels can be designed using naturally occurring enzymes that, when integrated with metabolic pathways for biofuel precursors will enable the biosynthesis of advanced biofuels in engineered host microbes.

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Photoelectrolysis occurs in a photoelectrochemical cell when light is used for electrolysis. In other words, photoelectrolysis is the conversion of light into an electric current that will drive an otherwise non-spontaneous chemical reaction. Photoelectrolysis can potentially of divide water to hydrogen and oxygen (water splitting).

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Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria. In plants, algae, and cyanobacteria, photosynthesis uses carbon dioxide and water, releasing oxygen as a waste product. Photosynthesis is vital for all aerobic life on Earth, as it maintain normal levels of oxygen in the atmosphere and is the source of energy for nearly all life on earth.

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Absorption of photons in a semiconductor particle may result in the generation of electron-hole pairs. A process, by which these photogenerated carriers separate and migrate of to the surface to promote chemical reactions with various substances, is referred to as photocatalysis. Semiconductor-mediated photocatalysis presents an attractive and promising solution for both renewable energy generation and other environmental applications, such as water treatment and air purification. Examples are the solar-driven photocatalytic splitting of water into hydrogen and oxygen, and the reaction of water and carbon dioxide (CO2 reduction), which provide potentially clean and renewable fuels.

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Solar-to-fuel energy conversion alleviates the energy storage problem, since fuel (chemical energy) can be stored more easily than either electricity or heat.

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In order to produce ethanol by fermentation, it is essential to extract the soluble sugars from the feedstock such as sugar-canes. A pre-treatment step to break down the cellulose and hemi-cellulose in the plants is required and adds to the feedstock cost. The extraction of soluble sugars from the raw materials can be performed either by an enzymatic approach or by a catalytic approach.

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Water splitting is the general term for a chemical reaction in which water is separated into oxygen and hydrogen. Efficient and economical water splitting would be a key technology component of a hydrogen economy. Hydrogen is considered by many to be a promising energy currency, particularly for the transportation sector and for mobile devices. The combustion of hydrogen yields water as its only waste product, and hydrogen is a perfect fuel for fuel cells.

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Supported by the I-CORE Program of the Planning and Budgeting Committee and The Israel Science Foundation

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