Renewable energy is energy that is collected from natural sources that replenish themselves over short periods of time, renewable energy resources exist over wide geographical areas. Rapid deployment of renewable energy and energy efficiency is resulting in significant energy security, climate change mitigation, and economic benefits. While many renewable energy projects are large-scale, renewable technologies are also suited to rural and remote areas and developing countries, where energy is often crucial in human development. Electricity can be converted to heat (where necessary generating higher temperatures than fossil fuels), can be converted into mechanical energy with high efficiency and is clean at the point of consumption. In addition to that electrification with renewable energy is much more efficient and therefore leads to a significant reduction in primary energy requirements, because most renewables don't have a steam cycle with high losses (fossil power plants usually have losses of 40 to 65%). Renewable energy systems are rapidly becoming more efficient and cheaper. Their share of total energy consumption is increasing. Growth in consumption of coal and oil could end by 2020 due to increased uptake of renewables and natural gas. Renewable energy flows involve natural phenomena such as sunlight, wind, tides, plant growth, geothermal heat and biofuels and hydrogen derived from renewable resources. It would also reduce environmental pollution such as air pollution caused by burning of fossil fuels and improve public health, reduce premature mortalities due to pollution.

Biomass is organic matter extracted from living, or recently living organisms. Biomass can be utilized as a source of energy and it most often directs to plants or plant-based matter which are not used for food or feed, and are precisely called lignocellulosic biomass. As an energy source, biomass can either be used directly via combustion to produce heat, or secondarily after transforming it to numerous forms of biofuel. Conversion of biomass to biofuel can be attained by various methods which are mainly categorized into: thermal, chemical, and biochemical methods.

Biomass is a renewable source of fuel to yield energy since waste residues will always prevail – in forms of scrap wood, mill residuals and forest resources and properly directed forests will always have additional trees, and we will invariably have crops and the unconsumed biological matter from those crops.

Algae fuel or algal biofuel is a substitute to liquid fossil fuels that utilizes algae as its source of energy-rich oils. Also, algae fuels are a substitute to common known biofuel sources, such as corn and sugarcane. Various companies and government agencies are sponsoring efforts to reduce capital and operating costs and make algae fuel production commercially feasible. Like fossil fuel, algae fuel releases CO2 when burnt, but unlike fossil fuel, algae fuel and other biofuels only release CO2 recently withdrawn from the atmosphere via photosynthesis as the algae or plant grew. The energy crisis and the world food crisis have sparked interest in algaculture (farming algae) for making biodiesel and other biofuels utilizing land unbefitting for agriculture. Among algal fuels' attractive characteristics are that they can be cultivated with negligible impact on fresh water resources, can be generated using saline and wastewater, have a high flash point, and are biodegradable and comparatively harmless to the environment if spilled. Algae cost more per unit mass than other advanced biofuel crops due to high capital and operating costs, but are declared to generate between 10 and 100 times more fuel per unit area.

Biodiesel indicates an animal fat-based or vegetable oil diesel fuel comprising of long-chain alkyl (methyl, ethyl, or propyl) esters. Biodiesel is customarily made by chemically reacting lipids (e.g., soybean oil, vegetable oil, animal fat (tallow)) with an alcohol generating fatty acid esters. Biodiesel is suggested to be utilized in standard diesel engines and is thus well-defined from the vegetable and waste oils used to operate fuel converted diesel engines. Biodiesel can be used singly, or blended with petrodiesel in any proportions. Biodiesel blends can also be utilized as heating oil.

Biomass is the organic matter derived from plants which is generated through photosynthesis. In particular it can be referred to solar energy stored in the chemical bonds of the organic material. In addition to many benefits common to renewable energy, biomass is attractive because it is current renewable source of liquid transportation of biofuel. The Bioenergy Conference and Biofuel Conferences will optimize and enhance existing systems. However, biomass could play in responding to the nation's energy demands assuming, the economic and advances in conversion technologies will make biomass fuels and products more economically viable? The renewable energy policies in the European Union have already led to a significant progress, energy mix should further change till 2020.

Biogas commonly refers to a mixture of various gases formed by the disintegration of organic matter in the absence of oxygen. Biogas can be manufactured from raw matters  such as agricultural waste, municipal waste, manure, plant material, green waste, sewage or food waste. Biogas is a renewable energy source and in diverse cases exerts a limited carbon footprint. Biogas can be manufactured by fermentation of biodegradable materials or anaerobic digestion with anaerobic organisms, which disintegrates material inside an isolated system. Biogas is basically methane (CH4) and carbon dioxide (CO2) and may have small traces of hydrogen sulfide (H2S), siloxanes and moisture. The gases methane, carbon monoxide (CO) and hydrogen can be combusted or oxidized with oxygen. This energy yield allows biogas to be benefitted as a fuel; it can be utilized for any heating purpose, such as cooking. It can also be practiced in a gas engine to transform the energy in the gas to electricity and heat.

Several technologies for converting bioenergy are commercial today while others are being piloted or in research and development. There are four types of conversion technologies currently available, each appropriate for specific biomass types and resulting in specific energy products such as Thermal Conversion, Thermochemical conversion, Biochemical conversion, Chemical conversion. The Biomass Technologies include Liquid Biofuels from Biomass and Cellulosic Ethanol from Biomass.

Biologically synthesized alcohols, most frequently ethanol, and rarely propanol and butanol, are formed by the reaction of microorganisms and enzymes through the fermentation of sugars or starches, or cellulose. Biobutanol (also called biogasoline) is often asserted to provide a direct stand-in for gasoline, because it can be used precisely in a gasoline engine. Ethanol fuel is the most widely used biofuel worldwide. Alcohol fuels are formed by fermentation of sugars derived from wheat, sugar beets, corn, molasses, sugar cane and any sugar or starch from which alcoholic liquors such as whiskey, can be produced (such as potato and fruit waste, etc.). The ethanol manufacturing methods applied are enzyme digestion (to release sugars from stored starches), distillation, fermentation of the sugars and drying. Ethanol can be used in petrol engines as a substitute for gasoline; it can be blended with gasoline to any concentration. Current car petrol engines can operate on mixes of up to 15% bioethanol alongwith petroleum/gasoline. Ethanol has lesser energy density than that of gasoline; this implies that it takes more fuel to generate the same amount of work. An asset of ethanol is it’s higher octane rating than ethanol-free gasoline accessible at roadside gas stations, which permits the rise of an engine's compression ratio for increased thermal efficiency. In high-altitude locations, some states direct a mix of gasoline and ethanol as a winter oxidizer to lower atmospheric pollution emissions.

Bioenergy is renewable energy made accessible from materials acquired from biological origin. Biomass is any organic matter which has deposited sunlight in the form of chemical energy. As a fuel it may comprise wood, straw, wood waste, sugarcane, manure, and many other by-products from different agricultural processes. In its most exclusive sense it is a synonym to biofuel, which is fuel obtained from biological sources. In its wider sense it includes biomass, the biological matter utilized as a biofuel, as well as the social, scientific, economic and technical fields related with utilizing biological sources for energy. This is a common misbelief, as bioenergy is the energy cultivated from the biomass, as the biomass is the fuel and the bioenergy is the energy stored in the fuel.

Biohydrogen is described as hydrogen produced biologically, most often by algae, bacteria and archaea. Biohydrogen is a potential biofuel attainable from both cultivation and from waste organic materials. Recently, there is a huge demand for hydrogen. There is no record of the production volume and use of hydrogen world-wide, however utilization of hydrogen was predicted to have reached 900 billion cubic meters in 2011.Refineries are large-volume producers and consumers of hydrogen. Today 96% of all hydrogen is extracted from fossil fuels, with 48% from natural gas, 30% from hydrocarbons, 18% from coal and about 4% by electrolysis. Oil-sands processing, gas-to-liquids and coal gasification projects that are existing, require a vast amount of hydrogen and is presumed to raise the requirement notably within the next few years. Environmental regulations administered in most countries, increase the hydrogen demand at refineries for gas-line and diesel desulfurization. A  significant future aspect of hydrogen could be as a replacement for fossil fuels, once the oil deposits are exhaustede. This application is however dependent on the advancement of storage techniques to enable proper storage, distribution and combustion of hydrogen. If the cost of hydrogen generation, distribution, and end-user technologies decreases, hydrogen as a fuel could be penetrating the market in 2020.Industrial fermentation of hydrogen, or whole-cell catalysis, requires a finite amount of energy, since fission of water is accomplished with whole cell catalysis, to reduce the activation energy. This permits hydrogen to be manufactured from any organic matter that can be copied through whole cell catalysis as this process does not rely on the energy of substrate.

A biorefinery is a center that melds biomass conversion processes and equipment to manufacture fuels, power, heat, and chemicals from biomass. The biorefinery concept is parallel to today's petroleum refinery, which makes various fuels and products from petroleum. Biorefining is the sustainable conversion of biomass into a spectrum of bio-based products and bioenergy. By producing various products, a biorefinery takes advantage of the various parts in biomass and their intermediates therefore maximizing the value acquired from the biomass feedstock. A biorefinery could, for instance, manufacture one or several low-volume, but high-value, chemical or nutraceutical products and a low-value, but high-volume liquid transportation fuel such as biodiesel.  At the same time generating electricity and process heat, by combined heat and power (CHP) technology, for its own use and perhaps adequate for sale of electricity to the local utility. The high-value products boost profitability, the high-volume fuel helps meet energy needs, and the power production aids to lower energy costs and minimize greenhouse gas emissions from conventional power plant facilities. Although some facilities prevail that can be called bio-refineries, the bio-refinery has yet to be fully accomplished. Future biorefineries may play a vital role in yielding chemicals and materials that are traditionally extracted from petroleum.

Food versus fuel is the plight regarding the risk of distracting farmland or crops for biofuels production to the drawback of the food supply. The biofuel and food price debate concerns wide-ranging views and is an abiding, controversial one in the literature. There is a conflict about the sense of the issue, what is creating it, and what can or should be rendered to remedy the situation. This intricacy and uncertainty is due to the wide number of concussion and criticism loops that can positively or negatively affect the price system. Furthermore, the relative strengths of these positive and negative impacts change in the short and long terms, and implicate delayed effects. The academic side of the debate is also obscured by the applicability of different economic models and competing forms of statistical analysis.

Aviation biofuel is a biofuel utilized for aircraft. It is reckoned by some to be the paramount means by which the aviation industry can diminish its carbon footprint. After a multi-year technical analysis from aircraft makers, engine manufacturers and oil companies, biofuels were advocated for commercial use in July 2011. Since then, some airlines have evaluated with using of biofuels on commercial flights. The limelight of the industry has now curved to advanced sustainable biofuels (second generation sustainable aviation fuels) that do not compete with food supplies nor are major consumers of prime agricultural land or fresh water.

Currently used liquid biofuels, which include ethanol produced from crops containing sugar and starch and biodiesel from oilseeds, are referred to as first-generation biofuels. These fuels only use a portion of the energy potentially available in the biomass. Various techniques are currently being developed to produce biofuels. However, it is uncertain when such technologies will enter production on a significant commercial scale. The production of Biofuels can be done from Biomass, Biodiesel from Biomass, and Biochemical from Biomass and Biogas from Biomass

Green chemistry, is an area of chemistry and chemical engineering focused on the creating and designing of products and processes that minimize the use and generation of hazardous substances.it still maintain economic growth and opportunities while providing affordable products and services to a growing world population.