Biofuel is defined as solid, liquid or gas fuel derived from recently dead biological material and is distinguished from fossil fuels, which are derived from long dead biological material. Theoretically, biofuels can be produced from any (biological) carbon source; although, the most common sources are photosynthetic plants. Various plants and plant-derived materials are used for biofuel manufacturing. Globally, biofuels are most commonly used to power vehicles, heating homes cornstoves and cooking stoves. Biofuel industries are expanding in Europe, Asia and the Americas.
Biofuels offer the possibility of producing energy without a net increase of carbon into the atmosphere. This is because the plants used in the production of the fuel removed from the atmosphere; unlike fossil fuels, which return carbon that was stored beneath the surface for millions of years back into the atmosphere. Therefore, biofuel is, in theory, more carbon neutral and less likely to increase atmospheric concentrations of greenhouse gases. (However, doubts have been raised as to whether this benefit can be achieved in practice, see below). The use of biofuels also reduces dependence on petroleum and enhances energy security.
There are two common strategies of producing biofuels. One is to grow crops high in sugar (sugar cane, sugar beet, and sweet sorghum) or starch (corn/maize), and then use yeast fermentation to produce ethyl alcohol (ethanol). The second is to grow plants that contain high amounts of vegetable oil, such as oil palm, soybean, algae, or jatropha. When these oils are heated, their viscosity is reduced, and they can be burned directly in a diesel engine, or they can be chemically processed to produce fuels such as biodiesel. Wood and its byproducts can also be converted into biofuels such as woodgas, methanol or ethanol fuel. It is also possible to make cellulosic ethanol from non-edible plant parts, but this can be difficult to accomplish economically.
Biofuels are discussed as having significant roles in a variety of international issues, including: mitigation of carbon emissions levels and oil prices, the "food vs fuel" debate, deforestation and soil erosion, impact on water resources, and energy balance and efficiency.
Nevertheless, before World War II, and during the high demand wartime period, biofuels were valued as a strategic alternative to imported oil. Wartime Germany experienced extreme oil shortages, and many energy innovations resulted. This includes the powering of some of its vehicles using a blend of gasoline with alcohol fermented from potatoes, called Monopolin. In Britain, grain alcohol was blended with petrol by the Distillers Company Limited under the name Discol, and marketed through Esso's affiliate Cleveland.
During the peacetime post-war period, inexpensive oil from the Middle East contributed in part to the lessened economic and geopolitical interest in biofuels. Then in 1973 and 1979, geopolitical conflict in the Middle East caused OPEC to cut exports, and non-OPEC nations experienced a very large decrease in their oil supply. This "energy crisis" resulted in severe shortages, and a sharp increase in the prices of high demand oil-based products, notably petrol/gasoline. There was also increased interest from governments and academics in energy issues and biofuels. Throughout history, the fluctuations of supply and demand, energy policy, military conflict, and the environmental impacts, have all contributed to a highly complex and volatile market for energy and fuel.
In the year 2000 and beyond, renewed interest in biofuels has been seen. The drivers for biofuel research and development include rising oil prices, concerns over the potential oil peak, greenhouse gas emissions (causing global warming and climate change), rural development interests, and instability in the Middle East.
Biomass is material derived from recently living organisms. This includes plants, animals and their by-products. For example, manure, garden waste and crop residues are all sources of biomass. It is a renewable energy source based on the carbon cycle, unlike other natural resources such as petroleum, coal, and nuclear fuels.
Animal waste is a persistent and unavoidable pollutant produced primarily by the animals housed in industrial sized farms. Researchers from Washington University have figured out a way to turn manure into biomass. In April 2008 with the help of imaging technology they noticed that vigorous mixing helps microorganisms turn farm waste into alternative energy, providing farmers with a simple way to treat their waste and convert it into energy.
There are also agricultural products specifically grown for biofuel production including corn, switchgrass, and soybeans, primarily in the United States; rapeseed, wheat and sugar beet primarily in Europe; sugar cane in Brazil; palm oil and miscanthus in South-East Asia; sorghum and cassava in China; and jatropha in India. Hemp has also been proven to work as a biofuel. Biodegradable outputs from industry, agriculture, forestry and households can be used for biofuel production, either using anaerobic digestion to produce biogas, or using second generation biofuels; examples include straw, timber, manure, rice husks, sewage, and food waste. Biomass can come from waste plant material. The use of biomass fuels can therefore contribute to waste management as well as fuel security and help to prevent global warming, though alone they are not a comprehensive solution to these problems.
Using waste biomass to produce energy can reduce the use of fossil fuels, reduce greenhouse gas emissions and reduce pollution and waste management problems. A recent publication by the European Union highlighted the potential for waste-derived bioenergy to contribute to the reduction of global warming. The report concluded that 19 million tons of oil equivalent is available from biomass by 2020, 46% from bio-wastes: municipal solid waste (MSW), agricultural residues, farm waste and other biodegradable waste streams.
Landfill sites generate gases as the waste buried in them undergoes anaerobic digestion. These gases are known collectively as landfill gas (LFG). This is considered a source of renewable energy, even though landfill disposal is often non-sustainable. Landfill gas can be burned either directly for heat or to generate electricity for public consumption. Landfill gas contains approximately 50% methane, the gas found in natural gas.
If landfill gas is not harvested, it escapes into the atmosphere: this is undesirable because methane is a greenhouse gas with much more global warming potential than carbon dioxide. Over a time span of 100 years, one ton of methane produces the same greenhouse gas (GHG) effect as 23 tons of CO2. When methane burns, it produces carbon dioxide in the ratio 1:1 -- CH4 + 2O2 = CO2 + 2H2O. So, by harvesting and burning landfill gas, its global warming potential is reduced a factor of 23, in addition to providing energy for heat and power.
It was recently discovered that living plants also produce methane. The amount is 10 to 100 times greater than that produced by dead plants in an aerobic environment but does not increase global warming because of the carbon cycle.
Anaerobic digestion can be used as a waste management strategy to reduce the amount of waste sent to landfill and generate methane, or biogas. Any form of biomass can be used in anaerobic digestion and will break down to produce methane, which can be harvested and burned to generate heat, power or to power certain automotive vehicles.
A 3 MW landfill power plant would power 1,900 homes. It would eliminate 6,000 tons per year of methane from getting into the environment. It would eliminate 18,000 tons per year of CO2 from fossil fuel replacement. This is the same as removing 25,000 cars from the road, or planting of forest, or not using of oil per year.
Most transportation fuels are liquids, because vehicles usually require high energy density, as occurs in liquids and solids. Vehicles usually need high power density as can be provided most inexpensively by an internal combustion engine. These engines require clean burning fuels, in order to keep the engine clean and minimize air pollution. The fuels that are easier to burn cleanly are typically liquids and gases. Thus liquids (and gases that can be stored in liquid form) meet the requirements of being both portable and clean burning. Also, liquids and gases can be pumped, which means handling is easily mechanized, and thus less laborious.
The most common first generation biofuels are listed below.
Edible vegetable oil is generally not used as fuel, but lower quality oil can be used for this purpose. Used vegetable oil is increasingly being processed into biodiesel, or (more rarely) cleaned of water and particulates and used as a fuel. To ensure that the fuel injectors atomize the fuel in the correct pattern for efficient combustion, vegetable oil fuel must be heated to reduce its viscosity to that of diesel, either by electric coils or heat exchangers. This is easier in warm or temperate climates. MAN B&W Diesel, Wartsila and Deutz AG offer engines that are compatible with straight vegetable oil, without the need for after-market modifications. Vegetable oil can also be used in many older diesel engines that do not use common rail or unit injection electronic diesel injection systems. Due to the design of the combustion chambers in indirect injection engines, these are the best engines for use with vegetable oil. This system allows the relatively larger oil molecules more time to burn. However, a handful of drivers have experienced limited success with earlier pre- "pumpe duse" VW TDI engines and other similar engines with direct injection.
Biodiesel can be used in any diesel engine when mixed with mineral diesel. The majority of vehicle manufacturers limit their recommendations to 15% biodiesel blended with mineral diesel. In some countries manufacturers cover their diesel engines under warranty for B100 use, although Volkswagen of Germany, for example, asks drivers to check by telephone with the VW environmental services department before switching to B100. B100 may become more viscous at lower temperatures, depending on the feedstock used, requiring vehicles to have fuel line heaters. In most cases, biodiesel is compatible with diesel engines from 1994 onwards, which use 'Viton' (by DuPont) synthetic rubber in their mechanical injection systems. Electronically controlled 'common rail' and 'pump duse' type systems from the late 1990s onwards may only use biodiesel blended with conventional diesel fuel. These engines have finely metered and atomized multi-stage injection systems are very sensitive to the viscosity of the fuel. Many current generation diesel engines are made so that they can run on B100 without altering the engine itself, although this depends on the fuel rail design.
Since biodiesel is an effective solvent and cleans residues deposited by mineral diesel, engine filters may need to be replaced more often, as the biofuel dissolves old deposits in the fuel tank and pipes. It also effectively cleans the engine combustion chamber of carbon deposits, helping to maintain efficiency. In many European countries, a 5% biodiesel blend is widely used and is available at thousands of gas stations. Biodiesel is also an oxygenated fuel, meaning that it contains a reduced amount of carbon and higher hydrogen and oxygen content than fossil diesel. This improves the combustion of fossil diesel and reduces the particulate emissions from un-burnt carbon.
In the USA, more than 80% of commercial trucks and city buses run on diesel. The emerging US biodiesel market is estimated to have grown 200% from 2004 to 2005. "By the end of 2006 biodiesel production was estimated to increase fourfold [from 2004] to more than 1 billion gallons,".
Biologically produced alcohols, most commonly ethanol, and less commonly propanol and butanol, are produced by the action of microorganisms and enzymes through the fermentation of sugars or starches (easiest), or cellulose (which is more difficult). Biobutanol (also called biogasoline) is often claimed to provide a direct replacement for gasoline, because it can be used directly in a gasoline engine (in a similar way to biodiesel in diesel engines).
Butanol is formed by ABE fermentation (acetone, butanol, ethanol) and experimental modifications of the process show potentially high net energy gains with butanol as the only liquid product. Butanol will produce more energy and allegedly can be burned "straight" in existing gasoline engines (without modification to the engine or car), and is less corrosive and less water soluble than ethanol, and could be distributed via existing infrastructures. DuPont and BP are working together to help develop Butanol.
Ethanol fuel is the most common biofuel worldwide, particularly in Brazil. Alcohol fuels are produced by fermentation of sugars derived from wheat, corn, sugar beets, sugar cane, molasses and any sugar or starch that alcoholic beverages can be made from (like potato and fruit waste, etc.). The ethanol production methods used are enzyme digestion (to release sugars from stored starches, fermentation of the sugars, distillation and drying. The distillation process requires significant energy input for heat (often unsustainable natural gas fossil fuel, but cellulosic biomass such as bagasse, the waste left after sugar cane is pressed to extract its juice, can also be used more sustainably).
Ethanol can be used in petrol engines as a replacement for gasoline; it can be mixed with gasoline to any percentage. Most existing automobile petrol engines can run on blends of up to 15% bioethanol with petroleum/gasoline. Gasoline with ethanol added has higher octane, which means that your engine can typically burn hotter and more efficiently. In high altitude (thin air) locations, some states mandate a mix of gasoline and ethanol as a winter oxidizer to reduce atmospheric pollution emissions.
Ethanol fuel has less BTU energy content, which means it takes more fuel (volume and mass) to produce the same amount of work. More-expensive premium fuels contain less, or no, ethanol. In high-compression engines, less ethanol, slower-burning premium fuel is required to avoid harmful pre-ignition (knocking). Very-expensive aviation gasoline (Avgas) is 100 octane made from 100% petroleum. The high price of zero-ethanol Avgas does not include federal-and-state road-use taxes.
Ethanol is very corrosive to fuel systems, rubber hoses and gaskets, aluminum, and combustion chambers. Therefore, it is illegal to use fuels containing alcohol in aircraft (although at least one model of ethanol-powered aircraft has been developed, the Embraer EMB 202 Ipanema). Ethanol also corrodes fiberglass fuel tanks such as used in marine engines. For higher ethanol percentage blends, and 100% ethanol vehicles, engine modifications are required.
It is the hygroscopic (water loving) nature of relatively polar ethanol that can promote corrosion of existing pipelines and older fuel delivery systems. To characterize ethanol itself as a corrosive chemical is somewhat misleading and the context in which it can be indirectly corrosive, somewhat narrow; i.e., limited to effects upon existing pipelines designed for petroleum transport.
Corrosive ethanol cannot be transported in petroleum pipelines, so more-expensive over-the-road stainless-steel tank trucks increase the cost and energy consumption required to deliver ethanol to the customer at the pump.
In the current alcohol-from-corn production model in the United States, considering the total energy consumed by farm equipment, cultivation, planting, fertilizers, pesticides, herbicides, and fungicides made from petroleum, irrigation systems, harvesting, transport of feedstock to processing plants, fermentation, distillation, drying, transport to fuel terminals and retail pumps, and lower ethanol fuel energy content, the net energy content value added and delivered to consumers is very small. And, the net benefit (all things considered) does little to reduce un-sustainable imported oil and fossil fuels required to produce the ethanol.
Although ethanol-from-corn and other food stocks has implications both in terms of world food prices and limited, yet positive energy yield (in terms of energy delivered to customer/fossil fuels used), the technology has lead to the development of cellulosic ethanol. According to a joint research agenda conducted through the U.S. Department of Energy, the fossil energy ratios (FER) for cellulosic ethanol, corn ethanol, and gasoline are 10.3, 1.36, and 0.81, respectively.
Many car manufacturers are now producing flexible-fuel vehicles (FFV's), which can safely run on any combination of bioethanol and petrol, up to 100% bioethanol. They dynamically sense exhaust oxygen content, and adjust the engine's computer systems, spark, and fuel injection accordingly. This adds initial cost and ongoing increased vehicle maintenance. Efficiency falls and pollution emissions increase when FFV system maintenance is needed (regardless of the fuel mix being used), but not performed (as with all vehicles). FFV internal combustion engines are becoming increasingly complex, as are multiple-propulsion-system FFV hybrid vehicles, which impacts cost, maintenance, reliability, and useful lifetime longevity.
Alcohol mixes with both petroleum and with water, so ethanol fuels are often diluted after the drying process by absorbing environmental moisture from the atmosphere. Water in alcohol-mix fuels reduces efficiency, makes engines harder to start, causes intermittent operation (sputtering), and oxidizes aluminum (carburetors) and steel components (rust).
Even dry ethanol has roughly one-third lower energy content per unit of volume compared to gasoline, so larger / heavier fuel tanks are required to travel the same distance, or more fuel stops are required. With large current un-sustainable, non-scalable subsidies, ethanol fuel still costs much more per distance traveled than current high gasoline prices in the United States.
Methanol is currently produced from natural gas, a non-renewable fossil fuel. It can also be produced from biomass as biomethanol. The methanol economy is an interesting alternative to the hydrogen economy, compared to today's hydrogen produced from natural gas, but not hydrogen production directly from water and state-of-the-art clean solar thermal energy processes.
Biogas is produced by the process of anaerobic digestion of organic material by anaerobes. It can be produced either from biodegradable waste materials or by the use of energy crops fed into anaerobic digesters to supplement gas yields. The solid byproduct, digestate, can be used as a biofuel or a fertilizer. In the UK, the National Coal Board experimented with microorganisms that digested coal in situ converting it directly to gases such as methane.
Biogas contains methane and can be recovered from industrial anaerobic digesters and mechanical biological treatment systems. Landfill gas is a less clean form of biogas which is produced in landfills through naturally occurring anaerobic digestion. If it escapes into the atmosphere it is a potent greenhouse gas.
Oils and gases can be produced from various biological wastes:
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. The wood gas generator is a wood-fueled gasification reactor mounted on an internal combustion engine. Syngas can be used to produce methanol and hydrogen, or converted via the Fischer-Tropsch process to produce a synthetic petroleum substitute. Gasification normally relies on temperatures >700°C. Lower temperature gasification is desirable when co-producing biochar.
Cellulosic ethanol production uses non food crops or inedible waste products and does not divert food away from the animal or human food chain. Lignocellulose is the "woody" structural material of plants. This feedstock is abundant and diverse, and in some cases (like citrus peels or sawdust) it is a significant disposal problem.
Producing ethanol from cellulose is a difficult technical problem to solve. In nature, ruminant livestock (like cattle) eats grass and then use slow enzymatic digestive processes to break it into glucose (sugar). In cellulosic ethanol laboratories, various experimental processes are being developed to do the same thing, and then the sugars released can be fermented to make ethanol fuel.
Algae fuel, also called oilgae or third generation biofuel, is a biofuel from algae. Algae are low-input, high-yield feedstocks to produce biofuels. It produces 30 times more energy per acre than land crops such as soybeans. With the higher prices of fossil fuels (petroleum), 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 roughly the size of Maryland.
Second and third generation biofuels are also called advanced biofuels.
Algae, such as Chlorella vulgaris, is relatively easy to grow, but the algal oil is hard to extract. There are several approaches, some of which work better than others. See: Prospects for the Biodiesel Industry.
IC Green Energy, a subsidiary of Israel Corp., aims by 2012 to process 4-5% of the global biofuel market (~4 million tons). It is focused solely on non-edible feedstock such as jatropha, castor, cellulosic biomass and algae. In June 2008, Tel Aviv-based Seambiotic and Seattle-based Inventure Chemical announced a joint venture to use CO2 emissions-fed algae to make ethanol and biodiesel at a biofuel plant in Israel.
In India, a bioethanol program calls for E5 blends throughout most of the country targeting to raise this requirement to E10 and then E20.
The biggest German biodiesel company is ADM Ölmühle Hamburg AG, subsidiary of the American group Archer Daniels Midland Company. Among the other large German producers, MUW (Mitteldeutsche Umesterungswerke GmbH & Co KG) and EOP Biodiesel AG. A major contender in terms of bioethanol production is the German sugar corporation, Südzucker.
The government of Brazil hopes to build on the success of the Proálcool ethanol program by expanding the production of biodiesel which must contain 2% biodiesel by 2008, and 5% by 2013.
In 2006, the United States president George W. Bush said in a State of the Union speech that the US is "addicted to oil" and should replace 75% of imported oil by 2025 by alternative sources of energy including biofuels.
Essentially all ethanol fuel in the US is produced from corn. Corn is a very energy-intensive crop, which requires one unit of fossil-fuel energy to create just 0.9 to 1.3 energy units of ethanol. A senior member of the House Energy and Commerce Committee, Congressman Fred Upton introduced legislation to use at least E10 fuel by 2012 in all cars in the USA. The 2007-12-19 US Energy Independence and Security Act of 2007 requires American “fuel producers to use at least 36 billion gallons of biofuel in 2022. This is nearly a fivefold increase over current levels.” This is causing a significant shift of resources away from food production. American food exports have decreased (increasing grain prices worldwide), and US food imports have increased significantly.
Most biofuels are not currently cost-effective without significant subsidies. "America's ethanol program is a product of government subsidies. There are more than 200 different kinds, as well as a 54 cents-a-gallon tariff on imported ethanol. This prices Brazilian ethanol out of an otherwise competitive market. Brazil makes ethanol from sugarcane rather than corn (maize), which has a better EROEI. Federal subsidies alone cost $7 billion a year (equal to around $1.90 a gallon).
General Motors is starting a project to produce E85 fuel from cellulose ethanol for a projected cost of $1 a gallon. This is optimistic, because $1/gal equates to $10/MBTU which is comparable to woodchips at $7/MBTU or cord wood at $6-$12/MBTU, and this does not account for conversion losses and plant operating and capital costs which are significant. The raw materials can be as simple as corn stalks and scrap petroleum-based vehicle tires, but used tires are an expensive feedstock with other more-valuable uses. GM has over 4 million E85 cars on the road now, and by 2012 half of the production cars for the US will be capable of running on E85 fuel. But by 2012, the supply of ethanol will not even be close to supplying this much E85. Coskata Inc. is building two new plants for the ethanol fuel. Theoretically, the process is claimed to be five times more energy efficient than corn based ethanol, but it is still in development and has not been proven to be cost effective in a free market.
The greenhouse gas emissions are reduced by 86% for cellulose compared to corn’s 29% reduction.
A bioethanol blend was introduced commercially in New Zealand for the first time by the company Gull on 1 August 2007. It contained 10% ethanol made from dairy by product by Anchor Ethanol, a subsidiary of Fonterra Ltd. On 8 August 2008, Gull introduced a 91-octane bioethanol blend in Albany, Auckland. The blend, 'regular plus', contained 10% ethanol and included bioethanol made from whey. Gull planned to release the fuel to 33 stations, and marketed it as under $2 per litre. On release, the company said it would try to keep the price two cents less than its standard 91-octane fuel.
Days earlier, it was reported that British fuel producer Argent Energy would abandon plans to build a plant in Tauranga to produce tallow-based biodiesel. The plant would have cost over $100 million to build, and would have competed with cheaper sugar-based ethanol imports from Brazil. The plant could not proceed because a 42c/L tax break on bioethanol until 2010 had not been approved by the government.
Ecodiesel, a company owned by a group of New Zealand farmers, plans to build a biodiesel plant by the end of 2008. The plant will be built in stages and cheaper than Argent's, and could produce 20 million litres of tallow-based biodiesel per year by April 2009.
The New Zealand government, lead by Helen Clarke, introduced a Biofuel Bill in October 2007.
Dickon Posnett, head of Argent's New Zealand subsidiary, said New Zealand had some of the best raw materials for biofuels in the world.
In rural populations in developing countries, biomass provides the majority of fuel for heat and cooking. Wood, animal dung and crop residues are commonly burned. Figures from the International Energy Agency (IEA) show that biomass energy provides around 30% of the total primary energy supply in developing countries; over 2 billion people depend on biomass fuels as their primary energy source.
The use of biomass fuels for cooking indoors is a source of health problems and pollution. 1.3 million deaths were attributed to the use of biomass fuels with inadequate ventilation by the International Energy Agency in its World Energy Outlook 2006. Proposed solutions include improved stoves and alternative fuels. However, fuels are easily damaged, and alternative fuels tend to be expensive. Very low cost, fuel efficient, low pollution biomass stove designs have existed since 1980 or earlier. Issues are a lack of education, distribution, corruption, and very low levels of foreign aid. People in developing countries often cannot afford these solutions without assistance or financing such as microloans. Organizations such as Intermediate Technology Development Group work to make improved facilities for biofuel use and better alternatives accessible to those who cannot get them.
However, biofuel production is questioned from a number of angles. The chairman of the Intergovernmental Panel on Climate Change, Rajendra Pachauri, notably observed in March 2008 that questions arise on the emissions implications of that route, and that biofuel production has clearly raised prices of corn, with an overall implication for food security. This is debatable because the extent or contribution to which biofuels have increased prices of corn may be overshadowed by the increase in the costs of all fuels--by increasing planting, harvesting, and transit costs of low energy density (and bulky) crops.
Biofuels are also seen as having limitations. The feedstocks for biofuel production must be replaced rapidly and biofuel production processes must be designed and implemented so as to supply the maximum amount of fuel at the cheapest cost, while providing maximum environmental benefits. Broadly speaking, first generation biofuel production processes cannot supply us with more than a few percent of our energy requirements sustainably. The reasons for this are described below. Second generation processes can supply us with more biofuel, with better environmental gains. The major barrier to the development of second generation biofuel processes is their capital cost: establishing second generation biodiesel plants has been estimated at €500million.
Field pennycress.(biofuels BUZZ)(Biofuels Manufacturers of Illinois LLC contract with ARS)(briefs)(Brief article)
Jan 05, 2009; A team of Agricultural Research Service (ARS) scientists in Peoria, Ill., led by Terry Isbell, has been researching the annual...