Renewable fuels

Renewable fuels are alternative fuel sources such as ethanol, biodiesel (e.g. soy, vegetable oils, animal fats, or recycled restaurant greases) or hydrogen, in contrast to non-renewable fuels such as natural gas, LPG (propane) and other fossil fuels. Renewable fuels have become particularly newsworthy with the signing of the Energy Bill, which expanded the current use of renewable fuels in the United States. The Bill called for a minimum of 4 billion U.S. gallons (15 million m³) of renewable fuels to be used in 2006, and 7.5 billion US gallons [28 million m³] by 2012.

The passage of the energy bill was motivated by a number of factors, including existing U.S. agricultural subsidies, and a powerful farm lobby, as well as the desire for independence from Middle Eastern oil. Other factors such as planetary warming due to increasing greenhouse effects was an additional factor. Unlike fossil fuel combustion, which unlocks carbon that has been stored for millions of years, use of ethanol results in low increases to the carbon cycle.

Thanks to advances in biotechnology, researchers have begun to transform corn, straw, and plant wastes into ethanol while simultaneously replacing oil with a sustainable biofuel. The environmental, financial, and geo-political ramifications of this endeavor are of interest, particularly in an industrialized economy that is energy dependent, and in which energy is the most significant unit of wealth that drives money in a world-wide economy.

Motivations for renewable fuel development

Hubbert's peak oil theory suggests that petroleum is a finite resource that is rapidly depleting. Of the world-wide total remaining petroleum reserves of approximately 1,277,702,000,000 barrels (about one half of the original virgin reserves) and a world-wide usage rate of 25,000,000,000 per year, only about 50 years worth of petroleum is predicted to remain at the current depletion rate. Petroleum is imperative for the following industries: fuel (home heating, jet fuel, gasoline, diesel, etc.) transportation, agriculture, pharmaceutical, plastics/resins, man-made fibers, synthetic rubber, and explosives. If the modern world remains reliant on petroleum as a source of energy, the price of crude oil could increase markedly, destabilizing economies world-wide. Consequently, renewable fuel drivers include: high oil prices, imbalance of trade, instability in oil exporting regions of the world, the Energy Policy Act of 2005, the potential for windfall profits for American farmers and industries, avoidance of economic depression, avoidance of scarcity of products due to a volatile ‘peak oil’ scenario expected to begin as early as 2021, and a slowing of global warming that may usher in unprecedented climate change.

Furthermore, the global debate on climate change, along with regional geopolitical instabilities have challenged nations to act to develop both alternative and carbon-neutral sources of energy. Renewable fuels are therefore becoming attractive to many governments, who are beginning to see sustainable energy independence as a valuable asset.

Hydrogen fuel from renewable sources

Hydrogen fuel requires the development of a specific infrastructure for processing, transport and storage.

Main article: Hydrogen economy

Hydrogen fuel refers to the use of hydrogen gas (H₂) for use as an energy source. Broadly speaking, the production of renewable hydrogen fuel can be divided into two general categories: biologically derived production, and chemical production. This is an area of current research, and new developments and technologies are causing this field to evolve rapidly.

The biological production of hydrogen fuel has been a topic of research since at least the 1970s. Hydrogen gas can be produced from biomass sources like agricultural and forest residues, consumer waste and other specific agricultural crops. Specifically, hydrogen fuel is produced by a process called gasification, where biomass is processed into a combustible gas and then burned, or by pyrolysis, a related process which can lead to hydrogen gas suitable for fuel-cell applications. One continuing subject of research regards the production of unwanted co-products in both of these processes. The presence of other contaminant gases often depend on specific composition of the biomass source, which can be difficult to control. Another source for biological production of hydrogen fuel is algae. In the late 1990s it was discovered that if algae are deprived of sulfur they will switch from the production of oxygen, as in normal photosynthesis, to the production of hydrogen. Experimental algae farms are attempting to make algae an economically feasible energy source.

There are also several physico-chemical methods for producing hydrogen; most of these methods require electrolysis of water. When this process draws its power from renewable energy sources like wind turbines or photovoltaic cells, the production requires little consumption of non-renewable resources. Hydrogen fuel, when produced by renewable sources of energy like wind or solar power, is a renewable fuel.

Hydrocarbons and carbohydrates

Global fossil carbon emissions, an indicator of consumption, for 1800-2000. Total is black. Oil is in blue.

Hydrocarbons, molecules of hydrogen and carbon, are combustible compounds resulting from eons of compression of vegetation, or fossil fuels. This means that when, for example, gasoline is fed into an internal combustion engine, a large amount of energy per pound (high energy density) is captured by the engine. Hydrocarbons are all substances with low entropy (meaning they hold a lot of energy potential), which can be released and harnessed by burning them. The downside is that they emit pollution such carbon monoxide and soot.

Carbohydrates, like hydrocarbons contain hydrogen and carbon atoms, as well as one additional atom: oxygen. They are a chief source of food energy. The simplest model is in which the sun’s energy is stored in plants as sugar, and used as a source of food to grow. When animals eat those plants – our metabolism releases that energy to us, enabling us to live. For example, the sugar in sugar cane and corn can be converted into 'moonshine', which is ethyl alcohol or ethanol, and is usable as fuel. It is also possible to convert the sugar in the corn husks, which are inedible and ordinarily thrown away, into ethanol. Refined ethanol is similarly inflammable and combustible. Also, because it possesses an oxygen atom, it is dubbed an 'oxygenate,' which endows it with the additional advantage over gasoline of combusting with reduced engine knocking; it also helps gasoline burn cleaner by reducing smog. Although many different renewable fuels can be derived from carbohydrate biomass, (e.g. methanol, dimethyl ether, methane, hydrogen, etc.), ethanol has generally received the most attention in the United States.

Ethanol

Main Article: Ethanol fuel

Ethanol is a grain alcohol that burns cleanly as a high-octane fuel, without the need for octane enhancements such as methyl tert-butyl ether (MTBE) which pollutes the environment. Ethanol, like MTBE is an oxygenate (adds oxygen)that is blended into gasoline as an additive and prevents engine "knocking" while simultaneously helping gasoline to burn cleaner and reduce smog. Most gasoline pumps in the United States utilize a formulation consisting of 90% gasoline and 10% of ethanol known as E10, but contribute to smog-forming oxides of nitrogen. In contrast, E85 is a mixture of 85% ethanol and 15% gasoline and is now available at a limited number of gasoline stations. Ethanol also degrades quickly in water and, therefore, if spilled, poses much less risk to the environment than an oil or gasoline spill. Thus, from an environmental perspective, E85 is less polluting. However, ethanol does emit acetaldehyde, a probable carcinogen, and a substance that standard emissions-testing equipment must be engineered to measure. Many of the nation's 100+ corn-ethanol plants are generating 35% profits, which is helping fuel a plant-building boom that could double the size of the industry by 2008. However, because the boom is pushing up the price of corn, the Renewable Fuels Association, the group that lobbies for the ethanol industry, is now helping to build a political coalition for cellulosic ethanol.

Sugar cane in Brazil

Main article: Ethanol fuel in Brazil

Brazil stands out as a model for ethanol production, as it's no longer dependent on oil. Approximately 77% of new cars sold in Brazil are flexible fuel vehicles. Brazilian ethanol is distilled from sugar cane into alcohol more efficiently for approximately $1 (U.S.) per gallon because of heavy rainfall levels and access to cheap labor. The fermentable sugar cost per gallon of ethanol is $0.30 (when compared to corn which is $0.91). Some argue that the development of an indigenous ethanol industry in South and Central America would help soothe social issues in Latin America. For example, a recent study from the Inter-American Development Bank posited that replacing as little as 10% of Mexico's petrol consumption with locally refined ethanol would save Mexico $2 billion a year and create 400,000 jobs.

Corn-derived ethanol

Main article: Corn ethanol

Currently, one bushel of corn produces 2.8 U.S. gallons of ethanol (390 L/t), in addition to approximately 17 lb (0.3 t/t) of by-products which may be used as animal feed. Corn-yields have improved from 86 to 150 bushels per acre (5.4 to 9.4 t/ha) since 1975; these genetic modifications correspond to a 75% increase in corn yield is due to genetic modification of corn seed. Currently, hybrid seeds are being designed (by DuPont and Monsanto) that will boost the starch content and improve fermentability of the corn used, thus raising its ethanol production value; moreover, this increase in corn yield counters criticism that the expected boom in ethanol production would raise food prices and reduce America's grain exports.

Ethanol production may occur through two corn processing methods: dry and wet corn milling; the main difference between the two is the initial treatment of grain. In dry milling operations, liquefied corn starch is produced by heating corn meal with water and enzymes. A second enzyme converts the liquefied starch to sugars, which are fermented by yeast into ethanol and carbon dioxide; released CO₂ during fermentation is captured and may be sold for use in carbonating beverages and in the manufacture of dry ice. Wet milling operations separate the bran, germ (oil), and protein from the starch before it is fermented into ethanol.

Corn-based ethanol will replace MTBE as an oxygenating agent in gasoline, eliminating a groundwater pollutant. Ethanol refineries are much cheaper and easier to build and expand than crude oil refineries. There is strong political support for corn-based ethanol because it opens a new market for U.S. farmers and helps automakers and oil companies meet clean air and renewable fuel regulations.

One environmental advantage to corn-derived ethanol is that corn is "carbon neutral" during its growth cycle. That means that the CO₂ that the corn plants use in photosynthesis is nearly equal to the amount of CO₂ emitted by making fertilizer, farming, and hauling the corn to an ethanol plant. Some American farmers have built ethanol plants in recent years in expectation of demand for ethanol as a substitute for middle eastern petroleum.

Cellulosic ethanol

Main Article: Cellulosic ethanol

Some of ethanol’s disadvantages can be avoided if a source other than corn is used. Cellulosic ethanol is ethanol derived from essentially inexhaustible resources by utilizing the cellulose that is found in all plant matter, in contrast to starch-based ethanol produced mainly from corn. Made from plant biomass using enzymatic or microbial action, cellulosic ethanol is potentially more energy efficient because the distillation temperatures are substantially lower than for corn ethanol. Consequently, very little energy is used directly in making the ethanol. A 10% blend of cellulosic ethanol would reduce greenhouse gas emissions by up to 10% compared with gasoline, and an 85% blend would reduce CO2 emissions by as much as 50%, mostly due to the reduced emissions from fertilizer production.

Scientist are seeking the fuel: a specific type of sugar chain locked away in the stalk and leaves of the plants in the form of cellulose, the basic building block of plants. Cellulose is a carbohydrate polymer that makes up the walls of all plant cells and is also found in green algae and some bacteria; it is most easily identified by the lay population as grass or tree bark. The most underutilized energy asset on the planet is cellulosic biomass.

Cellulosic ethanol holds promise of a much higher capacity than corn derived-ethanol, possibly as much of 45 million gallons per year—or 30% of U.S. oil consumption. This corresponds to the amount of foreign oil the U.S. currently imports from OPEC nations.

This newly emergent source of ethanol involves the conversion of cellulose (from sawdust, paper waste, and inedible plant waste) to ethanol, although the chemical conversion is not yet as efficient as the corn-to ethanol conversion, but is expected to become financially feasible relatively soon. Sources of cellulose include a wide variety of cellulosic biomass feed stocks including agricultural plant wastes (e.g., corn stover, cereal straws, sugarcane bagasse), plant wastes from industrial processes (e.g., sawdust, paper pulp) and energy crops grown specifically for fuel production, such as perennial grasses. These grasses include switchgrass (a tall prairie grass) that is highly drought resistant and other forage crops that are promising feed stocks for ethanol production. The perennial grass has a deep root system, anchoring soils to prevent erosion and helping to build soil fertility. Switchgrass (commonly used for hay) in particular has several advantages. As a native species, switchgrass is better adapted to US climate and soils, uses water efficiently, is highly drought resistant, does not need a lot of fertilizers or pesticides, and absorbs both more efficiently.

Over the short run, it is likely that the inedible parts of corn will most likely be utilized to manufacture cellulosic ethanol, especially as corn is both energy- and water-intensive to grow. In contrast, switch grass is cheaper to grow and requires less water, but requires special harvest and transport machinery which is not yet available. Additionally, farmers will likely be hesitant to grow switchgrass until there is a market for the crop, while industrialist who build cellulose ethanol manufacturing plants will not proceed until a ready supply of farmland is utilized for growing switchgrass.

Efficiency of cellulosic ethanol

When comparing ethanol production from corn, sugar, wheat, or soybeans, cellulosic ethanol purportedly requires less energy to produce. Cellulosic ethanol's favorable profile stems from using lignin, which makes up the bulk of the dry mass comprising cellulosic biomass; lignin is also a biomass by-product of the conversion operation, to fuel the process. Greenhouse gases produced by the combustion of biomass are offset by the CO₂ absorbed by the biomass as it grows, hence lignin has no net greenhouse emissions. From an environmental perspective, cellulosic ethanol may be a better alternative because the conversion process demonstrates greenhouse gas emission reductions of about 80%, when compared to gasoline. Moreover, cellulosic ethanol is not dependent on fluctuating corn or sugar prices. Additionally, corn production gobbles up a lot of power in the form of everything from fertilizer to pesticides. Finally, farmers in the agricultural states are lobbying to develop capacity and infrastructure, as well as mandates for use. An alternative source of biomass in more urban areas is the waste stream, where conversion could provide localized production and urban environmental improvements.

Ethanol in transportation fuels

Flexible fuel vehicles

Main article: Flexible-fuel vehicle

The first Ford Model T was engineered to run on ethanol so that farmers could produce their own fuel. Despite this early push for ethanolic fuel, most automobiles eventually were constructed to consume gasoline. Unfortunately, it would be prohibitively expensive to convert fuel systems originally designed for E10 to E85; it might also violate emissions-control laws in some states. The National Ethanol Vehicle Coalition estimates more than 2 million Flexible Fuel Vehicles (FFV's) have been sold in the United States. E85 vehicles are now sold by the Big Three automakers (General Motors, Ford, and Daimler Chrysler). Toyota, which surpassed General Motors in late 2006 as the World's largest automaker is eyeing the flex-fuel market. Because alcohol is relatively corrosive to critical fuel-system components, compared to gasoline, any car part that comes in contact with the fuel has been upgraded to be tolerant to alcohol. Normally, these parts include a stainless steel fuel tank and Teflon-lined fuel hoses. Other minor modifications include changes to their fuel tank, fuel lines, fuel injectors, computer system, anti-siphon device and dashboard gauges. The additional cost of these modifications is estimated to be less than $200 per vehicle. While there are millions of cars out on the American road that can run on either E85 or E10, most automobile owners instead fill up with regular gasoline because of a shortage of filling stations offering the alternative fuel. Other consequences of using ethanol as a fuel include clogging of the fuel filter, rough-running engines, and corrosion in aluminum gas tanks.

Ethanol has an energy content of 75,600 British Thermal Units (BTU's), while gasoline has 115,400 BTU. Another way of saying this, is that ethanol contains approximately 34% less energy per gallon than gasoline. This difference results in 27% poorer fuel economy for ethanol, although vehicle acceleration remains unaffected when used in flexible fuel vehicles; what this means is that a car engine has to burn more fuel to generate the same amount of energy to drive the engine. Flexible fuel engines are designed to run more efficiently on gasoline than ethanol, although E85 fuel economy could approach that of gasoline if manufacturers engineered engines to run optimally on ethanol. Such engines would be endowed with a 30%-40% larger carburetor jets (by area) or fuel injectors, and allow engines to benefit from ethanol's much higher octane rating. Subsequently, flexible fuel vehicles may be viewed as a bridge-technology prior to the introduction of engines that run most optimally on ethanol. Optimized ethanol-only automobile engines allow for an increase of the engine's compression ratio and correspondingly increased thermal energy, attaining efficiency comparable to a diesel engine.

E85 fuel stations

Main article: E85

There are nearly 800 public E85 fueling stations available in the United States (out of 176,000 nationwide), at prices comparable to regular gasoline (when discounting the reduced fuel economy of E85), primarily in the corn-growing Midwest, where corn is grown and the homegrown fuel is produced. The number of gas stations offering E85 is expected to double over the next year as service stations are being offered incentives from government and ethanol industry grants up to $30,000 for the costs of retro-fitting pumps and tanks for E85 fuel. Unfortunately, this does little to offset the cost to install pumps and tanks for E85—a hefty $200,000 per station. Although ethanol contains about 65% by volume of the energy that gasoline does, the per gallon cost of E85 is 75% the price of regular unleaded gasoline. Moreover, in addition to cutting down on dirty tailpipe emissions, E85 boosts performance because of its higher octane. The overall consumer cost of E85 is close to E10, and any short term price advantage is usually lost because vehicles usually burn E85 quicker than regular fuel.

A recent development in the expansion of E85 filling stations is Wal-mart's announcement that it will possibly sell E85 at its 385 gas stations countrywide. Wal-Mart along with its popular division, Sam's Club has a partnership with Murphy Oil Corp. which operates more than 900 gas stations in Wal-Mart parking lots. Should they decide to follow through with plans, Wal-mart has the potential to be the single largest retailer of E85 in the nation. Grocery retailers in Texas are also beginning to sell E85 at some fuel stations.

Business leaders like Richard Branson, Paul Allen, Steve Case, Vinod Khosla, John Doerr, and Bill Gates have become ethanol advocates and are investing heavily in ethanol. Microsoft co-founder Paul Allen is investing in a Seattle firm that wants to use canola oil, which comes from rapeseed, to create ethanol fuel. And Vinod Khosla, the Kleiner Perkins partner and Sun Microsystems co-founder, has investments in two cellulosic ethanol companies. Microsoft's Bill Gates, has bought 25% of Pacific Ethanol, a Fresno, California company that is planning to build dozens of ethanol refineries in the U.S. In July 2006 Goldman Sachs invested $27 million into a Canadian company called Iogen, which wants to produce ethanol from switchgrass, a perennial grass that is inexpensive to grow. Iogen, a non-publicly traded company, is building the world's first full-scale commercial cellulose-to-ethanol plant by 2010. Another reason for ethanol's popularity is its contribution toward providing economic revitalization in rural communities across the country.

Biofuel companies

Unfortunately, costs of producing ethanol from cellulosic feedstock such as wood chips are still about 70% higher than production from corn, because of an extra step in the production process, when compared to production of corn-derived ethanol. Until recently, the idea of extracting ethanol from farm waste and other sources was barely clinging to life in the recesses of university campuses and federal labs, because production problems, as well as the need to bring together a vast team of specialists. Consider: Finding a bacterium from a cow's intestinal tract or from elephant dung that has the correct enzyme to degrade cellulose, and then bringing in geneticists to modify that enzyme kept this discouraging feat from ever growing beyond its embryonic state. Now, that is all changing with a race by approximately thirty companies attempting to accomplish this alchemical feat, and in the process working directly or coordinating with: environmental groups, biotechnology firms, some major oil companies, chemical giants, auto makers, defense hawks and venture capitalists. The winner will be whoever can make cellulosic ethanol in mass quantities for as little money per gallon as possible.

With the majority of such biofuel companies (Iogen Corporation, SunOpta's BioProcess Group, Genencor, Novozymes, Dyadic International, Inc. (AMEX: DIL), Kansas City-based Alternative Energy Sources, Inc. [Nasdaq:AENS], Flex Fuels USA based in Huntsville, Alabama (now owned by Alternative Energy Sources), or BRI Energy, LLC, Abengoa Bioenergy) located in North America, the United States is in a unique position to lead the way in the development, production, and sale of a new source of energy.

One notable company that deserves special mention is Archer-Daniels-Midland Company (ADM) which has already invested heavily into building approximately 100 corn-ethanol production plants, known as bio-refineries, and churns out about one-fifth of the country's ethanol supply. This occurred due to seasonal overcapacity in its corn syrup plants when surplus was available to produce ethanol. Moreover, ADM is in a unique position to utilize unused parts of the corn crop, and convert previously discarded waste into a viable product. The hull surrounding corn contains fiber that the Decatur, Illinois, grain-processing giant's ethanol-making microorganisms can not use. Figuring out how to convert the fiber into more sugar could increase the output of an existing corn-ethanol plant by 15%. Consequently, ADM wouldn't have to figure out how to collect a new source of biomass but merely use the existing infrastructure for gathering corn - resulting in an advantage over its competitors. ADM executives want government help to build a plant that could cost between $50 million and $100 million. Prescient in their position in the quest for success, ADM recently hired the head of petroleum refining at Chevron, Patricia A Woertz, to metamorphasize ADM into the Exxon-Mobil of the ethanol industry. If ADM succeeds, it will catapult beyond the ethanol industry to compete with the larger, global energy industry. In essence, the old paradigm of processing a barrel of crude oil into gasoline will be replaced with processing a bushel of corn into ethanol.

Meanwhile DuPont, the chemical giant, is attempting to figure out how to construct a bio-refinery fueled by corn stover—the stalk and leaves that are left in the field after farmers harvest their crop. The company's goal is to make ethanol from cellulose as cheaply as from corn kernels by 2009. If it works, the technology could double the amount of ethanol produced by a field of corn.

Diversa Corporporation, a biotech company based in San Diego, examined how biomass is converted into energy in the natural environment. They have found that the enzymes inherent in the bacteria and protozoa that inhabit the digestive tracts of the household termite efficiently convert 95% of cellulose into fermentable sugars. Using proprietary DNA extraction and cloning technologies, they were able to isolate the cellulose-degrading enzymes. By reenacting this natural process, the company created a cocktail of high-performance enzymes for industrial ethanol production enablers. Although still in the early stages of this work, the initial results are promising. Currently, these expensive enzymes cost about 25 cents per gallon of ethanol, although this price is very likely to decline by half in the coming years.

Construction of the first U.S. commercial plant producing cellulosic ethanol begins will commence in the State of Iowa in February 2007. The Voyager Ethanol plant in Emmetsburg, owned by Poet Energy, LLC, will be converted from a 50 million-gallon-a-year conventional corn dry mill facility into a 125 million-gallon-a-year commercial-scale biorefinery producing ethanol from not only corn but also the stalk, leaves and cobs of the corn plant. Most ethanol plants rely on natural gas to power their processing equipment. The process to be used at the Emmetsburg plant will enable the plant to make 11% more ethanol by weight of corn and 27% more by area of corn. The process cuts the need for fossil fuel power at the plant by 83% by using some of its own byproduct for power. The $200 million plant is scheduled to begin in February and take about 30 months to complete. Project completion is contingent upon partial funding from a USDOE grant, which is likely as the U.S. Government views the renewable energy project as a full-blown national security issue.

Conclusion

Renewable fuels in the form of ethanol, bio-diesel, hydrogen, or other forms, have many benefits: because they are more carbon-neutral than petroleum-derived fuels, they will help diminish man-made contributions to the greenhouse effect, and economic benefits to American farmers and businesses are cited as a rationale for American investment in alternative fuels.

It is important to note that each fuel is still in development and no fuel is yet seen as a ready-made replacement for petroleum. For example, ethanol has both advantages and disadvantages. Some view corn-derived ethanol as a partial antidote to the nation's reliance on foreign oil. In contrast, proponents of cellulosic ethanol promise greater gains in energy efficiency, but suggest development will take time. Others envision a pragmatic future in which for the next five or ten years, corn-derived ethanol is viewed as a short term "bridge-fuel" until cellulosic ethanol reaches mainstream markets. However, during this transition time, fossil fuels will continue to dominate the world's energy supplies. Many caution that ethanol is only one part of a solution to a complex problem which must include an enormous ramp-up in alternative energy sources that include wind and solar power, hydroelectric power, bio-diesel, hydrogen fuel-cells, improved batteries, nuclear energy, and energy conservation.

References

Renewable Fuels - Ethanol | BioDiesel

See also

• Bioenergy Action Plan