Vegetable oil economy deals with the potential of Wikipedia:vegetable oil to replace Wikipedia:fossil fuels in the economy and how it compares to other potential replacements, including Wikipedia:renewable electricity. Vegetable oils are the basis of Wikipedia:biodiesel, which can be used like conventional diesel. Some Wikipedia:vegetable oil blends are used in unmodified vehicles, but Wikipedia:straight vegetable oil needs specially prepared vehicles which have a method of heating the oil to reduce its Wikipedia:viscosity and Wikipedia:surface tension. Another alternative is Wikipedia:vegetable oil refining.
The availability of Wikipedia:biodiesel around the world is increasing, although still tiny compared to other Wikipedia:fossil fuel sources. There is significant research in Wikipedia:algaculture methods to make Wikipedia:biofuel from algae.
Concerns have been expressed about growing crops for fuel use rather than food and the environmental impacts of large scale agriculture and land clearing required to expand the production of vegetable oil for fuel use. These effects/impacts would need to be specifically researched and evaluated, economically and ecologically, and weighed in balance with the proposed benefits of vegetable oil fuel in relation to the use of other fuel sources.
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The future of vegetable oil as an energy source is limited by the total worldwide oil production. The worldwide production of various types of Wikipedia:vegetable oil amounted to 130 million tons in 2008. Its energy content is sufficient to provide 111 millon tons of oil equivalent which is 1% of the Wikipedia:World energy consumption in 2008 (474 Exajoules or 11320 million tons of oil equivalent).
Future of energy for world economy Edit
There is a limited amount of Wikipedia:fossil fuel inside the Wikipedia:Earth. Since the current Wikipedia:world energy resources and consumption is mainly fossil fuels, we are very dependent on them for both Wikipedia:transportation and Wikipedia:electric power generation. The Wikipedia:Hubbert peak theory predicts that Wikipedia:oil depletion will result in oil production dropping off in the not too distant future. As time goes on our economy will have to transition to some Wikipedia:alternative fuels. Fossil fuels have solved two problems which could be separately solved in the future: the problem of a source of Wikipedia:primary energy and of Wikipedia:energy storage. Along with Wikipedia:straight vegetable oil and Wikipedia:biodiesel, some energy technologies that could play an important part in the future include:
No net CO2 or greenhouse gas production Edit
Plants use Wikipedia:sunlight and Wikipedia:photosynthesis to take Wikipedia:carbon dioxide (CO2) out of the Wikipedia:Earth's atmosphere to make Wikipedia:vegetable oil. The same CO2 is then put back after it is burned in an engine. Thus vegetable oil does not increase the CO2 in the atmosphere, and does not contribute to the problem of Wikipedia:greenhouse gas. It is really a way of catching and storing Wikipedia:solar energy. It is a true Wikipedia:renewable energy.
Burning Wikipedia:fossil fuels releases Wikipedia:sulfur dioxide (SO2) and other harmful Wikipedia:air pollution. Because vegetable oil has not been inside the earth for millions of years, it is not contaminated with things like sulfur and burns much cleaner, even than Wikipedia:ultra-low sulphur diesel. Burning fossil fuels also contributes to the Wikipedia:greenhouse gas problem.
Note that if fossil fuels are used in any aspect of production and distribution (making fertilizer, tractors, fuel trucks, etc.), then there would be some contribution to pollution. For it to be 100% non-polluting all aspects of vegetable oil production would have to be non-polluting as well.
[[Wikipedia:Image:Fryingplantains10-28-06.jpg|right|thumb|Wikipedia:Plantains frying in vegetable oil]]
Wikipedia:Vegetable oil is far less toxic than other fuels such as Wikipedia:gasoline, petroleum-based diesel, Wikipedia:ethanol, or Wikipedia:methanol, and has a much higher Wikipedia:flash point (approximately 275-290 °C). The higher flash point reduces the risk of accidental ignition. Some types of vegetable oil are Wikipedia:edible.
Generation and storage Edit
Technologies of Wikipedia:hydrogen economy, batteries, Wikipedia:compressed air energy storage, and Wikipedia:flywheel energy storage address the Wikipedia:energy storage problem but not the source of Wikipedia:primary energy. Other technologies like Wikipedia:fission power, Wikipedia:fusion power, and Wikipedia:solar power address the problem of a source of Wikipedia:primary energy but not Wikipedia:energy storage. Vegetable oil addresses both the source of Wikipedia:primary energy and of Wikipedia:energy storage. The cost and weight to store a given amount of energy as vegetable oil is low compared to many of the potential replacements for Wikipedia:fossil fuels.
Type of vegetable oil Edit
The list of vegetable oils article discusses which types of vegetable oil are used for fuel and where different types are grown.
For transportation the Wikipedia:energy density and cost to store the energy are important. If the density is low or the cost is too high it is not practical to make vehicles with reasonable range. Vegetable oil and biodiesel are close to regular diesel.
Another potential issue for new fuels is the Catch-22 conundrum: if there needs to be expensive new infrastructure before people will make cars running on a new fuel, and there needs to be new cars before people will build the infrastructure, how can the transition ever be made? With vegetable oil this is not nearly the problem that it is with some other fuels. The transition from petroleum oil based transportation to vegetable oil based transportation could be gradual and easy compared to hydrogen, ethanol, and most other alternatives. Vegetable oil is used for transportation in four different ways:
- Wikipedia:Vegetable oil blends - Mixing vegetable oil with diesel lets users get some of the advantages of burning vegetable oil and is often done with no modification to the vehicle.
- Wikipedia:Biodiesel - If vegetable oil is Wikipedia:transesterified it becomes Wikipedia:biodiesel. Biodiesel burns like normal diesel and works fine in any diesel engine. The name just indicates that the fuel came from vegetable oil.
- Wikipedia:Straight vegetable oil - Straight vegetable oil works in diesel engines if it is heated first. Some diesel engines already heat their fuel, others need a small electric heater on the fuel line. How well it works depends on the heating system, the engine, the type of vegetable oil (thinner is easier), and the climate (warmer is easier). Some data is available on results users are seeing. As vegetable oil has become more popular as a fuel, engines are being designed to handle it better. The Wikipedia:Elsbett engine is designed to run on straight vegetable oil. However, as of the start of 2007, it seems that there are not any production vehicles warrantied for burning straight vegetable oil, although Wikipedia:Deutz offer a tractor and John Deere are known to be in late stages of engine development. There is a German rapeseed oil fuel standard DIN 51605. At this point straight vegetable oil is only a niche market although the market segment in Germany is rapidly growing with large haulage vehicle fleets adopting the fuel, largely for economic reasons. A growing number of decentralised oil mills provide a large part of this fuel.
- Wikipedia:Vegetable oil refining - Vegetable oil can be used as feedstock for an Wikipedia:oil refinery. There it can be transformed into fuel by Wikipedia:hydrocracking (which breaks big molecules into smaller ones using hydrogen) or Wikipedia:hydrogenation (which adds hydrogen to molecules). These methods can produce Wikipedia:gasoline, diesel, or Wikipedia:propane. Some commercial examples of vegetable oil refining are Wikipedia:NExBTL, Wikipedia:H-Bio, and the ConocoPhilips Process.
The transition can start with Wikipedia:biodiesel, Wikipedia:vegetable oil refining, and Wikipedia:vegetable oil blends, since these technologies do not require the capital outlay of converting an engine to run on vegetable oils. Because it costs to convert vegetable oil into biodiesel it is expected that vegetable oil will always be cheaper than biodiesel. After there are production cars that can use Wikipedia:straight vegetable oil and a standard type available at gas stations, consumers will probably choose straight vegetable oil to save money. So the transition to vegetable oil can happen gradually.
Electricity generation Edit
Vegetable oil is a convenient safe way to store energy for transportation and is similar to the way things have been done. For Wikipedia:electricity generation these things are not so important. The most important thing is cost for the electricity produced. The world Wikipedia:coal reserves are far larger than the world oil reserves. So replacing the coal used in power plants is not as urgent as replacing the oil used for transportation. The motivation to use vegetable oil for power generation is much less than for transportation. Other methods, like Wikipedia:nuclear power, Wikipedia:fusion power, Wikipedia:wind power and Wikipedia:solar power, may provide cheaper electricity, so vegetable oil may only be used in Wikipedia:peaking power plants and small power plants, as diesel is limited to today. There is at least one 5 MW power plant that runs on biodiesel.. Wikipedia:MAN B&W Diesel, Wikipedia:Wärtsilä and other companies produce engines suitable for power generation that can be fueled with Wikipedia:pure plant oils.
Market / cost / price / taxes Edit
Availability of Wikipedia:biodiesel around the World is increasing. It is estimated that by 2010 the market for biodiesel will be 7.5 billion litres (2 billion USgallons) in the U.S and 9.5 billion litres (2.5 billion USgallons) in Europe. Biodiesel currently has 3% of the diesel market in Germany and is the number 1 alternative fuel. The German government has a Biofuels Roadmap in which they expect to reach 10% biofuels by 2010 with the diesel 10% coming from fuel made from vegetable oil.
From 2005 to 2007 a number of types of vegetable oil have doubled in price. The rise in vegetable oil prices is largely attributed to biofuel demand.
Much of the fuel price at the pump is due to Wikipedia:fuel tax. If you buy vegetable oil at the grocery store it does not have such high taxes. So at times people have bought vegetable oil at the store for their cars because it was cheaper. They did this in spite of the fact that packaging by the gallon adds to the cost and it was illegal to use in a car since no fuel tax had been paid on it.
Since vegetable oil (even as biodiesel) does not contribute to Wikipedia:greenhouse gas, governments may tax it much less than gasoline as they have done with Wikipedia:ethanol. This would help them reach Wikipedia:Kyoto protocol targets.
Production in sufficient quantity Edit
[[Wikipedia:Image:Elaeis guineensis0.jpg|left|thumb|African Wikipedia:Oil Palm (Elaeis guineensis]]
The World production of vegetable oil seed is forecast to be 418 million tonnes in 2008/09. After pressing this will make 131 million tonnes of vegetable oil. Much of this is from Wikipedia:Oil Palm, and Wikipedia:palm oil production is growing at 5% per year. At about 7.5 lb/USgal (900 g/L) this is about 38 billion USgallons (144 billion L). Currently vegetable oil is mostly used in food and some industrial uses with a small percentage used as fuel. The major fuel usage is by conversion to biodiesel with about 3 billion US gallons (11,000,000 m3) in 2009.
In 2004 the US consumed 530 billion litres (140 billion USgal) of gasoline and 150 billion litres (40 billion USgal) of diesel. In Wikipedia:biodiesel it says Wikipedia:oil palm produces 5940 litres per hectare (635 USgal/acre) of Wikipedia:palm oil each year. To make 180 billion US gallons (680,000,000 m3) of vegetable oil each year would require 1,150,000 square kilometres (440,000 sq mi) or a square of land 1,070 kilometres (660 mi) on a side.
"The gradual move from oil has begun. Over the next 15 to 20 years we may see biofuels providing a full 25 percent of the world's energy needs. While the move is good for reducing greenhouse emissions, soaring oil prices have encouraged most countries to 'go green' by switching to greater use of biofuels." - Alexander Müller, Assistant Director-General of Sustainable Development at the FAO.
Genetic modifications to soybeans are already being used. Genetic modifications and breeding can increase vegetable oil yields. From 1979 to 2005 the soybean yield in bushels per acre more than doubled. A company has developed a variety of Wikipedia:camelina sativa that yields 20% more oil than the standard variety.
thumb|right|Jungle burned for agriculture in southern Mexico. There is concern that the current growing demand for vegetable oil is causing Wikipedia:deforestation, with old forests being replaced with Wikipedia:oil palms. When land is cleared it is often burned, which releases lots of CO2. Vegetable oil production would have to increase substantially to replace gasoline and diesel. With current technology such an increase in production would have a substantial environmental impact.
While not immediately toxic to wildlife, spills are still potentially dangerous due to the physical damage caused to ecosystems. These effects may include contamination of tissues impeding their vital functions (e.g. plant Wikipedia:stomata, fish gills, bird feathers, and mammal hair), increased Wikipedia:biological oxygen demand and Wikipedia:chemical oxygen demand leading to deoxygenation of water, and infiltration into soil sediments and Wikipedia:aquifer contamination.
Food vs fuel debate Edit
- Main article: Food vs fuel
In some poor countries the rising price of vegetable oil is causing problems. There are those that say using a food crop for fuel sets up competition between food in poor countries and fuel in rich countries. Some propose that fuel only be made from non-edible vegetable oils like Wikipedia:jatropha oil. Others argue that the problem is more fundamental. Farmers can switch from producing food crops to producing biofuel crops to make more money, even if the new crops are not edible. The Wikipedia:law of supply and demand predicts that if fewer farmers are producing food the price of food will rise. It may take some time, as farmers can take some time to change which things they are growing, but increasing demand for biofuels is likely to result in price increases for many kinds of food. Some have pointed out that there are poor farmers and poor countries making more money because of the higher price of vegetable oil.
With the use of non-edible vegetable oils produced by trees such as Millettia Pinnata (formerly Pongamia Pinnata)or the Wikipedia:Moringa oleifera tree, both which grow on borderline or non-arable land, the food versus fuel debate becomes less of an either/or question.
Apart from their facility of growing in non-arable and/or marginal land, these trees offer major advantages over peanut, soy-bean, sunflower, etc., in that they have long lives (up to 100 years), very low maintenance (since the intensive husbandry is limited to the first few years of their producing lives) and can provide cash-crops to rural areas, such as rural India. In the case of Millettia Pinnata and a few others, the fact that they are nitrogen-fixing legumes is another very important factor, in that they do not deplete the soil.
Among other benefits of these trees is that they have root-systems that penetrate much deeper and do not compete with shallow-rooted plants, like grass (once the trees have attained a certain maturity). This means that the land can be used for multiple purposes, such as grazing for animals. Yet another benefit of using Millettia Pinnata to produce bio-diesel is that it can tolerate low rainfall (as little as 250 ml per year), far below what most food-crops require, thus reducing yet more their potential to compete.
Centralised vs. decentralised productionEdit
There is debate around the best model for fuel production.
One side promotes centralised processing of feedstock to vegetable oil fuels citing
- greater potential for fuel standardisation
- ease of administrating taxes
- possibility for rapid expansion
The other side of the argument points to
- increased fuel security
- rural job creation
- less of a 'monopolistic' market due to the increased number of producers
- benefits to local economy as a greater part of any profits stay in the local economy
- decreased transportation of feedstock and end product
- consumers close to and able to observe the effects of production
The majority of established biofuel markets have followed the centralised model with a few small or micro producers holding a minor segment of the market. A noticeable exception to this has been the Wikipedia:pure plant oil (PPO) market in Wikipedia:Germany which grew exponentially until the beginning of 2008 when increasing feedstock prices and the introduction of fuel duty combined to stifle the market. Fuel was produced in hundreds of small oil mills distributed throughout Germany often run as part of farm businesses.
Initially fuel quality could be variable but as the market matured new technologies were developed that made significantly improvements. As the technologies surrounding this fuel improved usage and production rapidly increased with Wikipedia:rapeseed oil PPO forming a significant segment of transportation biofuels consumed in 2007.
Urgency of transition to renewable transportation Edit
There are two very different views on the urgency of transitioning to renewable transportation so both are presented here:
- 1) As oil gets more expensive, people will invest in technologies to increase the supply of oil from petroleum and renewable sources. If renewable sources are less expensive than petroleum, or if the environmental effects are preferred, then they will eventually replace petroleum. As the price of oil goes up, more people will be willing to drive efficient vehicles, like hybrids or diesels, even if capital costs remain higher. The transition will have a Wikipedia:diffusion of innovation time on the order of 20 to 50 years. This should be enough time to figure out how to make lots of vegetable oil, assuming resources are put toward research and development. To the extent that a viable source of oil is not found, then Wikipedia:electric vehicles will be produced in greater numbers to supplement the oil-based transportation sector, and reduce demand for oil.
- 2) The effects of even a small drop in production can be devastating. For instance, during the Wikipedia:1973 oil crisis, world production of oil dropping 5% caused the price of oil to nearly quadruple. Current estimates are that oil production will drop by about 10% in the next 10 years. If forest land needed to be reclaimed to grow energy crops, then the extent of deforestation could be environmentally disastrous. We need to change our ways so we don't need so much fuel. For example, Wikipedia:plug-in hybrid electric vehicles and Wikipedia:diesel hybrids use much less fuel. Alternative technologies need to be invested in and brought to market so that they will be available if and when they are needed. To delay is to invite disaster.
Algae for vegetable oil production Edit
- Main article: biofuel from algae
The Wikipedia:silver bullet for the vegetable oil economy is harvesting vegetable oil from algae. Some species of algae contain as much as 50% vegetable oil. Algae have very high growth rates compared to plants normally used to produce vegetable oil. Potentially algae could produce much more oil per area of land than current farming methods. So producing vegetable oil this way should result in less deforestation and less competition for food production land. One expert wrote: "As demonstrated here, microalgal biodiesel is technically feasible. It is the only renewable biodiesel that can potentially completely displace liquid fuels derived from petroleum. Economics of producing microalgal biodiesel need to improve substantially to make it competitive with petrodiesel, but the level of improvement necessary appears to be attainable. "
Where there is existing electricity generation using fossil fuels, there is a source of sterile CO2. This makes Wikipedia:algaculture much easier. To grow algae you need lots of CO2, but if you get it from air you will also get all kinds of other organisms, some of which eat algae. Getting CO2 from a smokestack works out really well. Governments trying to address the Wikipedia:external costs of coal power plants may have a Wikipedia:carbon tax or Wikipedia:carbon credit that provides additional motivation to use CO2 from smokestacks. Several commercial pilot plants are under construction.
The fossil fuels used in Wikipedia:energy in the United States for electricity and transportation are roughly equal. If all CO2 emitting powerplants had Wikipedia:algaculture farms attached to them that were making Wikipedia:biofuel from algae, the total vegetable oil produced would be about equal to transportation needs. One could run a powerplant off the vegetable oil produced by it, in which case the electricity production would be Wikipedia:carbon neutral. However, because coal is so abundant and transportation fuel so valuable, the common case would probably be coal coming into the powerplant and carbon going out as vegetable oil to be used in transportation. After the carbon is used the second time for transportation, it would be released into the atmosphere as CO2. So the combination of powerplant and transportation would then release as much CO2 as either does alone now. The other benefit is that transportation fuel would last as long as coal, which is expected to be a long time.
There is substantial research and development work in this area but as of 2007 there is no commercial vegetable oil produced from algae and used as biofuel. ExxonMobil is investing $600 million and estimates they are 5 to 10 years from significant production, but could invest billions in final development and commercialization. If and when the commercialization challenges are overcome, vegetable oil production could expand very rapidly.
In 2012 President Obama supported the idea of getting oil from algae.
Net energy gain Edit
To evaluate potential sources of Wikipedia:primary energy it is useful to look at the Wikipedia:net energy gain or Wikipedia:EROEI. This is the ratio of energy out to energy input. These numbers can change as the technology changes. For example, early Wikipedia:photovoltaics technology had EROEI numbers of less than 1 but current cells achieve net energy gain numbers of 10 to 30.
- Wikipedia:Ethanol economy 1.09 to 1.34
- Wikipedia:Biodiesel 3.2
- Vegetable oil - Better/higher than biodiesel since less processing is required
There have been thousands of scholarly papers looking at how much energy goes into the production of biofuels compared to the energy in the fuel. Many claim ethanol is not worthwhile and some even claim biodiesel is not reasonable.
- Wikipedia:Biodiesel by region
- Wikipedia:Food price crisis
- Wikipedia:Hydrocarbon economy
- Wikipedia:List of vegetable oils
- Wikipedia:Low-carbon economy
- Wikipedia:Renewable energy
- Wikipedia:Straight vegetable oil
- Wikipedia:Strategic Fuel Reserve
- Wikipedia:Sustainable development
- Wikipedia:Vegetable oil blends
Further reading Edit
- Production of vegetable oils in decentral plants and aspects of quality management - Investigations on plants in practice to optimise the process, by Bernhard Widmann. Biomass for Energy and Industry 10th European Conference. (1998)
- Soil not Oil: Climate Change, Peak Oil and Food Insecurity, Vandana Shiva, Zed Books
- Processing in Decentralised Oil Mills also Decentralised Biodiesel Production in Agriculture
- Befraging von Betreibern dezentraler Olsaatenverarbeitungsanlagen
- Rapeseel oil fuel from decentralized oil seed processing - Lectures of the community conference, 16 and 17 June 2005
- Danish Folkecenter Publications about decentralised pure plant oil fuel production
- ↑ http://nesoybeans.unl.edu/
- ↑ The Hidden Cost of Fossil Fuels
- ↑ Chemical1-6_1
- ↑ Vegetable Oil as Vehicle Fuel
- ↑ Straight vegetable oil as diesel fuel: Journey to Forever
- ↑ Using Vegetable oil as a diesel fuel - database
- ↑ http://www.elsbett.com/engl/index.htm
- ↑ Stotz, Kathrin; Remmele, Edgar (200). "Oil Processing in Decentralised Oil Mills - Results of a Survey" (Wikipedia:PDF). 16–1. http://ltnet.lv-h.de/en/volltext/Lt20051/LT20051E_016_017.pdf. Retrieved 2007-10-25.
- ↑ Green Car Congress: ConocoPhillips Begins Production of Renewable Diesel Fuel at Whitegate Refinery
- ↑ Texas power plant runs on biodiesel | CNET News.com
- ↑ Biodiesel to drive up the price of cooking oil | CNET News.com
- ↑ ADM Biodiesel: Hamburg, Leer, Mainz
- ↑ Biofuels News (Green Portal)
- ↑ Farmers Journal: Vegetable oil prices soar - 17 November 2007
- ↑ Run A Diesel Car On Vegetable Oil
- ↑ WashingtonWatch.com - H.R. 196, The Renewable Fuels and Energy Independence Promotion Act of 2007
- ↑ http://www.abareconomics.com/interactive/08ac_Sept/htm/oilseeds.htm
- ↑ http://www.federalreserve.gov/pubs/ifdp/2009/967/Figure7.gif
- ↑ Biofuels for Transportation
- ↑ "AFRICA: Food to eat or to run your car?". UN Office for the Coordination of Humanitarian Affairs - Integrated Regional Information Networks (IRIN). 2007-10-23. http://www.irinnews.org/Report.aspx?ReportId=74941. Retrieved 2008-11-22.
- ↑ 21.0 21.1 Look back at the U. S. Department of Energy's Aquatic Species Program: Biodiesel from Algae; Close-Out Report
- ↑ ERS/USDA Briefing Room - Soybeans and Oilcrops: Market Outlook
- ↑ Gonzlez, Ángel (2007-11-21). "Seeding the way to better biofuels". The Seattle Times. http://seattletimes.nwsource.com/html/biotech/2004026594_biotechcrops21.html.
- ↑ 24.0 24.1 Why is oil palm replacing tropical rainforests
- ↑ biofuelwatch: home
- ↑ Biofuel demand makes fried food expensive in Indonesia - ABC News (Australian Broadcasting Corporation)
- ↑ The other oil shock: Vegetable oil prices soar - International Herald Tribune
- ↑ Food versus fuel debate escalates
- ↑ How Food and Fuel Compete for Land by Lester Brown - The Globalist > > Global Energy
- ↑ "The Economist – The End Of Cheap Food". 2007-12-06. http://www.economist.com/research/articlesBySubject/displaystory.cfm?subjectid=7216688&story_id=10252015.
- ↑ http://www.millettiaplantations.com/
- ↑ http://www.bioenergyresearch.com.au/home/
- ↑ http://www.winrock.org/fnrm/factnet/factpub/FACTSH/P_pinnata.html
- ↑ http://www.hort.purdue.edu/newcrop/duke_energy/Pongamia_pinnata.html
- ↑ Hybrid Universe Expanding Rapidly
- ↑ Marshall Brain's Blog: Peak oil will be a non-event
- ↑ Peak Oil: Life After the Oil Crash
- ↑ The Oil Drum | update
- ↑ Chisti, Yusuf (2007). "Biodiesel from microalgae" (Template:Dead link). 294–306. Template:Citation/identifier. Template:Citation/identifier. http://dels.nas.edu/banr/gates1/docs/mtg5docs/bgdocs/biodiesel_microalgae.pdf.
- ↑ McKenna, Phil (7 October 2006). "From smokestack to gas tank". Reed Business Information. 28–29. Template:Citation/identifier. 1233.
- ↑ "Algae: 'The ultimate in renewable energy' - CNN.com". CNN. 2008-04-01. http://www.cnn.com/2008/TECH/science/04/01/algae.oil/index.html. Retrieved 2010-05-27.
- ↑ "Template:Citation error". http://abcnews.go.com/International/algae-solve-worlds-fuel-crisis/story?id=14181088.
- ↑ "'Green goo' biofuel gets a boost - CNN.com". CNN. 2009-08-24. http://edition.cnn.com/2009/TECH/science/08/21/eco.algaebiofuel/index.html. Retrieved 2010-05-27.
- ↑ R-Squared Energy Blog: Grain-Derived Ethanol: The Emperor’s New Clothes
- ↑ John Sheehan, Vince Camobreco, James Duffield, Michael Graboski, Housein shapouri (May 1998). "Life Cycle Inventory of Biodiesel and Petroleum Diesel for Use in an Urban Bus" (PDF (1.9 Mb)). United States Department of Agriculture jointly with United States Department of Energy. http://www.nrel.gov/docs/legosti/fy98/24089.pdf. Retrieved 2007-01-02.
- ↑ http://scholar.google.com/scholar?hl=en&q=biofuel+energy+balance
- ↑ Ethanol And Biodiesel From Crops Not Worth The Energy