The U. Environmental Protection Agency EPA has been testing biodiesel for compliance with the Clean Air Act. The testing concluded that emissions from biodiesel are non-toxic and impose little or no health risks to humans. Rudolph Diesel designed and built the compression ignition engine or diesel engine in the 's.

Since then, diesel engines have provided enormous benefits throughout the world. But the continuing use of petrodiesel has substantial implications for environmental and public health issues.

The challenge is how to optimize the use of diesel engines in a more compatible manner with the environment. Biodiesel holds such promise but certain precautions must be noted.

B is seldom used as a fuel because of cost factors and availability. Furthermore, no engine manufacturers at this time warrant their engines and engine components if B is used as the fuel.

Biodiesel blends of B2 to B20 are most common. Even at low blends of B1 or B2, biodiesel provides environmental benefits and greatly improves the lubricity of low-sulfur diesel fuel. Lubricity of a fuel is the ability of the fuel to provide lubrication to reduce wear between moving parts of the diesel engine.

EPA requires low sulfur levels in petrodiesel, as of the early s, dropping the limit from 5, parts per million ppm to 15 ppm for "on-road" transportation fuel. Whenever sulfur is removed from petrodiesel, lubricity of the fuel is greatly reduced.

Biodiesel has virtually no sulfur content but has excellent lubricity properties. Whenever switching to biodiesel or a biodiesel blend fuel in an engine that had been running on petrodiesel, it is recommended to change fuel filters on a more frequent basis at least for the first six months after the transition.

Biodiesel is an excellent solvent and, as such, it will readily dissolve many of the deposits in a diesel engine, fuel injectors, fuel supply lines, and storage tanks that have accumulated over the years of engine operation with petrodiesel.

Continue changing fuel filters on an as-needed basis until the system has been cleaned of the petrodiesel deposits. Since biodiesel is a good solvent, it is necessary to quickly wipe any biodiesel spills from painted surfaces to avoid paint removal. With a flash point temperature of about °F compared to about °F for diesel fuel , biodiesel presents a very low fire hazard and is much safer to store and handle than other petroleum-based fuels.

Most of the standard storage and handling procedures used for petrodiesel can also be used for biodiesel. The fuel should be stored in a clean, dry, dark environment.

Recommended materials for storage tanks include aluminum, steel, polyethylene, polypropylene and Teflon, but not concrete-lined storage tanks. The storage tank should not include any copper, brass, lead, tin, zinc or rubber fittings. Since biodiesel is an organic liquid, the use of an algaecide or fungicide additive is recommended whenever the fuel is stored during warm weather.

B has a tendency to gel during cold weather as indicated by its higher cloud point and pour point temperatures than petrodiesel. Additives are available to prevent gelling, but gelling is generally not a problem for blends of B20 or lower.

Storage time for biodiesel and petrodiesel should be limited to six months for best performance. Utilizing food crops as fuel has yet to create significant competition with the supply of food that is needed for nourishment throughout the world.

Although malnutrition is a serious global problem affecting million people, the world is not experiencing a food production problem. Instead the world faces political challenges associated with providing infrastructure for effective food distribution and storage. Contemporary agricultural systems can and do produce sufficient quality and quantity of food for the world's population, with additional resources available so that agricultural products can be used for processing into fuel, pharmaceuticals, and chemical feedstocks.

The most reliable way to get up-to-date information is to check the website for the National Biodiesel Board. Click on "Guide to Buying Biodiesel. Make sure that you are buying biodiesel and not just crude, unprocessed vegetable oil.

Insist on certification that the biodiesel meets ASTM D standards. Biodiesel is an alternative, renewable fuel with significant promise for addressing major energy problems.

Effective energy management systems are needed to optimize energy use throughout all sectors of our economy. Using biodiesel as a fuel:. Brown, R.

Biorenewable Resources: Engineering New Products from Agriculture. Iowa State Press, Ames, IA. Knothe, G. Krahl, and J. Van Gerpen. The Biodiesel Handbook. AOCS Press, Champaign, IL. Sheehan, J. Camobreco, J. Duffield, M.

Graboski, and H. Life cycle inventory of biodiesel and petroleum diesel for use in an urban bus. The store will not work correctly when cookies are disabled. Biodiesel: A Renewable, Domestic Energy Resource. Save for later Print Share. Updated: March 9, Skip to the end of the images gallery.

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Personalize your experience with Penn State Extension and stay informed of the latest in agriculture. Sign Up for Our Newsletter:. Email address is required to login. For this reason, existing petroleum refineries can be converted for renewable diesel production with only modest retrofits.

However, hydrotreatment of renewable feedstocks requires significantly more hydrogen than desulfurization of diesel, and the source of the hydrogen could affect whether or not the renewable diesel can meet national or state standards for biofuels.

Other methods can be used for renewable diesel production, such as gasification and pyrolysis. Renewable heating oil is similar to renewable diesel fuel but meets ASTM D for fuel oils.

Renewable jet fuel may be called sustainable aviation fuel SAF , alternative jet fuel AJF , or biojet depending on the context or fuel standard under which it can be used. Renewable jet fuel meets ASTM D , which allows for up to a blend of biomass-derived blending components and petroleum jet fuel.

Other non-fuel ethanol biofuels include renewable naphtha, renewable gasoline, renewable propane a by-product of renewable diesel and SAF production , and other emerging biofuels. Another aviation biofuel that is being tested for use is alcohol-to-jet ATJ or ethanol-to-jet [ETJ].

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In addition, unlike petroleum, we can always grow new plants for biofuel when we need them. So, if biofuels are sustainable and environmentally friendly, then they must be the perfect solution to our energy problems, right? Unfortunately, the processes that scientists use to turn biomass into biofuel can be very expensive.

In addition, some biofuel reactions require harsh chemicals that can create their own environmental problems, leaving us right back where we started in terms of sustainability 2. To see how plants are turned into useful fuels and chemicals, we must first understand what they are made of.

The walls of plant cells are responsible for almost all of the weight of a plant and are composed of three complex molecules called cellulose, hemicellulose, and lignin Figure 1. The first two molecules, cellulose and hemicellulose, are bursting with simple sugar building blocks, all bound together in a compact structure that is supported by the third molecule — lignin Figure 1.

All three complex molecules in plants must be broken apart to access the sugar building blocks within, which can then be converted to biofuel. One way to accomplish this biomass breakdown is to use a lot of harsh chemicals to break apart the plant tissues.

However, these chemicals can be expensive — even toxic 2. Ideally, we would like to make breaking down plants easier, so we do not have to rely as much on these chemicals. One possible solution is to use a solvent — a liquid with chemical properties that allow it to dissolve other materials … like plants.

Most of us use solvents every day, even if we are not aware of it. For example, you use water as a solvent every time you wash your hands or make instant hot chocolate. Sometimes, only a certain kind of solvent can get the job done. For example, water may dissolve cocoa powder to make hot chocolate, but it would not remove nail polish — for that, you need chemicals called acetone, or ethyl acetate.

Unfortunately, until recently, energy researchers could not find a solvent that was a cheap, b sustainable, and c good at breaking down plants. But now, we have discovered a very interesting new solvent called γ- valerolactone GVL for short that can make biofuel production much cheaper and more efficient 3.

GVL is such an interesting solvent because it is not only cheap — it is renewable, because it is made from biomass itself. This process is illustrated in Figure 2 , which shows the chemical reaction as it proceeds inside a biofuel reactor.

Biofuel reactors are metal vessels that contain biofuel-processing reactions. They are specially designed to withstand the heat, pressure, and chemicals involved. For any chemical reaction to begin, the ingredients involved the reactants must first gather enough energy.

In common biofuel production reactions, lots of acids are mixed with water to help break down the biomass. This can take awhile, especially for very tough or woody plants, but adding GVL to the reaction gives the acids a big energy boost. This boost helps the system gather its activation energy faster, so the reaction can proceed more quickly 4 , 5 Figure 3.

To illustrate this phenomenon, imagine that two girls, Gemma and Valerie, are about to race each other to the top of a steep hill. Usually, both runners must stand behind a starting line to make sure that the race is fair. But in this race, Gemma is actually allowed a big head start: when the buzzer goes off, she gets to start running halfway up the steep hill, while Valerie must begin from the very bottom.

Who do you think will win? You guessed it — Gemma gets to the top of the hill way before Valerie. Just as the head start puts Gemma closer to the top of the hill in the race analogy, GVL brings the acid closer to the point of reacting with the biomass, allowing the reaction to proceed much faster.

To plants, lignin is really important: it gives them their shape and structure, and helps them grow healthy and strong. But to scientists, lignin is just a nuisance. It is a tough and stubborn molecule that is very hard to break down, and it interferes with obtaining simple sugars from cellulose and hemicellulose molecules.

One day, scientist hope to be able to break down lignin itself to make useful things, but for now, they just want it out of the way. GVL has the unusual ability to dissolve lignin, and to keep it from blocking the big prize: the energy-rich sugar building blocks. Perhaps, the best thing about it GVL that it is can be recycled.

At the end of a biofuel reaction, liquid CO 2 can be added to the reactor to separate each reactant into a distinct layer Figure 2. Think of a bottle of fancy salad dressing: the oil and vinegar, instead of mixing with each other, stay completely separate until the bottle is shaken.

Likewise, when CO 2 is added to the biofuel reactor, the GVL and sugar solution become just like that salad dressing. The sugars all move into one layer and become concentrated see Figure 2 , while the GVL forms its own separate layer. The GVL can then be easily removed and used again, while the sugar solution that scientists end up with is around five times more concentrated than it would be without GVL.

This increased concentration is very important, because it means that you need to spend less energy purifying the final product, making the whole process more efficient and less wasteful.

After the GVL has been removed, a concentrated — and very useful — sugar solution is left behind. Scientists have two options for using this energy-rich solution:. For all these reasons, using GVL gives scientists hope for creating biofuels and chemicals that can compete with petroleum products in the marketplace.

For centuries now, humans have been inventing new technologies and developing industry at an astounding rate — sometimes at a serious cost to the environment.

A biofuel production process that meets all the requirements of affordability, renewability, and sustainability has the potential to benefit both humans and the earth.

With the discovery of GVLs role in biofuel processing, we believe that we are one step closer to a sustainable future. Third generation biofuels use algae as a feedstock. Commercial cellulosic biofuel production began in the US in , while algae biofuels are not yet produced commercially.

Replacing fossil fuels with biofuels has the potential to generate a number of benefits. In contrast to fossil fuels, which are exhaustible resources, biofuels are produced from renewable feedstocks.

Thus, their production and use could, in theory, be sustained indefinitely. Academic studies using other economic models have also found that biofuels can lead to reductions in lifecycle GHG emissions relative to conventional fuels Hertel et al. Second and third generation biofuels have significant potential to reduce GHG emissions relative to conventional fuels because feedstocks can be produced using marginal land.

Moreover, in the case of waste biomass, no additional agricultural production is required, and indirect market-mediated GHG emissions can be minimal if the wastes have no other productive uses. Biofuels can be produced domestically, which could lead to lower fossil fuel imports Huang et al.

If biofuel production and use reduces our consumption of imported fossil fuels, we may become less vulnerable to the adverse impacts of supply disruptions US EPA Reducing our demand for petroleum could also reduce its price, generating economic benefits for American consumers, but also potentially increasing petroleum consumption abroad Huang et al.

Biofuels may reduce some pollutant emissions. Ethanol, in particular, can ensure complete combustion, reducing carbon monoxide emissions US EPA It is important to note that biofuel production and consumption, in and of itself, will not reduce GHG or conventional pollutant emissions, lessen petroleum imports, or alleviate pressure on exhaustible resources.

Biofuel production and use must coincide with reductions in the production and use of fossil fuels for these benefits to accrue. These benefits would be mitigated if biofuel emissions and resource demands augment, rather than displace, those of fossil fuels.

Biofuel feedstocks include many crops that would otherwise be used for human consumption directly, or indirectly as animal feed. Diverting these crops to biofuels may lead to more land area devoted to agriculture, increased use of polluting inputs, and higher food prices.

Cellulosic feedstocks can also compete for resources land, water, fertilizer, etc. that could otherwise be devoted to food production.

As a result, some research suggests that biofuel production may give rise to several undesirable developments. Changes in land use patterns may increase GHG emissions by releasing terrestrial carbon stocks to the atmosphere Searchinger et al. Biofuel feedstocks grown on land cleared from tropical forests, such as soybeans in the Amazon and oil palm in Southeast Asia, generate particularly high GHG emissions Fargione et al.

Even use of cellulosic feedstocks can spur higher crop prices that encourage the expansion of agriculture into undeveloped land, leading to GHG emissions and biodiversity losses Melillo et al. Biofuel production and processing practices can also release GHGs.

Fertilizer application releases nitrous oxide, a potent greenhouse gas. Most biorefineries operate using fossil fuels. Some research suggests that GHG emissions resulting from biofuel production and use, including those from indirect land use change, may be higher than those generated by fossil fuels, depending on the time horizon of the analysis Melillo et al.

Regarding non-GHG environmental impacts, research suggests that production of biofuel feedstocks, particularly food crops like corn and soy, could increase water pollution from nutrients, pesticides, and sediment NRC Increases in irrigation and ethanol refining could deplete aquifers NRC Air quality could also decline in some regions if the impact of biofuels on tailpipe emissions plus the additional emissions generated at biorefineries increases net conventional air pollution NRC Economic models show that biofuel use can result in higher crop prices, though the range of estimates in the literature is wide.

For example, a study found projections for the effect of biofuels on corn prices in ranging from a 5 to a 53 percent increase Zhang et al. A National Center for Environmental Economics NCEE working paper found a 2 to 3 percent increase in long-run corn prices for each billion gallon increase in corn ethanol production on average across 19 studies Condon et al.

Higher crop prices lead to higher food prices, though impacts on retail food in the US are expected to be small NRC Higher crop prices may lead to higher rates of malnutrition in developing countries Rosegrant et al.

The Energy Policy Act of used a variety of economic incentives, including grants, income tax credits, subsidies and loans to promote biofuel research and development. It established a Renewable Fuel Standard mandating the blending of 7. The Energy Independence and Security Act of EISA included similar economic incentives.

EISA expanded the Renewable Fuel Standard to increase biofuel production to 36 billion gallons by Of the latter goal, 21 billion gallons must come from cellulosic biofuel or advanced biofuels derived from feedstocks other than cornstarch.

To limit GHG emissions, the Act states that conventional renewable fuels corn starch ethanol are required to reduce life-cycle GHG emissions relative to life-cycle emissions from fossil fuels by at least 20 percent, biodiesel and advanced biofuels must reduce GHG emissions by 50 percent, and cellulosic biofuels must reduce emissions by 60 percent.

EISA also provides cash awards, grants, subsidies, and loans for research and development, biorefineries that displace more than 80 percent of fossil fuels used to operate the refinery, and commercial applications of cellulosic biofuel. In addition to EISA, numerous other policies have encouraged the production and use of biofuels in the US in recent decades.

Tax credits currently support advanced biofuels, including cellulosic and biodiesel. Condon, N. Klemick, and A. Accessed Sept. Hertel, T. Golub, A. Jones, M. Plevin, and D. Fargione, J. Fischer, G. Hizsnyik, S. Prieler, M. Shah, and H. van Velthuizen. Biofuels and Food Security.

OPEC Fund for International Development. Huang, H. Khanna, H. Onal, and X. Melillo, J. Reilly, D.