Natalie Smith

Energy, Resources and Public Policy

Paper #1

Biodiesel and Waste Vegetable Oil: Green Alternatives for “Dirty Fuel” Vehicles

Abstract: This paper examines the environmental problems associated with fuel consumption, particularly lifecycle energy efficiency and pollutants related to climate change. In addition, petroleum (and more broadly, fossil fuels) is a finite resource, but U.S. consumption remains on the rise, and so new sources of fuel must be explored and utilized. In response to these supply and environmental concerns, two biofuel alternatives to petroleum diesel fuel are explored- biodiesel and straight or waste vegetable oil (SVO/WVO). These options are both renewable energy sources, and have been shown to greatly reduce diesel emissions pollutants. The diesel engine was originally designed to run on vegetable oil-based products like Biodiesel and SVO/WVO, and so switching to these fuels is simple. Biodiesel is a clean alternative to petroleum diesel, and has lower emissions of all pollutants except nitrogen oxides. Available in blends with petroleum diesel, biodiesel is most “green” pure, as B100, but is most commonly used commercially as B20. Straight and waste vegetable oil (SVO and WVO) requires a retrofit system for a diesel engine, but produces even less dangerous emissions than biodiesel. SVO/WVO fuel is the least environmentally harmful, most human health safe, and most affordable fuel available today. The widespread adoption of biodiesel and SVO/WVO by the U.S. public could greatly affect the extent to which the U.S. contributes to global climate change, and so measure should be taken to promote diesel vehicles for biodiesel and SVO/WVO use.

Full text:

As fossil fuels costs grow and pollution increases, the need to invest seriously in renewable energy sources has become increasingly apparent. Imports of crude oil into the United States have increased fivefold in the last forty years, from 2 million barrels a day in 1960 to 10.2 million barrels a day in 2000. (BP, various years) Transportation uses two-thirds of all the oil used in the U.S., which is not surprising considering the transportation sector is 97% dependent on oil. (www.nesea.org) In addition to the political ramifications of the United States’ reliance on oil, there are dire environmental impacts. For every gallon of gasoline that a car burns, 22 pounds of carbon dioxide are released into the atmosphere. (Tickell, 2003) The combustion of fossil fuels contributes greatly to pollution and climate change, and so renewable fuels must be utilized so that these problems are not perpetuated. Biodiesel, waste veggie oil, and hybrid electric vehicles offer a new fuel alternative for gasoline and diesel cars and trucks that may help decrease transportation’s reliance on oil, and greatly decrease the environmental impacts of modern day transportation.

According to the U.S. Environmental Protection Agency (EPA), driving a car is the single most polluting thing that most of us do. Motor vehicles emit millions of tons of pollutants into the air each year. In many urban areas, motor vehicles are the single largest contributor to ground-level ozone, a major component of smog. Ground-level ozone is the most serious air pollution problem in the northeast and mid-Atlantic states. (www.nsc.org) Motor vehicles generate many major pollutants: hydrocarbons, nitrogen oxides, carbon monoxide, carbon dioxide and particulate matter. Hydrocarbons react with nitrogen oxides in the presence of sunlight and elevated temperatures to form smog (ground level ozone), and are toxic and carcinogenic. Nitrogen oxides also contribute to the formation of ozone and contribute to the formation of acid rain and water quality problems. Carbon monoxide is extremely harmful (and deadly) to humans, and in urban areas, motor vehicles are responsible for as much as 90 percent of carbon monoxide in the air. Carbon dioxide emissions help to trap the Earth’s heat, causing global warming. Particulate matter has been shown to be a serious health hazard. Cumulatively vehicle emissions significantly degrade air quality, impair visibility, contribute to global warming, contain toxic contaminants, and threaten public health and the environment.

These emissions result from both gasoline and diesel vehicles, but I have chosen to focus on diesel because of its options for improvement, and because of its significant role in the United States’ transportation pollution. Most heavy-duty trucks (the trucking industry) and buses (public transportation) are diesel. These vehicles account for under 6% of the miles driven by highway vehicles in the U.S., but they are responsible for 25% of smog causing pollution from highway traffic, over half of the soot (particulate matter) from highway traffic, and 6% of the nation’s global warming pollution. (Clean Cities, 2000) Rudolph Diesel developed the diesel engine in 1985 fully intending to run it on vegetable oil. When he showed his engine at the World Exhibition in Paris in 1900 he used peanut oil, and felt strongly about his engine’s potential role in supporting domestic agriculture. The diesel engine is different from the gasoline engine in that it uses compression ignition instead of spark ignition. This means that pressurized air is used to ignite the fuel instead of spark plugs.

Diesel vehicles have a stigma in the United States of being a “dirty” fuel. This is only partially true, however. While traditional, cheap petroleum diesel fuel is more harmful to the environment (and human health), diesel-powered cars achieve 20-40% better fuel economy than gasoline powered equivalents, especially in popular sport utility vehicles and light trucks, which now make up more than half of all new sales (Diesel Technology Forum, 2000) and offer better torque than gasoline engines. See Table 1 for fuel economy comparisons. Diesel vehicles can also be run using much greener alternative fuels, while gasoline vehicles can only run on gasoline or ethanol (a renewable fuel slightly “greener” than gas). Biodiesel is one example of a renewable, less environmentally harmful fuel that can be used in a diesel vehicle not requiring any retrofit. Biodiesel fuel “can be made from new or used vegetable oils, which are nontoxic, biodegradable, renewable resources…the oils are chemically reacted with an alcohol (usually methanol) to produce chemical compounds known as fatty acid methyl esters.” ( U.S. Department of Energy, 2000) These new chemical compounds are called “neat biodiesel”, or “B100”, and can be used as fuel for any diesel vehicle. They can also be blended with regular diesel fuel, the most common being a 20% biodiesel/80% diesel blend called “B20”. Neat biodiesel is nontoxic, biodegradable, and has lower emissions of environmentally harmful materials than conventional diesel. Another distinguishing characteristic is that biodiesel is domestically produced, so its use helps to support United States farmers. Soybeans are the most common source of new oil used for biodiesel production, but other domestically grown crops like mustard seed are used as well. Recycled cooking oil (also called “waste grease” or “trap grease”) can also be used for making biodiesel. Waste grease is oil that has been used in restaurants for cooking and frying, but has been thoroughly filtered into useable, clean oil.

In May of 1998, the U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA) published the results of their Biodiesel Lifecycle Inventory study that compared the materials used, energy resources used, and emissions generated by diesel and biodiesel blend B20 in order to evaluate the two fuels’ total “lifecycle” costs and benefits. The study found that the total fossil energy efficiency ratio for diesel .8337% and 3.215% for biodiesel, meaning biodiesel is four times as efficient in utilizing fossil energy. These numbers were obtained by the calculation: total fuel energy/total energy used in production, manufacture, transportation, and distribution. These numbers confirm the renewable nature of biodiesel, in that it yields 3.2 units of fuel product for every unit of fossil energy consumed. It is safe to assume that even better results would have been obtained if B100 was tested. The report also found that B20 had 2-3% lower fuel economy than diesel, due to biodiesel’s lower Btu/gallon ratio. As a direct result of carbon recycling in soybean plants and other crops used to make the oil for biodiesel, the overall lifecycle emissions of carbon dioxide from biodiesel are 78% lower than those of regular petroleum diesel. This trend continues for lifecycle emissions of carbon monoxide (35%), particulate matter (32%), sulfur oxides (8%) and methane (3%). Overall lifecycle emissions of nitrogen oxides were actually 8-13% higher for biodiesel than diesel. Lastly, the overall lifestyle production of wastewater and hazardous solid wastes were drastically lower (79% and 96%) for biodiesel than petroleum diesel. The study notes that “petroleum diesel generates roughly five times as much wastewater flow as biodiesel” and even though overall life cycle production of non-hazardous solid wastes from biodiesel is two times that of diesel, “given the more sever impact of hazardous versus non-hazardous waste disposal, this a reasonable trade-off.” (DOE, 1998)

In comparing biodiesel with diesel it is also helpful to look at each fuel’s respective tail pipe emissions. In Table 2 you can see that pure biodiesel (B100) has lower emissions than diesel in every pollutant except for nitrogen oxides. Hydrocarbons are reduced 67% with B100, carbon monoxide is reduced 48%, particulate matter 47% and sulfates 100%. Nitrogen oxide data is not conclusive, however, because it depends greatly on the engine family and testing procedures. Still, more research must be done to find a way to limit biodiesel’s nitrogen oxide emissions. Current options include additives and control technologies available due to biodiesel’s lack of sulfur.

Another option for improving the environmental effects of the diesel engine is to run on Straight Vegetable Oil (SVO) or Waste Vegetable Oil (WVO). As implied by the name, the only difference between SVO and WVO is that WVO is recycled oil, often gathered from restaurants and other trap grease sites. SVO/WVO is different from biodiesel in that it is not blended with chemicals, and therefore does not have similar viscosity or chemical properties to diesel fuel. In order to run a diesel vehicle on SVO/WVO, a retrofit system must be added to the vehicle so that it can be started and turned off with diesel or biodiesel, but run (once up to temperature) on SVO/WVO. The retrofit system involves adding a second fuel tank and set of fuel lines (if the vehicle does not already have them). Within this new tank (which will be used for the SVO/WVO) a metal pipe system or radiator is inserted that will transfer heat from the engine’s coolant to the SVO/WVO in order to warm it up so that it reaches diesel-like viscosity. SVO/WVO must have the same viscosity of diesel fuel in order to injected properly into the engine. Table 3 shows the viscosity of vegetable oil compared to diesel fuel at different temperatures. The SVO/WVO has a special additional fuel filter incorporated into the new fuel lines, and the original fuel filter is moved from the front of the engine so that it only filters the diesel (or biodiesel). There is no power loss with converted vehicles, and running on SVO/WVO has been shown to add superior lubrication and detergent values, reducing engine wear. (Greasecar, 2004)

Running a diesel vehicle on WVO does not improve the vehicle’s fuel economy, but it does greatly reduce emissions. Because there is no sulfur content in SVO/WVO, sulfur oxides are completely eliminated. Also, nitrogen oxides are also reduced. Biofuels like SVO/WVO are carbon neutral. Unlike petroleum fuels, they do not add new carbon to the atmosphere. Biofuels stay within the existing carbon cycle by using plant mass. Studies show that vehicles run on SVO/WVO are 75% cleaner overall than vehicles run on petroleum diesel. (Greasecar, 2004) Unfortunately there is little largely funded, comprehensive research as of yet on the environmental benefits of SVO/WVO fuel. This is in part due to the automobile industry’s efforts to block the expansion of SVO/WVO technology. The automobile industry has made it policy now to void all warranties on vehicles that employ SVO/WVO systems, and has pressured auto insurance companies to refuse insurance coverage to vehicles using vegetable oil. I recently converted my Ford F-250 to run on WVO and have had no problems with cold weather, filtration or the engine. By using waste grease from neighborhood restaurants, I have access to free fuel and am not affected by the constant fluctuations and “crises” in gas and diesel prices.

Diesel vehicles are the backbone of our country’s trucking industry and public transportation and are enjoyed by hundreds of thousands of citizens for personal use. The technology and resources are available to make diesel vehicles the most affordable and least environmentally harmful option for use today. Rudolph Diesel said in 1912, “the use of vegetable oils for engine fuels may seem insignificant today. But such oils may become in the course of time as important as petroleum and the coal products of our present time.” (Tickell, 2003) That time is now. In a decade where global warming is increasing at an alarming rate and fuel consumption is at record highs, biofuels such as biodiesel and SVO/WVO offer an important and viable alternative to fossil fuel products. The simplicity and low cost of these two alternatives makes “green” vehicles more accessible to and economically practical for the public. If diesel vehicles were widely introduced into the U.S. market (there are currently only two domestic diesel vehicle producers and three new diesel makes available) for the sole purpose of biodiesel or SVO/WVO use, the negative environmental effects of driving could be greatly reduced. Such a progressive change in transportation could drastically reduce the United States’ currently disproportionately large role (25%) in contributing to global climate change.

Tables:

Table 1

Source: From the Fryer to the Fuel Tank, Tickell 2003

Table 2

AVERAGE BIODIESEL EMISSIONS COMPARED TO CONVENTIONAL DIESEL, ACCORDING TO EPA
Emission Type	B100	B20
Regulated
Total Unburned Hydrocarbons	-67%	-20%
Carbon Monoxide Carbon Dioxide	-48% -75%	-12% 15%
Particulate Matter	-47%	-12%
Nox	+10%	+2%
Non-Regulated
Sulfates	-100%	-20%*
PAH (Polycyclic Aromatic Hydrocarbons)**	-80%	-13%
nPAH (nitrated PAH’s)**	-90%	-50%*******
Ozone potential of speciated HC	-50%	-10%

* Estimated from B100 result ** Average reduction across all compounds measured *** 2-nitroflourine results were within test method variability

Source: National Biodiesel Board, 2004

Table 3

Source: Saskatchewan Research Council