Efficiency and Environmental Effects


When using biodiesel in a diesel powered vehicle, it retains similar horsepower and torque. Biodiesel contains a higher cetane number, but also a lower energy content than traditional diesel. These properties result in a more lubricated, better performing engine, but a 2-8% decrease in fuel economy REF (http://www.epa.gov/SmartwayLogistics/growandgo/documents/factsheet-biodiesel.htm)

Energy Balance of Biodiesel
The long running controversy over biodiesel is the question of whether the fuel needed to harvest and process biodiesel is worth the fuel produced. Most of those against biodiesel state how the plants can only actually trap 3-6% of solar radiation throught the process of photosynthesis REF(http://www.fao.org/docrep/w7241e/w7241e05.htm) . Compared to solar cells, which catch just under 20%, this seems very small. However, the other side of the debate states that biodiesel is much less expensive and there are already many cars that can use biodiesel; if one wants a solar/electric car they would have to get rid of their current vechile and buy a new electric car.

Another important factor is which plants should be used to produce biodiesel. While some plants are very cheap, they many not produce per acre as much fuel as another plant can produce. While soybeans are one of the most popular plants used for the production of biodiesel, they are the most inefficient. Palm oil production is becoming more and more popular in Malaysia and Indonesia as it is fairly inexpensive and has such a high yield of biodiesel per acre of the feedstock crop. REF(http://www.landcoalition.org/cpl-blog/?p=779)
Food Vs Fuel
The use of land for the production of fuel doesn't seem like a waste to most people; however, to those in third world countries it is. Many poorer countries are now using land to grow agriculture for fuel, and not for the food needed by the people of those countries. Some suggest that only non-edible crops which can grow in more harsh conditions be used for biofuel. The idea behind this is that the fertile soil can still be used to grow crops to feed people, not fuel cars. The issue from this is that farmers will grow whatever will make them the most profit. If it is edible or not, they will make the most profit off of crops for biodiesel, so that is what they will grow.REF (http://www.bernama.com/bernama/v5/index.php)

Environmental Effects

Biodiesel is seen as cleaner alternative to fossil fuels. It is often seen as being much more earth friendly because the carbon dioxide emissions are "recycled" by the plants that will be made into biodiesel. This is often seen in as cycle diagram, as shown below.
Bidiesel Cycle
This image is often seen as misrepresenting the amount of carbon dioxide emitted from biodiesel powered engines. While they do reduce emissions compared to standard fossil fuels, their emissions are not immediately reabsorbed by plants.

Greenhouse Gas Emissions
Biodiesel is the only alternative fuel that has had its emission and potential health effects completely evaluated by the EPA under the Clean Air Act. Overall, biodiesel was found to reduce emissions when compared to standard diesel. REF (http://www.biodiesel.org/pdf_files/fuelfactsheets/emissions.pdf)

However, this is only a piece of the emissions. There is also energy used to grow, transport, and process the feedstocks; so if a farm uses energy inefficient tractors the overall emissions for the biodiesel is higher than a farm with more efficient machinery. Thus, even the local where the feedstocks are grown can effect the overall environmental impact of the biodiesel. In addition, biodiesel from one plant does not produce the same emissions as another. For example, most soy oil has a higher emission than most rapeseed (canola) oil and both have higher emissions than palm oil. Surprisingly, the biodiesel with the lowest amount of environmental impact is of cooking oil and tallow. The following chart shows the comparisons of biodiesels, as well as traditional fossil fuels.


Compared to diesel, biodiesel can reduce direct tailpipe emissions of sulfur, CO, hdyrocarbons, and other particulates. The benefits of the sulfur reduction could be a possible improvement of acid rain (which is caused by sulfur dioxide). Also, reduction of CO and hydrocarbons would improve air quality and potential health effects from breathing in emissions. However, using B100 biodiesel actually produces more nitrogen oxide (NOx) than standard diesel does. NOx is one of the main contributors to smog, so in areas like Los Angeles and Mexico city, which are known for car-produced smog, this could actually make the air quality worse. REF (http://www1.eere.energy.gov/vehiclesandfuels/pdfs/basics/jtb_biodiesel.pdf)
Demand for oil is vey high in tropical regions for the production of biodiesel. With this high demand comes the need for more space to grow the crops; and this land is coming at the price of tropical rainforests. Indigenous people are being forced to relocate, forests and waters are being contaminated by pesticides, and certain species of plants and animals are becoming endangered. This need for land to produce biodiesel is damaging ecosystems, creating social conflict, and destroying vegitation that could help reduce greenhouse gases.REF http://www.greenpeace.org/raw/content/international/press/reports/cooking-the-climate-full.pdf

As seen in this chart, that as production for soybeans used for biodiesel has increased, the deforestation of the Amazon has increased accordingly.

A study performed by the University of Idaho found that biodiesel degrades twice as fast as petroleum-diesel. Two types of biodiesel (rapeseed and soybean oils) were tested against different types of petroleum diesel. Even in soil, the biodiesels degraded much more rapidly than all the different types of diesel. REF (http://www.greenpeace.org/raw/content/international/press/reports/cooking-the-climate-full.pdf)