• Biodiesel fuel is considered to be a viable alternative to petroleum diesel, but there are still some concernsSaving fuel image by Katja Sucker from Fotolia.com
  
  Biodiesel fuel -- cleaner-burning, environmentally friendly and energy-efficient -- is considered by many to be a solution to the world's energy problems. The advantages to using a clean, renewable energy source are many. However, before biodiesel can be used as a replacement for petroleum diesel, there are issues that need to be addressed.
  
  

What is Biodiesel?

• Biodiesel is made from natural resources like animal fats, vegetable oils, and recycled cooking oil. It can be used in all diesel engines -- either modified or in its pure form -- and as such it is a viable alternative to petroleum-based fuel. Petroleum diesel produces a significant amount of air pollution, causing respiratory problems as well as contributing to the reduction of the ozone layer. Environmentalists assert that it is a major contributor to global warming.
  
  

Advantages of Biodiesel

• Scientific studies have shown that biodiesel is better for the environment than petroleum diesel fuel. Because it contains almost no sulfur, it emits significantly less greenhouse gas than standard diesel. According to a study by the U.S. Department of Energy, biodiesel emits nearly 80% less emission of carbon dioxide than petroleum diesel. The minimal amount of carbon dioxide produced can then be recycled by plants such as corn and soy, which can be processed into biofuel. This makes biodiesel a renewable energy source.
  
  The use of biodiesel poses far less of a threat to human health than standard diesel. It has been shown to produce significantly lower levels of particulate matter (which can cause asthma), as well as lower levels of certain hydrocarbons that have been linked to cancer.
  
  Biodiesel has a far greater energy balance than standard diesel. Energy balance is the relationship between the amount of energy is takes to create a fuel and the amount of energy produced by the fuel. Petroleum diesel, for example, has an energy balance of less than one-to-one, which means less than one unit of energy is received for each unit of energy used in the production of standard diesel. Biodiesel's energy balance is more than three to one.
  
  

Disadvantages of Biodiesel

• One of the main drawbacks of biodiesel is its cost. It is currently more expensive to produce biodiesel than petroleum diesel. Producing biodiesel on a large scale would also require a greater use of land, which could have a negative effect on the food supply. There has also been a concern that if the production of biodiesel plants becomes more lucrative for farmers than food crops, then more farmers will switch over to growing biodiesel plants full-time, causing the food supply to decline.
  
  While burning biodiesel produces far less carbon dioxide than regular diesel, it also produces more nitrogen oxide. The U.S. Biodiesel Board says the nitrogen oxide emissions can be mitigated by the use of additives. Biodiesel has also been shown to be less effective in cold weather than petrodiesel.