Environmental impact of biodiesel

The environmental impact of biodiesel is diverse.

Contents 1 Greenhouse gas emissions 2 Deforestation 3 Pollution 4 Biodegradation 5 See also 6 References

Greenhouse gas emissions

An often mentioned incentive for using biodiesel is its capacity to lower greenhouse gas emissions compared to those of fossil fuels. If this is true or not depends on many factors. Especially the effects from land use change have potential to cause even more emissions than what would be caused by using fossil fuels alone.^[3]

Carbon dioxide is one of the major greenhouse gases. Although the burning of biodiesel produces carbon dioxide emissions similar to those from ordinary fossil fuels, the plant feedstock used in the production absorbs carbon dioxide from the atmosphere when it grows. Plants absorb carbon dioxide through a process known as photosynthesis which allows it to store energy from sunlight in the form of sugars and starches. After the biomass is converted into biodiesel and burnt as fuel the energy and carbon is released again. Some of that energy can be used to power an engine while the carbon dioxide is released back into the atmosphere.

When considering the total amount of greenhouse gas emissions it is therefore important to consider the whole production process and what indirect effects such production might cause. The effect on carbon dioxide emissions is highly dependent on production methods and the type of feedstock used. Calculating the carbon intensity of biofuels is a complex and inexact process, and is highly dependent on the assumptions made in the calculation. A calculation usually includes:

• Emissions from growing the feedstock (e.g. Petrochemicals used in fertilizers)
• Emissions from transporting the feedstock to the factory
• Emissions from processing the feedstock into biodiesel

Other factors can be very significant but are sometimes not considered. These include:

• Emissions from the change in land use of the area where the fuel feedstock is grown.
• Emissions from transportation of the biodiesel from the factory to its point of use
• The efficiency of the biodiesel compared with standard diesel
• The amount of Carbon Dioxide produced at the tail pipe. (Biodiesel can produce 4.7% more)
• The benefits due to the production of useful by-products, such as cattle feed or glycerine

If land use change is not considered and assuming today's production methods, biodiesel from rapeseed and sunflower oil produce 45%-65% lower greenhouse gas emissions than petrodiesel.^[4][5][6][7] However, there is ongoing research to improve the efficiency of the production process.^[4][6] Biodiesel produced from used cooking oil or other waste fat could reduce CO₂ emissions by as much as 85%.^[1] As long as the feedstock is grown on existing cropland, land use change has little or no effect on greenhouse gas emissions. However, there is concern that increased feedstock production directly affects the rate of deforestation. Such clearcutting cause carbon stored in the forest, soil and peat layers to be released. The amount of greenhouse gas emissions from deforestation is so large that the benefits from lower emissions (caused by biodiesel use alone) would be negligible for hundreds of years.^[3][1] Biofuel produced from feedstocks such as palm oil could therefore cause much higher carbon dioxide emissions than some types of fossil fuels.^[8]

Deforestation

If deforestation, and monoculture farming techniques were used to grow biofuel crops, biodiesel may become a serious threat to the environment:^[9][10]

• Increasing the emission of climate change gases rather than helping curb them^[3]
• Damaging ecosystems and biodiversity^[11]
• Exacerbating social conflict^[12]

The demand for cheap oil from the tropical regions is of rising concern. In order to increase production, the amount of arable land is being expanded at the cost of tropical rainforest.^[8][13] Feedstock oils produced in Asia, South America and Africa are currently less expensive than those produced in Europe and North America suggesting that imports to these wealthier nations are likely to increase in the future.^[8][13][11]

In the Philippines and Indonesia forest clearing is already underway for the production of palm oil.^[8] Indigenous people are forced to move and their livelihood is destroyed when forest is cleared to make room for oil palm plantations.^[12] In some areas the use of pesticides for biofuel crops are disrupting clean water supplies,^[14] and the loss of habitat caused by deforestation is threatening many species of unique plants and animals. One example is the already-shrinking populations of orangutans on the Indonesian islands of Borneo and Sumatra, which face extinction if deforestation continue at its projected rate.^{[11][15][16][17]}

This should be compared with the ecological degradation associated with oil production. For instance, oil production from the Athabasca Oil Sands in Canada has required the clear cutting of vast swathes of the Boreal forest to create open pit mines, and the consumption of vast amounts of water and natural gas. Another example is the oil production in the Niger Delta, which has destroyed fisheries and mangrove forests, and led to health problems among the local population.

Pollution

In the United States, biodiesel is the only alternative fuel to have successfully completed the Health Effects Testing requirements (Tier I and Tier II) of the Clean Air Act (1990).

Biodiesel can reduce the direct tailpipe-emission of particulates, small particles of solid combustion products, on vehicles with particulate filters by as much as 20 percent compared with low-sulfur (< 50 ppm) diesel. Particulate emissions as the result of production are reduced by around 50 percent compared with fossil-sourced diesel. (Beer et al., 2004). Biodiesel has a higher cetane rating than petrodiesel, which can improve performance and clean up emissions compared to crude petro-diesel (with cetane lower than 40). Biodiesel contains fewer aromatic hydrocarbons: benzofluoranthene: 56% reduction; Benzopyrenes: 71% reduction.

Biodegradation

A University of Idaho study compared biodegradation rates of biodiesel, neat vegetable oils, biodiesel and petroleum diesel blends, and neat 2-D diesel fuel. Using low concentrations of the product to be degraded (10 ppm) in nutrient and sewage sludge amended solutions, they demonstrated that biodiesel degraded at the same rate as a dextrose control and 5 times as quickly as petroleum diesel over a period of 28 days, and that biodiesel blends doubled the rate of petroleum diesel degradation through co-metabolism.^[18]

See also

• Sustainable biofuel
• Issues relating to biofuels

References

Human impact on the environment Causes Agriculture Fishing · Irrigation · Meat production · Palm oil Energy industry Biodiesel · Coal mining and burning · Electricity generation · Nuclear power · Oil shale industry · Petroleum · Reservoirs · Wind power Manufactured products Cleaning agents · Nanotechnology · Paint · Paper · Pesticides · Pharmaceuticals and personal care products Transport Aviation · Roads · Shipping Other Mining · War Effects Coral reefs · Nitrogen cycle