One World BUSINESS OF GREEN Biodiesel the greener fuel full of problems.

Financial Chronicle, Delhi,20th July 2010


Switching to biodiesel on a large scale requires considerable use of our arable area

WHAT would you say a vehicle fuel which is do mestically produced, ren ewable, and produces dr amatically less greenhouse gas than petroleum-based fuels? These are exactly the characteristics of biodiesel. Biodiesel is made from processed vegetable or plant oil, and can be used in diesel engines on its own, or blended with petroleum-based fuel. In Berkeley, California, the pumps at "Biofuel Oasis" dispense diesel made from used cooking oil.

While one might think that biodiesel has its myriad advantages and benefits, there is a flip side as well.

The main problem The main problem with biodiesel is it is the more expensive fuel. The most common method of producing biodiesel is to react animal fat or vegetable oil with methanol in the presence of sodium hydroxide (a base, known as lye or caustic soda). This reaction is a base-catalyzed transesterification that produces methyl esters and glycerin. If ethanol is substituted for methanol, ethyl esters and glycerin are produced. Methanol is preferred, because it is less expensive than ethanol. In the US, the Energy Information Administration (EIA) estimates that the feedstock cost of soybean oil or yellow grease is the largest single component of biodiesel production costs. According to EIA, biodiesel from yellow grease is closer to being cost-competitive with petroleum diesel than is biodiesel from soybean oil, but the available supply of yellow grease will probably limit its use for biodiesel production to 100 million gallons per year (6,523 barrels per day) or less in the US. Unless soybean oil prices decline dramatically, it does not appear that biodiesel can be produced in large quantities at a cost that is competitive with petroleum diesel.

The second issue is related to land use. Biodiesel is produced from agricultural crops and involves additional land use. As land area is taken up and various agricultural inputs with their environmental effects are inevitable. Switching to biodiesel on a large scale requires considerable use of our arable area. Even modest usages of biodiesel would consume almost all cropland in some countries in Europe. For example, in the UK the main crop for producing biodiesel would be from rapeseed.

Assuming that all of the 644,000 hectares of UK is set aside as land to produce biodiesel from rapeseed, then, with an average yield of 3 tonne per hectare, the oilseed yield would be about 1.9 million tonne per year. There is generally a 40 per cent oil content available by mass within the seed, thus, the 1.9 million tonne per year of oilseed will produce 0.77 million tonne of oil yield per year. Furthermore, there is around a 97 per cent conversion from the raw vegetable oil to the biodiesel during the transesterification process. Thus, there will be 0.74 m tons of biodiesel per year.This amount to about 0.85 billion liters of biodiesel. As per Planet Energy, in 2002 the UK released for consumption about 20 billion litres of diesel. Thus, by volume, the biodiesel produced from the set-aside land could displace only about 4.3 per cent of this diesel. This is a very small fraction of the total land used to produce biodiesel.

The third issue is that it gives out more nitrogen oxide emissions than other petroleum-based hydrocarbons.According to, LG Schumacher at the department of agricultural engineering at the University of Missouri, "Fuelling with biodiesel/diesel fuel blends reduced particulate matter (PM), total hydrocarbons (THC), and carbon monoxide (CO), while increasing oxides of nitrogen (NOx). Retarded fuel injection timing reduced NOx emissions while maintaining the other emissions reductions." However, latest findings show that nitrogen oxide emissions from biodiesel blends could possibly be reduced by blending with kerosene or Fischer-Tropsch diesel. Within the US, the National Biodiesel Board (NBB), in a study published in 2004 showed, that a reduction in nitrogen oxides emissions from biodiesel is attainable when biodiesel is blended with B20 (for example, 20 per cent biodiesel and 80 per cent diesel). According to Steve Howell, technical director of the NBB, "This is a positive development for the industry as we search for ways to reduce NOx emissions in addition to other benefits."

However, there are other problems with biodiesel. For example, the transportation and storage of biodiesel require special management. Some properties of biodiesel make it undesirable for use at high concentrations. For example, pure biodiesel doesn't flow well at low temperatures, which can cause problems for customers with outdoor storage tanks in colder climates. A related disadvantage is that biodiesel, because of its nature, can't be transported in pipelines. It has to be transported by truck or rail, which increases the cost.

Furthermore, biodiesel is less suitable for use in low temperatures, than petroleum-based diesel. The "cloud point" is the temperature at which a sample of the fuel starts to appear cloudy, indicating that wax crystals have begun to form.At even lower temperatures, the fuel becomes a gel. The "pour point" is the temperature below which the fuel will not flow. As the cloud and pour points for biodiesel are higher than those for petroleum diesel, the performance of biodiesel in cold conditions is markedly worse than that of petroleum diesel.

But there are still other problems.

For example, another disadvantage of biodiesel is that it tends to reduce fuel economy. Energy efficiency is the percentage of the fuel's thermal energy that is delivered as engine output, and biodiesel has shown no significant effect on the energy efficiency of any test engine. The energy content per gallon of biodiesel is approximately 11 per cent lower than that of petroleum-based diesel. Vehicles running on biodiesel are therefore expected to achieve about 10 per cent fewer miles per gallon of fuel than petroleum-based diesel.

Finally, biodiesel has excellent solvent properties as a compound. Hence, any deposits in the filters and in the delivery systems may be dissolved by biodiesel and result in need for replacement of the filters.

What does this all mean for backyard biodiesel makers?

The fact is that biodiesel does happen to be a greener fuel but a 100 per cent biodiesel-run vehicle might be virtually impossible and will suffer equally from a host of problems. People in the community would like to see engine manufacturers and biodiesel makers working together to solve these challenges the fuel currently poses. In the meantime, we'll have to watch which vehicle we fill with our future fuel, biodiesel. The writer is doctoral candidate Carnegie Mellon University, USA and Knowledge Editor, Financial Chronicle