Biodiesel and its active role to good health a breath of fresh air

The US Department of Energy (DOE) and US Department of Agriculture (USDA) have published the results of the Biodiesel Lifecycle Inventory Study. The study compared findings for a comprehensive 'cradle to grave' inventory of materials used; energy resources consumed; and air, water and solid waste emissions generated by petroleum diesel fuels and biodiesel to compare the total 'lifecycle' costs and benefits of each of the fuels.

This three and a half-year study followed US Environmental Protection Agency (EPA) and private industry approved protocols for conducting this type of research.

The study was designed to provide policy makers with comparative information that they could use to formulate appropriate policies on biodiesel. The major findings of the study are:

On the total energy efficiency ratio (i.e., total fuel energy/total energy used in production, manufacture, transportation and distribution) the report notes: "Biodiesel and petroleum diesel have very similar energy efficiencies."

The total fossil energy efficiency ratio for diesel fuel and biodiesel (i.e. total fuel energy/total fossil energy used in production, manufacture, transportation and distribution) shows that biodiesel is four times as efficient as diesel fuel in using fossil energy - 3.215 for biodiesel vs 0.8337% for diesel.

The study notes: "In terms of effective use of fossil energy resources, biodiesel yields around 3.2 units of fuel product for every unit of fossil energy consumed in the lifecycle. By contrast, petroleum diesel's lifecycle yields only 0.83 units of fuel product per unit of fossil energy consumed.

"Such measures confirm the 'renewable' nature of biodiesel." The report also notes: "On the basis of fossil energy inputs, biodiesel enhances the effective utilisation of this finite energy source."

The overall lifecycle emissions of carbon dioxide, a major greenhouse gas, from biodiesel are 78% lower than the overall carbon dioxide emissions from petroleum diesel. "The reduction is a direct result of carbon recycling in soybean plants," the study notes.

The overall lifecycle emissions of carbon monoxide, a poisonous gas and a contributing factor in the localised formation of smog and ozone, from biodiesel are 35% lower than overall carbon monoxide emissions from diesel. Biodiesel also reduces bus tailpipe emissions of carbon monoxide by 46%. The study observes: "Biodiesel could, therefore, be an effective tool for mitigating CO."

The overall lifecycle emissions of particulate matter, recognised as a contributing factor in respiratory disease, from biodiesel are 32% lower than overall particulate matter emissions from diesel. Bus tailpipe emissions of PM10 are 68% lower for biodiesel compared to petroleum diesel. The study notes: "PM10 emitted from mobile sources is a major EPA target because of its role in respiratory disease. Urban areas represent the greatest risk in terms of numbers of people exposed and level of PM10 present.

"Use of biodiesel in urban buses is potentially a viable option for controlling both lifecycle emissions of total particulate matter and tailpipe emission of PM10."

The study also finds that biodiesel reduces the total amount of particulate matter soot in bus tailpipe exhaust by 83.6%. Soot is the heavy black smoke portion of the exhaust that is essentially 100% carbon that forms as a result of pyroysis reactions during fuel combustion.

The study notes there is research confirming the relationship between exposure to diesel soot and cancerous growths. Beyond the potential public health benefit from substantially reduced soot emissions, the study also notes: "There is an aesthetic benefit associated with significantly less visible smoke observed from the tailpipe. For urban bus operators, this translates into improved public relations."

The overall lifecycle emissions of sulphur oxides, major components of acid rain, from biodiesel are 8% lower than overall sulphur oxides emissions from diesel. Biodiesel completely eliminates emissions of sulphur oxides from bus tailpipe emissions. The study notes: "Biodiesel can eliminate sulphur oxides emissions because it is sulphur free."

The overall lifecycle emissions of methane, one of the most potent greenhouse gases, from biodiesel are almost 3.0% lower than overall methane emissions from diesel. The study notes: "Though the reductions achieved with biodiesel are small, they could be significant when estimated on the basis of its 'CO2 equivalent'-warming potential."

The bus tailpipe emissions of hydrocarbons, a contributing factor in the localised formation of smog and ozone, are 37% lower for biodiesel than diesel fuel. The fact that biodiesel's hydrocarbon emissions at the tailpipe are lower means that the biodiesel life cycle has beneficial effects on urban area pollution.

The overall life cycle production of wastewater from biodiesel is 79.0% lower than overall production of wastewater from diesel. The study notes: "Petroleum diesel generates roughly five times as much wastewater flow as biodiesel."

The overall lifecycle production of hazardous solid wastes from biodiesel is 96% lower than overall production of hazardous solid wastes from diesel.