Biodiesel can result in significant reductions in a number of air pollutants.
In general, reductions are greater as more biodiesel is used, depending on the
type of biodiesel (soybean, rapeseed or animal fats) and on the conventional
diesel used in the blend. Emission impacts of biodiesel do not appear to vary by
engine model year.
- Particulate matter dropped by almost half when using B100 (100% biodiesel),
and by 12 percent when using B20 (20% biodiesel).
- Global warming impact from CO2 dropped by almost 80 percent using
B100.
- Hydrocarbons were reduced by nearly 70 percent using B100 and 21 percent
using B20. Hydrocarbons include many different individual toxic compounds.
- Carbon monoxide decreased 48 percent with B100, 12 percent using
B20.
Biodiesel - Diesel Emissions Comparison (EPA Data)
EPA research shows that biodiesel reduces most emissions from unmodified
diesel engines; reduction depends on the blend and type (source) of biodiesel.
Pure biodiesel offers the greatest reduction benefit, but a 20% blend of
biodiesel (B20) can also substantially improve air quality.
| |
B20 |
B100 |
| Particles (also called particulates) |
-12% |
-47% |
| Total Unburned Hydrocarbons |
-20% |
-67% |
| Carbon Monoxide |
-12% |
-48% |
| Nitrogen Oxides |
+2% to +4% |
+10% |
| Greenhouse gases/global warming |
|
-~80% |
| Sulfates |
-20%* |
-100% |
| Polycyclic Aromatic Hydrocarbons |
-13%** |
-80% |
* Estimated from B100 result;
**Average reduction across all compounds
measured
Advantages
- Renewable
Diesel comes from petroleum, a non-renewable resource whose
supplies are dwindling. Biodiesel is produced from oilseed crops, animal fats
and waste cooking oils.
- Cleaner
Emissions from biodiesel are far cleaner than diesel. Pure
biodiesel is nontoxic and spills biodegrade easily in soil and water.
- Reduces waste
Biodiesel reduces waste oils that otherwise would have to be
disposed.
- Locally produced
Diesel is refined from petroleum oil, much of it is
imported from other countries. Biodiesel can be grown and produced in Oregon,
supporting local farmers and local economies.
- Energy efficient
It takes energy to produce fuels like diesel and
biodiesel. A life cycle analysis of diesel conducted by the US Department of
Energy and US Department of Agriculture shows that it takes more energy to
drill, transport and refine diesel than it produces when combusted. Petroleum
diesel use results in a net energy loss of 19.5%. Biodiesel produces 3.2 units
of fuel for every unit of energy consumed throughout its life cycle, creating a
net energy gain of 220%.
- Easy to use
Biodiesel can be used with current fueling infrastructure and
in all diesel vehicles with few or no engine modifications.
Disadvantages
- Cold weather.
Some users report problems getting biodiesel to "flow" in
close to freezing temperatures.
- There is a slight increase (2-4% depending on the blend) in NOx (forms
smog). Researchers are working on additives to address the problem.
Solvent properties
Solvent properties of higher biodiesel blends can
either be an advantage, as an additive to lower sulfur conventional diesel for
biodiesel's lubricity, or a disadvantage as higher biodiesel blends may cause
premature wear of natural rubber parts such as engine seals and hoses and clog
fuel filters.