DIESEL

WHAT IS DIESEL AND HOW IT WORKS

Petroleum fuel, or crude oil, is naturally found in the Earth. When crude oil is refined at refineries, it can be separated into several different kinds of fuels, including gasoline, jet fuel, kerosene and, of course, diesel.

If you have ever compared diesel fuel and gasoline, you know that they are different. They certainly smell different. Diesel fuel is heavier and oilier. Diesel fuel evaporates much more slowly than gasoline -- its boiling point is actually higher than the boiling point of water. You will often hear diesel fuel referred to as "diesel oil" because it is so oily.

Diesel fuel evaporates more slowly because it is heavier. It contains more carbon atoms in longer chains than gasoline does (gasoline is typically C9H20, while diesel fuel is typically C14H30). It takes less refining to create diesel fuel, which is why it used to be cheaper than gasoline. Since 2004, however, demand for diesel has risen for several reasons, including increased industrialization and construction in China and the U.S. [source: Energy Information Administration].

Diesel fuel has a higher energy density than gasoline. On average, 1 gallon (3.8 L) of diesel fuel contains approximately 155x10⁶ joules (147,000 BTU), while 1 gallon of gasoline contains 132x10⁶ joules (125,000 BTU). This, combined with the improved efficiency of diesel engines, explains why diesel engines get better mileage than equivalent gasoline engines.

Diesel fuel is used to power a wide variety of vehicles and operations. It of course fuels the diesel trucks you see lumbering down the highway, but it also helps move boats, school buses, city buses, trains, cranes, farming equipment and various emergency response vehicles and power generators. Think about how important diesel is to the economy -- without its high efficiency, both the construction industry and farming businesses would suffer immensely from investments in fuels with low power and efficiency. About 94 percent of freight -- whether it's shipped in trucks, trains or boats -- relys on diesel.

In terms of the environment, diesel has some pros and cons. The pros -- diesel emits very small amounts of carbon monoxide, hydrocarbons and carbon dioxide, emissions that lead to global warming. The cons -- high amounts of nitrogen compounds and particulate matter (soot) are released from burning diesel fuel, which lead to acid rain, smog and poor health conditions. On the next page we'll look at some recent improvements made in these areas.

Chemical composition

Diesel is immiscible with water

Petroleum-derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffins including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes).^[6] The average chemical formula for common diesel fuel is C₁₂H₂₃, ranging from approx. C₁₀H₂₀ to C₁₅H_28.

_EXAMPLE

_{DIESEL CAR OF THE YEAR 2007}merc DIESEL CAR OF THE YEAR 2005 jaguar

BIO DEISEL

WHAT IS BIO DIESEL AND HOW IT WORKS

Biodiesel refers to a non-petroleum-based diesel fuel consisting of short chain alkyl (methyl or ethyl) esters, typically made by transesterification of vegetable oils or animal fats, which can be used (alone, or blended with conventional petrodiesel) in unmodified diesel-engine vehicles. Biodiesel is distinguished from the straight vegetable oil (SVO) (aka "waste vegetable oil", "WVO", "unwashed biodiesel", "pure plant oil", "PPO") used (alone, or blended) as fuels in some converted diesel vehicles. "Biodiesel" is standardized as methyl ester and other non-diesel fuels of biological origin are not included.^[1]

Biodiesel is biodegradable and non-toxic, and typically produces about 60% less net-lifecycle carbon dioxide emissions, as it is itself produced from atmospheric carbon dioxide via photosynthesis in plants. Its emissions of smog forming hydrocarbon are 67% less, although the Nitrogen Oxide emissions are about 10% greater than those from petroleum-based diesel.^[2][3] Net-lifetime carbon dioxide emissions can actually differ widely between fuels depending upon production methods of the source vegetable oils and processing methods employed in their creation. It is therefore debatable as to the extent that biodiesel reduces total carbon dioxide emissions currently contributing to anthropogenic global warming compared to those from petroleum-based diesel.

Biodiesel is safe and can be used in diesel engines with little or no modification needed. Although biodiesel can be used in its pure form, it is usually blended with standard diesel fuel. Blends are indicated by the abbreviation Bxx, where xx is the percentage of biodiesel in the mixture. For example, the most common blend is B20, or 20 percent biodiesel to 80 percent standard. So, B100 refers to pure biodiesel.

Biodiesel isn't just a catch-all term, however. There is also a formal, technical definition that is recognized by ASTM International (known formerly as the American Society for Testing and Materials), the organization responsible for providing industry standards. According to the National Biodiesel Board (NBB), the technical definition of biodiesel is as follows.

a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, designated B100, and meeting the requirements of ASTM D 6751.

EXAMPLE
A BUS THAT RUNS ON BIO DIESEL