|
demand for farmer's products and provides increased employment
opportunities. However, it has been argued that fuel production from
agricultural crops reduces the amount of such crops available for feeding.
Consequently, to avoid dependence on food-based feedstocks, researches are continuously being conducted to identify new
feedstocks (plants) that are dedicatedly planted for fuel production.
Some of the plants that are planted specifically for the
generation of
ethanol and methanol,
include:
switchgrass, hemp,
hybrid
willow,
hybrid poplar (cottonwoods)
and sugarcane.
Ethanol is blended with gasoline to produce a fuel called "gasohol".
Gasohol can be used in gasoline-powered vehicles manufactured since the
1980's. Similar to Biodiesel blend, ethanol
blend is represented as Exx, where xx is the percentage of the ethanol in
the gasohol. For instance, a 10% ethanol to 90 % gasoline blend is
represented as E10; 15% ethanol to 85% gasoline blend as E15 etc.
Most gasoline-powered vehicles can run on a E10 blend. This blend is
already available in several service stations in North America. Some
vehicles are specially manufactured to operate on an E85 ethanol blend.
The 15 percent gasoline is needed to assist in engine starting because
pure ethanol is difficult to ignite in cold weather. This
E-85 blend cannot be used in standard gasoline vehicles, however
vehicles designed to run with a high ethanol blend can also operate using
gasoline when necessary.
Ethanol burns more cleanly and completely than gasoline or diesel fuel.
Gasohol seems to have slightly lower energy than gasoline which is
compensated for by its higher combustion efficiency. E10 blend can be used
directly in gasoline engines to produce same level of service without
modifications to the gasoline engine. For higher blends (e.g. E85), larger
petroleum tanks are designed and larger quantity of gasohol is required to
produce similar service levels as the gasoline fuel.
Ethanol is renewable and is better for the environment. Though the
conversion of biomass (feedstocks) produces GHG, on a Life Cycle basis,
Ethanol reduces greenhouse gas (GHG)
emissions. This is so because less emissions are produced during gasohol
usage and the plants used to produce the ethanol served as carbon sink
during their days of growing. Modifications are needed to an engine's
intake valves, fuel-injection system and ignition system. Certain vehicle
components must be made of alcohol-resistant materials (zinc, lead,
magnesium, aluminum and certain plastics and rubbers that are commonly
used in certain vehicles can be broken down by alcohol). For example,
flex-fuel vehicles require stainless steel storage tanks and fuel lines.
To overcome the problem of lower energy content, manufacturers have
equipped
E-85 vehicles with
larger fuel tanks.
Ethanol
is produced in
large heated tanks called digesters. Plant materials and chemicals or
yeasts are added to the
digester. The process converts cellulose in the plant
materials into sugars and then the sugars are converted into alcohol
through fermentation.
Other resources:
Ethanol.org and
Natural Resources
Canada – Energy Sector
|
