U.S. Green Home ®
April 2008
The Winners of the Shell Eco-marathon
Combustion Engine = 2,843.4 mpg
Mater Dei
Diesel Engine = 304.5 mpg
The College of the Redwoods in
LPG Engine = 163.5 mpg
Schurr
There are several types of green technologies that are utilized in vehicles today. These include Hybrid Electric, Ethanol, Natural Gas, Diesel and Biodiesel. Each have their own benefits and drawbacks, but all are more environmentally-friendly than the standard gasoline vehicle.
Hybrid Electric [1]
In the EPA fuel economy rating system, the top three vehicles are currently hybrids. During the oil crises in the 1970s and 1980s, companies began experimenting with hybrid technology. However, when the crises were over, the hybrid technology was largely abandoned until the early 1990s with
The parallel hybrid configuration contains an internal combustion engine that serves as a primary power source, with an electric motor that supplies additional power (serving as a supplement but never powers the car on its own). Examples of vehicles using this configuration are the Insight, Accord Hybrid and 2003-05 Civic Hybrid.
The series hybrid configuration uses an internal combustion engine solely to generate electricity for powering the drive motors and not the propulsion of the vehicle. This technology is not currently used in any production hybrid vehicle.
Most hybrids (including those from
Ethanol [2]
In 1991 another green technology appeared: Flex-fuel (Flexible-fuel) vehicles. A flex-fuel (FFV) is a vehicle that has the ability to run on either gasoline or E85 (a blend of 85% ethanol and 15% gasoline). Many cars are made to operate on both fuel types, but the vast majority of drivers don’t even know they have a flex-fuel vehicle.
Ethanol is manufactured from a number of sources, but corn is the primary source ( a bushel of corn can be processed into at least 2.7 gallons of ethanol). The benefits of using ethanol include a decreased reliance on oil and reduced environmental pollution (less greenhouse gas emissions and lower carbon monoxide levels). Ethanol is 100% renewable and non-carcinogenic, and 100% of the production is domestic. E85 also has a higher octane rating than gasoline, so it burns more fully. However, there are drawbacks. Ethanol has a lower energy content than gasoline – it is estimated that E85 reduces gas mileage 21 to 31% in city driving and 20 to 34% on the highway. E85 also generally costs slightly more than the current rate of gasoline and is only sold at about 640 filling stations nationwide (most of which are in the upper
Compressed natural gas (CNG) is cleaner and less expensive than gasoline and is generally produced domestically. Natural gas (which is 90% methane) also has a higher octane rating than gasoline and is therefore more efficient. Although natural gas burns cleanly – producing very few pollutants that cause smog - they also tend to have more greenhouse gas emissions than hybrids. Currently only one tenth of 1% of natural gas is used in vehicles and it is estimated that there are only 130,000 CNG vehicles in the
Diesel vehicles are known as “compression ignition engines” with a combustion cycle that is different than a gasoline engine. Diesels operate more efficiently than gasoline vehicles and a gallon of diesel fuel contains almost 10% more energy than a gallon of gasoline. Although diesels produce fewer greenhouse gas emissions than gasoline vehicles, they emit more particulate matter and NOx, which contributes to smog and acid rain. For this reason diesel vehicles are not sold in states with the strictest emissions requirements (
Biodiesel [5]
Biodiesel is an alternative fuel for diesel engines that is made from plant oils or animal fats rather than petroleum (in the
State Incentives for Green Vehicles
* In
Currently,
* In
As of
Federal Tax Credits for Green Vehicles:
As of
http://www.irs.gov/newsroom/article/0,,id=157557,00.html
