Reusing materials before discarding them is the most efficient and eco-friendly option. With WVO the oil was formly used, for example in a fast food restaurant, to fry food. Hence the joke that biodiesel cars smell like french fries. WVO is easier for the general public to use at home, thus making the conversion to this cleaner fuel a no-brainer. Additionally, petroleum diesel remains an option if biodiesel is not readily available.
One other point to keep in mind is that biofuels often do more harm than good. This is because to grow a biofuel crop, it requires changing land use from something like a forest, for example. Changing land use from a forest or grassland to agricultural land decreases the amount of carbon dioxide that's being absorbed, and land use change is actually the #1 largest contributor to human greenhouse gas emssions.
Biofuels involve the transformation of biomass energy into an equivalent form that is readily usable by an internal combustion engine. There are two main sources for biofuels: sugars/starches and plant oils. Biofuel derived from sugars/starches involves fermentation and distillation to covert the biomass into alcohols, such as ethanol. Direct oil recovery from plants, such as soybean or algae, is more efficient and results in an end product that is readily usable by diesel engines with a minimum of chemical processing required to meet fleet standards. In the United States, most of our biofuels are obtained from corn and soybeans at present; and in the near future, switchgrass. EROI is an important measure of positive, or negative, benefit for a given biofuel. Ethanol has an EROI of 0.9-1.3, while that of Soybean Biodiesel is 3.2. The low EROI, especially of ethanol from corn, has sparked a debate as to the utility of using food for fuel.
[Image source: Lisa Stiffler, Seattlepi.com, Bio-debatable: Food vs. fuel, May 3, 2008]
Another promising biofuel option for the future is oil from algae. Shell recently announced that it is partnering with HR Biopetroluem to create a facility on a Hawaiian island that will grow microalgae to be used as biofuel. Algae fuel is classified as a third-generation biofuel. Additionally, due to the high-density yield of algae biofuels, one acre of land is able to produce 100-420 Mb of biodiesel.
The most common alternative vehicle currently in productions is the gasoline/electric hybrid, of which the Honda Civic hybrid and Toyota Prius are two examples. Gasoline/electric hybrid vehicles have an internal combustion engine and the addition of an electric motor coupled to a rechargeable battery. The electric motor can provide primary propulsion for the engine and provide an assist to the engine during acceleration. The battery is recharged via regenerative braking, which recovers some energy normally lost as waste heat during the deceleration and braking. Since gasoline/electric hybrid vehicles are not recharged from the power grid, they are not classified as electric vehicles (EV). However, many hobbyists have added the ability to recharge the hybrid battery through the power grid, thus creating a partial-EV vehicle. Manufacturers may start offering this as on option on future hybrid cars (see the Chevy Volt, below).
Natural gas powered cars are another relatively eco-friendly option. The Honda Civic GX is the only natural gas car currently commercially available, and it has limited availability only in California. The Civic GX also requires that the vehicle owner lease the refueling system, which hooks up to a home natural gas line. The limited availability of natural gas vehicles, added expense of leasing the refueling equipment, and inconvenience of only being able to refuel at home limits the popularity of these vehicles.
In the near future, plug-in hybrids and fully electric cars will become available. In the distant future, hydrogen cars may also become an option. The Chevy Volt concept car has a plug-in hybrid version and a hydrogen fuel cell version. However, due to the high cost of fuel cells compared to newer lower cost lithium batteries, General Motors has publically suggested that the Volt will not be using fuel cells in any near term production vehicles.
Plug-in hybrids and electric vehicles produce lower emissions than gas cars and regular gas/electric hybrids, even with the current US power grid which is composed primarily of coal power. Studies have shown that because of the efficiency of electric motors and large power plants, plug-in hybrids and EVs decrease overall carbon emissions even when most of their power comes from coal burning power plants. Electric vehicles also provide the option of making their associated emissions as low as desired by recharging them with renewable energy.
[Image source: David Talbot, Technology Review, Plug-In Hybrids, March 2008]
So are gas-hybrid electric cars really environmentally friendly?
Pros
- Reduced greenhouse gas emissions
- The ability to continue driving
- Reduced noise pollution from automobiles
Cons
- Replacing older technology (increasing waste)
- Continued reliance on fossil fuels
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