• Made from fresh or used vegetable oils or animal fats
• More completely combusted than regular diesel, producing substantially less carbon dioxide, hydrocarbons, particulates, carbon monoxide
• Virtually no sulfur dioxide; inoffensive odor
• Can be used directly in existing diesel engines, or blended with petroleum diesel fuel in any ratio (usually 20:80)
• Higher lubricity than petroleum diesel can help extend engine life
• Available from domestic crops
• Usually get better mileage and last longer
• Renewable fuel source
• Reduce dependency on foreign oil

• Can slightly raise nitrogen oxide emissions
• Even though biodiesel cars emit less CO2, they still put out some nasty particles and pollutants
• Costs a little more than traditional diesel and significantly more than gasoline
• The higher the vegetable oil content of the biodiesel you use, the more viscous the fuel becomes in cold weather

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Pros:

• Reduce dependency on foreign oil
• Renewable fuel source
• Readily available sources for production
• Burns more completely that gas
• High octane level reduces need for antiknock additives

Cons:

• Increased ozone emissions
• Combustion emits formaldehyde, a highly toxic organic solvent
• Potential damage to fuel system components at concentrations higher than 10% on non-modified vehicles
• Ethanol production uses other fossil fuels during the process
• Contains only 2/3 the energy content compared to gas
• Excessive water concentrations may cause engine stalling or even severe engine damage
• The grain required to fill one 25 gallon (95 litre) fuel tank would feed one person for a year
• The US already uses nearly one-sixth of its grain crop (and over half of all its corn) to produce ethanol for cars, and while this represents only 3% of all fuel sold, it is starting to affect the global prices of wheat and corn, which feed into other food prices

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• Virtually no particulate emissions
• Abundant supply
• Cleanest burning of the fossil fuels
• Traditionally cheaper than gas

• Limited availability of fueling stations
• Only about 3% less carbon dioxide emissions than gas or diesel
• Higher fuel consumption rate
• Higher carbon monoxide and nitrogen oxide emissions
• Fire/explosion hazards associated with storage
• Non-renewable fuel resource

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• Energy content is the highest per unit of weight of any fuel
• The only byproducts are heat and water
• Renewable fuel source
• Reduce dependency on foreign oil

• While hydrogen always exists in conjunction with other elements, such as in water, it must be separated from these elements and is therefore considered an energy carrier, as opposed to an energy source
• Because hydrogen is a gas, it cannot be compressed into a liquid form without intensive cost and energy input
• The technology to produce, store, and transport hydrogen power at a reasonable cost is not yet in place and likely will not be for 10 to 20 years
• It is most commonly separated by a reforming process that uses natural gas and other fossil fuels
• Coal, one of the most feasible hydrogen feedstocks, is a source of major pollution
• Hydrogen fuel cell vehicles are highly cost prohibitive

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• More efficient than gas-powered vehicles because their fuel
  can be harnessed from any source of electricity, which is available
  in most homes and businesses
• Zero emission vehicle
• Reduce dependency on foreign oil
• Quiet operation
• Simplified mechanical construction of drive components
• Significantly lower cost per mile

• Current battery technology limits the distance an electric car can travel before its battery must be recharged
• Because electric cars have not been widely adopted, few public charging stations are in existence
• More expensive because the manufacturer cannot fully recover the cost of the discarded parts
• Electric vehicles are not completely "emission-free". If the electricity used is produced in a coal- or oil-fired generator, this only transfers the emissions from the tailpipe to the power plant.
• They change the composition of the pollution for the worse, by increasing the amount of sulfur oxide (a key cause of acid rain) and ultra-fine soot particles which also have negative health effects

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