Pure biodiesel, B100, costs roughly a dollar more per gallon than petrodiesel.
Biodiesel is less suitable for use in low temperatures, than petrodiesel. Need to heat storage tanks in colder climates to prevent the fuel from gelling
The energy content per gallon of biodiesel is approximately 11 percent lower than that of petroleum diesel. Vehicles running on biodiesel are therefore expected to achieve about 10% fewer miles per gallon of fuel than petrodiesel.
During photosynthesis, photosynthetic microbes such as algae and cyanobacteria (sometimes referred to as blue-green algae) capture carbon dioxide and sunlight and convert it into oxygen, biomass, and fat.
Photosynthetic microbes also store plenty of fat, which forms the basis for biofuel.
They also grow quickly—some forms double in just 12 hours, whereas grasses and other large plants can take weeks or months to do so.
Because of the gaseous nature of this fuel, it must be stored onboard a vehicle in either a compressed natural gas (CNG), a replacement for gasoline, or a liquefied natural gas (LNG), a replacement for diesel fuel.
The natural gas is be stored in high pressure cylinders usually located in the vehicle's trunk.
One of the biggest complaints about NGVs is that they aren't as roomy as gasoline cars. This is because NGVs have to give up cargo and trunk space to accommodate the fuel storage cylinders.
Not only that, these cylinders can be expensive to design and build -- a contributing factor to the higher overall costs of a NGV compared to a gasoline-powered car. NGVs tend to cost $3500 to $6000 more than gasoline powered ones
Another drawback is the limited driving range of NGVs, which is typically about half that of a gasoline-powered vehicle.
There are only about 1,300 NGV fueling stations in the United States and they are located in only certain parts of the U.S.
If a dedicated NGV ran out of fuel on the road, it would have to be towed to the owner's home or to a local natural gas refueling station, which might be harder to find than a "regular" gas station.
Ultimately natural gas, like gasoline, is a fossil fuel and cannot be considered a renewable resource. While natural gas reserves in the United States are still considerable, they are not inexhaustible.
Some predict that there are enough natural gas reserves remaining to last another 67.1 years, assuming that the 2003 level of production continues.
The electricity used to recharge EV batteries is generated mainly by burning fossil fuels.
According to the Electric Vehicle Association of Canada, even EVs recharged from coal-powered electric generators cut carbon emission roughly in half.
EVs recharged from cleaner forms of electrical power generation, such as nuclear plants, can reduce carbon emissions to less than one percent of those currently produced by internal combustion engines.
Some varieties of HEVs use their internal combustion engine to generate electricity by spinning an electrical generator (this combination is known as a motor-generator), to either recharge their batteries or to directly power the electric drive motors.
Many HEVs reduce idle emissions by shutting down the ICE at idle and restarting it when needed; this is known as a start-stop system.