14% of the world's greenhouse gas emissions come from transportation. When public transit or bicycling is either not available, or simply not practical; then more environmental cars are becoming more and more available every year.
Like appliances, e-cars are all about finding the least harmful option within your budget. There has, however, been some debate on whether or not the rechargeable lithium-ion batteries in electric cars (e-cars) are actually all that environmentally friendly. Scientists have researched the full life cycle of these batteries, including manufacturing, maintenance, and disposal. Their findings discovered that, at most, only 15% of the environmental burden of an e-car comes from this battery. The real harm in these types of cars are the rechargeable stations, actually! These are usually atomic, coal-fired, and hydroelectric power stations and generate 3-times the pollution than the batteries do. However, a standard, gasoline-fueled car would have to get more than 70 mpg in order to compete with the environmental benefits of electric cars.
Biofuels, or fuel derived from plants, are another popular option that has actually been around for a while! On the surface, this seems like a wonderful alternative to fossil fuels; it's made out of plants we can grow and these plants grown for biofuels filter out carbon dioxide through photosynthesis so it's even better! Wrong. Converting these plants to produce the fuel that can actually be used requires vast amounts of energy that comes from (you guessed it) fossil fuels. Furthermore, many times these fuels are derived from palm oil and sugarcane and harvesting these can be devastating to rainforests and endangered species. The other side of the argument is whether or not we should use agricultural land space that could otherwise be used to feed our world population. Though the future of biofuels might be more promising when grasses or algae are used instead, they are currently not as eco-friendly as it appears.
Hybrid electric vehicles (HEVs) combines a conventional internal combustion engine with an electric propulsion system. So, it still uses fossil fuel-gasoline, but it burns this with the electric motor so as to lower the gas emissions. Pretty nifty, actually, and the most popular environmental car on the market as it saves a lot of gas money, to boot! More advanced versions have plug-in features for their batteries, similar to electric cars, that allows the battery to be used for longer periods before it switches over to gasoline. These cars also offer an "idle-off" feature that turns the engine off when it's idle, like at a stop light, while still providing energy for air conditioning, radio, and accessories- and it restarts when you move. Furthermore, instead of friction brakes like conventional cars that dissipate the vehicle's kinetic energy as heat, HEVs use regenerative braking that captures that energy to be stored in the battery.
Hydrogen [fuel cell] electric vehicles use hydrogen gas to power an electric motor. This car is the newbie to the American market and is very similar to standard plugin e-cars, except it uses hydrogen and oxygen for power at hydrogen-specific stations. It also has idle-off features and regenerative braking like the HEV. The real difference between the hydrogen electric car and a standard electric car, is that it can fully charge in much less time (less than 10 minutes) and can run for as long as a conventional gas-guzzling car can, before having to recharge. Its emissions are water vapor. Which is preeetty clean! Though producing the hydrogen itself can lead to pollution, it can still cut gas emissions by 30% than conventional cars with even the dirtiest sources of hydrogen- future models will be even better. The only current downside to this car is not having enough hydrogen stations available in the US, currently.