Alternate vehicle technologies- A way to save the Earth

Currently in the world, we are facing quite a few problems - global warming, environmental pollution, depletion of resources etc. One of the main culprits here , which connects all these problems is the current technologies used in automobiles, and there are a lot of automobiles on the road . These use internal combustion engine technology which use petrol or diesel leading to depletion of resources. They also emit a lot of smoke which cause pollution. One of the components of these vehicle emissions is CO2 which is a major greenhouse gas. Thus any way you look at it , the current technology needs to be replaced as soon as possible. Its high time newer and cleaner propulsion technologies are developed.
The automobile industry has been experimenting heavily on alternate technology such as fuel cells, compressed air, hybrid and fully electric vehicles. The industry as a whole have arrived at a consensus that battery powered propulsion or electric vehicles are the future. High density Lithium ion batteries have been developed , which give better mileage between charges and are more reliable. The problem with these electric vehicles is that they are expensive and are not viable for mass use at the current prices.
So at the current level of tchnologies, the most viable alternatives to the old internal combustion engine are hybrid vehicles which use the internal combustion engine coupled with an electric propulsion system. The problem with hybrid electric vehicles is that even these cause tailpipe emissions as they use the internal combustion engine. The goal to be achieved is zero emissions.
While the hybrid or electric vehicles will enter the market, their rate of introduction will be slow. One of the reasons is the prohibitively high cost of cars with these technologies. Another reason is the introduction of cars with improved and more efficient engines. Low emission levels have been achieved at substantially lower cost. So customers would rather buy these cheaper cars than expensive hybrids. But internal combustion technology is on the way out and in about 10years or so will be completely phased out in favour of cleaner hybrid or electric vehicles