Alternative Energy

Can alternative energy successfully replace fossil fuels?
How soon should alternative energy be implemented?
What could be used as a successful source of alternative energy?

I believe that even though there are many different sources out there for alternative energy, you only have to look at the amount of machinery which this world uses to see how hard it would be to replace it. Sure, it'd be possible. However, people are very unlikely to change the way in which they've been doing something or countless years in order to "benefit" the planet, it'd have to become mandatory with our resources having been run dry. It's hard enough to get people to recycle, never mind switching our energy supply.

There are MANY other alternative energy sources out there. The real problem we have to ask is, how do we change the CONSUMPTION of the fuels we already use? It is difficult to change our machinery that has been so dependable throughout the years.

The problem is that our whole infrastructure would need to be changed. It'll be a rough change once we realize it will need to be made.
What are your opinions on the whole technology being suppressed due to oil companies?

Can alternative energy successfully replace fossil fuels? Such as vegetable juices, etc? I mean, maybe in due time.. but not yet. It is just way too under developed.
How soon should alternative energy be implemented? It should be implement ASAP, but not all at once.
What could be used as a successful source of alternative energy? There have been talks of vegetable juices I believe. Other than that, I've not done much research.