President Obama recently proposed a full-scale technological assault on the problem of finding a replacement for petroleum as an energy source. He is criticized on one side for wasting money on blue-sky fantasies by those who believe we have plenty of oil if we had no restrictions on where we could drill. http://article.nationalreview.com/436654/barack-obama-dreamer-in-chief/charles-krauthammer
On the other side he falls in line with people like Bill Gates who have great faith in technology and are calling for greatly increased government funding in this area.
I have less confidence in technology than Bill Gates; I think there is no guarantee that we will find an alternative to oil. Systems theory blogger Jeff Vail has also made the point that transitioning to a new energy source will require additional energy (on top of what we normally use). I.e. making a wind turbine requires a certain amount of energy, making enough of them to supply what we currently get from oil will require a lot of energy. Even if they work as a replacement there will be several years of ramp-up time before they provide much net energy; during this time we will need to use more oil than we normally use at the same time as oil production is declining. This means that we have basically a one-time shot with whatever alternative energy source we focus on. We have to use up the rest of our oil (by using it faster than we normally would) in order to make the transition to the new energy source. If this new source does not work as expected, we have lost our chance to try something else. http://www.jeffvail.net/2009/11/2009-aspo-presentation-renewables-gap.html
Vail is skeptical about the claims for the various alternative energy sources, but points out that even if they are as good as advertised, this is a big risk.
I look at this from a different angle. Even if we could theoretically find a replacement for oil, at some point we need to address the political issue that unlimited expansion is not possible. No matter how good the energy source, there will be some limit to it, at which point we need to accept this and alter our lifestyle accordingly. I think we have hit this limit with petroleum in both its supply and the effect it has on our environment. I don't think we will find a replacement for it. But even if we did, I would like to see us try to be less wasteful in how we live.
My green proposal is this: first put all our efforts into public transportation, using existing technology and restoring existing infrastructure. Get our passenger rail system working again as it worked back in the 1920's. Then convert it to electric rail. Ignore highway maintenance, forget about the car, stop spending money on this very inefficient system of transportation.
Second, provide incentive to thousands of small organic farms. A large use of petroleum is for agricultural fertilizer. Start farming the old fashioned way, put the animals back on the farm and use the manure. Use John Jeavons' techniques of growing the organic matter needed for the soil in the form of high carbon crops like corn and putting it back into the soil. http://www.johnjeavons.info/
Use Masanobu Fukuoka's method of fixing nitrogen in the soil with clover grown along with the crop, and no-plow farming to avoid the loss of the nutrients. http://www.onestrawrevolution.net/
In short, we don't need new technology, we need to change our way of life.