Green oil is the development that will utterly change the world and it will arrive in the next few decades.
Oil that we take out of the ground and burn is going to be replaced by oil that we grow. Bio-fuels based on corn are our first effort to grow green oil but they have clearly not succeeded. Current bio-fuels take too much land and too much energy to grow and too much of that energy goes into building parts of a plant that we can't easily convert into fuel. The answer will come from simple, engineered organisms that can soak up energy in a vat in any sunny spot and turn that sunlight straight into a precursor for fuel, preferably a precursor that can go straight into an existing oil refinery that can turn out gasoline.
The impacts of such a development are staggering. The power balance of the world will be completely changed. Petro-dictatorships, where an endless flow of oil money keeps the population quiet, will no longer be able to look forward to oil at $50, $100, $150 and so on a barrel as oil supplies tighten. Power will be back in the hands of innovators rather than resource owners. The quest for dirty oil in remote and sensitive parts of the world, whether the Arctic or the Alberta tar sands, will not make economic sense and the environment will gain. The burning of gasoline in automobiles will no longer add much to the amount of carbon dioxide in the atmosphere as the fuel will have soaked up an almost equal amount of carbon dioxide while it was being grown. The existing networks for delivering fuel to transportation (the 100,000 gas station in the US for example) won't become redundant as they would if we switched to electric autos, making plans for cutting emissions much less difficult.
Will the green oil come from algae, bacteria, archaea or something else? I don't know. Oil is a natural product arising from the transformation of plant material created by the capture of light. As it is a transformation in nature we can replicate it, not necessarily directly, but to arrive at a similar result. It is not magic.
Scientists around the world have seen the prize and hundreds of millions are going into start-up companies. There is a nice twist to this line of investment. Despite the ups and downs, the long-term trend for the price of oil is up. That means the size of the prize for replacing oil is going up while the size of the challenge is going down. Replacing $20-a-barrel oil would be difficult but replacing $100 oil is much easier.
There is an old saying: "The Stone Age didn't end because we ran out of stone. Someone came up with a better idea". The better idea is coming.