The end ok black oil
According to the best estimations, we just have oil for 60 years. The problem is that it represented in 2004 34 % of our energetic production ! We'll so have to replace it by something else... In the world, energy is also produced by natural gaz (21 %), coal (25 %), nuclear (6.5 %), renewables fuels (11 %), hydroelectricity (2 %) and others (only 0.5 % !). Which of them will take the succession ?
Because renewables energies (solar, biomass, wind, geothermic, ...) still only represent less than 1 % of the production, they're not a solution for the moment (but we'll probably have to use it later). Natural gaz ? It would be a solution for a few years but it's threaten too : one estimates the reserve at a little bit more than a century, which is better than oil but not infinite. And we must consider that most of the reserves are in politically unstable areas. Hydroelectricity ? There are few available sites, and the quantity of water will decrease...
In conclusion, there just are two credible candidates for the moment : the nuclear energy and, unexpected in this role of energy of the XXIst century, the coal !

The coal
This energy seems unusual in France, where the last mine closed in 2004. But the situation is not the same in the whole world, for example in China (75 %). The coal has many advantages. First it has reserves of at least 150 years, just for the deposits that are now exploited, to which we can add unknown some. Moreover, the coal is spread in all the Earth, except in the Middle-East. So we don't have to worry about some international tensions !
Other advantage, coal can be used as fuel when it's liquefied. This use is in fact already known since the 1920's and it helped Germany during the Second World War to run its motors without oil.
Despites this, coal has a big disadvantage. Its combustion produces 35 % more of carbonic gaz than oil, and 72 % more than gaz ! According to the current knowlenges, coal is the first reponsible of the world productions of CO2, and so on of the green effect. So we would have to « clean-up » the coal's power plants. This is technically possible, with three techniques. The « post-combustion capture » is the more efficient but it costs up to 60 euros for every MWh of power. An other solution of the « oxy-combustion » which consists in burning coal with pure oxygen in place of air. So it needs enormous quantities of oxygen. It can be technically made but it's expensive. Lastly, we can use a gaz called « syngaz », which permits to reduce the needed quantity of coal and to clean-up the CO2. And, happy coincidence, the syngaz would provide a clean fuel ! But there too, it's very, very expensive.

The nuclear energy
We know it, between the energies we skill, the nuclear is the most efficient and the cleanest (for the carbonic gaz, by only considering energies that can today provide enough electricity). Moreover, it has the advantage to minimize the costs in combustible : the uranium represents only 5 % of the price of the electricity. So even if it fastly increased, that would almost not be feeled. An important argument for geopolitics.
The two well-known problems of this energy are big, like for the coal. This energy is potentially the most dangerous, like Ukrainians know it (read the article about Tchernobyl). The risk, for the use of the power plants as well as for the transport of uranium, can come from technical accidents, natural disasters or terrorist attacks... And still we don't skill the fusion, the problem of wastes (read the article) is entire, and heavy !

What to do ?
In front of these established facts, unless we succeed in making a nuclear fusion (a myth for the moment), the better strategy seems to be in a first time to reduce the cost of the methods that decrease the production of CO2 of the coal, in order to maximize this resource, and to develop renewable and clean energies because the coal will also disappear. A strategy ecologically acceptable, but that we'll have to highly pay, ... To choose, let us not forget what should be our main goal : permit our descendants to decently live in the Earth they lend us.