Many of the EnergySources that we use these days are NonRenewable. By this, we mean that at the EnergySource at some point in the future run out.
Actually, although many people think that there is some clean dividing line between Renewable and NonRenewable EnergySources, this is a bit of a fallacy. It's fairly obvious that all EnergySources will run out at some point in the future. Take, for example, SolarPower. Eventually, the Sun will explode, and SolarPower will cease (if we are still around we are likley to have other worries at the time).
Equally, some forms of NonRenewable are likely to be around for so far into the future, that them running out is not likely to be a problem. So while many of the CarbonBased Fuels are likely to run out within a few generations, NuclearFission fuels will probably not.
So, we can divide NonRenewable Fuel into two different categories.
- the practically finite - the practically infinite
Is the use of the latter are problem? One consequence of being NonRenewable, is that these EnergySources are generally consuming something which would not otherwise be consumed. So NuclearFission, for example, accelerates a RadioActiveDecay process, while the PetrolEngine burns Oil products. Contrast this with SolarPower, where only light which was likely to hit the ground anyway, is consumed. Normally, this results in the production of something else. In this case of Oil, this means CarbonDioxide and some other CombustionProducts.
These products are often highly polluting, unless you can get rid of them in someway.