With recent advances in "reverse combustion," Mars could become the solar system's biggest power-plant. For a while now, scientists have known how to create fuels (methane, butane, propane, propylene) out of carbon dioxide and hydrochloric acid fused together under pressure. However, this process required more power than could be created from the fuel. Hoping to solve yet another "where will we get it" question, Japanese scientists stumbled upon a magnetite catalyst that, when mixed the hydrochloric acid and CO2 allows these two chemicals to be fused together using only waste heat from a power plant. This means that a Martian power plant would need only an initial power boost to create fuel, then the fuel would be burned. The heat would fuse together more fuel and the electrical power would go out to the Martian populace. The CO2 and the CO1 would go to create more fuel. An even greater advantage is that when this process takes place, the oxygen molecules separate from the carbon molecule, meaning that power-plants could literally "scrub" the CO2 out of the air and create pure oxygen in its place.
This system has many advantages:
1. No exhaust (except for heat)
2. Efficient power production
3. Surplus oxygen can be released back into the atmosphere
4. Fuel could be created at cheap prices
5. Current demand of fuel would speed terraforming
Someday, when Mars is completely terraformed, heated and magnetized, methane will be the cheapest thing you can buy. We will have more methane than we know what to do with. If we put it in space... well, the saved costs of the fuel would pay off the ship in no time, meaning a steady population boom on Mars since ships could travel between the planets with reduced interstellar rates (because of cheap fuel). Just what we want (I think).