The problem with many alternatives, like wind, solar, etc. is that they simply aren’t practical. Transporting enough stored electricity derived from these mechanisms to make an average journey is very difficult. Many experts believe that practical breakthroughs in these technologies are decades away at best. So, the challenge is to find a fuel that can replace the practical qualities of oil (like being easy to drive around), but which does not pollute the same way.
The solution, at least for now, appears to be algal-based biofuels, which are still years if not decades away from commercialization. The idea is simple. Algae have lipid and lipid can be converted to a number of fuels including diesel, ethanol, butanol, and methanol. Because algae absorb CO2 to make lipid, the net impact on the environment should be very small. Additionally, biofuels are biodegradable, so if they do spill, less harm is done compared to when fossil fuels spill. What is the hold-up you ask? At this point in time, developing fuel from algae requires huge investments of water and fertilizer because the algae must be killed in order to harvest the lipid and then a new stock is grown back up again. The energy needed to grow algae from a seed stock to “harvest-ready” is orders of magnitude larger than the energy obtained from harvesting them. In other words, more energy is put into the system than is taken out, so it leads to a net loss. Until the input of energy is lower than what the system produces (excluding energy from the sun of course), the system will not be viable.