While various predictions about when we will run out of fossil fuels have proven to be erroneous, it is obvious that the reserves are finite. As such, if human civilization continues to use these fuels long enough, we will exhaust them. Assuming that we will continue to need an energy source that is comparable to fossil fuels, then we will need to find a suitable replacement as a matter of practicality.
Some people are also concerned with the moral aspects of fossil fuels, specifically regarding the various harms associated with them. These typically include environmental harms which range from the pollution generated by lawn mowers to the impact of huge oil spills.
One proposed solution to both the practical problem (getting more fuel) and the moral problem is biofuel. Put rather simplistically, biofuels are created from biological sources (hence the name). These sources are typically plants (such as the corn used for ethanol) but other sources (such as animal waste) can be used.
Like many people, I sort of vaguely favor biofuel development—after all, we will probably need a renewable fuel source and “biofuel” sounds vaguely environmentally friendly. However, it is well worth considering the matter critically.
While I am not an expert on biofuel, one does not need to be an expert to grasp one of the basic requirements for a successful biofuel, namely a viable energy cost. In general, the creation of a usable biofuel is analogous to converting oil to gasoline in that the process involves changing the starting material into a usable form. To use a specific example, we obviously cannot burn corn (even creamed corn) in our vehicles. To be used as fuel, it has to be processed and distilled into ethanol. This process takes energy and so does growing the corn crop in the first place. Intuitively, to be a viable source of energy the creation of the biofuel needs to cost us less energy than the biofuel provides. In the case of corn, we get some of the energy for “free” from the sun. However, corn is now typically processed into ethanol using fossil fuels and this process is not very efficient. Adding to the matter is the fact that ethanol (and other biofuels) provide less energy than fossil fuels. This efficiency problem is a significant hurdle for the development of biofuels.
As might be suspected, people have proposed using other renewable sources of energy to provide the energy needed to create biofuels. For example, solar power could be used to provide the heat needed to distill a biofuel.
Provided that the renewable sources are adequately efficient in terms of their own energy costs, this could be a viable option. However, one rather obvious concern is that it might make more sense to just use the alternative energy source directly rather than adding in the extra step of creating biofuel. For example, instead of using solar power to turn corn into ethanol to fuel cars, use the solar power to charge the batteries of electric cars. That said, for applications that require actual fuel (such as running the millions of existing internal combustion engines), then the alternative energy would not be a viable option.
Another basic requirement is simply the matter of cost in terms of dollars (or whatever). After all, even if the energy cost of a biofuel makes it viable (that is, the process is efficient enough) it could be the case that the overall cost is too high. Calculating this cost is not a simple matter of considering the direct cost of the fuel, but also the indirect costs. For example, some biofuels are based on food crops, such as corn. Using food crops in this manner will tend to drive up the cost of the foods based on the crop, thus adding to the cost of the fuel. This specific cost can be offset or even eliminated by using non-food crops grown in areas that are not used to grow food crops or by using the “waste” from food crops. However, these options would also have costs as well.
As another example, replacing older vehicles with those that can burn certain biofuels could be costly. This could be offset by gradually replacement as older vehicles are phased out normally due to age and damage.
In regards to cost, it is worth noting that energy sources have traditionally had high start-up costs. In many cases, such as with fossil fuels, this cost was shifted to the taxpayers in the form of subsidies for the energy companies (a practice that still continues). While this fact does not diminish the cost of developing biofuels, it does show that the high startup cost is not unusual. Of course, there is the concern that the subsidies of biofuels will continue past the startup time, just as the needless subsidies for the fossil fuel industry continues to this day.
As a final point, biofuel will need buy in from those with political influence, especially fossil fuel corporations. While it might be tempting to think that the fossil fuel corporations would want to prevent the development of biofuels, they can have excellent reasons to want to get into the business themselves. After all, there is an existing network for fossil fuels that could be partially converted to biofuels and the fossil fuel companies know that their main product will eventually run out, so they will need something else to sell (and get subsidies for). In fact, I suspect that biofuels will only become really viable when the fossil fuel companies start selling them.