Biodiesel as a Biofuel

In my previous posting I talked about ethanol. I know there are other promising ways of producing ethanol but lets be honest, nothing from the ethanol camp, as of yet, has as much promise as some of the biodiesel production methods. Currently the major source used to produce biodiesel is soybeans. Soybeans unfortunately do not have a very good EROI(Energy Return Of Investment), much like corn does not. EROI is the ratio of the amount of usable energy acquired from a particular energy resource to the amount of energy expended to obtain that energy resource (http://en.wikipedia.org/wiki/EROEI). Basically, energy return on investment is the measure of the amount of energy needed to create biofuel (for example) and then the amount of usable energy you have from the biofuel. If the amount of energy needed to create a biofuel is not significantly less than the amount of useful energy contained in the biofuel then the energy source becomes less and less useful, much like soybeans or corn. Soybeans, at this point, are a major biodiesel fuel source used for mass production. Soybeans have worked as a beginning biodiesel producer but the effects on our water table and environment won't allow them to be a viable mass production source into the future. Rapeseed and canola are better options when comparing them to soybeans but you still have to use farmland to grow a crop, to make a fuel and to power society. This requires the use of farmland, farm equipment, fertilizers and pesticides, and water. Though canola and rapeseed both produce more oil per acre, which requires less farmland, neither of these crops are solutions to the problem. Now I am not against using crops like canola or rapeseed to produce biodiesel in small quantities, but to do so at a scale that would even come close to meeting the diesel demand would be detrimental. We need to stop using food products and valuable farmland to produce fuels, we need to use food products for food and farmland to grow food.
There is one biofuel source that has great promise to alleviate many of the common drawbacks to biofuels, algae. Algae is just now starting to get some of the attention it deserves. Algae can be grown in open ponds and closed systems. Open pond systems have been studied for quite some time but one of the biggest challenges with an open pond system is controlling the type of algae growing in the pond. Naturally open pond systems are susceptible to contamination from outside sources, this is where closed systems excel. An example of a closed system is a bioreactor. A bioreactor is a closed system that pumps water though a network of tubing, the algae is then harvested from the water (http://img.alibaba.com/photo/100453709/Jeruz_Algaelink_Photo_Bio_Reactor.jpg) for biofuel production. Though some closed systems like bioreactors can use more energy than an open pond system and are more complex, the control over the type of algae growing in the system is very beneficial. Companies like GreenFuel Technologies have a bioreactor design that use CO2 from coal power plants to grow the algae within the system, this gives the bioreactor a steady flow of "food" for the algae. Valcent Products has one of the most interesting and promising closed systems that I have seen so far. It uses plastic bags hung vertically, these plastic bags have channels in them to direct the water through a series of paths to maximize the amount of sun the algae is exposed to for photosynthesis. This method is relatively simple in comparison to many other methods used to create biofuels. Valcent thinks their company can create a algae system that can create "...about 100,000 gallons of algae oil a year per acre, compared to about 30 gallons per acre from corn; 50 gallons from soybeans." (http://www.cnn.com/2008/TECH/science/04/01/algae.oil/index.html). If you research oil production from algae you will find the estimated amount of oil per acre to have varying numbers. I am somewhat skeptical that 100,000 gallons of algae oil a year per acre is possible but even if that number is significantly less, like 15,000 or even more conservatively around 1800 like some estimate, it is still a much more viable option than any other biofuel source at this point.
Each biofuel source can and probably will play a role in replacing crude oil with a renewable energy source; but we need to stop giving the majority of the research and funding to sources that will not benefit society. Algae is by far the most promising of all biofuel sources but ethanol may also play a role in the future. Anytime an energy source is considered we must not forget the law of thermodynamics and energy return on investment, these two things will give you the true benefits and negatives of a biofuel.