Algae are a diverse group of simple organisms that are usually autotrophic. During the oil crisis in 1978 US investigated the possibility of algae being an alternative fuel to fossil ones. Ever since research is being carried out but the recent increase in oil prices has reheated interest for the production of biodiesel from algae.
According to the Department of Energy for algae biofuels to replace petroleum fuels they would require 15 thousand square miles which is just 0.42% of US land. This is about a seventh of the area used to cultivate corn in 2000 but it should be noted that algae doesn’t
require any arable land to be cultivated since it can be grown anywhere. This is one of algae fuels advantages since other forms of biofuels have been accused of driving the prices of food up (i.e. corn and soya). In addition algae cultivations don’t require fresh water but waste water or even seawater can be used.
Production of Algae
The most common way of producing algae is with photobioreactors. Glass or plastic tubes are exposed to the light of sun while water with algae is pumped through them. This results into photosynthesis and the growth of algae. In addition, the water used can be recycled and the quantities needed for the process are far less than the ones used for other sort of biofuel cultivations.
The initial method used to produce algae was the open pond method which by its name is self explanatory. This method has a number of disadvantages since algae becomes vulnerable to external factors such as temperature changes, competition from other bacteria and even viral infections. As a result the popularity of this method has decreased with time.
Expression is a method that is done in two steps. The first one is similar to the one used to extract olive oil where algae is pressed in order to extract its oil. The second step is a chemical process which is used to extract further oil. The percentage of oil extracted from this method is estimated to around 80%. Another mechanical method is ultrasonic in which ultrasonic waves are used in order to create bubbles in a solvent. The bubbles produced burst close to the cell walls of the algae causing the cell walls to break down thus releasing the oil into the solvent.
The most common method is Hexane that can be used either on its own or coupled with expression method. In case that is used with mechanical methods up to 95% of the algae oil can be extracted. Furthermore, it can be mixed with the remaining pulp to extract more oil.
Algae are essentially carbon neutral. What this means is that carbon dioxide released when we use them to produce energy can be reabsorbed by producing more algae to replace it. As a result, algae biodiesel doesn’t burden the environment and given the fact that a large percentage of carbon dioxide emissions come from the use of fossil fuels used in transportation it can help reduce environmental pollution.
Producing biodiesel from algae might be one of the solution to our quest for cleaner and renewable fuels. Currently the main reason of not having a mass production is the cost since producing it is quite capital intensive and includes a high level of operating expenses. The current price for a gallon of algae has been estimated to be at around 33 dollars. But the future is not bleak. There are claims that algae can be in parity with diesel if proper tax breaks are given by 2018 which will immediately translate into independence from imported fossil fuels.