(202b) Seaing Green

1-1 Background: Biodiesel is a renewable energy source that could be used in place petroleum diesel fuel thus reducing the dependence of the United States on Foreign Oil. One of the greatest benefits of biodiesel is that it is clean burning, meaning that when it is burned, fewer harmful greenhouse gases are emitted into the air such as Sulfur Oxides, and more importantly Carbon Dioxide. As oil and diesel prices begin to increase, the economic feasibility of using Biodiesel as an alternative fuel source to power the cars and trucks of America begins to look more promising. This and the fact that biodiesel will be good for the environment, make it a very attractive fuel source.

1-2 Drawbacks: While biodiesel is a clean burning fuel source, in order to make it you must start with a feedstock. Traditional feedstocks have included corn, soy, canola, rapeseed, sugar cane, and animal fats. All of these feedstock's contain that fats that can then be turned into biodiesel via the transesterfication process. However these feedstocks have several major drawbacks. The first and most important is that these feedstocks are already used as a source of food for the people of the world. If these food crops were all of a sudden sold to make biodiesel instead of being sold for food, food prices would increase, and there would be a competition for land usage. The next major drawback is that while these traditional feedstock's can be used to produce biodiesel, they do not have a very high oil yield. For example 1 acre of soy beans will only produce roughly 50 gallons of oil per year and 1 acre of canola will only produce roughly 90 gallons of oil per year. Currently the U.S. demand for oil is about 65 billion gallons of oil per year. In order for feedstock's such as soybean or canola to produce enough oil to meet the U.S. current oil demand, an immense amount of land would be required, far more land than the U.S. has at its disposal to allocate to the production of biodiesel. The final drawback of these traditional feedstocks is that they require a lot of energy to produce. First the farmer must harvest the crops, and then transport the crops to a processing plant which finally turns the crops into biodiesel. Both of these steps are very energy intensive.

1-3 Algae a Solution?: While there seem to be many obstacles that are hindering biodiesel from replacing the U.S. dependence on petroleum-diesel, there is a ray of hope. Microalgae, i.e., pond scum, are single celled plant-like organisms that can grow in almost any environment, as long as they are provided with three things, nutrients, sunlight, and air. Like plants, algae need sunlight, so that they can convert carbon dioxide into glucose, a food source that they then use later to power the cell. Because algae can grow in almost any environment, they could easily be grown in a number of places such as an open pond or a photobioreactor. A photobioreactor, is a reactor in which the algae is contained in a closed system containing nutrients, and is bubbled air. In this system light can be introduced to the algae, either from the Sun, or from synthetic light sources (fluorescent bulbs).

1-4 Salt Water as the nutrient source: While algae need a nutrient source in order to grow, there have been a number of different theories about which nutrient source would be the best to use. So far there have been tests done where nutrient solutions are created using chemicals. One of the chemicals that is found in greatest quantities in most nutrient solutions, is sodium chloride, table salt. If salt is indeed one of the major ingredients needed to produce algae that have high oil yields, then this would make the process of growing algae for biodiesel much more economical. The reason for this is because if algae can be grown in pure seawater, which is essentially salt and water, then a lot of money would be saved, since ocean water could be used to grow the algae which would then be converted into biodiesel.

2-Goals: The goal of this research project is to find a more economical way of growing algae that not only grows the algae quickly, but also allows the algae to have high oil yields. This research was conducted by placing algae in pure ocean water, and nutrient solutions that contained more salt (approximately 0.1 molar)

3-Experimental setup and Results:

To analyze the growth and lipid content of algae grown in salt water solutions, first two algae strains that grew relatively fast and have good oil yields were selected. Once the algae were selected the first phase of the experiment began.

In phase one of the experiment the two algae strains were placed in a regular nutrient solution (the control), and a 0.1 M sodium chloride and nutrient solution. This was done to determine whether or not an increase in the amount of salt would have positive effects on the growth and oil content for the algae. After growing the algae over a period of two weeks, the oil yields and growths of the algae strains in both solutions were tested, and it was found that the algae strains when grown in the 0.1M sodium chloride and nutrient solution grew much better than their counterparts.

After phase one was concluded, the two algae strains were placed in pure ocean water. This was done for two reasons. The first was the results from phase one indicated that the algae had grown better and produced more oil in when the amount of sodium chloride had increased. The second reason for phase two was that if the algae could in fact grow better in pure salt water, than they had in the nutrient solutions, then the process of growing the algae would be much more economical. At the end of phase tow it was determined that the algae could not grow in pure salt water, because it lacked the nutrients that the algae needed to survive.

In phase three of the experiment, the algae were grown in 50% ocean water and 50% .1M sodium chloride and nutrient solution, vs. the .1M sodium chloride and nutrient solution, to determine the affects a mixture of nutrient solution and pure ocean water would have on the oil content and growth of the two algae strains being investigated.

In order to test the algae in all three phase two machines were used. First the spectrophotometer was used to measure the absorbance of the algae strains. The reason that this was done is because absorbance is proportional to the actual concentration of the algae, so by measuring the absorbance of the algae over a period of time it would be possible to determine how quickly the algae were growing in the test-tubes. The second machine that was used in analyzing the algae strains was the spectroflurometer. The spectroflourometer was used to measure the oil content of the algae. By measuring the oil content of the algae over a period of time (in this case a two week period) it was possible to determine how much oil the algae were producing.

4-Conclusions:

In conclusion it was determined from the three phases of this experiment that while the two algae strains do in fact produce more oil and grow faster in a salt enriched environment, they can not be grown in a pure salt water solution because the algae require other nutrients to survive. None-the-less the fact that algae can be grown in a mixture of ocean water and nutrient solution provides a possible way to produce oil and make bio diesel more economically feasible.