Growing Algae for Biofuel; Potential Methods and Costs

Abstract

One of the largest challenges in the world of today is fossil fuel consumption. Human beings consume huge quantities of fossil fuels every day, yet there is a limited supply in the world. In the long term, an alternative source of energy needs to be found. Few of the replacements available for fossil fuels are suitable for generating electricity, which is necessary to sustain modern society. One of the recently available alternatives that seems to hold the greatest potential is harvesting oil from algae. All methods of growing algae are based on either an open-pond system, or an enclosed growing container (also known as a photo-bio-reactor, or PBR). A particular PBR design is proposed here, and its advantages and disadvantages relative to an open-pond system are examined and quantified. It is found that the power cost of operating the PBR is more than seven times that of the open-pond system. However, the open-pond system produces energy at only about one-sixth the rate of the PBR. This makes their net costs of operation similar: about 18 cents per day for the open pond, vs. 22 cents per day for the PBR. A further disadvantage of the open-pond system, however, is that it occupies about 113 square feet of space, as compared with 28 square feet for the PBR. Thus, for applications with limited space available, the PBR would be the preferable method.