Project Number: 5320-21000-014-05
Start Date: Aug 24, 2012
End Date: May 31, 2015
Hamakua and other parts of Hawaii Island produce a range of feedstocks that could be potential sources for biofuel production. Many of them are food crops, such as papaya and sweet potato, for which the waste stream (as culled fruits, parts of the plant) could be an inexpensive and excellent source for production of biofuel. Others may be trees or plants which could be used for biofuel production, while still others may be grown to produce an inexpensive source of feedstock (such as sweet sorghum on very marginal land) that would be used specifically for biofuel. All of these crops could ensure a sustainable, available and efficient supply of biomass which will serve as the beginning point for all conversion technologies. The proposed research falls under our broad “zero waste” approach to simultaneously make agriculture in Hawaii more profitable and address food and energy security issues. While the available feedstock sources may be useful and plentiful, cost-effective technologies need to be deployed to produce biofuels. In this proposal, we will focus on the development of biodiesel or derivatives, and not alcohol. Using a systematic approach, a range of potential feedstocks will be analyzed to determine the qualitative and quantitative components (such as sugars, oils, cellulose content) that could be converted to biofuels. One specific approach that the investigators plan to focus on will be the use of heterotrophic algae for converting waste material from food crops to biodiesel. We have made significant progress in using papaya as a feedstock for algae and we will optimize growth conditions of the algae for increasing the fatty acid production and analyze the economics of the process. We are currently trying to determine how to go from robust algae growth, as indicated by an increase in biomass and the presence of replicating cells, to limited cell replication and increased lipid production. We will also look at the potential for sweet potato and sweet sorghum as feedstock using a similar approach as we used for papaya. Since Hawaii Island has a vast array of agricultural and nonagricultural plants that could be used in our 'zero waste' concept, additional conversion approaches will also be utilized for crops that are not amenable to heterotrophic algae. Anaerobic digesters are ideal for utilizing these waste streams because the output of this process results in production of energy, fertilizer, and value added products. Our ultimate goal is to adapt the process so it is scalable for Hawaii farm systems. We will focus on identifying feedstocks and on optimizing conditions for selected microbes to efficiently digest feedstock combinations under anaerobic conditions. Some of the possible feedstocks available are wastes from papaya, sweet potato, guava and other fruits (lychee, longan, mango, etc.), and albizia (Falcatatia moluccana), a fast growing invasive legume tree/weed that has infested an estimated 100,000 acres in East Hawaii Island. Two anaerobic digesters are slated to be constructed on Hawaii Island, one in Waimea the other in Hilo. Thus, our research could have an immediate impact.