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Despite the significant interest in algae production systems, there is relatively little known about the actual lifecycle emissions associated with algae production. A very flexible algae production and algae to biodiesel pathway was added to GHGenius in 2009. The model can handle a wide range of inputs into the algae production system, separate inputs for the algae oil extraction and for the biodiesel production processes. The non-oil portion of the algae can be used for fertilizer, animal feed, or energy production. The model is thus well positioned to analyze a wide variety of algae systems.
The current default data in the model is based on information from three studies that quantified the inputs and outputs for micro algae production in open ponds and undertook an estimation of the GHG emissions. One study was conducted by NREL (2001), another was an Australian study undertaken by Campbell et al (2009), and the third was a French study (Lardon, et al., 2009). Each study considers a very different system so comparisons between the studies are difficult to make. There is a wide range in the projected GHG emissions in the three studies.
With the continued interest in algae production, there is a steady release of new data on the techno-economical parameters of algae production becoming available. Two aspects of this project have been the review of recent literature and discussions with algae researchers. In addition, researchers are also now moving to the stage where some feedback on the overall performance of their systems would be valuable.
A number of new papers have been identified that have considered the energy and environmental impacts of various algae production systems. There continues to be wide variation in the projected performance of algae and algal oil systems. This is not unexpected given the theoretical nature of the analysis that has been undertaken. None of the papers was based on the actual measured performance of any commercial system.
Some of the difference in the results is a function of different assumptions concerning system boundaries. While the biomass production rates of algal systems can be significant, a major issue for the systems will be the relatively low concentration of biomass in the production systems. This means that very large quantities of water must be used in the systems, the energy requirements for moving, processing, and treating the water are also large and will be critical to the overall environmental performance of the systems.
There is increased interest in the production and use of algae to produce fuels for the transportation sector. In spite of all of the interest, there has been very little quantification of the energy and emission benefits of such an algae to biodiesel pathway published, although there is some information on the energy and material balances of some of the proposed algae systems. The available literature on algae production systems has been reviewed to gather the data that is required for modelling and the data has been added to an algae to oil pathway and an algae oil to biodiesel pathway, the same combination of systems that we use for other biodiesel systems, in the GHGenius model.
The GHGenius has been modified so that the SuperCetane pathway that was in the model and could process both tallow and canola oil can now process all eight types of vegetable oils or animal fats. The data that is used for the process is now the operating information for the Neste NExBTL and the SuperCetane description has been replaced by a more generic description of hydrotreated renewable diesel (HRD).
The version of the GHGenius model that accompanies this work is version 3.16. There are other changes that have been made to version 3.16 to update the data in the model but these are described in a separate report.
Tags: Algae - Biodiesel - GHGenius 3.16 - HRD - Jatropha - SuperCetane