The existence of climate change and the connection to green house gas emissions has been studied and debated by scientists, industrialist, and policy makers for roughly 200 years. Today it is widely accepted that warming of the planet is occurring, and that human activity is the primary driver. Fossil fuels have become the source for more than 80% of the world’s energy consumption, powering the transportation, industry, electricity production, and commercial/residential sectors’ energy demand. The desire for alternative fuels stems from the many problems we face today. Effort to produce renewable cleaner-burning fuels has not yet produced any single method which has the capability of meeting global fuel demand alone, and many of the biofuel sources come with difficulties of their own. Biofuel from oil-yielding biomass sources is a vital part of the solution for climate change. Biodiesel, most commonly made from waste animal fats or vegetable oils, is a renewable fuel with many advantages. The Argonne National Laboratory found that the use of biodiesel blending reduced total carbon dioxide emission by 74%. Lastly, the growth and development of biofuel production serves to lessen the political influence on global energy supply, as these alternative fuel processes are not strictly bound to the occurrence of natural resources in any specific place. However, biodiesel production at mass-scale faces several difficulties regarding its traditional feedstock. Soybeans and other vegetable oil-producing crops require an immense amount of fresh water and land, and commercial-scale biodiesel farms would be in competition with agricultural food production. Microalgae can combat these issues, as it requires much less land to farm and can be manipulated by diet to create a high lipid density crop. For these reasons, algae-based biodiesel is the most promising source for achieving mass-scale production.
In this work, an Aspen Plus® simulation for biodiesel production from microalgae was developed. Modelling parameters were referred from relevant literature reviews and through trial and error during the development of the simulation. Sizing and cost estimates were conducted based on a minimal production capacity of 10,000,000 gallons of biodiesel per year. Equipment Sizing, materials, and their respective prices were taken from literature and online estimators.
The economic considerations include costs such as land, equipment, installation, utilities, and waste treatment, but do not consider labor, permits, or insurance. Finally, the required selling prices of algae biodiesel and DHA, and the relationship between their selling prices, were investigated. For a capital recovery time of five years, and at a moderate interest rate of 10%, economically competitive prices were obtained for both biodiesel and DHA, of $2.04 per gallon of biodiesel and $12.70 per kilogram of DHA. This indicates that the process is economically feasible, though it is heavily dependent on the revenue from DHA.
