Bio-derived Fuels for Aeronautic and Space Propulsion Systems
Dependence on fossil fuel sources has depleted the supply of natural energy reserves on a global scale, and much attention has been focused on the United States as the main culprit for the rapid exhaustion of resources. Reliance on fossil fuels has also resulted in dependence on foreign suppliers, posing a strategic risk to the nationÂ’s political independence. These issues are coupled to rising concerns over the survival of the planet in the long term, requiring the growth of environmentally conscious technologies. A common solution to both energy and environmental issues is the creation of biologically-derived fuels, which can replace both liquid and solid fuels in ground, air, and space vehicles. Usage of waste and inedible plant-based materials can further improve positive environmental impact without affecting the food market, and the creation of new fuels provides a means to control and potentially reduce the production of emissions harmful to the environment, which is a mission that is aligned with NASAÂ’s goal to significantly reduce aircraft emissions within the next quarter century.
Uninhabited Aerial Vehicles and commercial and jet aircraft are still primarily operated on petroleum fuels. Biodiesel and similar long-chain hydrocarbons can replace gasoline and diesel fuels in UAVs, and synthetic jet fuels can replace JP-8 and Jet-A fuels in aircraft, as has already been demonstrated by the NASA Glenn Alternative Fuels Lab. Related work has been performed at UCI. The production of these alternative fuels will be based upon acidic, enzymatic, and microbial technologies that convert inedible biological and waste material to hydrocarbon fuels. Resulting liquid fuels will be analyzed using liquid chromatography to determine fuel components, and will then be blended with each other and with petroleum fuels to produce various combustible mixtures. Flame speed, ignition energy, saturation current from flame ions, flame temperature, species composition, and pollutant emission concentrations will be measured to provide a performance baseline for the fuels and fuel blends, and combustion characteristics will be compared to those of traditional petroleum-based fuels.
The NASA space shuttle currently employs a composite propellant that contains ammonium perchlorate oxidizer in its solid rocket boosters. A primary concern associated with the use of this oxidizer is the human health risk resulting from ingestion of perchlorate, which from a recent study published by the Board on Environmental Studies and Toxicology, has been detected in the water supply of 35 states as well as in foods like cowÂ’s milk and lettuce. Perchlorate causes thyroid deficiency, which can lead to thyroid tumors in adults, birth defects in fetuses, and developmental problems in children.
The Center will develop bio-derived hybrid rocket fuels to replace perchlorate-based fuels by testing mixtures of beeswax, paraffin wax, and lard combined with typical metal powder fuels. To determine whether a structurally stable matrix can be created when combined with bio-derived materials, preliminary research will include traditional binders like PBAN and HTPB. Early work will also employ liquid oxygen and nitrous oxide and lead to alternative oxidizers. These fuel composites will be tested for structural and chemical stability at room temperature, and then ignited to measure flame temperature, burning rate, and specific impulse to compare performance with that of solid oxide propellants. NASA has already funded related research to develop hybrid motors to serve as potential low-cost replacements for the Space ShuttleÂ’s solid rocket boosters as well as for boost propulsion in future launch vehicles. The proposed activity provides a logical place to introduce bio-derived fuels to the commercial and federal space industries.
The continuing global industrialization has caused an increase in demand for energy. Alternative fuels such as the renewable biofuel have shown great promise to reduce the dependency in fossil fuel and cleaner combustion. Interest in vegetable oil-based fuel dated back in 1900s when Rudolf Diesel designed his first compression ignited engine to operate using peanut oil. The development of the petroleum industry following the oil discovery in the Middle East during the 1908-1938 reduced interests in vegetable oil. However, the recent oil crisis and Clean Air Act have revived interest in biofuel combustion. There is a limited pool of data in the literature in the field of biodiesel combustion properties. The goal of the Combustion Diagnostic Team of the California State University of Los Angeles SPACE Center is to investigate the combustion properties of biofuel such as auto-ignition, flame stability, flame temperature, flame speed as well as emission properties such as soot particulates. The research is centralized around the counter flow flame burner, where combustion and emission properties can be measured on the quasi-one dimensional flat flame.