Ultrasonication and Renewable Fuels
Biodiesel, bioethanol and biogas are three ways to convert organic material into green fuels. Ultrasonication improves energy yield and conversion efficiency.
Renewable fuels enjoy increasing demand as oil prices mark new heights. The application of ultrasonic technology to the production of green fuels, like biodiesel, bioethanol and biogas improves the technical and the commercial efficiency.
Biodiesel is a renewable fuel that can be used in diesel engines as an alternative to diesel fuel made from petroleum. Biodiesel is made by transesterification from sources, such as vegetable oils, animal fats or grease. Most common are feedstocks like soybean, rapeseed or algae oil. The manufacturing of biodiesel involves the catalytic reaction with alcohol (methanol or ethanol). Ultrasonic mixing of the oil, fat or grease with the alcohol improves the reaction speed and yield significantly. This reduces investment and operational costs.
Bioethanol is used as a green alternative to gasoline. It is made from corn, wheat, potatoes, sugar cane, rice and other grains by fermentation. Yeast is used to ferment the starch and sugars found in these crops to ethanol. Ultrasonic disintegration of cellular structures and extraction of intracellular material reduces the particle size and exposes a much larger surface area to enzymes during liquefaction. This improves the bioavailability of starch and sugar and results in faster and more complete fermentation leading to more ethanol.
Municipal organic waste, sewage sludge, muck and manure serves as a source of biogas. The processing of such material in aerobic or anaerobic digesters converts the organic material into biogas. Ultrasonic disintegration of the organic material prior to digestion alters the material structure, and releases and activates enzymes. This improves the digestion of the organic material leading to faster processing, more gas and less residual sludge. This in turn increases the capacity of existing digesters and reduces disposal costs.
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Ultrasonic Energy Balance
The processed mentioned above do not require much ultrasonic energy. In general the surplus energy as a result sonication makes up for the energy used to generate the ultrasound. Hielscher ultrasonic devices have an overall efficiency of more than 85%. This means that more than 85% of the electric energy is converted and delivered to the liquid by means of mechanical energy. The actual energy requirement of a process can be determined in small scale using a 1kW ultrasonic processor in bench-top scale. All results from such bench-top trials can be scaled up easily. Hielscher supplies industrial ultrasonic processing equipment, worldwide. With ultrasonic processors of up to 16kW power per single device, there is no limit in plant size or processing capacity.