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Title: Geothermal Energy Market Study on the Atlantic Coastal Plain: Technical Feasibility of use of Eastern Geothermal Energy in Vacuum Distillation of Ethanol Fuel

Abstract

The DOE is studying availability, economics, and uses of geothermal energy. These studies are being conducted to assure maximum cost-effective use of geothermal resources. The DOE is also aiding development of a viable ethanol fuel industry. One important point of the ethanol program is to encourage use of non-fossil fuels, such as geothermal energy, as process heat to manufacture ethanol. Geothermal waters available in the eastern US tend to be lower in temperature (180 F or less) than those available in the western states (above 250 F). Technically feasible use of eastern geothermal energy for ethanol process heat requires use of technology that lowers ethanol process temperature requirements. Vacuum (subatmospheric) distillation is one such technology. This study, then, addresses technical feasibility of use of geothermal energy to provide process heat to ethanol distillation units operated at vacuum pressures. They conducted this study by performing energy balances on conventional and vacuum ethanol processes of ten million gallons per year size. Energy and temperature requirements for these processes were obtained from the literature or were estimated (for process units or technologies not covered in available literature). Data on available temperature and energy of eastern geothermal resources was obtained from the literature. Thesemore » data were compared to ethanol process requirements, assuming a 150 F geothermal resource temperature. Conventional ethanol processes require temperatures of 221 F for mash cooking to 240 F for stripping. Fermentation, conducted at 90 F, is exothermic and requires no process heat. All temperature requirements except those for fermentation exceed assumed geothermal temperatures of 150 F. They assumed a 130 millimeter distillation pressure for the vacuum process. It requires temperatures of 221 F for mash cooking and 140 F for distillation. Data indicate lower energy requirements for the vacuum ethanol process (30 million BTUs per hour) than for the conventional process (36 million BTUs per hour). Lower energy requirements result from improved process energy recovery. Data examined in this study indicate feasible use of eastern geothermal heated waters (150 F) to provide process heat for vacuum (130 mm Hg) ethanol distillation units. Data indicate additional heat sources are needed to raise geothermal temperatures to the 200 F level required by mash cooking. Data also indicate potential savings in overall process energy use through use of vacuum distillation technology. Further study is needed to confirm conclusions reached during this study. Additional work includes obtaining energy use data from vacuum ethanol distillation units currently operating in the 130 millimeter pressure range; economic analysis of different vacuum pressures to select an optimum; and operation of a pilot geothermally heated vacuum column to produce confirmatory process data.« less

Publication Date:
Research Org.:
Carltech Associates, Columbia, MD
Sponsoring Org.:
USDOE
OSTI Identifier:
892713
Report Number(s):
JHU/APL; QM-81-066
TRN: US200623%%553
DOE Contract Number:  
N00024-81-C-5301
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; 10 SYNTHETIC FUELS; DISTILLATION; ECONOMIC ANALYSIS; ECONOMICS; ENERGY BALANCE; ENERGY RECOVERY; ETHANOL; ETHANOL FUELS; FERMENTATION; GEOTHERMAL ENERGY; GEOTHERMAL RESOURCES; HEAT SOURCES; MARKET; PRESSURE RANGE; PROCESS HEAT; VACUUM DISTILLATION; Geothermal Legacy

Citation Formats

. Geothermal Energy Market Study on the Atlantic Coastal Plain: Technical Feasibility of use of Eastern Geothermal Energy in Vacuum Distillation of Ethanol Fuel. United States: N. p., 1981. Web. doi:10.2172/892713.
. Geothermal Energy Market Study on the Atlantic Coastal Plain: Technical Feasibility of use of Eastern Geothermal Energy in Vacuum Distillation of Ethanol Fuel. United States. https://doi.org/10.2172/892713
. 1981. "Geothermal Energy Market Study on the Atlantic Coastal Plain: Technical Feasibility of use of Eastern Geothermal Energy in Vacuum Distillation of Ethanol Fuel". United States. https://doi.org/10.2172/892713. https://www.osti.gov/servlets/purl/892713.
@article{osti_892713,
title = {Geothermal Energy Market Study on the Atlantic Coastal Plain: Technical Feasibility of use of Eastern Geothermal Energy in Vacuum Distillation of Ethanol Fuel},
author = {},
abstractNote = {The DOE is studying availability, economics, and uses of geothermal energy. These studies are being conducted to assure maximum cost-effective use of geothermal resources. The DOE is also aiding development of a viable ethanol fuel industry. One important point of the ethanol program is to encourage use of non-fossil fuels, such as geothermal energy, as process heat to manufacture ethanol. Geothermal waters available in the eastern US tend to be lower in temperature (180 F or less) than those available in the western states (above 250 F). Technically feasible use of eastern geothermal energy for ethanol process heat requires use of technology that lowers ethanol process temperature requirements. Vacuum (subatmospheric) distillation is one such technology. This study, then, addresses technical feasibility of use of geothermal energy to provide process heat to ethanol distillation units operated at vacuum pressures. They conducted this study by performing energy balances on conventional and vacuum ethanol processes of ten million gallons per year size. Energy and temperature requirements for these processes were obtained from the literature or were estimated (for process units or technologies not covered in available literature). Data on available temperature and energy of eastern geothermal resources was obtained from the literature. These data were compared to ethanol process requirements, assuming a 150 F geothermal resource temperature. Conventional ethanol processes require temperatures of 221 F for mash cooking to 240 F for stripping. Fermentation, conducted at 90 F, is exothermic and requires no process heat. All temperature requirements except those for fermentation exceed assumed geothermal temperatures of 150 F. They assumed a 130 millimeter distillation pressure for the vacuum process. It requires temperatures of 221 F for mash cooking and 140 F for distillation. Data indicate lower energy requirements for the vacuum ethanol process (30 million BTUs per hour) than for the conventional process (36 million BTUs per hour). Lower energy requirements result from improved process energy recovery. Data examined in this study indicate feasible use of eastern geothermal heated waters (150 F) to provide process heat for vacuum (130 mm Hg) ethanol distillation units. Data indicate additional heat sources are needed to raise geothermal temperatures to the 200 F level required by mash cooking. Data also indicate potential savings in overall process energy use through use of vacuum distillation technology. Further study is needed to confirm conclusions reached during this study. Additional work includes obtaining energy use data from vacuum ethanol distillation units currently operating in the 130 millimeter pressure range; economic analysis of different vacuum pressures to select an optimum; and operation of a pilot geothermally heated vacuum column to produce confirmatory process data.},
doi = {10.2172/892713},
url = {https://www.osti.gov/biblio/892713}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Apr 01 00:00:00 EST 1981},
month = {Wed Apr 01 00:00:00 EST 1981}
}