Co-generation, Ethanol Production and CO2 Enhanced Oil Recovery
Model for Environmentally and Economically Sound Linked Energy Systems

Kansas Geological Survey
Open-file Report 2002-6

Potential Energy Gains and CO2 Avoided on Annual Basis

541 MBOE Gained
(3.1 Trillion BTUs)

Co-Generation MMBTU Barrels Oil Equiv.
  Steam 462,300 MMBTU/Year    
  DDG Dryer 96,360 MMBTU/Year    
  (assumes co-gen running at 100%)        
  Net energy saved by using co-gen heat 558,660 96,321
Cattle Feeding    
  Distillers' Dried Grains Produced 167,910,448 lbs/year    
  Grain Corn Equivalent (by weight) 263,619,403 lbs/year    
  (1 lb. DDG is equivalent to 1.57 lbs. Corn)        
  Grain Corn Equivalent (by volume) 4,707,489 Bushels/year    
  Grain Corn Equivalent (Acreage) 62,685 Acres/year    
  Energy conversion factor, Russell Co., KS 14,695 MBTU/acre    
  Net energy saved by offsetting corn acreage 921,145 158,818
Enhanced Oil Recovery        
  Carbon Dioxide Generated (lbs) 165,600,000 lbs/year    
  (Tons) 82,800 tons/year    
  (MCF) 1,426,644 MCF/year    
  CO2 Utilized (MCF) (90%) 1,283,980 MCF/year    
  Net utilization of CO2 4.3 MCF/BO    
  Oil from EOR @ 4.3 MCF CO2/BO 298,600 BO/Year    
  Energy required (per BO produced) 78.1 kwh/BO    
  (Dehydrate, compress, pipeline, recycle CO2, plus lifting energy)        
  Energy required (total) 73,273 MMBTU/Year    
  Energy Value of Oil 1,731,879 MMBTU/Year    
  Net energy value of oil produced by EOR 1,658,606 285,967
  Total Potential Energy Gains 3,138,412 541,105

Net Energy Gained = Co-gen Gain + Cattle Feed Gain + CO2 EOR Gain

For the power plant/ethanol plant co-generation, data was provided by the operators of these facilities. The Russell Municipal power plant uses two Solar™ Taurus 70 single-cycle gas turbines, rated at a total 15 Mwe (Augustine, 2001, personal communication). The turbines' waste heat passes through a heat recovery boiler that generates steam used to heat the mash at the adjacent United States Energy Partners Ethanol plant. The waste heat from the heat recovery boiler is also used by the USEP ethanol plant for the purpose of drying the Distillers' Dried Grains. The amount of waste heat used by the USEP facility for each process is shown in the results.

Cattle Feed
The energy saved for cattle feed was based on the amount of Distillers' Dried Grains (DDG) produced as a by-product of the Ethanol process. The by-product of a bushel of milo in the ethanol process creates 18 lbs of DDG (Mork, 2001 personal communication). The energy value of the DDG was calculated by determining how much energy would be used to create a substitute for DDG, which in this case was grain corn at the rate of one pound of DDG replaces 1.57 lbs. of corn (Delucchi, 1998). Corn weighs 56 lbs. per bushel (EPA, 1985) and in Russell County, Kansas, the average corn crop yield from 1996-2000 was 75 bushels per acre (KASS, 2001). The energy required to grow an acre of corn was based on results from Pimentel (1991) with substitutes of local fertilizer and herbicide data for Russell County, Kansas and Kansas Region 2, which includes Russell (KSU, 1998).

Enhanced Oil Recovery (EOR)
The energy gained from Enhanced Oil Recovery (EOR) is that which is projected in a hypothetical case where the entire CO2 stream (less 10% for losses) from the Russell ethanol plant is compressed and piped to a small commercial scale project in the Hall-Gurney Field. An assumption is made that all CO2 EOR oil is new oil that would not have otherwise been produced.

Energy Gained = Energy of Oil Produced Energy Used in Production

Oil recovered per net volume of CO2, 4.3 MCF CO2 per barrel of oil, is that which was determined to be reasonable in the current DOE funded demonstration project. Assuming 90% of the CO2 (3.5 MMCFPD, 1.3 BCF per year) and a 4.3 MCF/BO net utilization, there is potential for 300 MBO per year production. Energy value was calculated on the basis of 5,800 MBTU/barrel (EIA, 2001). The energy used in production includes that related to the CO2, dehydration, compression and transportation via pipeline, injection and recycling, and that related to artificial lift. These were all related to the energy costs per barrel of oil produced (78.1 kWh per barrel of oil). Energy use data to make the calculations were from various industry sources gathered in the DOE project and from Egbert (1996, 2000).

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Last updated March 2002