Energy-Related Carbon Dioxide Opportunities Can Enhance Ethanol Projects

Growing industrial gas applications will diversify markets beyond carbonation.
By Sam A. Rushing | June 08, 2015

For decades, carbon dioxide has been recovered from concentrated sources like fermentation and sold to a handful of merchant markets, primarily beverage carbonation, food and meat processing. There are several industrial applications of note as well. As we have all noticed in the press, there is increased pressure being placed on hydraulic fracturing projects, due to water contamination and absolute water shortages. Opportunities exist for ethanol plants to provide their CO2 product for both dry frac demands to replace the water-based hydraulic fracturing applications and large, ongoing sums of CO2 for supply to enhanced oil recovery projects.

With the dire need to reduce or slow ongoing carbon emissions and atmospheric carbon content, which many claim to be reaching 400 parts per million these days, a dent in turning the tide can be achieved via novel techniques for replacing water and fluids in concrete curing, and the generation of power and geothermal energy using CO2 as a working fluid. Other opportunities for CO2 are growing in the industrial sector. Novel chemistry is creating opportunities in polymer processing, renewable methanol and the production of formic acid, all using CO2 as a feedstock. In the advanced biofuels industry, algal biofuels fixation is an excellent means of utilizing carbon dioxide in renewable energy. Other energy twists include using the commodity in wind energy projects as a cushion gas, enhancing the recovery of natural gas in coal bed seams and in situ uranium leaching.

Dry Frac Delivers
Many CO2 marketing firms are expanding dry frac technology, as opposed to the currently more common hydraulic fracking technique. In regions where water is scarce, unavailable, or where recycling and spillage is a problem, CO2 is the logical choice and solution. In dry frac, CO2 replaces water, tapping into the energized nature of CO2 as it rapidly expands from a liquid to a vapor. The technology can deliver the well much better than water and is sometimes applied along with foam, sand and other materials to save water and eliminate the need for clean-up, recycling and the risk of spills from hydraulic fracturing techniques.

Before hydraulic fracturing took hold, dry frac provided abundant CO2 demand. Today, many CO2 refiners and marketers are returning to this service, as pressure on the hydraulic fracturing industry grows. Many of those firms buy raw gas across the fence from ethanol producers, supplying one grade of CO2 commodity to a variety of markets, including frac, beverage and food.

Ethanol for EOR
It is hoped that enhanced oil recovery (EOR) will be one of the best options for both sequestration of CO2 emissions as well as making money from otherwise depleted oil wells. Of the approximate 140 CO2-based EOR projects found in the United States, there is one project of particular interest to the ethanol industry.

 The U.S. DOE-funded CO2 demonstration project started in 2002 at the regional Russell County, Kansas, Hall - Gurney oil field, aimed at both carbon sequestration and enhanced oil recovery. This oil field, on a 10-acre patch of land some seven miles from a 48 MMgy ethanol plant near Russell, Kansas, has produced more than 150 million barrels of oil since the original discovery in 1931. However, oil production dropped significantly into the 2000 era, when the EOR process began reviving oil production.

The integrated White Energy (sometimes referred to as the Energy Partners) ethanol plant at Russell receives its process heat from a nearby cogeneration plant. A colocated CO2 facility captures the gas and delivers it via pipeline to the central Kansas oilfield. 

When launching an EOR project, smaller quantities of CO2 are usually trucked or railed in as an initial test. This project planned a truckload per day of CO2 for six months, followed by alternating injections of CO2 and water for about four years. This EOR project pumps liquid CO2 about 3,000 feet underground to reach the cracks and crevices among rocks, clay and other geologic formations. CO2 acts as a solvent and reduces the swelling of clay, dissolves carbonate compounds, and much more. The oil is swept to nearby wells for recovery. Some estimates indicated an additional 20,000 barrels of oil could be recovered over the four-year period, in order to be successful. From this data, a greater expanse of EOR projects will be evaluated for CO2.  If industrial (anthropogenic) sources of CO2 are not adequate, some of this demand could be serviced by natural, geologic sources from regional New Mexico Bravo Dome and Colorado natural sources.

Given the highly agricultural nature of the region, raw CO2 sources from both ethanol and ammonia are fairly abundant, albeit, CO2 is already recovered for the merchant markets from some of the plants. Ethanol sources could well supply at least part of this EOR demand in various regions of the United States, including the West, Southwest, Central and Middle Atlantic regions. The consideration of EOR as a mechanism for both sequestration and additional oil production, linked with CO2 byproduct from ethanol represents many benefits, from increased oil production, to creating a form of carbon sequestration, to the development of business opportunities and more jobs.

Cost Comparison
Supplying CO2 for such energy-related projects is a function of source type, location and infrastructure costs of the oil wells. Supply of CO2 to the Russell, Kansas, project is integrated with nearby cogenerated process heat from the power plant for ethanol fermentation, aided by DOE funding. The cost of recovering CO2 is a function of the raw gas composition. In the case of large anthropogenic sources, such as power production, the flue gas is weak in CO2 concentration when compared to ethanol sources that are often 98 percent CO2 by volume in a water-saturated sample. Power plant flue gas holds 12 to 20 percent by volume at best, meaning the CO2 would have to be concentrated upstream of liquefying and purifying, making it a very expensive form of EOR product.  Ethanol projects often average 430 to 800 tons per day of raw CO2; indeed, some larger CO2 ethanol projects do exist and are flourishing. Some EOR projects could be candidates for 1,000 to 2,000 or even 5,000 tons per day. While that could be recovered from the large amounts of flue gas emitted from coal-fired power plants, these sources are expensive to construct. Not only does the gas need to be concentrated prior to liquefaction, most require an expensive MEA (monoethanolamine) recovery plant. 

Given this, industrial sources such as ethanol are already concentrated, and are often located within a reasonable distance of a wide variety of markets, and in some cases, prospective EOR ventures. The ultimate goal is locating the most economical source of raw CO2 gas for liquefaction and possible purification. Then, there is the hurdle surrounding the costs and existence (or new construction) of a pipeline plus, of course, oil well infrastructure asset costs. It is believed the demand for EOR-based CO2 long term will outstrip supply capabilities. I have often evaluated CO2 opportunities for all markets including captive and sequestration options such as EOR, particularly with a sequestration- and energy-producing slant. Findings have represented potential EOR markets throughout the continent; therefore, this is an avenue to explore for the ethanol project owner near oil producing regions. With the proper ingredients surrounding sources, destinations, logistics and infrastructure, coupled with geological and well characteristics, there will be opportunities for CO2 to supply EOR projects in the future, particularly when value-added elements are included in the equation.

Author: Sam A. Rushing
President, Advanced Cryogenics Ltd.