Carbon dioxide is both a product of energy (related power and chemical projects) and a product which is consumed in numerous energy-related applications, some of which are critical in the production of oil and gas.

According to some surveys, when further defining CO2 applications in industry, much of the market is energy-related, at large. This is true when further considering CO2 as a cryogen in freezing applications, since with this large sector often 40% of the merchant gas business in the developed markets, could be viewed as energy related.

Energy related, as for cryogenic freezing applications, in lieu of cryogenic freezing the alternative could be mechanical refrigeration, a high energy-consuming form of refrigeration. On the other hand, with this article, I am strictly defining the more direct by-product or off-gas from energy projects, as well as the major CO2 consuming markets in the energy production sector.

Carbon Dioxide from energy production
CO2 from flue gas can be as basic as the simple combustion of wood in a fireplace; however I am reviewing larger commercial projects which yield CO2 as a flue gas, when speaking of this subject. With respect to this sector, some good examples include commercial cogeneration projects which yield CO2, and a slipstream of this flue gas is recovered, liquefied and purified to meet food standards in US, and other international projects.

During the 1990’s numerous CO2 projects were evaluated and planned for supply to the merchant gas sector, as a wholesale refined liquid product; and from these prospects emerged three US located merchant projects. Not all of these projects remain, such as the remaining AES Corporation’s Shady Point, Oklahoma CO2 source. The refined liquid CO2 from this cogeneration project is sold to the regional poultry industry as primarily a cryogen.

Other world markets have developed larger plants (greater than 50 tonnes per day) which recover from lean turbine exhaust or coal fired plants; which further require economic subsidies or placement in very expensive markets, in order to be economically viable.

Small plants (less than 50 tonnes per day) with dedicated combustion burn such fuels strictly for the sake of generating CO2 in flue gas, for an on-site CO2 recovery source. This is common in places such as Latin America, the Caribbean, and other regions where small gas companies generate for merchant supply, or sometimes remote soft drink plants generate CO2 on-site for process supply.

These situations require high CO2 values, and scarce supply from any other source type, such as a more enriched chemical production site (ethanol, ethylene oxide). Beyond specific opportunities for flue gas CO2 source plants, which usually include power generation and fuel combustion, CO2 is sometimes a commercial by-product from hydrocarbon separation plants of a larger commercial nature, again often utilising MEA or other amines in this solution recovery process.

This source of CO2 is a small percentage of merchant sourcing, compared to the rapid developments throughout the years from sectors such as ethanol production. As for ethanol production, here is a particularly interesting example of an energy-based fuel additive or replacement, which has grown by geometric proportions over the last few years.

Today, ethanol as a source for commercial CO2 is in the state of re-evaluation, since the critics have blamed ethanol production and the grains used for ethanol as leading to the coincidental or untimely foodstuff shortfalls and high prices, during a time when oil and food are at all time high levels. A very small percentage of grain is dedicated to ethanol production when compared with the food industry.

High food prices are driven by the high cost of energy – including the cost of fertiliser production, crop production, energy used in food processing, and the distribution of raw and processed foodstuffs. In any event, Brazil is flourishing with the ethanol and biodiesel industries today; and these sectors are expanding in this region of the world.

The other world markets will continue with ethanol, since there are few or no reasonable alternatives for hydrocarbon replacement; and as time progresses, more feedstock materials for fermentation will be derived from sweet sorghum, sugarcane, and cellulose-based materials; some of which as the enzymes and syngas processes are refined.

Many new ethanol projects from grains will continue in North America and elsewhere, despite the grain price and so-called shortage controversy. Ethanol as an energy-related fuel production source is a major CO2 emitter today. Some of this CO2 is recovered for the merchant CO2 trade, since it is generally very high in raw CO2 content and rather easy to refine.

Numerous CO2 streams from ethanol projects have been considered, or are now planned for enhanced oil recovery projects, when these projects meet specific strategic locations with respect to oil production feasibility and ethanol locations.

CO2 consumed in energy-based materials
The major areas of CO2 consumption include a very old technology; yet one re-emerging with great interest is that of EOR or enhanced oil recovery. Another old technology, but with less volume, in most cases would be so-called ‘frac’ used in natural gas stimulation projects.

Since nuclear power is now at the forefront of interest again globally, uranium value has risen substantially. In the recovery of uranium via in-situ applications, carbon dioxide is often a feedstock, along with other materials such as anhydrous ammonia; thus leaching via ammonium carbonate/bicarbonate.

The uranium production sector was somewhat dormant for decades and now, there is great interest due to many nuclear plants now under consideration or development.

With respect to a possible longer term home for CO2 in the energy sector, tests and applications with the use of nitrogen or carbon dioxide have taken place for enhanced coal bed methane (CBM) projects, which in short replace the molecules of methane with carbon dioxide in the coal bed seams.

With respect to EOR, the electric power firms have evaluated enhanced oil recovery as a possible home for their carbon dioxide emissions; however, developing successful cost-effective CO2 recovery methods (outside of the well proven amine projects) are very challenging – plus they essentially do not exist.

Adding to the cost of recovering CO2 from flue gas, there is also the demand for distribution and horsepower downstream of CO2 recovery as a further cost, but this could perhaps in part be borne by the oil company seeking the commodity for EOR use.

The electric utility sector has a way to go, from technology, cost effective, and strategic location perspectives. In the major existing and long-lived regions for EOR in the US, generally speaking of the Permian Basin (Texas, New Mexico region), and the Jackson Dome (Mississippi region), these projects have primarily been sourced by natural CO2 wells with high pressure.

These forms of CO2 sourcing have been of large volume and have been in place for years – plus have traditionally been the cheapest means of supply. Today, ethanol projects using grain as a feedstock are planned for EOR projects in the West of the US including projects in Kansas and Texas.

EOR projects are also sourced from natural means in Wyoming; and the Dakota Gasification plant near Beulah, ND is sourcing the large EOR projects operated by oil companies including Encana (which are under operation in Saskatchewan) with the CO2 delivered by pipeline.

Ethanol is supplying over 30 merchant plants in the US and growing; all of which are corn and grain based plants, and these plants are in some ways supplying CO2 to various projects which relate to certain aspects of the energy industry outside of oil and gas. For example, this includes CO2 for the uranium leaching process and CO2 use in metal fab operations which go to the energy producing sector.

The term ahead
Over the time ahead, environmentally friendly energy projects will of course try to reduce CO2 emissions from projects which generate energy, such as power plants and biofuels manufacturing.

As was mentioned before, the practical cost of recovering from lean CO2 streams, such as from gas and coal-fired power generation plants must concentrate the CO2 before the product travels through liquefaction/purification steps; and even today, the options for concentrating this lean raw CO2 gas stream are either too expensive, or not proven in technical and economic terms.

To achieve this end, certain membrane and ammonia refrigeration systems have been proposed; but we do not appear to have any proven technologies other than amine solution (and other old) methods as the feasible means of achieving this end. Until better or more efficient means of concentrating the flue gas sourced CO2 can be proven without a doubt, subsidies will be needed to use today’s successful options.

In the 1990’s, under now expired US energy laws, subsidies existed with cogeneration plants in the form of a thermal host. The cogenerated steam was used in the amine recovery process; thus the so-called thermal host. Something such as this must exist, in order to make the economics work; or new fully proven technologies will emerge which will then make flue gas recovery of CO2 a viable commercial option for sourcing CO2 to the energy and other sectors.

The demand for CO2 used in all forms of enhanced recovery of natural gas, oil, uranium and coal bed methane projects will grow even stronger. Today, as I am proofing this article, the value of oil is under US$130 per barrel and even if the value falls to $100/barrel, EOR remains a very viable option for production – assuming strategic location and CO2 sourcing make sense.

The basis for economic viability in all CO2 sourcing and applications projects in energy related ventures requires strategic location. This is why, even if economically viable flue gas recovery methods for supply to the EOR sector existed, the source would have to remain within a reasonable distance to the point of application.

The very large CO2 use for EOR projects will have to be delivered by pipeline rather than via road trucks, rail, or barge. The pipeline option has been the method for EOR supply to large project always, and this is the only means of effectively planning and controlling the cost of delivery.

Ensuring economic extraction
Enhanced oil recovery, can be a huge CO2 market, but the price of the commodity is a fraction of the value for the merchant sector; therefore a strategically located and long term placement is essential to make these projects viable.

In terms of the aforementioned frac technique, this sector is essentially the supply of CO2 to the natural gas producers, often via the service companies such as JB Hughes. The product is pumped downhole under high pressure, to stimulate gas production. The jobs which use CO2 in this form are priced considerably higher than EOR, and the volumes can range from a few tonnes, to several hundred tonnes per site.

Such larger jobs then require sizable on-location storage for the commodity, which is a part of the long-term investment in this sector. Both EOR and frac are tried and true, and are in high demand for today’s high priced energy markets, which are looking to squeeze as much hydrocarbon product out of the wells as economically possible.