FEATURE
Exploring Options for
CO2 Capture and Management Technologies for limiting emissions can be integrated into business operations, but some first require further development. CAROLA HANISCH
T
he Conference on Greenhouse Gas Control Technologies held last fall in Interlaken, Switzerland, revealed that interest in technological solutions to climate change has increased significantly since the Kyoto conference, Framework Convention on Climate Change. The meeting at Interlaken was attended by more than 500 participants, among them ABB CEO Goeran Lindahl, Shell Oil managing director Jeroen von der Veer, and Michael Zammit Cutajar, Executive Secretary of the United Nations Framework Convention on Climate Change. "Two years ago, capture and storage could easily be dismissed as something researchers [were] just dreaming of," said Paul Freund, project director at the International Energy Agency's (IEA) Greenhouse Gas R&D Program in Cheltenham, England. Now more and more, researchers see it as one possible option to achieve long-term stabilization of carbon dioxide concentrations. "This is the impulse from Kyoto. Suddenly, things come up that were unthinkable a couple of years ago," explained Baldur Eliasson, head of the Energy and Global Change section of ABB Corporate Research, Ltd., in Baden, Switzerland. Projects that offer economic benefit, such as using captured C0 2 for enhanced oil recovery or enhanced coalbed methane recovery, are being actively pursued. In Norway, advanced membrane
6 6 A • FEB. 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
absorption techniques for capture of C0 2 from offshore gas turbines are being developed. Financial benefit is being achieved by circumventing the country's high carbon taxes. A similar capture technique, which aims to separate C0 2 from cogeneration power plants and then to sell the gas to greenhouse owners, is being explored in The Netherlands. The most prominent new development project in power generation technology is under way in Norway. The huge energy, chemicals, and metals conglomerate Norsk Hydro is planning a 1300megawatt (MW) installed capacity hydrogen power plant. Almost three times the power-generating capacity of a standard European power plant, it will produce 10% of Norway's electricity. The facility will be built at Karmoy, on the country's west coast. Underground storage of C0 2 is currently the most advanced storage option. On the basis of two years' experience with C0 2 injection into an aquifer under the Norwegian North Sea, an international European research project is establishing guidelines for regulators—a best-practices manual to help them make decisions about future injection projects. Less mature storage options, such as ocean storage, are being investigated further through field experiments and computer simulations. © 1999 American Chemical Society
Hydrogen power looks promising The Norsk Hydro project will produce hydrogen from natural gas in a reforming process, which is a technology similar to that used for ammonia production. C0 2 is produced as a waste product. It will be separated using a conventional chemical absorption process and then pumped into the offshore Grane oilfield for use in enhanced oil-recovery operations. Over a period of 15 years, 4-5 million metric tons of C0 2 will be injected at the disposal site. The remaining hydrogen-rich gas stream will serve as a fuel in a combined-cycle power plant, producing electricity without emission of any C02. Tlie main emission of the power station will be water vapor. Some technical adjustments of existing turbines will be performed to accommodate this use of the hydrogen-rich fuel. "What we have here is the idea [that] instead of capturing C0 2 from exhaust gases, you do it before you burn," explained Olav Kaarstad, researcher at the Statoil R&D Center in Trondheim, Norway. This is much easier to do because C0 2 in the precombustion gas stream is more highly concentrated than in the postcombustion exhaust gases, and no oxygen is present that could degrade the liquid absorbant used to separate the C0 2 at this stage of the process. Harry Audus, project manager at the IEA Greenhouse Gas Programme, and Olav Bolland, from the Norwegian University of Science and Technology in Trondheim, calculated that the efficiency of a process similar to the Norsk Hydro project would be 49-50%, which is 9% lower than that of a natural gas-fired, combined-cycle power plant without C0 2 capture (1,2). Audus expects the cost of electricity to rise from about 2.5 cents per kilowatt hour to 3.4 cents per kilowatt hour, the increase reflecting the cost of avoiding carbon emissions. Why is Norsk Hydro engaging in such a project? There is a need for more electricity production in Norway. For two years the country has had to import more electricity than it exports. Moreover, Norsk Hydro is among the biggest consumers of electricity in Norway—it also produces aluminum and fertilizer and is very dependent on a stable power supply. "We have been holding back investment projects because of the lack of sufficient long-term [power supply] capabilities," explained Tor Steinum, from the Norsk Hydro press office. Despite pressing power supply needs, the Norwegian government is very reluctant to allow construction of regular gas-fired power plants, because the additional emissions of such plants would render it even more difficult for the country to meet its Kyoto convention goals. An emissionsfree power plant, however, is likely to be approved by the authorities. Another possible reason for the Norsk Hydro initiative is the country's carbon tax. Today, the tariff mainly applies to offshore operations, because no onshore power production from fossil fuels exists; however, if a substantial amount of C0 2 emissions were produced from land-based generation, the tax might be extended to cover that source, too.
Kvaerner Oil & Gas and W. L Gore & Associates GmbH have initiated a joint industry research and development project that will remove C0 2 from flue gas using gas-liquid membrane contactors. For comparison purposes, the pilot unit shown here, which is located at Statoil K-lab, Karste, Norway, has been designed with both membrane absorber and desorber, as well as conventional columns. (Courtesy Kvaemer Oil & Gas)
The operators of a C02-free plant would not have to worry about that possibility. "For Norsk Hydro, this is a very important project, and we are presently putting huge resources into it," said project vice president Niels Schweigaard. The economics of the hydrogen plant are still unclear. The sale of C0 2 for enhanced oil recovery will provide some commercial benefit, and the electricity generated by the new Norsk Hydro power plant might partly replace demand for power from offshore gas turbines, thereby avoiding carbon taxes and contributing to a lowering of C0 2 emissions. However, despite these benefits, some researchers, such as Erik Lindeberg of IKU Petroleum Research Institute in Trondheim, do not believe that the company will realize a profit from the use of the process. "In my opinion, they are doing it for some other This is a strategic decision. They sire accepting that in the future the cost of fossil energy is going to be higher so they adapt now" he said. Norsk Hydro is currently working out the technical details of the project. They must file an application with government authorities who must then decide whether to approve the project. Once the project is approved, commercial negotiations can begin. The owners (Norsk Hydro, Exxon, and Statoil) of the Grane oil field must be convinced to purchase the C0 2 , and the purchase of natural gas, as well as the sale of electricity, must be negotiated. The final decision on the construction of the plant is expected to be made in April. The hydrogen power station could start production in 2002 or 2003. FEB. 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 6 7 A
Stevens estimated the worldwide sequestration CO2 management incentives There are practicalreasonsfor wanting to capture C02— potential of C02 in deep coalbeds, using the Allison Unit Norway will be the first to use C0 2 from a power plant pilot test results as a benchmark. He calculated that for enhanced oil recovery. C0 2 obtained from a coal 5-15 Gt (metric ton units) of C0 2 could be sequesgasification plant in the United States will be used for tered, generating a net profit at $15 per metric ton; 60 Gt the same purpose. In the United States, C0 2 is com- may be sequestered at moderate costs of under $50 per monly used for enhanced oil recovery (EOR). About metric ton; and 150 Gt (metric ton units) could be 60 million cubic meters per day (since mid-1998) sequestered at costs of $100-$120 per metric ton. of pure C0 2 are being injected at 67 commercial Although naturally occurring C0 2 is currently used EOR projects, mostiy in west Texas—50% stays in in the pilot project, researchers believe the process the reservoir, and the might be used in future commercial applications— remaining 50% comes for null-greenhouse-gas-emission power plants. Bill up with the oil during Gunter, group leader of Applied Geochemistry at the "This is a strategic recovery (3). This gas Alberta Research Council in Edmonton, envisions a decision. They [Norsk is collected, compress- cycle in which power plants are fueled by methane ed, and reinjected. In that originates from coal beds at the same time that Hydro] are accepting this way, the majority waste C0 2 is injected into the coal reservoirs to proof the greenhouse gas duce more methane, thereby closing the cycle (5). The t h a t in t h e future t h e remains permanently Alberta Research Council is also leading another pilot project for enhanced coalbed methane recovery stored underground. cost of fossil energy is In most cases, how- in Alberta, supported by Canadian and U.S. governever, C0 2 from natural ment organizations and industry partners. going t o be higher, so sources is used, such as they adapt n o w , " C0 2 from natural gas Membrane technology options processing. In June Currently, C0 2 capture and sequestration applications 1997, PanCanadian Pe- are limited to special projects that offer commercial troleum, Ltd, of Cal- benefits, because capture is a very energy-intensive proErik Lindeberg gary, agreed to buy C0 2 cedure thatrequireslarge—and expensive—equipment IKU Petroleum from the Great Plains New membrane technologies, however, might allow furResearch Institute, coal-gasification plant ther applications of C0 2 capture technology (6). in Beulah, N.Dak. Be- Kvaerner, a Norwegian company, has developed a novel Trondheim, Norway. ginning in late 1999, ap- membrane absorption process that is small and comproximately 5000 met- pact (see photo on previous page). This process will be ric tons per day of the used on offshore gas turbines. These facilities are catgreenhouse gas will be pumped through a 330-km egorically a major emitter of C0 2 in Norway and pay pipeline to the Weyburn oil field in the Canadian very high (carbon) taxes. province of Saskatchewan (3). Through enhanced oil Total Norwegian offshore C0 2 emissions were aprecovery the lifetime of the oil field will be ex- proximately 11 million metric tons per year in 1998. tended by as much as 25 years The contribution from offshore gas turbines is apAt the synthetic fuels plant operated by the Da- proximately 83%, which could be reduced by 30% if kota Gasification Company, 16,200 metric tons of lig- the new C0 2 removal process were installed on suitnite coal are converted daily into 3.54 million cubic able platforms. Currently available C0 2 capture prometers of pipeline-quality natural gas, 900 metric tons cess technology cannot be used on offshore platof anhydrous ammonia, and other byproducts. Rev- forms because the equipment is too big and too enues from byproducts exceed those realized from heavy. It consists of absorption towers 20-40 meters sale and use of the synthetic natural gas. Capture of high, in which exhaust gas is bubbled through an C0 2 and its utilization for enhanced oil recovery rep- amine solution that is used as an absorption liquid. resent a further diversification of the company's by- In an additional desorption tower, as needed, the C02-loaded liquid is heated to free the gas. products business. Besides enhanced oil recovery, another commerIn the new process, the exhaust gas flows through cially interesting use of captured C0 2 is emerging: in- small Teflon membrane fibers, which are surjection into deep coal seams to enhance methane re- rounded by the absorption liquid. C0 2 passes through covery. Initial results from the world's first pilot project the membrane and is carried away by the liquid. The show this new technology to be technically and eco- huge membrane surface area results in a highly nomically feasible, according to Scott H. Stevens, vice efficient absorption process, thereby reducing the size president of Advanced Resources International, Inc., of the equipment that is used by 78% and the weight in Arlington, Va. Since 1996, Burlington Reeources has by 66%. Kvaerner is planning to build the first sequestered over 57 million cubic meters of C0 2 in commercial capture unit in 2000 or 2001. coal seams at its Allison Unit production pilot, loThe Dutch TNO Institute of Environmental Studcated in the northern San Juan basin in New Mex- ies in Apeldoorn, The Netherlands, is developing a simico (4). The C0 2 gas is absorbed on the coal sur- ilar membrane gas absorber that can be used for C0 2 face, thereby replacing and freeing methane. Two capture in cogeneration plants. This would be an enmolecules of CO are trapped for every molecule of vironmentally friendly way of delivering both heat and methane released. C0 2 to greenhouse growers. Currently, in The Nether6 8 A • FEB. 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
lands, greenhouse growers often burn natural gas in small boilers to produce C0 2 and heat. This is very inefficient; they need C0 2 during the day and heat during the night. A cogeneration plant that produces electricity, waste heat, and waste C0 2 would be a much better use of fossil resources. However, regular C02 capture equipment is again too expensive, and absorption tower height is a problem. "In a flat country like The Netherlands, in many areas you are not allowed to erect structures more than 15 meters high," explained project manager Paul H. M. Feron, of TNO. He explained further that die membrane gas absorber is only 2 meters high (7) and mat the CO, available from application of the membrane technology would be 20% cheaper man mat produced by just burning gas. In contrast to Kvaerner, TNO uses commercially available polypropylene membranes. They cannot be used with the conventional amine absorption liquid so Dutch engineers had to develop a new type of liquid to absorb the gas The principle of the process however is similar to Kvaerner's In four or five year,s a full-scale plant is expected to be constructed Feron estimated that a market exists for 10 coeeneration plants in The Netherlands that use memhrane-hased CO capture thus sunnlving 1 (W of the rnuntrv's total ereenhous'es with CO Ocean and aquifer storage Even as new capture and sequestration options are being developed, the world's first project of mis kind is well under way in the Norwegian Norm Sea (see photo at right). "After a few small disturbances in the beginning, the Sleipner project is running fine," said Tore Torp from the Statoil Research and Development Center in Trondheim, Norway. He noted that scientists and an environmentally engaged public are interested in what happens when C0 2 is spread out in a salt water layer. He explained that this is why Statoil, several industrial partners, and European research institutes started an international monitoring project last November. Project researchers want to learn where and how the C0 2 bubble moves in order to validate computer simulation models. Investigators are using seismic and gravimetric measurements to collect data needed to put the models on a firm basis. At the end of this three-year, European Community (EC)supported project, they want to put together a bestpractice manual for future C0 2 injection projects. Torp explained, "This is supposed to help regulators set up guidelines. They need to decide on what terms C0 2 injection should be allowed, for example, what research exploration should be done in advance, what models should be used, what methods can be relied on and what documentation should be presented." Meanwhile, ocean storage, a less mature storage option, is being explored further. In December 1997, Japan, Norway, and the United States signed a project agreement for collaboration on a pilot-scale field experiment for the Climate Technology Initiative of die Framework Convention on Climate Change. Since then, Canada and ABB, a Swiss company based in Zurich, have joined the project. The experiment will
As part of an ongoing project, C0 2 is being separated from natural gas and pumped into a huge aquifer 800 meters below the ocean floor off the coast of Norway in the North Sea. Information obtained from this undertaking will guide the development of a best-practices manual for similar future projects by other companies to limit uncontrolled emissions of C0 2 . (Courtesy 0yvind Hagen, Statoil)
take place off die Kona coast of Hawaii in the summer of 2000. A pipeline will be laid on the seafloor, and liquid, buoyant C0 2 droplets will be released at a depth of 1000 meters (8). So far, researchers have gained all their knowledge on ocean disposal from laboratory and theoretical work; they need validation with real-world results. Up to 1 kilogram per second of C0 2 will be injected into the ocean, an amount that is roughly equivalent to 1% of the C0 2 exhaust from a 500-MW coal-fired power plant. The behavior of the injected C0 2 plume will be monitored with the help of instruments mounted on a remotely operated vehicle and on the seafloor. "We want to learn the physics and the chemistry of the C02-seawater interaction," explained Eric Adams, senior research engineer at Massachusetts Institute of Technology in Cambridge. Collected, information can then be fed into computer models to scale up and simulate biological impacts. James C. Orr, researcher at the Laboratoire des Sciences du Climat et de l'Environnement/ Commisariat a l'Energie Atomique in Gif sur Yvette, France, is trying to address the question of how long the injected C0 2 might stay isolated from the atmosphere. Orr is coordinating a project called GOSAC (Global Ocean Storage of Anthropogenic Carbon), which has just started and is funded by the EC and the IEA Greenhouse Gas R&D Program. The GOSAC effort includes a comparison of seven European general ocean circulation models to estimate the time for injected C0 to be lost back to the atmosphere. Orr's preliminary results reveal a negative feedback, due to indirect effects, which reduces the effectiveness of permanent ocean sequestration (9). FEB. 1, 1999/ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 6 9 A
After a 200-year simulation of a permanent sequestration scenario, he found that the approach was only 80% efficient compared with a business-as-usual reference scenario with no COz capture. The reason is that, in the permanent sequestration scenario, there is a lower atmospheric concentration of C0 2 than in a scenario with no C0 2 capture. Ocean uptake of C0 2 is reduced compared with a situation in which a higher C0 2 atmospheric concentration exists. In re-
(3)
(4)
ality, not all injected C02 would remain in t h e ocean. Orr s i m u l a t e d t w o s c e n a r i o s , one with C0 2 sequestration at 1500-meters depth and the other at 3000-meters depth. His results show that after 200 hundred years, 18% of the C02 injected at 1500 meters is lost to the atmosphere, and 8% of the
(5) (6)
CO injected at d i e greater o c e a n d e p m escapes after
that period. Researchers agree that more studies are necessary to determine the effectiveness of C0 2 sequestration, to learn about biological impacts and odier environmental risks, and to lower costs. Then, they say, it is up to the politicians, the lawyers, and the public to decide whether C0 2 capture and storage should be applied on a broad scale or whetiier alternatives are necessary.
(7)
(8)
(9)
References (1) Audus, H.; Kaarstad, O.; Skinner, G. C0 2 Capture by PreCombustion Decarbonisation of Natural Gas. Presented at the Fourth International Conference on GHG Control Technologies, Interlaken, Switzerland, Aug. 1998. (2) Bolland, O.; Undrum, H. Removal of C0 2 from Gas Tur-
bine Power Plants: Evaluation of Pre- and Postcombustion Methods. Presented at the Fourth International Conference on GHG Control Technologies, Interlaken, Switzerland, Aug. 1998. Hattenbach, R. P.; Wilson, M.; Brown, K. R. Capture of Carbon Dioxide from Coal Combustion and Its Utilization of Enhanced Oil Recovery. Presented at the Fourth International Conference on GHG Control Technologies, Interlaken, Switzerland, Aug. 1998. Stevens, S. H.; Kuuskraa, V A.; Spector, D.; Riember, P. C0 2 Sequestration in Deep Coal Seams: Pilot Results and Worldwide Potential. Presented at the Fourth International Conference on GHG Control Technologies, Interlaken, Switzerland, Aug. 1998. Gunter, W. D.; Gentzis, T; Rottenfusser B. A.; Richardson, R.J.H. Energy Convers. Mgmt. 1997, 38(Suppl.), S217S222. Dannstroem, H.; Sobye, M.; Gronvold, M.K.S. Development of Absorption Process for Separation of Carbon Dioxide from Offshore Gas Turbine Exhaust. Presented at the Fourth International Conference on GHG Control Technologies, Interlaken, Switzerland, Aug. 1998. Feron, P.H.M.; Jansen, A. E. Technoeconomic Assessment of Membrane Gas Absorption for the Production of Carbon Dioxide from Flue Gas. Presented at the Fourth International Conference on GHG Control Technologies, Interlaken, Switzerland, Aug. 1998. Adams, E.; Akai, M.; Golmen, L.; Haugan, P.; Herzog, H.; Masuda, S.; Masutani, S.; Ohsuma, T; Wong, C. S. An International Experiment on C0 2 Ocean Sequestration. Presented at the Fourth International Conference on GHG Control Technologies, Interlaken, Switzerland, Aug. 1998. Orr, J. C; Aumont, O. Exploring the Capacity of the Ocean to Retain Artificially Sequestered C0 2 . Presented at the Fourth International Conference on GHG Control Technologies, Interlaken, Switzerland, Aug. 1998.
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