Science in Society Archive

Carbon Capture and Storage: Still Not An Option

Eliminating carbon from power plant emissions is cost-prohibitive and environmentally counterproductive Jeffrey H. Michel

Editor’s note: This is an important update on our previous assessment [1] Carbon Capture and Storage A False Solution (SiS 39)

Capping emissions at large point sources

A general consensus prevails that carbon dioxide emissions from fossil fuel combustion are the most significant cause of climate change. Rising anthropogenic CO2 concentrations in the atmosphere are likewise diminishing ocean pH levels, imperilling aquatic food chains. Heating furnaces and automobiles are majority culprits, but the infinitesimal emissions from these individual sources have yet to be eliminated by alternative technologies. By comparison, large coal-fired plants collectively emit several billions tonnes of carbon dioxide worldwide that could be hypothetically captured at source and stored in geological repositories.

Suitable amine-based washing columns and selective diffusion membranes are already being employed by the natural gas industry for removing carbon dioxide from raw gas to meet market requirements. This separated CO2 may be subsequently injected into oil and gas fields to increase extraction yields. More than 6 000 kilometres of dedicated pipelines have been laid in North America since the 1970s for distributing CO2 to existing well heads for enhanced oil recovery (EOR).  

A quarter million barrels of petroleum are extracted per day in the United States alone by EOR, comprising about 5% of total domestic production [2]. On average, a short ton of injected CO2 coaxes an additional 3.6 barrels of oil from reservoirs abandoned after conventional drilling [3].  As oil prices rise, even greater quantities can be recovered using more intensive production techniques. Up to 1.5 billion barrels of oil may ultimately be produced by flooding candidate fields in Texas with 200 million tons of CO2 [4], realizing an EOR ratio of 1 to 7.5. North of the Canadian border in Weyburn, Saskatchewan, a production ratio of 1:6 has been attained using carbon dioxide piped from a lignite gasification plant in North Dakota.

Although some EOR opportunities exist in the European Union, the dominance of offshore production makes higher oil revenues necessary to justify investment expenditures. However, six pilot carbon capture and storage (CCS) projects are currently being subsidized by the EU Strategic Energy Technology (SET) Plan [5] only for reducing CO2 burdens under the Emissions Trading Scheme (ETS). Carbon capture technologies not employed for natural gas purification are being additionally developed. The oxyfuel process burns carbon in pure oxygen to produce a CO2 effluent stream that may be directly captured. Integrated gasification combined cycle (IGCC) plants convert fossil fuels to hydrogen and carbon dioxide for pre-combustion gas separation. In the carbonate looping process, effluent CO2 is combined with calcium oxide to form the carbonate (limestone CaCO3), which releases the carbon dioxide when subsequently heated for calcium recycling. These high-efficiency technologies are employed for new plant construction. Yet unless EOR revenues or public subsidies are available, the expense of CCS implementation can only be covered by avoided emission trading costs, supplemented if necessary by increased utility rates for CO2-reduced electricity.

Pricing CO2 emissions

In North America, a ton of CO2 at a field-delivered price of less than $30 can generate EOR income worth hundreds of dollars. CCS provides no comparable profit opportunities within the scope of EU climate protection strategies, as the market price of carbon dioxide avoidance is essentially determined by ETS trading penalties. At this level, a climate-driven CO2 capture and storage infrastructure has no commercial justification anywhere in the world.

A 2009 symposium at the Massachusetts Institute of Technology estimated that retrofitting existing power stations using “current and evolutionary amine-based capture technology” would involve equipment expenditures “generally in the $50-70/ton of CO2 range for the Nth-plant” (i.e., with plant costs reduced by standardized construction, but exclusive of transport and storage) [6]. The average expense of a complete CCS process chain in the United States has been estimated at $125 per ton of CO2 [7]. The US Department of Energy (DOE) calculates that “carbon capture will add over 30 percent to the cost of electricity for new integrated gasification combined cycle (IGCC) units and over 80 percent to the cost of electricity if retrofitted to existing pulverized coal (PC) units [8].

In a German study released in March 2009, McKinsey & Company assumed that CO2e trading certificates in the EU would be rising to 35 € per tonne in 2020 and 40 €/t in 2030 [9]. The potential inaccuracy of these expectations is indicated by the projection of 25 €/t made for 2010, nearly twice the ETS levels actually achieved. An EU study released in August 2010 predicted that certificate prices would increase by only 7 percent to 16.5 €/t in 2020 and 18.7 €/t in 2030 [10]. McKinsey has relied on a significantly higher “median carbon price of € 35 per tonne CO2” [11] in assessing the international prospects of carbon reduction funding.

The ETS and other means of CO2 reduction cannot ultimately be priced higher than the cost of ecological detriments they are capable of preventing. In 2002, the British Department of Environment Food and Rural Affairs (DEFRA) surveyed previous estimates of the Social Cost of Carbon (SCC) that expresses the comprehensive effects of carbon emissions on social and economic life [12]. By 2007, a SCC figure of 42 €/t CO2 had been estimated for the year 2020 [13], which is considerably higher than ETS projections.

The alternative Shadow Price of Carbon (SPC) indicates the cost of technologies and policies currently necessary for achieving a future atmospheric CO2 concentration target [14]. The British SPC of £25/tCO2e set in 2007, equivalent to roughly 35 €/tCO2e at the prevailing exchange rate, was considered necessary at that time to prevent CO2 concentrations from ultimately rising above 450 to 550 ppm under the assumption of equitable international participation.

These earlier estimates have since been eclipsed by growing carbon dioxide emission levels from global fossil fuel use. The United Kingdom abandoned calculation of the SCC altogether in 2009, basing its carbon price estimates instead on mitigation costs in [15] “a range of $41 - $124 per ton of CO2, with a central case of $83.”

Although increasing social costs for carbon may justify more expensive avoidance measures, the international dimension of climate change also requires CO2-reduced technologies that are affordable for less affluent countries. The prospect of cost-effective solutions being adopted from Europe is limited, however, by insufficient capital returns on the required outlays.

The German Advisory Council on the Environment (SRU) quotes figures from various studies between 30 and 64 € per tonne of avoided CO2 for new power plants and 53 to 97 €/t for retrofits [16]. The German Institute for Economic Research (DIW) calculates that electricity generation costs would increase by 48 - 92% when produced by coal plants with CO2 capture [17]. Power markets cannot honour these projections to the exclusion of lower priced alternatives that range from nuclear generation to renewable energies and load management techniques. 

An investigation coordinated by the VTT Technical Research Centre of Finland has determined that a reduction of that country’s carbon dioxide emissions by 10 – 30 percent “could be achieved with CCS technology by 2050” only if “the price level for emission allowances rises to 70 - 90 euros per tonne carbon dioxide” by that time [18]. The Norwegian Bellona Foundation has justified the adoption of CCS with allowances rising to 50 €/t in 2030 and 90 €/t in 2050 [19]; these forecasts are assumed to reflect a “relatively conservative future EU climate policy, which imposes a slow and steady reduction in the European cap on CO2 emissions through 2050”. However, Bellona notes that raising emissions prices to the level required for CCS investments has proved to be “incredibly difficult” as a political objective [20]. Planning complexities and major cost overruns have resulted in revisions, postponements, and cancellations of projects in several European countries as well as the United States and Australia.

Impediments to CCS implementation

In a CCS process chain, as much as a third of a power plant’s output may be required for CO2 separation, compression, and transport. An energy-intensive pipeline pressure of up to 200 atmospheres (atm) is necessary to preclude phase changes occurring before the compressed carbon dioxide reaches the geological storage repository, where it is injected to a depth exceeding 800 meters to maintain a supercritical pressure of 72.9 atm for maximum penetration.

Additional generating capacities are therefore required, often at a second power plant, to restore the electrical energy lost to CCS. Up to twice the water per delivered kilowatt-hour must be ultimately withdrawn from local rivers or aquifers for expanded steam production, and to dissipate the heat of CO2 compression [21]. Local water usage restrictions may thus preclude a CCS power plant retrofit. Conventional generation without CO2 controls can prove equally competitive, even under a highly restricted carbon regime, due to lower fuel and water requirements.

Early CCS proposals assumed that CO2 post-capture retrofits could be easily realized at existing coal power stations. However, flue gas separation equipment the size of an airplane hangar and intensified water withdrawal are not practicable at many plant sites. Most installations have already absolved a significant portion of their normal service life and are unsuitable for cost-intensive reconfiguration. Initial commercial CCS implementation is anticipated only after 2020. Hundreds of plants already under construction or in final planning, and all existing coal generating facilities worldwide have been designed with no intention of CO2 capture or geological storage. A comprehensive CCS programme capable of moderating climate impacts would thus only be feasible after current plants had been retired. By that time, however, adequate fuel supplies cannot be guaranteed for coal-based replacement capacities, as will be discussed below.

Revenue enhancement from oil extraction with carbon dioxide

Improved CO2 separation technologies benefit the petroleum industry. The Alberta Carbon Capture and Storage Development Council has estimated that with an oil price of $75 per barrel and a field-delivered CO2 price of $20 per tonne, “proven recovery techniques have the potential to add 1.4 billion barrels of incremental oil and sequester 450 Mt of CO2” [22]. EOR may thus deliver several times the revenues of CO2 procurement even after associated energy expenditures have been deducted.

Pressurized CO2 may also be used as a fracturing agent for extracting both conventional and shale gas trapped in dense geological formations. In the German natural gas industry, several thousand tonnes of carbon dioxide were injected by Exxon in 26 instances between 2007 and 2010, with CO2 comprising 30 – 70 percent of the fracture fluid [23].

CCS obstructive to climate protection

CCS as a future corrective technology serves as a pretext to continue inherited coal usage. In addition, improving the means of CO2 capture may contribute to expanding oil and gas production. This capability contradicts emission reduction efforts by introducing additional hydrocarbons into the biosphere that otherwise would have remained geologically inaccessible. In these respects, the EU-SET Plan reinforces fossil fuel infrastructures rather than superseding them.

When all factors contributing to the extraction, processing, and combustion of crude oil are combined, the average life cycle emissions (excluding petroleum product transport) of North American petroleum are approximately 500 kg CO2e per barrel [24]. In Alberta, the injection of one tonne of CO2 therefore results in 0.625 net life cycle tonnes of greenhouse gas emissions ((3.25 x 0.5) - 1). The current average for EOR operations in the United States is 0.8 tonnes, while the corresponding ratio in Texas may be as high as 1:2.75.

Dwindling coal reserves amid rapidly increasing demand

Global coal consumption has greatly surpassed levels anticipated only a few years ago. A Chinese industry study released in 2003 predicted domestic coal usage of 1,720 million tonnes in the year 2010 and 1 950 – 2 100 million tonnes by 2020 [25]. The actual demand trajectory has since exceeded twice these amounts and outdistanced earlier forecasts for global consumption. Chinese coal production is now expected to attain four billion tonnes by 2015 [26], which nevertheless will be less than half of worldwide demand. With imports rising, China and India have begun to buy foreign mining operations to secure long-term supplies of coal [27].

If present usage trends continue, all published coal reserves of some 800 billion tonnes [28] would be mathematically depleted within 60 years even without the added energy requirements of CCS process chains. Coal exporting countries may therefore become highly restrictive in supplying the world market, fundamentally limiting fuel availabilities for CO2-reduced generation. Under this circumstance, CCS could remain the preoccupation of coal-endowed countries, particularly when employed for enhanced oil recovery. Certain CCS costs would thereby be defrayed, but at the expense of additional environmental detriments.

Global climate projections that predicate wide coal availability in the latter part of this century rest on untenable premises. Climate change models should be revised accordingly, particularly since twice as much CO2 is currently being emitted from coal than earlier assumed.

Jeffrey H. Michel is a US-born energy researcher living in Hamburg, Germany. His investigations include German lignite and CCS policy issues, electronic power metering, and renewable energy deployment. He is a regular contributor to the Air Pollution & Climate Secretariat in Gothenburg, Sweden.

Article first published 04/07/11



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There are 2 comments on this article so far. Add your comment above.

Rory Short Comment left 4th July 2011 17:05:44
The reality is that humans have been living in an unsustainable manner for millennia. The deleterious impact of this way of living has just become more and more serious with the passage of time until now it is increasingly threatening the very existence of more and more people. We actually have no option but to devote all our efforts to switching to sustainable ways of living, anything else is nothing but fiddling whilst Rome burns.

Todd Millions Comment left 5th July 2011 22:10:40
A good overveiw-Not many remember that this 'new'C02 injection that requires such massive technology subsidy has being used since the 1970's to enhance recovery of old well feilds. A couple points not covered- 1- CBC reports that the gov of Alberta is going to count each unit of C02 from the tar sands injected as 2 units on their carbon trade accounting.Guess tar sands gas is the new 'reserve currency', how enron. 2-Under Nafta(chapter11),Canadian C02 injected into americian feilds,or Americain gas into canadian ones,in the event of a blow out or other problems,leaves the corprations whose gas feilds that are injected- exempt from all liability.Any damages are the liability of the goverment that approved the shipment.A point some provincial preimers(see; Saskatchewan),seem incapable of grasping.

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