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“Green coal”: how to scale up Carbon Capture and Storage from power generation?

April 26th, 2012 by Francois Hamon, Mines ParisTech

According to the IEA, Carbon Capture and Storage (CCS) technologies are crucial to cut down greenhouse gas (GHG) emissions. In the most ambitious scenario in terms of reduction of GHG emissions (450 scenario ), CCS has a significant role to play and would be implemented worldwide before the end of the 2020′s. Is it realistic to consider CCS technologies, which are still not mature and uncertain, as a major climate change mitigation option?

The power sector currently causes 41% of global energy-related CO2 emissions. Furthermore, the IEA expects coal use for electricity generation to rise by 25% by 2035. In this context, it is crucial to cut down GHG emissions in the power sector in order to contain temperature increase. That is why CCS applied to power generation (mainly to coal-fired power plants) could have a massive impact.

Currently, there are only 14 large-scale CCS projects in operation or under construction in the world (only 2 of them are dedicated to power generation). Their total CO2 storage capacity is 33 million tons a year (Mt/yr). To contribute significantly to the reduction of GHG emissions, CCS projects have to reach a storage capacity on the scale of several billion tons a year (Gt/yr). It implies a massive investment during the next decades. Let’s examine some of the issues that need to be addressed in order to scale up CCS projects for power generation and make “green coal” commercially viable.

The cost of Carbon Capture and Storage from power generation

Estimating the cost of CCS technologies (measured in $/ton of CO2 avoided) is a great challenge. There are currently various technologies in competition for the capture of CO2 (pre-, post- and oxyfuel combustion) and for the geological storage. Most of them have already been implemented separately for other purposes (mainly in the oil & gas industry), but large-scale and fully integrated CCS applications are still in the demonstration phase.

Building and operating a coal-fired plant with CCS generates additional expenses. The additional capture-specific equipment is not the only cost-driver. Coal-fired power plants with CCS would be at least 20% less efficient than without CCS (“energy penalty”). To produce the same amount of power as the reference plant without CCS, coal-fired plants with CCS require greater fuel consumption and need to be oversized. As a result, CCS technologies generate an increase in both initial capital expenditures and operating expenditures. (Note that the cost of retrofitting existing coal-fired plants would be significantly higher). The cost of electricity produced would increase by 55-65%, depending on the technology.

To the IEA, the cost of CO2 capture for a large-scale commercial deployment of CCS technology in 2020 (the early commercial phase) is expected to be around 55 $/ton of CO2 avoided. When the costs of CO2 transportation and storage (highly dependent on location) are added up, the total cost is expected to reach 60-65 $/ton of CO2 avoided.

Such a cost implies that the commercial deployment of CCS is dependent on policy and regulatory frameworks. It requires a climate policy that would set a carbon price and fund innovative CCS demonstration projects to make the cost of the ton of CO2 avoided decrease thanks to a learning effect. Without such a framework, the widespread deployment of CCS seems unlikely.

(Scaling up carbon dioxide capture and storage: From megatons to gigatons, H. Herzog)

Transportation infrastructure and storage capacity

Pipeline transport of CO2 is a well developed technology that has been used for Enhanced Oil Recovery in the US. However, building a vast pipeline network to link coal-fired power plants and storage areas would require a huge investment. To H. Herzog from MIT, this issue is a “chicken and egg” problem: on the one hand, an existing pipeline network is a prerequisite to scale up CCS power generation facilities, but on the other hand, investors won’t finance pipeline network if CCS deployment is still at an early stage.

Several kinds of geological storage can be considered: depleted reservoirs, non-depleted reservoirs (EOR), deep saline aquifers. In its 2008 report about CCS, McKinsey underlines that the availability and location of sites developed for CO2 storage will strongly affect the design of the transportation network. For instance, in Europe, depleted reservoirs are mainly offshore, located in the North Sea, far from the most industrialized areas, which could greatly increase the transportation costs.

The overall storage capacity was estimated in the IPCC 2005 report at 1678 Gt of CO2 (lower estimate), which is a significant amount compared to the expected CCS contribution to the reduction of CO2 emissions (on the scale of billion tons per year).

François Hamon, Mines ParisTech

SOURCES
− World Energy Outlook 2011, International Energy Agency
− IPCC Special Report on Carbon Dioxide Capture and Storage, 2005
− The Global Status of CCS: 2011, The Global CCS Institute
− Scaling up carbon dioxide capture and storage: From megatons to gigatons, H. Herzog (MIT) in Energy Economics, 2009
− Cost and Performance of Carbon Dioxide Capture from Power Generation, International Energy Agency, 2011
− Carbon Capture and Storage, Assessing the economics, McKinsey, 2008
− Sectoral approaches in electricity, IEA, 2009

However, the biggest uncertainty is on how the CO2 stored in the subsurface will behave after the injection. CO2 migration and leakage might occur, that is why long-term monitoring of the storage area will be required. Even if oil companies have a long experience in subsurface monitoring technologies, the duration of the monitoring is still highly controversial (see discussions in the IPCC 2005 report), as well as the potential leakage amounts. A leaking storage reservoir might become a CO2 emissions source. Solving this issue is a prerequisite for the commercial deployment of CCS technologies, and would enable them to gain public acceptance.

Conclusion

Given all these uncertainties about CCS technologies and their cost, the commercial deployment of “green coal” in the medium-term remains unlikely. Some countries like Australia count on CCS technologies to reduce their GHG emissions, and conduct advanced research on the subject. This is a risky bet. However, setting a carbon price could trigger off CCS deployment. Thanks to major technological breakthroughs, the cost of electricity produced with coal-fired plants with CCS could also sharply decrease, which would make CCS technologies relatively cheaper than the other power generation technologies (solar, offshore wind).

François Hamon, Mines ParisTech

Sources

− World Energy Outlook 2011, International Energy Agency
− IPCC Special Report on Carbon Dioxide Capture and Storage, 2005
− The Global Status of CCS: 2011, The Global CCS Institute
− Scaling up carbon dioxide capture and storage: From megatons to gigatons, H. Herzog (MIT) in Energy Economics, 2009
− Cost and Performance of Carbon Dioxide Capture from Power Generation, International Energy Agency, 2011
− Carbon Capture and Storage, Assessing the economics, McKinsey, 2008
− Sectoral approaches in electricity, IEA, 2009

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3 Responses to ““Green coal”: how to scale up Carbon Capture and Storage from power generation?”

  1. Steven Stoft Says:

    Excellent article. Thanks.
    This might be of interest. It’s from some correspondence with the Clean Air Task Force.

    More encouragingly, our separate effort to connect innovative US and Chinese energy companies has continued to make important strides. Most recently, we helped facilitate the partnership between GreatPoint Energy and Wanxiang Holdings Group. Wanxiang’s investment will allow GPE’s catalytic gasification technology (with 90% carbon capture) to be built at commercial scale.

    We’ve also been working to familiarize Chinese energy companies with CO2-flood enhanced oil recovery (EOR). From what we can tell, a shortage in deliverable CO2 is actually serving as a brake on expanded EOR use in the US. Consequently, EOR could be an important driver in the development of carbon capture technologies around the world — most notably, post-combustion capture systems for China’s enormous fleet of brand new conventional coal units.

    We’re supportive of a legislative measure that would promote EOR in the US. According to initial projections, if the proposal is enacted it would increase US oil production after 10-12 years by approximately 3.6 million barrels per year.

  2. Steve Leary Says:

    “Green Coal”?

    The suggestion that coal can be made ‘green’ because potentially CCS can reduce Carbon emissions assumes that the extraction of coal in the first place is non problematic. This is a highly contentious assumption. In the UK more than half of our domestic coal production is from opencast / openpit / surface mining. Each new application normally generates local opposition because of the environmental impact of such proposals unless land remediation is involved and even that can be controversial, witness the ongoing controversy over the Foss-y-Fran scheme in Wales.

    In the USA the similar issue of Mountaintop Removal also invokes similar resistance because of the destructive and polluting procedures associated with such strip mining methods.

    I just cannot see how coal can ever be thought of as ‘green’ as long as a significant proportion of the coal used for power generation and in the metallurgical industries is produced by such methods. Until this method of coal extraction is significantly reduced,coal will always be black and environmentally damaging as a source of fuel.

  3. Steve Leary Says:

    “Clean or what David Cameron once called “Green” Coal”?

    The suggestion that coal can be made ‘clean’ ‘because potentially CCS can reduce Carbon emissions assumes that the extraction of coal in the first place is non problematic. This is a highly contentious assumption. In the UK more than half of our domestic coal production is from opencast / openpit / surface mining. Each new application normally generates local opposition because of the environmental impact of such proposals unless land remediation is involved and even that can be controversial, witness the ongoing controversy over the Foss-y-Fran scheme in Wales.

    In the USA the similar issue of Mountaintop Removal also invokes similar resistance because of the destructive and polluting procedures associated with such strip mining methods.

    I just cannot see how coal can ever be thought of as ‘clean’ as long as a significant proportion of the coal used for power generation and in the metallurgical industries is produced by such methods. Until this method of coal extraction is significantly reduced,coal will always be black and environmentally damaging and unacceptable as a source of fuel.

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