What are the options for the vast stores of coal around the world?
- What are the options for the vast stores of coal around the world?
- Rising Coal Emissions Compared with Needed U.S. Economy-wide Emissions Reductions by 2050
- U.S. CO2 Emissions by Source, 2006
- Public Health Consequences
- Carbon capture and storage (CCS) explained
- Using coal to create a vehicle fuel
- Coal use in developing countries
- References
What are the options for the vast stores of coal around the world?
If the countries of the world continue burning coal the way they do today, it will be impossible to achieve the reductions in carbon emissions needed to have a reasonable chance of preventing the worst consequences of global warming. Coal-fired power plants represent the United States’ largest source of carbon dioxide (CO2, the main heat-trapping gas building up in our atmosphere and causing climate change).[1,2] While existing coal power technologies are incompatible with climate protection, advanced coal technologies not yet in widespread use may provide an opportunity for the world’s coal reserves to continue playing a role in the energy mix of the future.
Figure 1. Rising Coal Emissions Compared with Needed U.S. Economy-wide Emissions Reductions by 2050
As of May 2009 there is no commercially available control technology that can be added to coal-fired power plants in order to reduce their carbon emissions. However, carbon capture and storage (CCS) is an emerging technology that, especially when combined with advanced combustion technology, could allow plant operators to capture carbon emissions, transport it to a storage location (also known as a “geological sequestration” site), and pump it into the ground, where it would ideally remain safely stored over the very long term.
This complete process (i.e. capture plus storage) has not yet, as of May 2009, been deployed on a commercial scale at any power plant, although several projects that would deploy commercial-scale CCS are under development. In addition, there are several locations already operating to store carbon in deep geologic strata such as in the North Sea. CCS technology faces many barriers, including its currently very high cost and unanswered questions about the feasibility and safety of long-term, large-scale geologic storage. Widespread use of CCS, moreover, would require construction of an extensive infrastructure to capture, process, and transport the carbon emissions to appropriate storage sites. 2009 cost estimates apportion far greater cost to the capture portion compared to the storage portion.
Despite these challenges, CCS has the potential to play a useful role in the fight against global warming, warranting further investment of commercial-scale demonstration projects. In the meantime, new coal plants that do not capture carbon emissions should not be built. In the meantime, current and projected energy demands can be met through efficiency and accelerated deployment of renewables.[3]
As one strategy for reducing coal-related carbon emissions globally, especially in coal-rich China and India, the United States and other developed nations could facilitate the financing, transfer, and deployment of renewable energy technologies, energy efficient technologies, and other climate friendly energy options.
Coal, a sedimentary organic rock with a high concentration of carbon (between 40 and 90 percent by weight), is the most widely used fuel for generating electricity in both the United States and most countries of the world. It has the advantages of being relatively abundant and widely distributed.
Unfortunately, coal is the most carbon-intensive of the fossil fuels. Even newer coal plants produce more than two times the carbon emissions of a new natural gas combined cycle plant.[1] Global warming is primarily caused because we are putting too much carbon into the atmosphere, and coal plants represent the single biggest source (about one-third) of the U.S. carbon load—more than all of our cars, trucks, buses, trains, and boats combined. (See figure below).[2]
Figure 2. U.S. CO2 Emissions by Source, 2006
Heavy reliance on coal to meet our electricity needs imposes costs on society and the environment that are rarely accounted for in the price of the coal. Throughout its fuel cycle, from mining through waste disposal, coal has adverse environmental affects. Coal power plants require withdrawal of 25 gallons of water for each kilowatt-hour generated and coal mining consumes an estimated 70-260 million gallons of water per day in the U.S.[4] This means that U.S. citizens may indirectly use as much water turning on the lights and running appliances as they directly use taking showers and watering lawns. Burning coal in power plants can also inflict health consequences, including illness caused by poor air quality (see Figure 3) and mercury poisoning. Before investing in additional coal plants, the full costs of burning coal should be taken into account.[5]
Figure 3. Public Health Consequences
Every year, air pollution from existing coal-fired power plants--many of which still donot employ modern pollution controls--causes hundreds of thousands of asthma attacks and contributes to thousands of premature deaths from heart and lung disease. Photo: James Estrin/The New Times/Redux.
The United States has 500 or so large, operating coal plants, and more than 100 plants are currently proposed to be built. None of the existing plants capture their carbon emissions because at the current time there is no commercially available control technology that can be added to existing coal-fired power plants in the way that scrubbers and baghouses can be installed to capture sulfur dioxide and particulate emissions, respectively.[6]
Carbon capture and storage (CCS) explained
The world’s ability to continue using coal while making the emissions reductions it needs [7] depends on the technology of carbon capture and storage (CCS).
Figure 4. Geologic Sequestration of CO2
(Click image to enlarge)
Detailed analyses of CCS have concluded that long-term storage is technically feasible, and that the risks are not unlike those faced in other industrial activities.[8,9] The authors of one prominent report concluded that they have “confidence that large-scale CO2 injection projects can be operated safely.”[9] The Intergovernmental Panel on Climate Change (IPCC) recently concluded that CO2 could generally be contained for millions of years, with over 99 percent of the injected CO2 likely to be retained for more than 1,000 years provided the storage sites are well-selected, -designed, and -managed.[10]
The key to minimizing the risks of CCS, then, will be implementing a regulatory system that imposes strict standards on site selection, project design, operation, and long-term monitoring. The United States’ experience with enforcement of coal mining and nuclear power regulations, however, creates uncertainty about how current and future regulators would balance the costs and risks of CCS, particularly if the economic stakes for the industry are high.
The risks of CCS must also be considered in light of the sheer scale of the industry. For example, even if CCS were responsible for just one-tenth of the needed CO2 reductions, the volume of liquefied CO2 being shipped, presumably via pipeline, to the storage site could approximately equal the amount of oil currently flowing around the world.[11] If CCS becomes a global strategy for reducing CO2 emissions, the quality of regulation in other countries also becomes important. Regulation of China’s coal mining and emissions, for instance, is considered far weaker than U.S. regulation.
Perhaps the greatest challenge that CCS technology faces today is the very high cost of capturing CO2 from a coal plant—in fact, the expense explains why virtually none of the more than 100 proposed new coal plants include CCS. Incorporating CCS into the design of a new pulverized coal plant has been estimated to increase the cost of power from that plant between 60 to 78 percent.[9,13] Even in technologically advanced plants considered more amenable to capture and storage —such as an integrated gasification combined cycle (IGCC) plant [11]—adding CCS is still estimated to increase its cost of energy by roughly one-third.[9,12]
A reasonable next step for CCS
Because the United States and the world must reduce carbon emissions substantially in a very short period of time, many energy analysts suggest that CCS could be a longer term option for emissions reductions if its challenges are addressed. To that end, the federal government could fund a limited number of demonstration projects to determine whether the cost, technology, and other challenges faced by CCS can be overcome. Such demonstrations will help determine whether it is more cost-effective to retrofit old coal plants with post-combustion capture, replace them with IGCC plants using pre-combustion capture, or replace them with other low-carbon technologies.[13]
Using coal to create a vehicle fuel
The coal industry has plans to develop new markets for coal in the form of liquid fuels for transportation. Compared to gasoline, however, “liquid coal” from a conventional coal plant produces much higher carbon emissions (i.e., 83 percent higher than gasoline).[14] Even with (yet to be commercialized) CCS technology, carbon emissions from “liquid coal” would be slightly higher than gasoline emissions.[14] It is difficult to see what role coal-to-liquid technology could play in a rational energy future.[15,13]
Coal use in developing countries
While the risks posed by the potential expansion of the U.S. coal plant fleet are high, so too are those posed by the widespread expansion of coal-fired power plants in the emerging economies, especially in China and India. China is reportedly building the equivalent of two new 500 MW conventional coal plants per week, and the country already consumes far more coal than the United States.[9]
Ideally, all U.S. projects would be carefully integrated with the ongoing international effort to investigate and demonstrate CCS technology. The International Energy Agency (IEA) has released a CCS development road map that contemplates the involvement of numerous countries in Asia, Europe, and North America.[16] CCS demonstration projects are already under development in Australia, Canada, Europe, and the United States, while China and India are pursuing advanced IGCC and supercritical pulverized coal demonstrations.[16] The urgent need to prevent the construction of coal plants without CCS in the developing world is another reason for the United States and other developed nations to invest capital into researching CCS technology, and where appropriate, to help finance, transfer, and deploy CCS technology—another low-carbon technologies—to developing countries as it evolves.
[1] Based on fossil fuel emissions rates and heat rates for new power plants. From: EIA. 2008c. Annual energy outlook 2008. Washington, DC: U.S. Department of Energy. And: EPA. 2007a. Inventory of U.S. greenhouse gas emissions and sinks: 1990-2005. Washington, DC. April 15. Online at the Environmental Protection Agency website (pdf).
[2] EIA. 2008b. Figure 97: Carbon dioxide emissions by sector and fuel, 2006 and 2030. Washington, DC: U.S. Department of Energy. Online at the Energy Information Administration website.
[3] UCS. 2009. Climate 2030 Blueprint, Union of Concerned Scientists, Cambridge, MA, May 2009. Online at the Union of Concerned Scientists website.
[4] U.S. Department of Energy. December 2006. Energy Demands on Water Resources: Report to Congress on the Interdependency of Energy and Water. Online at the Sandia National Laboratories website (pdf).
[5] U.S. Environmental Protection Agency (EPA). 2008a. Air emission sources. Washington, DC. Online at the EPA, Air Emission Sources website. And: Schnieder, C.G. 2004. Dirty air, dirty power: Mortality and health damage due to air pollution from power plants. Boston, MA: Clean Air Task Force. Online at the Clean Air Task Force website (pdf). And: EPA. 2008b. Clean Air Mercury Rule: Basic information. Washington, DC. Online at the EPA, Clean Air Mercury Rule website. And: EPA. 2003. Mountaintop mining/valley fills in Appalachia: Draft programmatic environmental impact statement. Washington, DC. Appendix I, 91. Online at the EPA, Mid-Atlantic Mountaintop Mining website. And: NRC. 2006. Managing coal combustion residues in mines. Washington, DC: National Academies Press, 13-14. Online at the National Academies Press website. And, more generally: Goodell, J. 2006. Big coal: The dirty secret behind America’s energy future. New York, NY: Houghton Mifflin Co. 38.
[6] A handful of demonstration projects have been announced where CCS technology would be added to new or existing coal plants. Most of these projects await federal funding support before going forward. For more information on CCS projects under development, see the Massachusetts Institute of Technology (MIT) Carbon Capture and Sequestration Technologies Program database. MIT. 2008a. Carbon dioxide capture and storage projects. Cambridge, MA. Online at the Carbon Capture and Sequestration Technologies Program at MIT website.
[7] A detailed analysis of the reductions needed to have a reasonable chance of avoiding the worst consequences of global warming, along with the assumptions made about reductions needed from other developed nations and the developing world is available in: Luers, A.L., M.D. Mastrandrea, K. Hayhoe, and P.C. Frumhoff. 2007. How to avoid dangerous climate change: A target for U.S. emissions reductions. Cambridge, MA: Union of Concerned Scientists. September. Report (pdf) available online at the Union of Concerned Scientists website.
[8] Intergovernmental Panel on Climate Change (IPCC). 2005. IPCC special report on carbon dioxide capture and storage. Prepared by Working Group III of the IPCC. Metz, B., O. Davison, H.C. de Coninck, M. Loos, and L.A. Meyer (eds.). Cambridge, UK, and New York, NY: Cambridge University Press, 4. Online at the IPCC Special Reports website.
[9] MIT. 2007. The future of coal: Options for a carbon-constrained world. Cambridge, MA.
[10] Smil, V. 2006. Energy at the crossroads. Background notes for a presentation at the Global Science Forum Conference on Scientific Challenges for Energy Research, May 17-18. Report (pdf) available online at the Organisation for Economic Co-operation and Development website.
[11] A technology known as integrated gasification combined cycle (IGCC) converts coal into a gas, runs the gas through a combustion turbine to generate electricity, and uses the excess heat from that process to generate additional electricity via a steam turbine (hence the term “combined cycle”). There are only four coal-fired IGCC plants operating in the world, two in the United States and two in Europe.
[12] Almost all coal plants operating today and most of those proposed for construction are pulverized coal plants. Pulverized coal plants grind the coal, burn it to create steam, and use the steam to generate electricity. IGCC plants are significantly more expensive to build than pulverized coal plants when neither plant includes carbon capture. However, the cost advantage might switch to IGCC plants over pulverized plants if CCS were added.
[13] A fuller discussion of the CCS technology, including its potential and the challenges it faces, along with recommendations for funding CCS demonstration projects, preventing the construction of coal plants without CCS, and otherwise changing coal policy is available in: Freese, B., S. Clemmer, and A. Nogee. 2008. Coal Power in a Warming World: A Sensible Transition to Cleaner Energy Options. Cambridge, MA: Union of Concerned Scientists. October. Report (pdf) available online at the Union of Concerned Scientists website. And: MIT. 2007.
[14] Wang, M.Q. 2006. Greenhouse gases, regulated emissions, and energy use in transportation. GREET 1.7 (beta) Spreadsheet Model. Center for Transportation Research, Energy Systems Division, Argonne National Laboratory, U.S. Department of Energy. January. Online at the Argonne National Laboratory, Transportation Technology R&D Center website.
[15] EPA. 2007c. Greenhouse gas impacts of expanded renewable and alternative fuels use. Emission facts. April. Online at the EPA, Office of Transportation and Air Quality website (pdf). And: Wang, M., M. Wu, and H. Huo. 2007. Life-cycle energy and greenhouse gas results of Fischer-Tropsch diesel produced from natural gas, coal, and biomass. Presented at 2007 Society of Automotive Engineers government/industry meeting, Washington DC. Center for Transportation Research, Argonne National Laboratory. May. And: Gray, D., C. White, G. Tomlinson, M. Ackiewicz, E. Schmetz, and J. Winslow. 2007. Increasing security and reducing carbon emissions of the U.S. transportation sector: A transformational role for coal with biomass. Pittsburgh, PA: NETL, U.S. Department of Energy. August 24. Online at the National Energy Technology Laboratory website. And: Bartis, J.T. 2007. Policy issues for coal-to-liquid development. Testimony to the Senate Energy and Natural Resources Committee. May 24. Online at the RAND Corporation, Policy Issues for Coal-to-Liquid Development webiste.
[16] The IEA’s road map for CCS is part of “Energy technology perspectives 2008: Scenarios and strategies for 2050,” an in-depth analysis of multiple emissions-reducing technologies. This document and a brief summary of IEA’s CCS road map are available online at the International Energy Agency website.
[17] Morrison, G. 2008. Roadmaps for clean coal technologies: IGCC, supercritical, and CCS. Presentation at the Energy Technology Roadmaps Workshop, International Energy Agency, Paris, May 15-16.
Summary prepared by N. Cole and reviewed by B. Ekwurzel, B. Freese, P. Frumhoff, and S. Shaw (UCS).
