Coal pollution mitigation

Clean coal is a term for technology (Clean coal technology) that mitigates emissions of carbon dioxide (CO₂) and other greenhouse gases that arise from the utilization of coal, mainly for electrical power generation. Currently, the term clean coal is used in the coal industry in reference to carbon capture and storage, which pumps and stores CO₂ emissions underground, and plants using integrated gasification combined cycle (IGCC). IGCC involves coal gasification, which provides a basis for increased efficiency and lower cost in capturing CO₂ emissions. Prior to the current focus on carbon capture and storage, the term clean coal had been used to refer to technologies for reducing emissions of NOx, sulfur, and heavy metals from coal combustion.

Within the United States, Carbon Capture and storage technologies are mainly being developed in response to regulations by the Environmental Protection Agency—most notably the Clean Air Act—and in anticipation of legislation that seeks to mitigate climate change. Currently, the electricity sector of the United States is responsible for about 41% of the nation's CO₂ emissions, and half of the sector's production comes from coal-fired power plants.

Technology

Main article: Clean coal technology

The United States Department of Energy works with private industry to develop carbon capture and storage (CCS) technologies. Several methods are available under this technology including:

• Pre-combustion capture - This involves gasification of a feedstock (such as coal) to form synthesis gas, which may be shifted to produce a H₂ and CO₂-rich gas mixture, from which the CO₂ can be efficiently captured and separated, transported, and ultimately sequestered, This technology is usually associated with Integrated Gasification Combined Cycle process configurations.
• Post-combustion capture - This refers to capture of CO₂ from exhaust gases of combustion processes, typically using sorbents, solvents, or membrane separations to remove CO₂ from the bulk gases.
• Oxy-fuel combustion - Fossil fuels such as coal are burned in a mixture of recirculated flue gas and oxygen, rather than in air, which largely eliminates nitrogen from the flue gas enabling efficient, low-cost CO₂ capture.

The Kemper County IGCC Project, a 582 MW coal gasification-based power plant, will use pre-combustion capture of CO₂ to capture 65% of the CO₂ the plant produces, which will be utilized/geologically sequestered in enhanced oil recovery operations.

The Saskatchewan Government's Boundary Dam Integrated Carbon Capture and Sequestration Demonstration Project will use post-combustion, amine-based technology to capture 90% of the CO₂ emitted by Unit 3 of the power plant; this CO₂ will be pipelined to and utilized for enhanced oil recovery in the Weyburn oil fields.

A well-known example of a coal-based plant using (oxy-fuel) carbon-capture technology is Vattenfall’s Schwarze Pumpe plant in Germany. In Biloela, Queensland, Australia, Callide Power Station has retrofitted a 30-MWth existing PC-fired power plant to operate in oxy-fuel mode; in Ciuden, Spain, Endesa has a newly built 30-MWth oxy-fuel plant using circulating fluidized bed combustion (CFBC) technology. Babcock-ThermoEnergy's Zero Emission Boiler System (ZEBS) is oxy-combustion-based; this system features near 100% carbon-capture and according to company information virtually no air-emissions.

Other carbon capture and storage technologies include those that dewater low-rank coals. Low-rank coals often contain a higher level of moisture content which contains a lower energy content per tonne. This causes a reduced burning efficiency and an increased emissions output. Reduction of moisture from the coal prior to combustion can reduce emissions by up to 50 percent.

The UK government's Department for Energy and Climate Change (DECC) is working towards a clean energy future and supports clean coal projects across the country. In August 2010, UK-based company B9 Coal announced a clean coal project with 90% carbon capture to be put forward to DECC. This would help the UK raise its profile amongst green leaders across the world. This proposed project, gasifies coal underground and processes it to create pure streams of hydrogen and carbon dioxide. The hydrogen is then used as an emissions-free fuel to run an alkaline fuel cell whilst the carbon dioxide is captured. This UK project could provide a world-leading template for clean coal with CCS globally.

Environment

See also: Environmental effects of coal

According to the United Nations Intergovernmental Panel on Climate Change, the burning of coal, a fossil fuel, is a significant contributor to global warming. (See the UN IPCC Fourth Assessment Report). For 1 ton of coal burned, 2.86 tons of carbon dioxide is created. As 25.5% of the world's electrical generation in 2004 was from coal-fired generation (see World energy resources and consumption), reaching the carbon dioxide reduction targets of the Kyoto Protocol will require modifications to how coal is utilized.

Sequestration technology has yet to be tested on a large scale and may not be safe or successful. Sequestered CO₂ may eventually leak up through the ground, may lead to unexpected geological instability or may cause contamination of aquifers used for drinking water supplies. There are also concerns that plans to pump some of the sequestered CO₂ into certain oil and gas reserves, to help make the fuel easier to pump out of the ground, will lead to increased concentrations of CO₂ in potential fuel supplies. This would have to be removed or released during the refining process.

Technologies related to reducing the environmental impact of extracting energy from coal do not address environmental impacts of coal mining. Examples of environmental impacts of coal mining include the Kingston Fossil Plant coal fly ash slurry spill.

Underground coal gasification is not considered to be a clean coal application.

Byproducts

The byproducts of coal combustion are considerably hazardous to the environment if not properly contained.

While it is possible to remove most of the sulfur dioxide (SO₂), nitrogen oxides (NO_x), and particulate matter (PM) emissions from the coal-burning process, carbon dioxide (CO₂) emissions and radionuclides will be more difficult to address.

Coal-fired power plants are the largest aggregate source of mercury: 50 tons per year come from coal power plants out of 150 tons emitted nationally in the USA and 5000 tons globally. In the USA, neither the combustion products of oil, nor their associated solid or liquid waste streams, are considered to be major contributors to mercury pollution.

Potential financial cost of clean coal

Whether carbon capture and storage technology is adopted world wide will “…depend less on science than on economics. Cleaning coal is very expensive.”

Projected costs for CCS can be found in that article. Credit Suisse Group says $15 billion needs to be invested in CCS over the next 10 years for it to play an important role in climate change. The International Energy Agency says $20 billion is needed. The Pew Center on Global Climate Change says the number is as high as $30 billion. Those figures dwarf the actual investments to date.

In the US, the Bush administration spent about $2.5 billion on clean coal technology — a large amount, but far less than what will be needed. CCS proponents say both the government and the private sector need to step up their investments.

Projects in the United States

In the late 1980s and early 1990s, the U.S. Department of Energy (DOE) conducted a joint program with the industry and State agencies to demonstrate clean coal technologies large enough for commercial use. The program, called the Clean Coal Technology & Clean Coal Power Initiative (CCPI), has had a number of successes that have reduced emissions and waste from coal-based electricity generation. The National Energy Technology Laboratory has administered three rounds of CCPI funding and the following projects were selected during each round:

• Round 1 CCPI Projects
  • Advanced Multi-Product Coal Utilization By-Product Processing Plant
  • Demonstration of Integrated Optimization Software at the Baldwin Energy Complex
  • Gilberton Coal-to-Clean Fuels and Power Co-Production Project
  • Increasing Power Plant Efficiency: Lignite Fuel Enhancement
  • TOXECON Retrofit for Mercury and Multi-Pollutant Control on Three 90-MW Coal-Fired Boilers
  • Western Greenbrier Co-Production Demonstration Project
  • Commercial Demonstration of the Airborne Process
  • Integration of Advanced Emission Controls to Produce Next-Generation Circulating Fluid Bed Coal Generating Unit

• Round 2 CCPI Projects
  • Airborne Process^TM Commercial Scale Demonstration Program
  • Demonstration of a Coal-Based Transport Gasifier
  • Mercury Species and Multi-Pollutant Control Project
  • Mesaba Energy Project

• Round 3 CCPI Projects
  • American Electric Power Project
  • Antelope Valley Station Post-Combustion CO2 Project
  • Hydrogen Energy California Project
  • NRG Energy Project
  • Southern Company Carbon Capture and Sequestration Demonstration
  • Summit Texas Clean Energy Project

These programs have helped to meet regulatory challenges by incorporating pollution control technologies into a portfolio of cost-effective regulatory compliance options for the full range of boiler types. This portfolio has positioned the U.S. as a top exporter of clean coal technologies such as those used for NOx and mercury. The DOE continues its programs and initiatives through regional sequestration partnerships, a carbon sequestration leadership forum and the Carbon Sequestration Core Program, a CCS research and development program.

According to a report by the assistant secretary for fossil energy at the U.S. Department of Energy, clean coal technology has paid measurable dividends. Technological innovation introduced through the CCT Program now provides consumers cost-effective, clean, coal-based energy.

Sulfur dioxide (SO₂) and nitrogen dioxide (NO₂) control technologies emerging from clean coal technology have moved into the utility and industrial marketplace and now provide cost-effective regulatory compliance. A new generation of advanced coal-based power systems has been placed in commercial service that has improved efficiency and environmental performance to meet increasingly stringent environmental regulations and market demands. These advanced power systems projects will provide a springboard for widespread, global deployment. This in turn will contribute greatly to reductions in greenhouse gas emissions.

FutureGen is a US government project, announced by President George W. Bush in 2003 to build a near zero-emissions coal-fueled power plant to produce hydrogen and electricity while using carbon capture and storage. Funding for the original FutureGen project was withdrawn by the Department of Energy on 29 January 2008. FutureGen 2.0 is the replacement project currently in development, which involves upgrading a power plant in Meredosia, Illinois with oxy-combustion technology to capture approximately 1.1 million tons of CO₂ each year—more than 90 percent of the plant’s carbon emissions - to be transported and stored underground at a nearby site.

Support

In the United States, clean coal was mentioned by former President George W. Bush on several occasions, including his 2007 State of the Union Address. Bush's position was that carbon capture and storage technologies should be encouraged as one means to reduce the country's dependence on foreign oil.

During the 2008 US Presidential campaign, both candidates John McCain and Barack Obama expressed interest in the development of CCS technologies as part of an overall comprehensive energy plan. The development of clean coal technologies could also create export business for the United States or any other country working on it.

The American Reinvestment and Recovery Act, signed in 2009 by President Obama, allocated $3.4 billion for advanced carbon capture and storage technologies, including CCS demonstration projects.

Former Secretary of State Hillary Clinton has said that "we should strive to have new electricity generation come from other sources, such as clean coal and renewables,” and former Energy Secretary Dr. Steven Chu has said that “It is absolutely worthwhile to invest in carbon capture and storage," noting that even if the U.S. and Europe turned their backs on coal, developing nations like India and China would not.

In Australia, carbon capture and storage was often referred to by former Prime Minister Kevin Rudd as a possible way to reduce greenhouse gas emissions. (The previous Prime Minister John Howard has stated that nuclear power is a better alternative, as CCS technology may not prove to be economically favorable.)

During the first 2012 United States presidential election debate, Mitt Romney expressed his support for clean coal, and claimed that current federal policies were hampering the coal industry.

Criticism

Environmentalists such as Dan Becker, director of the Sierra Club's Global Warming and Energy Program, believes that the term clean coal is misleading: "There is no such thing as clean coal and there never will be. It's an oxymoron." The Sierra Club's Coal Campaign has launched a site refuting the clean coal statements and advertising of the coal industry.

Complaints focus on the environmental impacts of coal extraction, high costs to sequester carbon, and uncertainty of how to manage end result pollutants and radionuclides. In reference to sequestration of carbon, concerns exist about whether geologic storage of CO₂ in reservoirs, aquifers, etc., is indefinite/permanent.

The paleontologist and influential environmental activist Tim Flannery made the assertion that the concept of clean coal might not be viable for all geographical locations.

Critics also believe that the continuing construction of coal-powered plants (whether or not they use carbon sequestration techniques) encourages unsustainable mining practices for coal, which can strip away mountains, hillsides, and natural areas. They also point out that there can be a large amount of energy required and pollution emitted in transporting the coal to the power plants.

The Reality Coalition, a nonprofit organization composed of Alliance for Climate Protection, Sierra Club, National Wildlife Federation, the Natural Resources Defense Council and the League of Conservation Voters, ran a series of television commercials in 2008 and 2009. The commercials were highly critical of clean coal, stating that without capturing CO₂ emissions and storing it safely that it cannot be called clean coal.

Greenpeace is a major opponent of the concept because they view emissions and wastes as not being avoided but instead transferred from one waste stream to another. According to Greenpeace USA Executive Director Phil Radford, "even the industry figures it will take 10 or 20 years to arrive, and we need solutions sooner than that. We need to scale up renewable energy; “clean coal” is a distraction from that."

Prior terminology

The term "clean coal" is increasingly used in reference to carbon capture and storage, an advanced process that eliminates or significantly reduces carbon dioxide emissions from coal-based plants and permanently sequesters them. More generally, the term has been found in modern usage to describe technologies designed to enhance both the efficiency and the environmental acceptability of coal extraction, preparation, and use.

U.S. Senate Bill 911 in April, 1987, defined clean coal technology as follows:

"The term clean coal technology means any technology...deployed at a new or existing facility which will achieve significant reductions in air emissions of sulfur dioxide or oxides of nitrogen associated with the utilization of coal in the generation of electricity."

In historical usage, "clean coal" has had quite different meanings:

• In the early 20th century, prior to World War II, clean coal (also called "smokeless coal") referred to anthracite and high-grade bituminous coal, used for cooking and home heating.

• The term also appeared in a speech to mine workers in 1918, when clean coal referred meant coal that was "free of dirt and impurities".

See also

• Asia-Pacific Partnership for Clean Development and Climate
• Biochar
• Bio-energy with carbon capture and storage
• Clean coal technology
• Carbon Capture and Storage
• Carbon sink
• Coal in the United States
• Coal phase out
• Energy development
• Energy Policy Act of 2005
• Fluidized bed combustion
• James E. Hansen
• JEA Northside Generating Station (Jacksonville)
• Low carbon power generation
• Mitigation of global warming
• Mountaintop removal mining
• Pleasant Prairie Power Plant
• Refined coal
• Syngas
• Waste management
• World Coal Institute

External links

• BBC News - Clean coal technology: How it works
• International Energy Agency - Clean Coal Centre
• US Department of Energy's clean coal technology web page
• National Energy Technology Laboratory compendium homepage
• The Future of Coal An Interdisciplinary MIT Study
• Institute for Clean & Secure Energy