Emissions Monitoring and Control Technology Resources
Technical Report On The Environmental Footprint and Costs of Coal-Based Integrated Gasification Combined Cycle and Pulverized Coal Technologies Action
On July 7, 2006, the Environmental Protection Agency (EPA) released a technical report titled "The Environmental Footprints and Costs of Coal-Based Integrated Gasification Combined Cycle and Pulverized Coal Technologies." The Report provides information on the environmental impacts and costs of the coal-based integrated gasification combined cycle (IGCC) technology relative to conventional pulverized coal (PC) technologies.
IGCC is a power generation process that uses a gasifier to transform coal (and other fuels) to a synthetic gas (syngas), consisting mainly of carbon moNOxide and hydrogen. The high temperature and pressure process within an IGCC creates a controlled chemical reaction to produce the syngas, which is used to fuel a combined cycle power block to generate electricity. Combined-cycle power applications are one of the most efficient means of generating electricity because the exhaust gases from the syngas-fired turbine are used to create steam, using a heat recovery steam generator (HRSG), which is then used by a steam turbine to produce additional electricity.
For traditional pollutants such as nitrogen oxides (NOx), sulfur dioxide (SO2), particulate matter (PM) and mercury (Hg), IGCC is inherently lower polluting than the current generation of traditional coal-fired power plants. IGCC also has multi-media benefits, as it uses less water than PC facilities. IGCC also produces a solid waste stream that can be a useful byproduct for producing roofing tiles and as filler for new roadbed construction. IGCC also has the potential to reduce solid waste by using as fuel a combination of coal and renewable biomass products.
IGCC is considered one of the most promising technologies to reduce the environmental impacts of generating electricity from coal. EPA has undertaken several initiatives to facilitate the development and deployment of this technology. This report is the result of one of these initiatives and represents the combined efforts of EPA and the Department of Energy (DOE) to advance IGCC technology.
IGCC is a dynamic and rapidly evolving technology. The Report evaluates a snapshot of conditions in a changing industry. EPA restricted the technology options evaluated to those that can be commercially applied by 2010. The IGCC plant configurations addressed in the study include:
- coal slurry-based and;
- dry coal based, oxygen blown gasifiers.
- The PC plant configurations include:
- supercritical; and
- ultra-super critical boiler designs.
All study evaluations are based on the use of three different coals: bituminous, sub-bituminous, and lignite. In addition, the same electric generating capacity of 500 megawatts is used for each plant configuration. State-of-the-art environmental controls are also included as part of the design of each plant.
The sources used in the environmental impact assessments and cost estimates developed for the Report include: air permit documents, information received from technology suppliers and published literature covering various aspects of the technologies considered. These data form the basis for the environmental and cost comparisons presented in the Report for both IGCC and PC technologies.
The technical report concludes the following:
IGCC thermal performance (efficiency and heat rate) is significantly better than current generation pulverized coal technologies in the US; Future generation, ultra-supercritical pulverized coal technologies may match or exceed current IGCC thermal performance; IGCC results in better environmental performance, including lower air emissions of criteria pollutants, lower water usage, and lower solid waste generation requiring landfilling, than conventional PC plants; IGCC has a potential advantage in capturing and sequestrating CO2 at lower costs; and; IGCC has higher capital costs than conventional PC plants. The report does not establish or change any EPA policy or legal interpretation with respect to the regulation and permitting of IGCC or PC facilities.
Currently, over 50 percent of electricity in the United States is generated from coal. Given that coal reserves in the US are estimated to meet our energy needs over the next 250 years, coal will continue to play a major role in the generation of electricity in this country. With dwindling supplies and high prices of natural gas and oil, a large portion of the new power generation facilities built in the US will likely use coal as the main fuel. The environmental impact of these facilities can only be minimized by innovations in technology that allow for efficient burning of coal, along with an increased capture of the air pollutants that are an inherent part of coal combustion.
IGCC has received renewed attention because the process can be modified to separate carbon dioxide (CO2) at normal pressure. While additional compression and treatment may be needed before the CO2 can be transported and permanently captured or sequestered, IGCC has the potential to make carbon capture and sequestration much easier and cheaper than traditional PC plants. To the extent an IGCC plant is able to sell the CO2 as a usable product for enhanced oil and gas recovery or other beneficial uses, the cost of capture and sequestration may be reduced and mitigated further.
Development and implementation of IGCC technology is relatively new compared with the PC technology that has hundreds or thousands of units in operation globally. Currently in the US there are two gasification unit installations using coal to make electric power as the primary product. The two IGCC plants in commercial operation include the Tampa Electric Polk Power Station in Florida and the Wabash River Coal Gasification Repowering Plant in Indiana. Each has been in operation since the mid-1990s. Recently, however, a number of companies have announced plans to build and operate additional IGCC facilities in the US.
Historically, concerns about operational reliability and costs presented issues of uncertainty for IGCC technology and impeded its deployment. Such conditions are changing toward the more rapid advancement of the IGCC option. IGCC is a versatile technology and is capable of using a variety of feed stocks. In addition to various coal types, feed stocks can include petroleum coke, biomass and solid waste.
Along with electricity production, IGCC facilities are able to co-produce other commercially desirable products that result from the process. Some of these products include steam, oxygen, hydrogen, fertilizer feed stocks and Fischer-Tropsch fuels.
The operational versatility noted above for IGCC technology may mitigate the risk of higher costs. In addition, under the Energy Policy Act of 2005, there are provisions for tax credits and a DOE Loan Guarantee Program to provide incentives to facilitate the deployment of IGCC technology.
In 1994 EPA established the Environmental Technology Council (ETC) to coordinate and focus the Agency's technology programs. The ETC strives to facilitate innovative technology solutions to environmental challenges, particularly those with multi-media implications. The Council has membership from all EPA technology programs, offices, and regions and meets on a regular basis to discuss technology solutions, technology needs and program synergies. One of the technologies identified as a promising option to address the production of energy from coal in an environmentally sustainable way is IGCC. This technical report is part of the ETC initiative and supports the combined efforts of EPA and the Department of Energy to advance the use of IGCC technology.
For further information about the Report, contact Mr. Sikander Khan at EPA's Office of Atmospheric Programs at 202-343-9781.