integrated coal gasification combined cycle (igcc) power plants and geologic carbon sequestration...
Post on 27-Mar-2015
Embed Size (px)
- Slide 1
Integrated Coal Gasification Combined Cycle (IGCC) Power Plants and Geologic Carbon Sequestration Joe Chaisson April 21, 2004 www.catf.us Slide 2 IGCC: What is it? Integrated coal Gasification Combined Cycle or IGCC Chemical conversion of coal to synthetic gas for combustion in a modified gas turbine Inherently cleaner process because coal is not combusted and the relatively small volumes of syngas are easier to clean up than the much larger volumes of flue gases at a coal combustion plant. Slide 3 Steam Hydrogen Ammonia F-T Liquids Clean Syngas End Products Feeds Gas Cleanup Refinery Residues Heavy Oil Orimulsion Coal Petroleum Coke Oxygen Electricity Solid Sulfur Slag (ash) Gas & Steam Turbines Gasification Combined Cycle Power Block SULFUR RECOVERY Marketable Byproducts: Alternatives: SULFUR REMOVAL Coal IGCC Process 1 1 Texaco Gasification Power Systems (TGPS) Natural Gas Slide 4 Tampa Electric Polk Power Station. 250 MW operating since 1996 Slide 5 IGCC Environmental Impacts - Air Pollution Commercially available IGCC power plant technologies can have much lower air pollution emissions than new conventional coal plants. Actual air emissions performance will likely depend, at least in in part, on what control technology and performance levels are required by regulators. Mercury capture at IGCC plants is quite feasible and much less costly than at conventional coal plants and the potential exists to indefinitely sequester mercury captured at IGCC facilities. Commercially available IGCC power plant technologies produce substantially smaller volumes (about one half) of solid wastes than do new conventional coal plants using the same coal IGCC solid wastes are less likely to cause environmental damage than fly ash from conventional coal plants because IGCC ash melts in the gasification process, resulting in an ash much less subject to leaching pollutants than is conventional coal combustion fly ash. Slide 6 Slide 7 Slide 8 Coal Gasification and Mercury Management Proven, low cost mercury controls can remove most of the mercury from coal syngas produced (14 years experience at Eastman Chemical). Mercury is captured in a small volume activated carbon bed (see next slide). Bed contents are currently managed as hazardous wastes (due to other toxics captured), but could be sequestered in a long-term mercury storage facility or the mercury contained could be economically recycled. Thus coal IGCC with a carbon bed plant mercury control is today the only technology that can convert coal to power and capture nearly much of the coal mercury in a form and volume suitable for permanent sequestration. Slide 9 Slide 10 IGCC Carbon Emissions IGCC plants are more efficient in converting coal to electricity than conventional coal plants and thus produce less CO2 per unit of electricity generated. Near-term IGCC plants would produce about 20% less CO2 - per unit of electricity produced - as would the average existing coal plant. The longer term potential could be for IGCC plants to produce about one-third less CO2 - per unit of electricity produced - as would the average existing coal plant. IGCC plants can potentially capture and geologically sequester up to 90% (or more) of coal fuel carbon content. Slide 11 Geologic Carbon Sequestration CO2 is today mined, transported and injected into the ground in operations to enhance oil field recovery. CO2 is also removed at some production fields along with hydrogen sulfide gas from natural gas prior to injection of the natural gas into pipelines. The removed CO2 and hydrogen sulfide are then often injected into geologic formations for permanent disposal. These technologies are today in commercial practice and are essentially the same as would be used to transport and sequester (geologic injection and containment) CO2 captured at an IGCC plant. Statoils Sleipner gas field project, off the coast of Norway, is one example of a climate- driven CO2 sequestration project that injects captured CO2 into a saline aquifer. Domestic carbon sequestration would likely focus initially on sites where CO2 injection would enhance oil recovery (as a credit would be earned to reduce costs) or possibly to recover methane form deep coal beds. Costs of purchasing CO2 for these applications are reported to be about $45/ton of carbon. Longer term sequestration options being explored include binding captured CO2 into a mineral that would be environmentally stable and that could be readily be disposed. Slide 12 Sleipner Carbon Sequestration Project Slide 13 Costs of Carbon Capture and Geologic Sequestration IGCC carbon capture costs are currently estimated by the Electric Power Research Institute (EPRI) to be about 1.2 to 1.9 cents/kWh for a range of commercially available IGCC technologies. Geologic storage costs for captured carbon are likely to vary significantly by power plant location and type of storage setting (storage in deep saline aquifers, active enhanced oil recovery projects, deep coal beds, etc.). Transport of captured carbon and storage at a typical saline aquifer site is estimated by MIT to add about 0.2 cents/kWh, for total CCS cost of about 1.4 to 2.1 cents/kWh today. Recent analysis by Carnegie Mellon University researchers suggests that IGCC repowerings with carbon capture and sequestration could enter mid-western power markets at carbon allowance prices of $50 - $75/metric ton. Commercially available CO2 capture and sequestration technologies have not been optimized for IGCC power plant carbon capture. Capture costs are projected (by MIT and others) to drop as commercial applications move forward. Carbon capture and sequestration costs will remain uncertain until operational experience accumulates with commercial-scale IGCC carbon capture and sequestration demonstration projects. Slide 14 Slide 15 A Bridge to Hydrogen Fuels Movement of IGCC technology into the power market could facilitate use of coal to produce valuable products beyond electricity - FT diesel fuel Chemical feed stocks Synthestic natural gas Hydrogen, or hydrogen-rich liquid fuels for transportation and building energy Hydrogen is the ultimate fuel cell fuel (current fuels cells often include equipment to convert other fuels - natural gas, etc. - to hydrogen). IGCC is seen by key experts as being critical to economic deployment of hydrogen transportation fuels and widespread use of fuel cells. Successful deployment of IGCC technology in the power sector may be critical to the economic viability of other potential coal-derived products.