Coal Gasification Economics and Efficiency A Comparison Study

Coal Gasification Economics and Efficiency: A Comparison Study By David Fenton November 20 th, 2006

Contents • Purpose • Conventional – Basis – Results • IGCC – Basis – Results • Comparisons • Conclusions

Purpose • To compare conventional coal and IGCC power plants in the following aspects: – Plant efficiency – Pollution amounts – Capital cost – Operating cost

Conventional Coal Basis • 500 MW, supercritical steam power plant – Dry gas scrubbing for SOx – Low NOx burners – Baghouses for PM • Data for economics taken from TXU data for new Texas power plants

Conventional Plant Layout

Conventional Results: Efficiency • Net efficiency: 38% – Supercritical steam loop increases efficiency – Ultra-supercritical technology could increase net efficiency to 45 -50%

Conventional Results: Pollution Pollutant CO 2 Pre-Control (lb/hr) 1, 300, 000 Post-Control (lb/hr) 1, 300, 000 PM 3, 750 37. 5 SO 2 8, 600 960 NOx 1, 840 920

Conventional Results: Costs • Expected capital cost: $550 million – $1100 / k. W for supercritical plant • Expected operating costs: – Fuel: 213 tons / hr = $87. 7 million / year – O&M: $2. 7 / MWh = $11. 1 million / year – Total: = $100 million / year • Data from TXU for current power plants – Expected parameters for new Texas power plants

IGCC Basis • 500 MW net, coal-gasification • High-pressure, high-temp Texaco gasifier – MDEA sulfur removal system to pure sulfur – Includes air separations plant for oxygen gen. – Does not include CO 2 sequestration (costs) • Data and economics from Tampa Electric IGCC and Wabash River IGCC plants

IGCC Basis (cont. ) • Texaco gasifier: – High-pressure • High throughput per reactor volume • Reduces compression needed during combustion – High-temperature • Increases ratio of CO and H 2 to CO 2 and CH 4 • Higher efficiency at higher temperature • Also allows syngas cooler to generate high pressure steam

IGCC Plant Layout

IGCC Results: Efficiency • Gross power generation is 50% efficient – Gasifier efficiency: 82. 5% • Based on heat balance, literature was 80 -85% – Power train efficiency: 60% • Matches efficiency of natural gas • Net generation is 40% efficient – After including ASU and auxiliary power – 20% of generated electricity used within plant

IGCC Results: Pollution Pollutant CO 2 Post Control (lb/hr) 1, 300, 000 PM 20 SO 2 100 NOx 350

IGCC Results: Costs • Expected capital cost: $700 million – $1400 / k. W for supercritical plant • Expected operating costs: – Fuel: 208 tons / hr = $85. 6 million / year – O&M: 5. 2% of cap = $36. 3 million / year – Total: = $122 million / year • Data from DOE for current power plants – Capital cost based on economy of scale and applying past experience

Comparisons Parameter Conv. Efficiency 38% PM 37. 5 lb/hr SOx* 960 lb/hr NOx 920 lb/hr Capital $550 M cost Oper. cost $100 M/yr *Using 1% sulfur coal IGCC 40% 20 lb/hr 100 lb/hr 350 lb/hr $700 M % Change +5% -47% -90% -62% +27% $122 M/yr +22%

Conclusions • IGCC is successful in lowering chemical emissions (particularly SO 2), – CO 2 sequestration would lower emissions, although it could add capital cost • There is not a significant gain in overall thermodynamic efficiency compared to current coal technologies – Advantages of combined cycle offset by gasification and utilities requirements

Conclusions (cont. ) • Capital and operating costs are significantly higher for IGCC power plants – Results from added complexity of process, as well as need for ASU and sulfur treatment units • Unless environmental factors are the driving force, IGCC does not provide an economical or fuel conservative alternative to conventional coal power plants – Environmental credits?