National Gasification Strategy Act of 2005 - Directs the Secretary of Energy to establish a federal incentive program that provides loan guarantees and grants for either an integrated gasification combined cycle or an industrial gasification project that will: (1) gasify coal, biomass, or petroleum residues; (2) remove pollutants from the resulting gas; (3) use the resulting gas for industrial purposes or burn it in a turbine to generate electricity; and (4) remove pollutants from the resulting flue gas.

Directs the Secretary to provide financial assistance (including grants and loan guarantees) for a project to produce energy from coal mined in the western United States using appropriate advanced integrated gasification combined cycle technology, including repowering of existing facilities, that minimizes and offers the potential to sequester carbon dioxide emissions.