Will the United States undertake a large effort to reduce CO2 emissions?
Will the technologies of CCS become commercially viable?
Will the domestic natural gas price be close to its highest recent value or its lowest recent value?
By 2020, decision makers will probably have sorted out the first question. It is inconceivable that CCS will prosper if there is not a large effort to reduce CO2 emissions, because unless a significant cost is imposed on CO2 emissions at a power plant it will nearly always be less expensive to vent the CO2. The committee assumes here that government will formulate policies to reduce CO2 emissions, thereby spurring already-existing technologies for generating electric power with reduced CO2 emissions. The committee focuses here on pathways that deploy such technologies.
With a significant suite of demonstration plants, the country can also sort out the second question. Not enough is known yet to demand that all new plants be equipped with CCS, but much can be learned in the next decade.
The answer to the third question depends in part on the extent to which the U.S. market for natural gas links to the international market. That, in turn, depends, again in part, on the future role of natural gas in electric power generation. Thus the future mix of uses of natural gas and coal for electric power generation will depend sensitively on a combination of the constraints on carbon emissions, the costs of fuels, and the costs of conversion technologies. In particular, whether coal plays a larger or a smaller role in future electric power generation will depend strongly on whether CCS can be applied at the scale of many large power plants.
To examine these questions, the committee considers below three types of power plants: supercritical pulverized coal (PC), integrated gasification and combined cycle (IGCC) coal, and natural gas combined cycle (NGCC).
For large U.S. power generation projects, utilities and independent power producers are evaluating two ways of producing power from coal: PC and IGCC.15
The committee focuses on coal here but notes that biomass can be substituted for limited quantities of coal in PC and IGCC plants without major changes in plant design. This approach can help alleviate limits on biomass conversion plant size arising from the need to collect biomass over a wide area and from seasonal availability. Biomass can also be used as a feedstock