Multi-fueled electric utilities are commonly seen as offering relatively greater opportunities for reasonably priced carbon abatement through changes in the dispatch of generating units from capacity using high emission fuels, coal or oil, to capacity using lower emitting fuels, natural gas (LNG) or nuclear. This paper examines the potential for such abatement using Japanese electric utilities as an example. We show that the potential for abatement through re-dispatch is determined chiefly by the amount of unused capacity combining low emissions and low operating cost, which is typically not great. Considerably more abatement potential lies in changing planned, base load, fossil-fuel fired capacity additions to nuclear capacity. Our results are at odds with the common view that the demand for natural gas or LNG would increase, or at least not fall, as the result of a carbon constraint; and our analysis suggests that this result may not be limited to Japan. / Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/) / Includes bibliographical references (p. 31).