The valuation of external costs: An overview of issues and state actions

The valuation of externalities helps determine the cost effectiveness of environmentally superior resources that would not be cost effective on a direct cost comparison to utility avoided costs. Explicitly monetizing externalities appears to be the best way to meet the criteria of consistency across resource options and pollutants and allowing selection of societally least-cost resources among a variety of resource types. Environmental costs should be defined so as not to exclude any potential external effects, including all environmental, social, and economic effects. For practical purposes, the definition could probably include only environmental externalities without materially affecting resource decisions in the foreseeable future for most North American utilities. More specifically, a comprehensive list of external costs should at least include emissions of pollutants such as SO2, CO, NOx, volatile organics, and greenhouse gases; thermal effluents; solid wastes; risk of catastrophic accidents; and for hydro projects, destruction of habitat and recreational areas, and mercury accumulation in reservoirs. Environmental effects should then be counted and valued, most commonly by damage costing or regulatory cost of control. Some utilities and other parties have proposed a market-based approach to valuing externalities, determining the marginal cost of controlling emissions by the market price of emissions allowances. Quantification of environmental costs, ensuring consistency among externality sources, and estimation of avoided externality costs are also discussed. Examples are presented of externality values selected in a number of areas of the USA. 11 refs., 5 figs