ESD Search Seminar

The costs, air quality and human health effects of using backup generators to meet peak electricity demand

By Elisabeth A. Gilmore
Engineering and Public Policy & Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA

Abstract:
Instead of constructing a new peaking plant, existing generators installed for backup power during blackouts could operate at their marginal costs during periods of peak electricity demand. Many generators, however, are diesel internal combustion engines (ICE) which have non-negligible air emissions. Of specific concern is fine particulate matter (PM_2.5). In this work, I compare the backup generators to a peaking plant on the private costs and social costs from air quality. To generate the social cost, first, I model the ambient concentrations from operating diesel ICEs, natural gas ICEs, and natural gas microturbines with a 3-D chemical transport model. Second, I transform the concentrations into their equivalent health endpoints using concentration-response functions and multiply the resulting morbidity and mortality by “willingness to pay” to avert ill-health. For several urban centers in the Eastern US, small but noticeable enhancements in PM_2.5 (~ 5 _g/m³) are observed for uncontrolled diesel ICEs. While secondary PM_2.5 is formed, the PM_2.5 mass is dominated by direct emissions. A diesel particulate filter (DPF), therefore, is a suitable control technology. We find that an uncontrolled diesel ICE has a full (private + social) cost that exceeds all other options (< 2 $/kWh) including the new peaking plant (~ 60 ¢/kWh). Retrofitting the diesel ICE with a DPF reduces the social cost from PM_2.5 mortality to ~ 10 ¢/kWh; the full cost is now comparable to natural gas generators. On a full cost basis, controlled diesel backup generators are a cost-effective method of meeting peak demand.