Research Program Area: Health & Exposure
Private sector and governmental organizations recently have promoted the deployment of small-scale, distributed electricity generation (DG) technologies for their many benefits as compared to the traditional paradigm of large, centralized power plants. However, there is reason to caution against an unmitigated embrace of combustion-based DG. We conducted a series of case studies that combined air dispersion modeling and an exposure assessment. This investigation has revealed that the fraction of pollutant mass emitted that is inhaled by the downwind, exposed population (i.e., the intake fraction) can be more than an order-of-magnitude greater for natural gas-fired, microturbine DG technologies than for large, natural gas-burning, central-station power plants. This result is a consequence mainly of the closer proximity of DG sources to densely populated areas as compared to typical central stations. Considering uncontrolled emission factors for DG technologies (e.g., those installed before the 2003 California DG emission standard), the mass of pollutant inhaled normalized by the electricity delivered (i.e., the intake factor) can be up to four orders-of-magnitude greater for microturbines as compared to central stations. In order to equalize the exposure burden between DG and central station technologies, microturbine emission factors will need to be reduced to a range between the level of the cleanest, new central stations and two orders of magnitude below those levels, depending on the pollutant and siting. Continued research to refine our preliminary results could lead to an emissions target for DG sources so that they do not pose a greater public health burden than the current electricity generation system.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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