Power Plant Fuel Switching and Air Quality in a Tropical Forested Environment

Abstract

<p><strong>Abstract.</strong> How a changing energy matrix for power production affects air quality is considered for an urban region in a tropical, forested environment. Manaus, the largest city in the central Amazon basin of Brazil, is in the process of changing its fossil fuel power energy matrix from entirely fuel oil and diesel to nearly entirely natural gas across an approximately ten-year period. Three scenarios of urban air quality, specifically afternoon ozone concentrations, were simulated using the Weather Research and Forecasting (WRF-Chem) model. The first scenario used fuel oil and diesel for power production, which was the reality in 2008. The second scenario was based on the fuel mix from 2014, the most current year for which data were available. The third scenario considered nearly complete use of natural gas for power production, which is the anticipated future, possibly for 2018. For each case, inventories of anthropogenic emissions were based on power generation, refining operations, and transportation. Transportation and refinery operations were held constant across the three scenarios to focus on effects of power plant fuel switching in a tropical context. The results of the simulations indicate that a change to natural gas significantly decreases maximum afternoon ozone concentrations over the population center, reaching reductions of 73 % (110 to 30 ppb) on the most polluted days. NO<sub><i>x</i></sub> and CO emissions decreased by approximately 89 % and 55 %, respectively, after the complete change in the energy matrix. The sensitivity of ozone concentrations to the fuel switchover is consistent with a NO<sub><i>x</i></sub>-limited regime, as expected for a tropical forest having high emissions of biogenic volatile organic compounds, high water vapor concentrations, and abundant solar radiation. Thus, policies favoring the burning of natural gas in place of fuel oil and diesel have great potential for ozone reduction and improve air quality for growing urban regions located in tropical, forested environments around the world.</p>

Contributions of mobile, stationary and biogenic sources to air pollution in the Amazon rainforest: a numerical study with the WRF-Chem model

“…In addition, a companion study by Medeiros et al (2017) focuses on how the changing energy matrix for power production affects air quality in the Manaus region. Both studies were conducted using the Weather Research and Forecasting with Chemistry (WRF-Chem) model, where the simulations for diverse scenarios were performed according to the current conditions of the region.…”

“…This indicates that the TPPs are mainly responsible for the high concentrations of most chemical species in the grid. The influence of matrix change is discussed in the companion paper of Medeiros et al (2017), and more details can found in this paper.…”

Influence of urban pollution on the production of organic particulate matter from isoprene epoxydiols in central Amazonia

“…Organic compounds comprise up to 90 % of the mass concentration of submicron organic particulate matter (PM) over tropical forests (Kanakidou et al, 2005). Submicron PM has adverse effects on human health (Nel, 2005;Pope III and Dockery, 2006) and influences air quality and climate by scattering radiation and acting as cloud condensation nuclei (Ramanathan et al, 2001;Kaufman et al, 2002). A significant fraction of the submicron organic material originates from secondary processes, mainly by the atmospheric oxidation of volatile organic compounds (VOCs) emitted as part of natural and human activities (Zhang et al, 2007;Hallquist et al, 2009;Jimenez et al, 2009).…”

Response to reviews

“…Organic compounds comprise up to 90 % of the mass concentration of submicron organic particulate matter (PM) over tropical forests (Kanakidou et al, 2005). Submicron PM has adverse effects on human health (Nel, 2005;Pope III and Dockery, 2006) and influences air quality and climate by scattering radiation and acting as cloud condensation nuclei (Ramanathan et al, 2001;Kaufman et al, 2002). A significant fraction of the submicron organic material originates from secondary processes, mainly by the atmospheric oxidation of volatile organic compounds (VOCs) emitted as part of natural and human activities Hallquist et al, 2009;Jimenez et al, 2009).…”