69 research outputs found
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Heat Island Mitigation Assessment and Policy Development for the Kansas City Region
Lawrence Berkeley National Laboratory partnered with Mid-America Regional Council (MARC) to quantify the costs and benefits from the adoption of urban heat island (UHI) countermeasures in the Kansas City region (population 1.5 million), and identify the best regional implementation pathway for MARC. The team selected cool (high-albedo) roofs and increased vegetation as the two countermeasures to evaluate. For vegetation, there were two strategies: (1) planting new trees to shade building surfaces, and (2) increasing urban irrigation (a surrogate for the use of vegetation to manage stormwater) to increase evapotranspiration. Using the Weather Research and Forecasting (WRF) model we simulated selected weeks during summer time, across five years (2011 2015) representing a range of normal summer conditions. We also simulated six of the most intense heatwaves that occurred between 2004 and 2016. We found under typical summer conditions (non-heatwave) average daytime (07:00 19:00 local standard time) regional near-ground air temperature reductions of 0.08 and 0.28 C for cool roofs and urban irrigation, respectively. We calculated the building electricity, electricity cost, and emission savings that result from the reduction in outdoor air temperature (indirect savings) and found maximum regional annual indirect electricity savings of 42.8 GWh for cool roofs and 85.6 GWh for urban irrigationyielding maximum regional annual indirect electricity cost savings of 0.05/m2 roof) and 0.01/m2 irrigated land), respectively, and maximum regional annual CO2 savings of 43.4 kt and 80 kt, respectively.We next evaluated the building energy, energy cost, and emission savings from reducing direct absorbed radiation on the building surfaces using cool roofs and shade trees (direct savings). For cool roofs, we found regional annual direct energy cost savings of 0.15/m2 roof) with regional annual CO2 savings of 66.4 kt. For shade trees, the regional annual direct energy cost savings were 21/tree) with regional annual CO2 savings of 126 kt. We investigated cool roof cost premiums (the additional cost for selecting a cool roof product in lieu of a conventional roof product, estimated to be zero to 100 per tree). The regional cool roof cost premium was calculated using the regional roof area per roofing material type and the range of cool roof product premiums for each material type. The extra cost of selecting cool roofs across the region ranged from 87.1M, while the additional shade trees planted across the region were assumed to cost $102M. When we compared the regional annual direct cost savings to the regional cool-roof cost premium and the regional shade-tree first cost, we found regional simple payback times up to 8.0 years for cool roofs and 4.9 years for trees, respectively.Since this comprehensive assessment of UHI countermeasures is a valuable methodology for other local governments to apply, we developed a step-by-step guide for others to follow. Based on the benefits and costs of the UHI countermeasures, MARC will pursue the inclusion of these countermeasures in existing regional plans where they can complement other regional priorities for transportation, climate resiliency, clean air, and hazard mitigation. They hosted a local workshop in 2016 for stakeholders to introduce the topic and will continue to share these resources to further appropriate adoption of UHI countermeasures
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Impact of Wind, Solar, and Other Factors on Wholesale Power Prices: An Historical Analysis—2008 through 2017
Wholesale power markets have evolved. Some of the most prominent changes over the last decade in the United States include growth in wind and solar, a reduction in the price of natural gas, weakened load growth, and an increase in the retirement of thermal power plants. Here we empirically assess the degree to which wind and solar—among other factors—have influenced wholesale electricity prices. We show that wind and solar have contributed to reductions in overall average annual wholesale electricity prices since 2008, but that natural gas prices have had the largest impact. More notable is that expansion of variable renewable energy has led to significant changes in locational, time of day, and seasonal pricing patterns in some regions. These altered pricing patterns reflect a fundamental shift, and hold important implications for the grid-system value of wind and solar, and for other electric-sector planning and operating decisions
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Air Quality Responses to Changes in Black Carbon and Nitrogen Oxide Emissions
Fine particulate matter (PM) affects public health, visibility, climate, and influences ecosystem productivity and species diversity. Diesel engines are an important source of air pollution and will face a variety of new regulations, so emissions from these vehicles are expected to undergo changes over the next decade that will have important effects on primary PM emissions, especially black carbon (BC) emissions, as well as nitrogen oxide (NOx) emissions and therefore secondary pollutants such as ozone and PM nitrate. Analysis of observed and modeled air quality responses to changes in diesel engine emissions provides insights into the relative importance of diesel emissions and the effects of future emission controls.Yearlong records of online measurements of black/elemental carbon at Fresno, St. Louis, and Pittsburgh were analyzed as part of this research. Diesel truck activity decreases substantially on weekends, and the pollutant time series were analyzed to look for corresponding reductions in ambient BC concentrations. Significant weekend BC reductions of 22±6 and 25±5% were found at Fresno and St. Louis, respectively. Smaller reductions were observed at Pittsburgh. Continuous measured records of fine particulate nitrate were also analyzed over yearlong periods at the three locations mentioned above and at Claremont, CA, an inland location within the Los Angeles basin. Reductions in PM nitrate were observed on Sundays and Mondays, indicating a delayed response to NOx emission reductions that occur on Saturdays and Sundays. Nitrate reductions of 23±12, 29±23, and 16±9% were observed on Mondays at Fresno, Claremont, and St. Louis, respectively, relative to 7-day moving averages.Exhaust emissions from diesel-powered construction equipment are typically estimated using statistical models. Both the emission estimates and the underlying engine activity estimates are subject to large uncertainties that are not routinely quantified. A fuel-based inventory of construction equipment emissions for California was developed and showed NOx and exhaust PM emissions to be 4.5 and 3.1 times smaller, respectively, than official emission inventory estimates developed by California Air Resources Board staff. Also, a revised description of the spatial distribution of diesel engine activity based on construction permit data showed construction activities had moved on from older housing development projects along the coast to new locations further inland in Southern California. Updating the construction inventory had significant effects on air quality model predictions for NOx, BC, and ozone.A gridded Eulerian model was used to assess weekend effects on particulate matter and compare model predictions weekly nitrate cycles to the observational analysis described above. The model incorporated the new construction inventories described above. This model was further employed to analyze the air quality effects of new regulations on in-use diesel trucks.The model was run over two seasons, and a baseline scenario was compared to a scenario including weekday emissions substituted for weekend emissions. The model analysis showed similar weekend reductions of BC to changes at ground-based observation sites in southern California. Unlike BC, particulate nitrate is a secondary pollutant with non-linear and non- intuitive dependence on precursor emissions. Analysis of particulate nitrate effects was also challenging because observed weekend effects were smaller than for BC, and meteorological variability made the signal harder to discern. Both modeled and observed reductions in nitrate were found on summer Mondays at Claremont (inland site). Process analysis showed that in some locations weekend NOx reductions could lead to higher nitric acid production and higher nitrate levels, as there are factors that offset the effect of lower weekend NOx on the rates of both daytime (OH+NO2) and nighttime (via N2O5) pathways to nitric acid formation. An important difference between modeled nitrate and observed nitrate was found during the fall season: modeled nitrate increased on Monday.The effects on future air quality of new regulations requiring the retrofit of in-use heavy-duty diesel trucks and buses to meet stringent PM emission requirements were evaluated. By 2014, the in-use retrofit rule is predicted to reduce average ambient BC concentrations in southern California by 12±2 and 14±2% during the summer and fall, respectively, relative to a baseline scenario that included emission decreases due to fleet turnover effects but no retrofits. Primary NO2 emissions are predicted to increase with greater use of oxidative particle filters, however, ambient NO2 concentrations are not predicted to increase as parallel, but less stringent, retrofit requirements reduce total NOx emissions. Increases in ambient ozone and particulate nitrate concentrations were predicted to occur within the Los Angeles basin, especially during the fall season, due to an increase in the NO2/NOx emission fraction and reduced total NOx emissions
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Effects of Retrofitting Emission Control Systems on In-Use Heavy Diesel Vehicles
Diesel engines are now the largest source of nitrogen oxides (NOx) and fine particulate black carbon (soot) emissions in California. The California Air Resources Board recently adopted a rule requiring that by 2014 all in-use heavy trucks and buses meet current (2007) exhaust particulate matter (PM) emission standards. Also by 2023 all in-use heavy-duty vehicles will have to meet current NOx emission standards, with significant progress in achieving the requirements for NOx control expected by 2014. This will require retrofit or replacement of older in-use engines. Diesel particle filters (DPF) reduce PM emissions but may increase the NO2/NOx emission ratio to ∼35%, compared to ∼5% typical of diesel engines without particle filters. Additionally, DPF with high oxidative capacity reduce CO and hydrocarbon emissions. We evaluate the effects of retrofitting trucks with DPF on air quality in southern California, using an Eulerian photochemical air quality model. Compared to a 2014 reference scenario without the retrofit program, black carbon concentrations decreased by 12 ( 2% and 14 ( 2% during summer and fall, respectively, with corresponding increases in ambient ozone concentrations of 3 ( 2% and 7 ( 3%. NO2 concentrations decreased by 2-4% overall despite the increase in primary NO2 emissions because total NOx emissions were reduced as part of the program to retrofit NOx control systems on in-use engines. However, in some cases NO2 concentrations may increase at locations with high diesel truck traffic
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Effects of Retrofitting Emission Control Systems on In-Use Heavy Diesel Vehicles
Diesel engines are now the largest source of nitrogen oxides (NOx) and fine particulate black carbon (soot) emissions in California. The California Air Resources Board recently adopted a rule requiring that by 2014 all in-use heavy trucks and buses meet current (2007) exhaust particulate matter (PM) emission standards. Also by 2023 all in-use heavy-duty vehicles will have to meet current NOx emission standards, with significant progress in achieving the requirements for NOx control expected by 2014. This will require retrofit or replacement of older in-use engines. Diesel particle filters (DPF) reduce PM emissions but may increase the NO2/NOx emission ratio to ∼35%, compared to ∼5% typical of diesel engines without particle filters. Additionally, DPF with high oxidative capacity reduce CO and hydrocarbon emissions. We evaluate the effects of retrofitting trucks with DPF on air quality in southern California, using an Eulerian photochemical air quality model. Compared to a 2014 reference scenario without the retrofit program, black carbon concentrations decreased by 12 ( 2% and 14 ( 2% during summer and fall, respectively, with corresponding increases in ambient ozone concentrations of 3 ( 2% and 7 ( 3%. NO2 concentrations decreased by 2-4% overall despite the increase in primary NO2 emissions because total NOx emissions were reduced as part of the program to retrofit NOx control systems on in-use engines. However, in some cases NO2 concentrations may increase at locations with high diesel truck traffic
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