Climate Policy

Impacts of wind power on air quality, premature mortality, and exposure disparities in the US

Abstract: Understanding impacts of renewable energy on air quality and associated human exposures is essential for informing future policy. We estimate the impacts of US wind power on air quality and pollution exposure disparities using hourly data from 2011-2017 and detailed atmospheric chemistry modeling.

Wind power associated with Renewable Portfolio Standards (RPS) in 2014 resulted in $2.0 billion in health benefits from improved air quality. 29% and 32% of these health benefits accrued to  racial/ethnic minority and low income populations respectively, below a 2021 target by the Biden administration that 40% of overall benefits of future federal investments flow to disadvantaged communities. Wind power worsened exposure disparities among racial and income groups in some states, but improved them in others.

Health benefits could be up to $8.4 billion if displacement of fossil fuel generators prioritized those with higher health damages. However, strategies that maximize total health benefits would not mitigate pollution disparities, suggesting more targeted measures are needed.

We will assess the threshold cost and performance parameters that fusion technology must deliver to become a substantial contributor to decarbonization at the global scale. This project will determine the parameters for fusion viability and identify which of these parameters are most important for the successful deployment of fusion energy at scale. Even if fusion power is available for deployment in all countries, the expectation is that deployment will be heterogenous due to the availability of other low-carbon energy resources, population density, grid infrastructure, etc.

Global Outlook for Fusion Energy Deployment

The preeminent conference for the advancement of Earth and space sciences, the AGU (American Geophysical Union) Fall Meeting draws more than 25,000 attendees from over 100 countries each year to share research findings and identify innovative solutions to complex problems. Organized around the theme “Science Leads the Future,” this year’s AGU Fall Meeting will take place in Chicago and online on December 12 - 16.

AGU Fall Meeting frames science as engine of a better future
Climate Extremes and the Future of the Power Sector in the U.S. Heartland: A Multi-Sector Dynamics Perspective

Abstract: A wide range of electric generation technologies can play a major role in future power production in the heartland of the U.S. for consumption. Different generation technologies have different vulnerabilities to a changing climate and its extremes. The cooling cycle of thermal power plants are vulnerable to rising summer temperatures that increase cooling water temperatures and subsequently add cost and possible curtailments. Drought could limit hydropower availability and further limit thermoelectric cooling. Photovoltaics are less efficient in higher temperatures, and wind resources may change or shift with the changing climate. Rising temperatures are also likely to increase summer peak demands as a result of more intense and broad use of air conditioning, even in currently cooler climates. In addition, high temperatures and high demand pose risks for failure of critical grid infrastructure, such as large power transformers. This combination of stressors raises important research questions: What is the risk of a “perfect storm” that could lead to a tipping point failure of the power system? Are some evolutions of the power sector more or less vulnerable to climate change?

As a preliminary investigation, we review existing word in the area and consider a range of realistic power generation scenarios in the US Heartland (Figure 1). We evaluate the sensitivities of various technologies and demand to climate change and associated extremes, and consider the possible range of changes in their production. We then examine the possible effects on the evolution of the power sector by mid-century in various scenarios, taking a Multi-Sectoral Dynamics perspective by focusing on the interaction of sectors (different supply technologies and different demand sectors) and the effects of multiple stressors (both gradual climate change and changes in extreme events) on the systems. Preliminarily, summer months are a more likely period for a potential “perfect storm,” where a combination of extreme heat, drought, and stagnant meteorological conditions could have significant negative effects on all technologies, while increasing peak power demands across the region. Our results are expected to help develop a research agenda to better resolve future vulnerabilities and suggest strategies to increase power sector resilience.

Exploring Injection Locations for Stratospheric Aerosol Geoengineering to Maximize Particle Lifetime in the Stratosphere

Abstract: Stratospheric Aerosol Injection (SAI) aims to mitigate climate change by releasing aerosols into the stratosphere to reflect incoming shortwave radiation. The radiative efficiency of SAI (i.e., the ratio of injected mass flux to radiative forcing) depends strongly on the stratospheric lifetime of injected particles. In this study, we use a Lagrangian trajectory model (LAGRANTO), modified to account for sedimentation, to analyze the sensitivity of particle lifetime to injection locations.

For the first time, we find that choosing injection longitude could notably increase particle lifetime in the stratosphere, especially for injections below 20 km. For example, the particles injected over the Indian Ocean (60° E to 105° E) in winter have a mean lifetime of 1.33 years, which is 23% larger than particles injected at the same altitude and latitude range (18 km, 10° S to 10° N) over the East Pacific (75° W to 120° W).

We explore four injection strategies to maximize particle lifetime in the stratosphere by selecting injection locations. Selecting injection latitude and longitude can help to achieve a lower injection altitude (more than 1 km lower) without sacrificing lifetime. For example, a uniform injection in the tropical area at 20 km has a mean particle lifetime of 2.0 years, we can select the injection latitude and longitude to lower the injection altitude by 1.5 km (at 18.5 km) to achieve a similar mean lifetime (i.e., 2.0 years). Because maximizing particle lifetime by selecting injection location will increase the interhemispheric imbalance, we designed an injection strategy that can maximize the particle lifetime in the stratosphere subjecting to the interhemispheric balance constraint.

Our results complement SAI studies with GCMs to inform future injection strategy design. The modified LAGRANTO model uses 3-hourly ERA5 data as input, which provides a better estimate of stratospheric transport than GCMs. But the LAGRANTO model cannot model aerosol dynamics nor the response of the climate to SAI.

Large Mitigation Potential of Smoke PM2.5 in the US from Human-Ignited Wildfires and Agricultural Fires

Abstract: Increasing fire activity and the associated degradation in air quality in the United States has been indirectly linked to human activity via climate change. In addition, the direct attribution of fires to human or natural causes provides potential for near term smoke mitigation. We quantify the contribution of agricultural fires and human ignited wildfires to smoke emissions in the United States using the GFED4s inventory combined with the US Forest Service Fire Program Analysis-Fire Occurrence Database. We use the GEOS-Chem model to simulate how fires driven by these two human levers impact fire particulate matter under 2.5 microns (PM2.5) concentrations in the contiguous United States (CONUS) from 2003 to 2018. We find that these human-driven fires dominate fire PM2.5 in both a high fire and human ignition year (2018) and low fire and human ignition year (2003). Across CONUS, human drivers of fire account for more than 80% of the population-weighted exposure and premature deaths associated with fire PM2.5. These findings indicate that a large portion of the smoke exposure and impacts in CONUS are driven by human activities with large mitigation potential that could be the focus of future management choices and policymaking.

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