Madalsa Singh

Light-duty transportation continues to be a significant source of air pollutants that cause premature mortality and greenhouse gases that lead to climate change. To reduce the damages from air pollution and climate change, the U.S. light-duty fleet will need to transition to more sustainable transportation strategies. Electric vehicles (EVs) are one of the possible strategies. Internal combustion vehicles that comply with the latest emissions standards (currently, Tier 3 emission standard) are another possible alternative, although their emissions increase with age and mileage. While pollution from ICV occurs at ground level and its effects are largely confined to nearby areas, pollution from EVs occurs at the smokestacks of power plants used to charge the EVs which can spread to longer distances. We estimate and compare the health impacts (and disparities of) the current stock of light-duty vehicles across the United States with a large-scale shift to EVs or Tier-3 ICVs. We couple a fine-scale emissions inventory with a reduced complexity air quality model. We find that either strategy reduces premature mortality by 80-93% compared to today’s light-duty vehicle damages. As the grid decarbonizes, EVs would lead to even larger health benefits from reduced air pollution and greenhouse gas emissions (a benefit not present for ICV). The health and climate mitigation benefits of electrification are larger in the West and Northeast. The Midwest and the South have larger mortality reductions when choosing Tier 3 ICV due to present-day high electricity emission intensity; this aspect too may shift as those regions clean their electric grid emissions. We also focus on the 50 most populous metropolitan areas, and find that in almost all cases electrification leads to lower health damages. Pollution from ICV (current LDV and Tier 3) impacts people of color more than White Americans across all states, levels of urbanization, and household income. Consequently, electrification reduces health disparities more than Tier 3 ICV in most states and MSAs, especially in urban parts of the Western United States. EV impacts are on average more equitable by race-ethnicity but damages from them are geographically concentrated in Ohio Valley, New York, and Pennsylvania; retiring or retrofitting with CCS 50 power plants with high SO2 emissions achieves health benefits parity for EVs and new Tier 3 ICVs in all regions.

Emissions from electric vehicles depend on when they are charged, and which power plants are meeting the electricity demand. We introduce a new metric, the grid emissions factors (CEFs), as the emissions intensity of electricity that needs to be achieved when charging to ensure electric vehicles achieve lifecycle greenhouse gas emissions parity with some of the most efficient gasoline hybrid vehicles across the US. We use a consequential framework, consider 2018 as our reference year, and account for the effects of temperature and drive cycle on vehicle efficiency to account for regional climate and use conditions. We find that the Nissan Leaf and Chevy Bolt battery electric vehicles reduce lifecycle emissions relative to Toyota Prius and Honda Accord gasoline hybrids in most of the United States. However, in rural counties of the Midwest and the South power grid, marginal emissions reductions of up to 208 gCO2/kWh are still needed for these electric vehicles to have lower lifecycle emissions than gasoline hybrids. Except for the Northeast and Florida, the longer-range Tesla Model S battery-electric luxury sedan has higher emissions than the hybrids across the U.S., and the emissions intensity of the grid would need to decrease by up to 342 gCO2/kWh in some locations for it to achieve carbon parity with hybrid gasoline vehicles. Finally, we conclude that coal retirements and stricter standards on fossil fuel generators are more effective in the medium term at reducing consequential electric vehicle emissions than the expansion of renewable capacity.

Census data is crucial to understanding energy and environmental justice outcomes such as poor air quality which disproportionately impacts people of color in the U.S. With the advent of sophisticated personal datasets and analysis, the Census Bureau is considering adding top-down noise (differential privacy) and post-processing 2020 census data to reduce the risk of identification of individual respondents. Using the 2010 demonstration census and pollution data, I find that compared to the original census, the differentially private (DP) census significantly changes ambient pollution exposure in areas with sparse populations. White Americans have the lowest variability, followed by Latinos, Asians, and Black Americans. DP underestimates pollution disparities for SO2 and PM2.5 while overestimates the pollution disparities for PM10.

Ensuring reliable and affordable access to modern energy services, especially for the poorer and deprived section of the population, is a basic requisite for sustainable development. Given that a majority of the energy-deprived population lives in rural regions of developing countries, effective rural electrification is critical for bridging the rural-urban divide. Microgrid electricity systems, especially with hybrid renewable energy resources, can be a good alternative for centralized electricity grid expansion. In this paper, we report the techno-economic feasibility and sustainability analysis of a hybrid solar-biomass system in India. The system consists of 30-kW solar photovoltaic (PV) and 20-kW biomass gasifier modules. Energy demand and resource availability are estimated with inputs from extensive stakeholder discussions and field surveys, and they account for daily and seasonal variations in both supply and end uses and availability and productive hours. The expected temporal electricity demand is estimated for households, communities, irrigation, and commercial needs. Furthermore, opportunities for the development of productive uses and their expansion through a sustainable business model are explored.

California contributes 0.75% of global greenhouse gas (GHG) emissions and has a target of reaching economy-wide net zero emissions by 2045, requiring all sectors to rapidly reduce emissions. Nearly 8% of California's GHG emissions are from the heavy-duty transportation sector. In this work, we simulate decarbonization strategies for the heavy-duty vehicle (HDV) fleet using detailed fleet turnover and air quality models to track the evolution of the fleet, GHG and criteria air pollutant emissions, and resulting air quality and health impacts across sociodemographic groups. We assess the effectiveness of two types of policies: zero-emission vehicle sales mandates and accelerated retirement policies. For policies including early retirements, we estimate the cost of early retirements and the cost-effectiveness of each policy. We find even a policy mandating all HDV sales to be zero-emission vehicles by 2025 would not achieve fleetwide zero emissions by 2045. For California to achieve its goal of carbon neutrality, early retirement policies are needed. We find that a combination of early retirement policies and zero-emission vehicle sales mandates could reduce cumulative CO2 emissions by up to 64%. Furthermore, we find that decarbonization policies will significantly reduce air pollution-related mortality and that Black, Latino, and low-income communities will benefit most. We find that policies targeting long-haul heavy-heavy duty trucks would have the greatest benefits and be most cost-effective.

The design of residential electricity rates varies across the United States. Some utilities charge a fixed charge as well as a volumetric rate, whereas others include only a volumetric rate which can change depending on the time of the day and total electricity consumption. The average values of electricity rates per kWh consumed range from 12.7 to 47.7 cents across the U.S. Other differences across states include subsidies for low-income, real-time prices, time-of-use prices, and special retail rates for distributed energy resources and electric vehicle charging. Despite the varying designs in electricity rates, there are commonalities in the goals of electricity service provision by utilities, such as reliably providing electricity, while recovering generation, transmission, and distribution costs of electricity. In regions where constant volumetric rates are used, these costs are lumped together often failing to reflect the true social marginal costs of electricity. In most regions, utility revenue requirements will likely continue to increase as end-uses electrify and electricity decarbonizes. Progress in rate reform and utility innovation has been slow, with less than 1% of Americans facing an electricity price that varies with time, and the implications of different designs of electricity rate designs for consumers are poorly understood. In this perspective, we discuss the challenges and progress in designing an efficient and equitable retail rate for a decarbonizing grid. Specifically, we delve into two aspects of retail rate design: one, how do we make efficient retail rates – i.e., rates that reflect the varying social marginal cost of electricity, recoup required costs, and enable proper utilization of the grid infrastructure, and second, are current and new retail rates designs equitable, particularly with bill impacts across income and race gradients. Given California’s high and increasing retail rates, high distributed energy generation and EV penetration, and rising utility-related wildfire risk, we also discuss the case of California, using it as a case study with potentially generalizable results across the country

California has ambitious climate goals. The state aims to achieve economy-wide net zero emissions by 2045 and 100% zero-emissions vehicle sales by 2035. Decarbonizing transportation will be vital to achieving climate goals, as the sector is currently the state's largest source of greenhouse gas emissions. In this work, we develop a fleet turnover and retirement model for California’s light-duty vehicle fleet. We simulate fleet characteristics, air emissions, and premature mortality under the following policy scenarios: (i) business-as-usual, (ii) zero-emissions vehicle sales mandates, and (iii) zero-emissions vehicle sales mandates combined with accelerated retirement policies. We test for policy stringency by considering different onset years (2025 to 2040) and vehicle retirement ages (10 and 15). Even with the current policy of selling only zero-emissions vehicles by 2035, 20% of the light-duty fleet in 2045 would still be powered by gasoline. Our work emphasizes the importance of retiring old vehicles. A policy mechanism that retires vehicles older than 15 years starting in 2025 would reduce cumulative CO2 and premature mortality by more than 40 percent compared to business-as-usual between 2019 and 2045. Finally, a policy that provides an incentive of $6,000 for each retired vehicle starting in 2025 is cost-effective.

Electricity affordability is a salient policy concern in California. We compare trends and drivers of increasing utility costs and electricity rates for three types of power providers in California: investor-owned utilities (IOUs), publicly-owned utilities (POUs), and community choice aggregators (CCAs). Since 2019, the IOU and CCA residential baseline electricity rates have increased by 44-80% after accounting for inflation, making them some of the most expensive power providers in the United States. POU prices, on the other hand, have remained constant. We compile long-term trends in California power providers' capital assets, returns, and operation & maintenance expenses to identify sources of increasing utility costs and customer rates. Across IOUs, generation expenses have decreased or remained in historical ranges but transmission and distribution (T&D) expenses have increased. The rise is sharpest for T&D operations and maintenance expenses, which practically remained constant until wildfires occurred due to power lines. CCAs, which procure their electricity but use the IOU T&D network, reach price parity with IOUs because of high T&D costs as well as exit fees levied on them. POUs, which service smaller territories with low wildfire risks, have also increased T&D capital assets and overall operations and maintenance expenses but the increases are modest. We foresee continued price divergence among power providers owing to wildfire mitigation costs, which will have important affordability consequences across the state.

Rooftop solar and storage (distributed electricity generation, DER) can play an important role in enabling decarbonization and improving reliability. Households can consume, store, or send the electricity produced by DER back to the grid. Under net-energy metering policies, households with DER are compensated for the surplus electricity produced at the retail electricity rate. Retail rates typically charge residential users a volumetric rate that covers the bulk of energy, transmission, and distribution costs. The resulting price, charged per unit of electricity, neither reflects the marginal costs of producing the electricity nor does it vary by space and time. Non-time-varying volumetric electricity rates also don’t accurately reflect the true benefits that DERs provide to the electricity grid and have led to interest among policymakers to modernize the electricity rates. Significant concerns about cross-subsidies have also been raised. By realizing significant bill savings under net-energy metering, adopters of DERs effectively shift part of their obligation for the grid operation costs to non-adopters. Hence, the challenge to modernize the electricity rate entails aligning prices to the true cost of generation of electricity; pricing benefits to the true benefits DERs provide; and ensuring that non-adopters, often low-income and/or renters, don’t bear the burdens of cost-shift. In this work, we propose an electricity pricing and household electricity consumption model that tests different electricity rates to enable efficiency and equity for adopters and non-adopters. California, which has one of the highest electricity rates and penetration of DERs in the United States, is used as a case study for demonstration.