arXiv subjects

Nicholas Balasus

Publications and source records attributed to Nicholas Balasus.

5 recordsLinked to original sources

arXiv2026

Quantifying AI data center nitrogen oxide (NO$_x$) emissions from space

AI data center power demand is spurring rapid deployment of on- and near-site natural gas turbines. Nitrogen oxide (NO$_x$) pollution from this equipment is a growing concern but has not previously been quantified with atmospheric observations. Here we demonstrate space-based detection and quantification of NO$_x$ emissions from the SpaceXAI Colossus 2 power plant in Southaven, Mississippi. Using observations from the geostationary TEMPO satellite instrument, we detect a strong increase in local mean NO$_2$ column concentrations after the plant began operations in late 2025. We then use TEMPO to estimate two-week-average NO$_x$ source rates from August 2025 to mid-August 2026, calibrating against continuous emission monitoring system (CEMS) data from US power plants. TEMPO first detected NO$_x$ emissions in December 2025 at 460$\pm$180 kg h$^{-1}$. We find that emissions increased through August 2026, averaging 730$\pm$185 kg h$^{-1}$ after February 2026, roughly 16 times higher than expected from the facility's March 2026 permit for 41 turbines operating under best available control technology (BACT) requirements ($\sim$47 kg h$^{-1}$). Emissions at the expected level would be undetectable by our TEMPO analysis.

physics.ao-ph↗

arXiv2026

Mapping ammonia emission plumes using shortwave infrared imaging spectroscopy

Atmospheric ammonia emissions are harmful to ecosystems and human health. These emissions have traditionally been monitored using thermal infrared spectrometers, though such techniques are limited by thermal contrast requirements, the coarse spatial resolution of existing satellite sensors, and low measurement frequency of higher-resolution aerial surveys. Here, we show that ammonia emissions can be quantified using shortwave infrared imaging spectroscopy, circumventing these challenges by using reflected sunlight instead of thermal emission for signal and by enabling a large class of existing and future imaging spectrometers to enter the ammonia observing system. As a proof of concept for this newly discovered capability, we use Tanager-1 satellite data to quantify emissions from industrial point sources of ammonia in Pakistan and Uzbekistan.

physics.ao-ph↗

arXiv2025

Quantifying urban and landfill methane emissions in the United States using TROPOMI satellite data

Urban areas are major sources of methane due to population needs for landfills, natural gas distribution, wastewater treatment, and residential combustion. Here we apply an inversion of TROPOMI satellite observations of atmospheric methane to quantify and attribute annual methane emissions at 12x12 km2 resolution for 12 major US urban areas in 2022. The US Environmental Protection Agency Greenhouse Gas Inventory (EPA GHGI) is used as prior estimate. Our results indicate that the GHGI underestimates methane emissions by 80% on average for the 12 urban areas, with 22%-290% underestimations in most urban areas, except Los Angeles and Cincinnati where emissions are overestimated by 32%-37%. This is corroborated by independent surface-based observations in the Northeast Corridor and Los Angeles. Landfills are the principal cause of urban emission underestimates, with downstream gas activities contributing to a lesser extent than previously found. Examination of individual landfills other than in Los Angeles shows that emissions reported by facilities with gas collection and control systems to the Greenhouse Gas Reporting Program (GHGRP) and used in the GHGI are too low by a factor of 4 when using the prevailing recovery-first reporting method. This is because GHGRP-estimated gas collection efficiencies (average 70%, range 40-87%) are much higher than inferred from our work (average 38%, range 5-90%). Los Angeles landfills have much higher collection efficiencies (average 78% in GHGRP; 85% in our work) than elsewhere in the US, suggesting that operational practices there could help inform methane mitigation in other urban areas.

physics.ao-ph↗

arXiv2024

Satellite monitoring of annual US landfill methane emissions and trends

We use satellite observations of atmospheric methane from the TROPOMI instrument to estimate total annual methane emissions for 2019-2023 from four large Southeast US landfills with gas collection and control systems. The emissions are on average 6$\times$ higher than the values reported by the landfills to the US Greenhouse Gas Reporting Program (GHGRP) which are used by the US Environmental Protection Agency (EPA) for its national Greenhouse Gas Inventory (GHGI). We find increasing emissions over the 2019-2023 period whereas the GHGRP reports a decrease. The GHGRP requires gas-collecting landfills to estimate their annual emissions either with a recovery-first model (estimating emissions as a function of methane recovered) or a generation-first model (estimating emissions from a first-order-decay applied to waste-in-place). All four landfills choose to use the recovery-first model, which yields emissions that are one-quarter of those from the generation-first model and decreasing over 2019-2023, in contrast with the TROPOMI observations. Our TROPOMI estimates for two of the landfills agree with the generation-first model, with increasing emissions over 2019-2023 due to increasing waste-in-place or decreasing methane recovery, and are still higher than the generation-first model for the other two landfills. Further examination of the GHGRP emissions from all reporting landfills in the US shows that the 19% decrease in landfill emissions reported by the GHGI over 2005-2022 reflects an increasing preference for the recovery-first model by the reporting landfills, rather than an actual emission decrease. The generation-first model would imply an increase in landfill emissions over 2013-2022, and this is more consistent with atmospheric observations.

physics.ao-ph↗

arXiv2023

African rice cultivation linked to rising methane

Africa has been identified as a major driver of the current rise in atmospheric methane, and this has been attributed to emissions from wetlands and livestock. Here we show that rapidly increasing rice cultivation is another important source, and estimate that it accounts for 7% of the current global rise in methane emissions. Continued rice expansion to feed a rapidly growing population should be considered in climate change mitigation goals.

physics.ao-ph↗