Kevin J. Kircher

@kevinjkircher.com

22418 Followers 3820 Following

Engineering prof (mechanical + electrical) at a big Midwest state school. Energy, climate, buildings, power grid, control, optimization, data science. He/him. Personal account. https://kevinjkircher.com/ Email: my last name at purdue dot edu

From the linked EIA report: Table 1. Total U.S. energy-related carbon dioxide emissions by sector, 2021–2025 Rows show energy-related greenhouse gas emissions, in units of million tonnes of CO2, from the residential, commercial, industrial, transport, and electricity sectors. The 2024/2025 numbers for the sectors were 304/331, 239/256, 955/960, 1863/1871, and 1427/1482, respectively. Total energy-related CO2 emissions rose from 4789 to 4904, a 2.5% year-over-year increase.
Graph from the linked paper: US GHG emissions from 1990 to 2022 with EPA methane accounting and with adjusted methane accounting to reflect a large body of independent peer-reviewed measuring far higher methane emissions than EPA estimates. Using methane's 100-year GWP, US economy-wide emissions are about as high now as they have ever been. Using the 20-year GWP, emissions are 20% higher than EPA's estimated 6.6 Gt/a 2005 peak.
Graph of Texas economy-wide greenhouse gas emissions from 1990 to 2022, in units of Mt CO2e. Emissions start around 724 Mt in 1990 and end at 846 Mt in 2022, 17% higher.
Bar graph from the paper, showing net annual electricity costs at the test house. Conventional AC configuration: $367.4. Non-ideal DC retrofit configuration: $321.6. Ideal DC configuration: $306.2.
Graph from the paper showing monthly energy bills with a one-to-one net metering scheme. Bills are positive in winter (meaning the residents pay the utility) and negative in summer (meaning the utility effectively pays the residents through credits against future winter bills). In winter, bills are highest in the conventional AC configuration, lowest in the ideal DC configuration, and nearly as low in the non-ideal DC retrofit configuration. Similarly, credits from the utility to the house are lowest on AC and highest on ideal DC.
Schematic from the paper, showing solar panels, a stationary battery, a heat pump, and the rest of the house. The solar, battery, and heat pump connect along a shared DC bus. The AC distribution system serving the rest of the house connects to the DC bus through a bidirectional inverter.
Schematic from the paper, showing three residential power distribution system configurations that connect solar panels, a battery, and a heat pump. Left: In a conventional AC system, the DC power from the solar panels is inverted to AC, the rectified back to DC either to charge a battery or power the heat pump's motor. The variable-speed heat pump motor rectifies the AC then inverts the resulting DC back to AC at a given frequency to drive the heat pump compressor at a desired speed. Center: In the system we implemented in our test house, the DC solar power passes through a higher-efficiency DC/DC converter that implements Maximum Power-Point Tracking, then through another DC/DC converter that controls battery charging or an inverter that drives the heat pump's variable-speed AC motor. Right: An ideal DC configuration includes a heat pump designed to run natively on DC. The only converters in this configuration are the DC/DC converters that control the solar power output (MPPT) and the battery charging.
Screenshot from the article, quoting the following text: Pacala rejected the concern that BP’s influence on their thinking might be subtle, stating that people who are subconsciously influenced in this way have “weak character.” In fact, decades of peer-reviewed research has found that, across fields of study, industry funding tends to bias researchers whether they are aware of it or not, affecting what people choose to study and what they find. Industry-funded studies of food or drugs are more likely to conclude they are safe. In medical settings even a small gift from a drug company — like a box of doughnuts — can lead doctors to prescribe its brands more often. One of the few studies to look at the impact of oil and gas funding in academia found that reports out of fossil-fuel-funded research centers describe natural gas more favorably than renewables, whereas reports from centers less reliant on that funding do not. The influence of this funding, according to a working paper from Harvard researchers, is not always visible to those swayed by it. “It’s the whole subconscious bias problem,” said Harvard historian of science and corporate influence expert Naomi Oreskes. If “continued funding relies on having this good relationship and having this alignment, you are going to be influenced by it.”
Photo of a big (for small-city Indiana) seven-story apartment building next to a wide road with fast, heavy traffic.
Article quote: "At a time when resistance to AI data centers and economic populism are powering politics, Abundance Network is telling its donors that they can rebuild the Democratic Party in a more billionaire-positive vision. Despite calling the movement “democratic” and repeatedly talking about the need for “bottom-up” organizing, what Rosen and company clearly want is a political infrastructure that reorients politics away from anger at economic elites. Despite reassurances otherwise, abundance certainly appears to be an attempt to steer Democrats away from class war and toward renewing the party’s vows in its increasingly unhappy marriage between the party and the tech sector."
Graph of US net annual greenhouse gas emissions, in units of Gt CO2e, from 1990 to 2022. Adjusted for methane pollution from oil and gas infrastructure, US emissions (solid red curve) are basically flat: 6.6 Gt in 2025, 6.3 Gt in 2022. Relative to 1990 levels - the benchmark many other countries chose for emission reduction targets - US 2022 emissions were *up* 13% from the 1990 value of 5.6 Gt. Nibbling around the edges will not get US pollution to zero anytime soon. Bigger action needed.
Meme of a guy going "noooo" to "write a 1,000-word pre-proposal," then going "yessss" to "write 10,000 shitposts"
Graph of expected US liquified natural gas export capacity from 2026 through 2031. Export capacity is about 18.4 billion cubic feet per day today, but (if all plants that are permitted or under construction come online as expected) will rise 88% to 34.5 billion cubic feet per day by 2031.
Plot of US wholesale natural gas price (Henry Hub) over the last year. The price stays fairly stable around $3-5 per million Btu from May 2025 through January 2026, when it briefly spikes by a factor of 10 due to Winter Storm Fern. After the storm, prices return to their pre-storm levels and stay fairly flat through May 2026.
Graph of the US average gasoline price over the last year. Gasoline prices are fairly stable around $3.25 per gallon from May 2025 through February 2026, but spike around March 1, when the Iran war began, and continue rising to $4.63 per gallon today - 42% higher than they were this time last year.
Block diagram showing 1 unit of electricity flowing from the power grid to the heat pump, 2 units of heat flowing from the outdoors to the heat pump, 3 units of heat from the heat pump to the indoors, and 3 units of heat from the indoors back to the outdoors. The outdoors -> heat pump -> indoors -> outdoors flows form a circular pattern of heat recycling.
Graph of the US average retail heating oil price vs. time, from May 2025 to March 2026 (the most recent data available). Prices spike immediately after Trump bombs Iran on 2/28/26. March '26 prices are 61% higher than May '25 prices.
Graph of the electricity CO2 intensity vs. time, in grams per kWh, in California and Texas from 1990 to 2024. Texas CO2 intensity decreases gradually from 1990 to 2024. The decrease accelerates slightly around 2015. In 2024, Texas electricity was about as dirty as a grid powered entirely from natural gas combined cycle (about 385 g/kWh).
Graph of annual electricity sector CO2 emissions vs. time, from 1990 to 2024, for California and Texas. The Texas curve is about five times higher than the California curve. The texas curve increases a bit from 1990 to 2000, is pretty steady from 2000 to 2015, then decreases a bit from 2015 to 2024. The California curve also decreases a bit from 2015 to 2024.
Closing paragraph of a blog post (https://www.theclimatebrink.com/p/using-a-20-year-period-for-comparing): "But the simplest approach – and one increasingly espoused by the climate science community – is to avoid conversions altogether by setting separate targets for CO2 and short-lived climate pollutants like methane. Rather than having a goal of reducing the (not-physically-meaningful) “CO2e” emissions 40% by 2030, set separate goals for both CO2 and methane. That way we know what we are getting, and we don’t create the problem of having to trade off between the two."
photo of a bend in the Wabash river, trees budding, morning light
Plot of New York heating oil, kerosene, and propane prices vs. time over the last year. Prices were fairly stable until last month, when they skyrocketed due to the Iran war.
Graph of US net greenhouse gas emissions over time, in units of gigatonnes per year of CO2 equivalent. A black curve shows the EPA's estimates of US emissions. A solid red curve shows my adjusted estimates, which use CH4 emission rates from oil and gas infrastructure that are consistent with the current scientific evidence. The solid red curve converts CH4 emissions to CO2e emissions using a 100-year horizon. A dashed red curve uses the updated CH4 emission rates and a 20-year horizon. The black curve (EPA estimate) ends at 5.5 Gt/a in 2022, 17% below the EPA's estimate of US peak emissions in 2005, 6.6 Gt/a. The solid red curve ends at 6.3 Gt/a in 2022, 4% below the 2005 EPA estimate. The dashed red curve ends at 7.9 Gt/a, 20% above the 2005 EPA estimate.
Abstract The Biden Administration enacted the largest federal policy framework to incentivize clean energy and decarbonization in U.S. history. We examine whether Biden-era green investments produced political returns by affecting public opinion. Using geolocated survey data linked to investment records and a database of company and politician statements, we assess project visibility and credit attribution. People closer to new renewable energy and green manufacturing facilities are more likely to notice these investments but are not more likely to credit the Biden Administration. Instead, the public sees governors as most responsible. This credit allocation pattern aligns with the political message environment: Governors more frequently claim credit than the White House and companies spread recognition broadly across political actors. This fragmented information environment illustrates the limits of using less traceable forms of green spending to generate electoral gains and public support for climate policy.
Graph of the percent of Americans who favor more solar power vs. time, from 2020 to 2025. Dem/lean Dem: 94 -> 91%. Rep/lean Rep: 84 -> 61%. All adults: 90 -> 77%.
Side by side graphs of retail residential electricity prices vs. time for 3 big investor-owned utilities (left) and 2 big municipal utilities (right). The IOU prices rise from 10-15 c/kWh in 2010 to 30-40 c/kWh in 2024. The municipal prices stay nearly flat, ending at 11-18 c/kWh in 2024.
pic of a white-butt eagle with an accurately white butt
Graph of TAE's claimed target year of commercial power production vs. the year in which they made the claim. Their target years evolve steadily and have consistently been 5-10 years away since at least 2010.
A US map with a 950-mile-radius circle centered on Kansas City. The circle roughly includes the points that are faster to reach by high-speed train than by flying. It extends from Mexico to Canada and from New York to Phoenix.
Screenshot of a spreadsheet showing the data from the top post
Screenshot of a spreadsheet that shows the data reported in the post.
Ember's modified Sankey diagram showing global energy flows. Starts at left with useful energy, broken roughly 50/50 into work and heat, with wasted energy roughly double total useful energy. In the middle is final energy, broken into electrons and molecules, with about half of the energy content in molecules being wasted. At the right is primary energy, divided into electricity sources and thermal sources. About half of thermal sources go straight to waste heat in the production of molecules or electricity.
Flyer for the LightsUp conference showing photos of students working on a range of renewable energy projects
graph of US oil and gas exports by year. both are low until 2010-15, when they sharply increase and keep on increasing
Flyer - CAUSES AND RESPONSES TO EXTREME WINTER WEATHER February 18, 1-2 PM (EST) Recent winter extremes have raised new questions about how a warming Arctic may be reshaping weather far beyond the polar regions. Hosted by URI's Metcalf Institute and Solutions Journalism Network, this training for journalists explores the links between Arctic ice loss, polar vortex disruptions, and the growing frequency of severe winter weather across the Northern Hemisphere, as well as solutions that show how communities are adapting to these emerging risks.
Graph of Human Develppment Index, a UN metric that combines per-capita GDP, education, and health, vs. annual energy use per person. Each dot is a country. HDI increases with energy use to a point, then saturates. The US is twice as far to the right on energy use per person as the "kink point" where energy use stops influencing HDI. The UK and Switzerland are near the kink point, using about half the per-capita energy of the US, but have better health and education outcomes.
Title: (Almost) all energy on earth is solar energy hydro ←solar (via the water cycle) wind ←solar (via hot air rising) biomass ←solar (via photosynthesis) fossil fuels ←biomass (via rotting underground) ←solar but nuclear x←solar geothermal ←nuclear (via reactions underground) and solar ←nuclear so really, all (?) energy on earth is nuclear energy
a photo of a heating element (a hunk of metal that works as an electric heater in all weather and never has frost buildup because it has no outdoor parts)
Spreadsheet showing US 2025 net worth distribution. The richest 0.1% have $178 million per household. The next richest 0.9% have $25 million per household. The next richest 9% have $5.1 million per household. The next richest 40% have $937k per household. The bottom 50% have $63.4k per household.
Chart showing how far data centers are from urban areas, compared to factories, power plants, steel plants, coal mines, and mineral mines. Data centers are usually within 6-12 miles (10-20 km) of an urban area, much closer than the other stuff.
Heat map of annual excess deaths per 100k people per year from illnesses rellated to fine particulates and ozone. The map is darkest (worst impacts) in Asia, North and Central Africa, and South and Central America.
Photo of an eagle perched on a branch overlooking the Wabash river
Bar graph from the World Inequality Report 2026 showing share of global annual greenhouse gas emissions by economic group. The bottom 10% by wealth emit 10% or 3% if emissions are allocated based on consumption or on ownership. Middle 40%: 43% or 20%. Top 10%: 47% or 77%. Top 1% (a subset of top 10%): 15% or 41%.
picture of a squid whose face tentacles look like ketan's graph, kind of
Share of human wealth held by the richest 1%, by year from 2000 to 2050. From 2000 to 2025, the curve fluctuates around 35-40%, hitting 38.4% in 2025. Under Scenario 1, "The richest 1% of the world population finance and own all climate investments," their share of human wealth grows to 45.9%. Under Scenario 2, "The richest 1% finance all climate investments via a wealth tax," their share drops to 25.5%.
Graph of US oil and gas exports vs. time. Exports ramp up dramatically for both oil and gas starting in the late Obama years.
Graph of 2023 per-capita energy-related CO2e emissions vs. 2020 rural percent of state population, showing a significant upward trend.
photo of a snowy railroad bridge running between fall-covered trees and over a river
Bar graph of cumulative historical emissions by country from fossil fuels, cement, land use and forestry. The US is the world's worst cumulative climate polluter at just over 500 billion tonnes of CO2, with China a distant second at about 280 billion tonnes. Russia, Brazil, Indonesia, India, the UK, Japan, and Canada follow.
Schematic of the system: Prediction and decision software runs on an edge computer, which pulls data from the cloud and pushes control actions to the water heater.
Schematic showing a traditional electric resistance water heater with two heating elements, a hybrid HPWH with both a heat pump and heating elements, and a heat-pump-only water heater that has the heat pump but no resistance heating elements.
Paper front matter. Title: Model predictive control lowers barriers to adoption of heat-pump water heaters: A field study Abstract: Electric heat-pump water heaters (HPWHs) could reduce the energy costs, emissions, and power grid impacts associated with water heating, the second-largest energy use in United States housing. However, most HPWHs today require 240 V circuits to power the backup resistance heating elements they use to maintain comfort during large water draws. Installing a 240 V circuit can increase the up-front cost of a HPWH by half or more. This paper develops and field-tests the first control system that enables a 120 V HPWH to efficiently maintain comfort without resistance heating elements. The novel model predictive control (MPC) system enables pre-heating in anticipation of large water draws, which it forecasts using an ensemble of machine learning predictors. By shifting electrical load over time, MPC also reduces energy costs on average by 23% and 28% under time-of-use pricing and hourly pricing, respectively, relative to a 240 V HPWH with standard controls. Compared to the increasingly common practice in 120 V HPWHs of storing water at a constant, high temperature (60 °C) to ensure comfort, MPC saves 37% energy on average. In addition to demonstrating MPC’s benefits in a real, occupied house, this paper discusses implementation challenges and costs. A simple payback analysis suggests that a 120 V HPWH, operated by the MPC system developed here, would be economically attractive in most installation scenarios.
6 year old's marker-on-paper portrait including peanut ears and eyes with red pupils and jet-black whites
The history of billion-dollar disasters in the United States each year from 1980 to 2025, showing event type (colors), frequency (left-hand vertical axis), and cost (right-hand vertical axis) adjusted for inflation to 2025 dollars. The number and cost of disasters per year rise steadily from 2000 to today, with some noise.
photo showing half a dozen cranes over big apartment construction projects
Scatter plot of state-average retail price vs. wind+solar share. There's a slight downward trend, with states with very high shares having the lowest prices, but among states with less than 30% share there's no clear trend.
Bar chart showing investor-owned utility expenditure changes from 2019-2024 for generation, transmission, and distribution.
Histograms illustrating 2023 prices and 2019-2023 price increases for investor-owned utilities, municipal utilities, and rural co-operatives.
Bar graph of retail electricity prices and 2019-2024 price increases for the residential, commercial and industrial sectors.
Infographic: last year, 34% of households reduced or forewent basic necessities like food or medicine to pay an energy bill. 22% kept their home at a temperature that felt unsafe or unhealthy. 24% were unable to pay an energy bill in full. 13% (about 1 in 8) of households were behind on electricity bills. 2.7 million households suffered electricity shutoffs. 73% of households are very or somewhat concerned that electricity and/or gas bills will increase this year