Kevin J. Kircher

@kevinjkircher

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

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Kevin J. Kircher@kevinjkircher· 1d

Congress will soon vote on energy permitting. To evaluate the bill's potential impacts, it helps to understand what energy infrastructure people are trying to build. I wrote a bit about what we can learn from the Mid-Atlantic grid's updated interconnection queue: kevinjkircher.com/what-energy-...

Donut chart from https://insidelines.pjm.com/over-700-new-generation-projects-accepted-into-first-cycle-of-reformed-interconnection-process/

The chart shows the breakdown of PJM's 201 GW interconnection queue: 100 GW gas, 60 GW storage, 17 GW nuclear, 12 GW solar, 8 GW solar/storage, 4 GW wind, 1 GW other (biomass, coal, etc.).

Kevin J. Kircher@kevinjkircher· 21d

All US economic sectors emitted more carbon dioxide from energy use in 2025 than in 2024, according the the latest Energy Information Administration report. www.eia.gov/environment/...

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.

Kevin J. Kircher@kevinjkircher· Jul 3

This is EPA data, which undercounts methane emissions from oil and gas and converts CH4 to CO2e using an outdated 100-year GWP of 28. Texas has a LOT of leaky oil and gas wells, pipelines, and other infrastructure, so its true emissions are likely far higher. kevinjkircher.com/wp-content/u...

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.

Kevin J. Kircher@kevinjkircher· Jul 3

Yes, and Texas' electricity is its climate success story, at least relative to other sectors. TX economy-wide emissions are 7% higher than 2005 levels and 17% higher than 1990 levels. Power sector is making some progress, other sectors are not, on balance TX is harming the climate more each year.

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.

Kevin J. Kircher@kevinjkircher· Jun 30

The ideal DC configuration reduced annual net energy bills by 16.7% relative to the AC configuration. The non-ideal DC configuration reduced bills by 12.5%. Those percent savings are pretty good - it's not easy to improve equipment energy efficiency by ~15%! - but the $ savings were only ~$60/yr.

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.

Kevin J. Kircher@kevinjkircher· Jun 30

We modeled real-time performance over a year in NW Indiana, which sees cold winters and hot summers. We modeled net metering, where summer power exports from the house to the grid offset winter power imports (to a degree). Bills were highest (and export credits lowest) in today's AC configuration.

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.

Kevin J. Kircher@kevinjkircher· Jun 30

We then used data from performance testing, as well as solar and load data from our test house, to model different power distribution configurations connecting solar photovoltaics, a stationary battery, and a heat pump (which uses ~70% of our all-electric Indiana test house's annual energy).

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.

Kevin J. Kircher@kevinjkircher· Jun 30

New paper! Housing increasingly has big devices that run natively on Direct Current (solar panels, EVs, batteries, motors on heat pumps and air conditioners, etc). What if we connected them on DC, rather than today's AC distribution + lossy AC/DC conversions? 🧵 www.sciencedirect.com/science/arti...

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.

Kevin J. Kircher@kevinjkircher· Jun 26

The scientists involved are smart people who recognize the risk of oil and gas funders corrupting the research. However, as the Pacala quote below shows, they can also be overconfident in their own ability to resist that corruption. Research has shown that few of us are, in fact, resistant.

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.”

Kevin J. Kircher@kevinjkircher· Jun 23

Dense housing is necessary but insufficient for good neighborhoods. This new apartment building will add a couple hundred beds - great! - but every window overlooks at least 4 lanes of fast traffic, including semis. Noise, air pollution, poor walkability and wheelchairability, poor transit access.

Photo of a big (for small-city Indiana) seven-story apartment building next to a wide road with fast, heavy traffic.

Kevin J. Kircher@kevinjkircher· Jun 13

Hopefully we can all stop talking about abundance now that we know the "movement" has been co-opted by a bunch of Silicon Valley billionaires, crypto bros, and Trump donors, to the tune of at least a quarter-billion per year in funding. prospect.org/2026/06/12/n...

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."

Kevin J. Kircher@kevinjkircher· Jun 10

Keep eyes on prize, m'dudes. Red line basically flat. Red line gotta go to zero.

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.

Kevin J. Kircher@kevinjkircher· May 25

Meme of a guy going "noooo" to "write a 1,000-word pre-proposal," then going "yessss" to "write 10,000 shitposts"

Kevin J. Kircher@kevinjkircher· May 17

None of this is forever. On #1, US LNG export capacity is expected to double in the next five years. On #2, winter is coming, my sweet summer child. On #3, see #1.

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.

Kevin J. Kircher@kevinjkircher· May 17

What's your favorite explanation of why US domestic natural gas prices have stayed fairly stable despite the Iran war, even as gasoline and diesel prices have skyrocketed? (For context, the Iran war shut down about 20% of global oil supply and about 20% of global liquified natural gas supply.)

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.

Kevin J. Kircher@kevinjkircher· May 17

Oil and gas companies have made some $50 billion in windfall profit since Trump started the Iran war. These profits come mainly from higher gasoline and diesel prices most people pay and go mainly to the owners and major shareholders of oil and gas companies, who are already very rich.

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.

Kevin J. Kircher@kevinjkircher· May 15

One cool thing about heat pumps: The heat they provide is at least ~2/3 renewable, regardless of the electricity source. (Note the circular flow between the indoors and outdoors.) If the power source is renewable, then the system operation is 100% renewable, although manufacturing generally is not.

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.

Kevin J. Kircher@kevinjkircher· May 14

5 million households in the Northeast burn heating oil to heat space or water. Due to Trump's Iran war, heating oil prices are up 60% over last year. Risks are high of more severe price spikes this fall/winter. These households should switch to electric heat pumps this summer. States should help.

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.

Kevin J. Kircher@kevinjkircher· May 8

Here is the CO2 emission intensity of electricity in Texas and California, in grams of CO2 per kWh generated. Texas electricity in 2024 was dirtier than California electricity in 1990. Texas electricity in 2024 was, on average, no better than a grid run entirely on natural gas combined cycle plants.

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).

Kevin J. Kircher@kevinjkircher· May 8

In 2024, the Texas electricity sector emitted 5.4 times more climate pollution than the California electricity sector. Per-capita 2024 electricity emissions in TX were 6.7 times higher than in CA. Electricity in Texas is getting better, but it's still godawful. Don't confuse rates with magnitudes.

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.

Kevin J. Kircher@kevinjkircher· Apr 8

Whatever opinions you might have about global warming potentials, I don't think "different mitigation targets for different gases" gets around the basic problem of having to make a value-based judgment on the exchange rate between CO2 and CH4 (or other short-lived greenhouse gases). Quick 🧵 on why.

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."

Kevin J. Kircher@kevinjkircher· Apr 7

Spring on the Wabash. Crisp but sunny walk to work today

photo of a bend in the Wabash river, trees budding, morning light

Kevin J. Kircher@kevinjkircher· Mar 21

One in five households in New York State heats with propane or oil. Those prices are up 30% and 40%, respectively, from this time last year due to Trump's Iran war. At these prices, switching to electric heat pumps could cut heating bills *in half*. www.nyserda.ny.gov/Energy-Price...

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.

Kevin J. Kircher@kevinjkircher· Mar 21

To see the difference between the 20- and 100-year horizons, check out this graph from my 2025 paper. The solid red curve is my estimate of net US greenhouse gas emissions with CH4 from oil and gas systems assessed over 100 years. The dashed red curve uses 20 years: Way higher than the solid red.

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.

Kevin J. Kircher@kevinjkircher· Mar 15

The new paper "Why Biden-era clean energy investment policies had limited political returns" by @agazmararian.bsky.social, @natemjensen.bsky.social and @dustintingley.bsky.social has great data, but it's wild in a paper about messaging and information environments to... www.pnas.org/doi/10.1073/...

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.

Kevin J. Kircher@kevinjkircher· Mar 15

Americans in both parties long viewed solar energy more favorably than any other energy source. Solar favorability among Republicans dropped a lot in recent years, due part to opinion-shaping by right-wing media. Bundling solar with data centers, which are pretty unpopular, probably doesn't help.

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%.

Kevin J. Kircher@kevinjkircher· Mar 13

I knew municipal utilities generally provide lower electricity prices than investor-owned monopoly utilities, but I had no idea the difference was *this stark* in California. No wonder CA electeds are pushing to make municipalization easier and cheaper. energyathaas.wordpress.com/2026/03/09/t...

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.

Kevin J. Kircher@kevinjkircher· Mar 10

Saw 5 bald eagles fishing as I crossed the Wabash on my way to work this morning and look they're not even bald (that's vultures), their main feature is big white butts. Our national bird is the white-butt eagle

pic of a white-butt eagle with an accurately white butt

Kevin J. Kircher@kevinjkircher· Mar 9

"TAE is a very curious fusion company: It has promised that its fusion power plant is just over the horizon for over 25 years." www.fusionconclusion.com/how-taes-fus...

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.

Kevin J. Kircher@kevinjkircher· Mar 4

Assuming a 30-min commute to/from train station, 45-min to/from airport, 30-min early arrival for train and 90-min for plane, 500 mph plane (LAX-JFK is ~450), a 280 mph train is faster than flying any distance less than 950 miles. Here is a 950-mile radius circle centered on Kansas City.